Replacing printf, putchar and snprintf in the hot path with custom functions

Replacing snprintf(), localtime() and strftime() with custom formating
functions

Reworking progress_thread(), instead of composing the progress printing
with multiple printf() and putchar, we compose it in a buffer and write
it at onse using WriteConsole in Windows and write in Linux

.gitignore

@@ -3,11 +3,13 @@ file_hasher.ilk
 file_hasher.rdi
 file_hasher.exe
 file_hashes.txt
-Binaries/file_hashes.txt
+/Binaries
 file_list.txt
 temp_code.c
-/.cache/clangd/index
+/.cache
 /file_hasher
 /io_uring_test
 /file_hasher
 /io_uring_test
+/compile_commands.json
+/build

CMakeLists.txt

@@ -0,0 +1,284 @@
+cmake_minimum_required(VERSION 3.20)
+project(dfin
+    VERSION 1.0.0
+    DESCRIPTION "High-performance duplicate finder with I/O Ring/io_uring support"
+    LANGUAGES C
+)
+
+# ---------------------------------------------------------------------------
+# Force compiler search order
+# ---------------------------------------------------------------------------
+
+# On Windows, prefer clang-cl, then GCC, then Clang
+if(WIN32)
+    # Try to force compiler order if not already set
+    if(NOT CMAKE_C_COMPILER)
+        # Search in preferred order
+        find_program(CLANG_CL_COMPILER NAMES clang-cl)
+        find_program(GCC_COMPILER NAMES gcc)
+        find_program(CLANG_COMPILER NAMES clang)
+        
+        if(CLANG_CL_COMPILER)
+            message(STATUS "Found clang-cl as preferred compiler: ${CLANG_CL_COMPILER}")
+            set(CMAKE_C_COMPILER "${CLANG_CL_COMPILER}" CACHE STRING "" FORCE)
+        elseif(GCC_COMPILER)
+            message(STATUS "Found GCC as fallback compiler: ${GCC_COMPILER}")
+            set(CMAKE_C_COMPILER "${GCC_COMPILER}" CACHE STRING "" FORCE)
+        elseif(CLANG_COMPILER)
+            message(STATUS "Found Clang as last-resort compiler: ${CLANG_COMPILER}")
+            set(CMAKE_C_COMPILER "${CLANG_COMPILER}" CACHE STRING "" FORCE)
+        endif()
+    endif()
+else()
+    # On Linux, prefer GCC, then Clang
+    if(NOT CMAKE_C_COMPILER)
+        find_program(GCC_COMPILER NAMES gcc)
+        find_program(CLANG_COMPILER NAMES clang)
+        
+        if(GCC_COMPILER)
+            message(STATUS "Found GCC as preferred compiler: ${GCC_COMPILER}")
+            set(CMAKE_C_COMPILER "${GCC_COMPILER}" CACHE STRING "" FORCE)
+        elseif(CLANG_COMPILER)
+            message(STATUS "Found Clang as fallback compiler: ${CLANG_COMPILER}")
+            set(CMAKE_C_COMPILER "${CLANG_COMPILER}" CACHE STRING "" FORCE)
+        endif()
+    endif()
+endif()
+
+# Now project() will use the compiler we found
+# However, since we needed project() first to get C support,
+# we check what we actually got
+message(STATUS "Using compiler: ${CMAKE_C_COMPILER} (${CMAKE_C_COMPILER_ID})")
+
+# ---------------------------------------------------------------------------
+# Platform and Compiler Detection
+# ---------------------------------------------------------------------------
+
+if(WIN32)
+    set(PLATFORM_WINDOWS TRUE)
+    set(PLATFORM_NAME "Windows")
+else()
+    set(PLATFORM_LINUX TRUE)
+    set(PLATFORM_NAME "Linux")
+endif()
+
+# Compiler type
+if(CMAKE_C_COMPILER_ID STREQUAL "Clang")
+    # Check if it's clang-cl
+    if(CMAKE_C_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC")
+        set(COMPILER_CLANG_CL TRUE)
+        message(STATUS "Detected clang-cl (MSVC-compatible frontend)")
+    else()
+        set(COMPILER_CLANG_GNU TRUE)
+        message(STATUS "Detected Clang (GNU-compatible frontend)")
+    endif()
+elseif(CMAKE_C_COMPILER_ID STREQUAL "GNU")
+    set(COMPILER_GCC TRUE)
+    message(STATUS "Detected GCC")
+elseif(CMAKE_C_COMPILER_ID STREQUAL "MSVC")
+    # We don't want MSVC, but if it's found, warn user
+    message(FATAL_ERROR 
+        "MSVC (cl.exe) detected!\n"
+        "This project requires clang-cl, GCC, or Clang.\n"
+        "Please install one of these compilers or specify manually:\n"
+        "  cmake .. -DCMAKE_C_COMPILER=clang-cl\n"
+        "  cmake .. -DCMAKE_C_COMPILER=gcc\n"
+        "  cmake .. -DCMAKE_C_COMPILER=clang\n"
+    )
+endif()
+
+# ---------------------------------------------------------------------------
+# Build System Selection
+# ---------------------------------------------------------------------------
+
+if(NOT CMAKE_GENERATOR OR CMAKE_GENERATOR STREQUAL "")
+    find_program(NINJA_EXECUTABLE NAMES ninja)
+    if(NINJA_EXECUTABLE)
+        message(STATUS "Using Ninja build system")
+        set(CMAKE_GENERATOR "Ninja")
+    else()
+        message(STATUS "Ninja not found, using default generator: ${CMAKE_GENERATOR}")
+    endif()
+endif()
+
+# ---------------------------------------------------------------------------
+# Source Files
+# ---------------------------------------------------------------------------
+
+set(SOURCES
+    duplicate_finder.c
+    xxhash.c
+    xxh_x86dispatch.c
+)
+
+# Headers for dependency tracking and IDE
+set(HEADERS
+    arena.h
+    base.h
+    xxhash.h
+    mt_mpmc.h
+)
+
+# ---------------------------------------------------------------------------
+# Create Executable
+# ---------------------------------------------------------------------------
+
+add_executable(${PROJECT_NAME}
+    ${SOURCES}
+    ${HEADERS}
+)
+
+# Include directories
+target_include_directories(${PROJECT_NAME} PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}
+)
+
+# ---------------------------------------------------------------------------
+# Compiler Flags - Exact match to your commands
+# ---------------------------------------------------------------------------
+
+if(PLATFORM_WINDOWS)
+    if(COMPILER_CLANG_CL)
+        # === clang-cl flags ===
+        # Release: /O2
+        target_compile_options(${PROJECT_NAME} PRIVATE
+            $<$<CONFIG:Release>:/O2>
+        )
+        # Debug: /Zi /Od
+        target_compile_options(${PROJECT_NAME} PRIVATE
+            $<$<CONFIG:Debug>:/Zi /Od>
+        )
+        # Common warnings
+        target_compile_options(${PROJECT_NAME} PRIVATE /W4)
+        
+    elseif(COMPILER_GCC)
+        # === GCC flags (Windows/MinGW) ===
+        # Release: -O3
+        target_compile_options(${PROJECT_NAME} PRIVATE
+            $<$<CONFIG:Release>:-O3>
+        )
+        # Debug: -g -O0
+        target_compile_options(${PROJECT_NAME} PRIVATE
+            $<$<CONFIG:Debug>:-g -O0>
+        )
+        # Common warnings
+        target_compile_options(${PROJECT_NAME} PRIVATE -Wall -Wextra)
+        
+    elseif(COMPILER_CLANG_GNU)
+        # === Clang flags (Windows, GNU frontend) ===
+        # Release: -O3
+        target_compile_options(${PROJECT_NAME} PRIVATE
+            $<$<CONFIG:Release>:-O3>
+        )
+        # Debug: -g -O0
+        target_compile_options(${PROJECT_NAME} PRIVATE
+            $<$<CONFIG:Debug>:-g -O0>
+        )
+        # Common warnings
+        target_compile_options(${PROJECT_NAME} PRIVATE -Wall -Wextra)
+    endif()
+    
+    # Windows-specific libraries
+    target_link_libraries(${PROJECT_NAME} PRIVATE
+        kernel32
+    )
+    
+    # Windows-specific defines
+    target_compile_definitions(${PROJECT_NAME} PRIVATE
+        WIN32_LEAN_AND_MEAN
+        _WIN32_WINNT=0x0A00  # Windows 10+
+    )
+    
+    # Set output name with .exe
+    set_target_properties(${PROJECT_NAME} PROPERTIES
+        SUFFIX ".exe"
+    )
+    
+elseif(PLATFORM_LINUX)
+    # === Linux GCC/Clang flags ===
+    if(COMPILER_GCC OR COMPILER_CLANG_GNU)
+        # Release: -O3
+        target_compile_options(${PROJECT_NAME} PRIVATE
+            $<$<CONFIG:Release>:-O3>
+        )
+        # Debug: -g -O0
+        target_compile_options(${PROJECT_NAME} PRIVATE
+            $<$<CONFIG:Debug>:-g -O0>
+        )
+        # Common warnings
+        target_compile_options(${PROJECT_NAME} PRIVATE -Wall -Wextra)
+    endif()
+    
+    # Linux-specific libraries
+    find_package(Threads REQUIRED)
+    find_library(LIBURING_LIBRARY NAMES uring)
+    
+    if(LIBURING_LIBRARY)
+        message(STATUS "Found liburing: ${LIBURING_LIBRARY}")
+        target_link_libraries(${PROJECT_NAME} PRIVATE
+            Threads::Threads
+            ${LIBURING_LIBRARY}
+        )
+    else()
+        message(FATAL_ERROR "liburing not found! Install liburing-dev or equivalent")
+    endif()
+    
+    # Linux-specific defines
+    target_compile_definitions(${PROJECT_NAME} PRIVATE
+        _GNU_SOURCE
+    )
+endif()
+
+# ---------------------------------------------------------------------------
+# C Standard
+# ---------------------------------------------------------------------------
+
+set_target_properties(${PROJECT_NAME} PROPERTIES
+    C_STANDARD 11
+    C_STANDARD_REQUIRED ON
+    C_EXTENSIONS OFF
+)
+
+# ---------------------------------------------------------------------------
+# Build Configurations
+# ---------------------------------------------------------------------------
+
+# Set default build type if not specified (matching your Release command)
+if(NOT CMAKE_BUILD_TYPE)
+    set(CMAKE_BUILD_TYPE "Release" CACHE STRING 
+        "Choose the type of build: Release or Debug" FORCE)
+    message(STATUS "No build type specified, defaulting to Release")
+endif()
+
+# ---------------------------------------------------------------------------
+# IDE Support
+# ---------------------------------------------------------------------------
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# ---------------------------------------------------------------------------
+# Info Target
+# ---------------------------------------------------------------------------
+
+add_custom_target(info
+    COMMAND ${CMAKE_COMMAND} -E echo "=== Build Configuration ==="
+    COMMAND ${CMAKE_COMMAND} -E echo "Project: ${PROJECT_NAME}"
+    COMMAND ${CMAKE_COMMAND} -E echo "Compiler: ${CMAKE_C_COMPILER} (${CMAKE_C_COMPILER_ID})"
+    COMMAND ${CMAKE_COMMAND} -E echo "Frontend: $<IF:$<BOOL:${COMPILER_CLANG_CL}>,clang-cl,GNU>"
+    COMMAND ${CMAKE_COMMAND} -E echo "Generator: ${CMAKE_GENERATOR}"
+    COMMAND ${CMAKE_COMMAND} -E echo "Build Type: ${CMAKE_BUILD_TYPE}"
+    COMMAND ${CMAKE_COMMAND} -E echo "Platform: ${PLATFORM_NAME}"
+    COMMAND ${CMAKE_COMMAND} -E echo "============================"
+)
+
+# ---------------------------------------------------------------------------
+# Print final configuration
+# ---------------------------------------------------------------------------
+
+message(STATUS "----------------------------------------")
+message(STATUS "Configuration Summary:")
+message(STATUS "  Compiler: ${CMAKE_C_COMPILER}")
+message(STATUS "  Build Type: ${CMAKE_BUILD_TYPE}")
+message(STATUS "  Generator: ${CMAKE_GENERATOR}")
+message(STATUS "  Platform: ${PLATFORM_NAME}")
+message(STATUS "----------------------------------------")

README.md

@@ -1,7 +1,7 @@
-# filehasher
+# Duplicate Finder
 
 # Presentation  
-Collects some metadata and hashes files. It outputs the path, hash, size, creation and 
+Collects some metadata and hashes files then detects duplicate files and directories. It outputs the path, hash, size, creation and 
 last modification dates and the author in file_hasher.txt.  
 Creation and modification dates and author can be disabled in the config file.  
 
@@ -20,36 +20,80 @@ It is a high performance cross platform Windows and Linux compatible program, it
   * Fallback to buffered I/O if there is errors in the IO Ring path.  
 
 # Building  
-## Windows  
-### Release  
 
-**Note**: Make sur to use UCRT64 environment from MSYS2 instead of the standard MinGW environment. 
+## Windows  
+**Requirements**: Make sur to use UCRT64 environment from MSYS2 instead of the standard MinGW environment. 
 UCRT64 uses the modern Universal C Runtime (ucrtbase.dll), which supports the newest APIs, 
 the standard MSYS2 uses the legacy msvcrt.dll and does not support IO Ring.  
 To install:  
-pacman -S mingw-w64-ucrt-x86_64-gcc  
 pacman -S mingw-w64-ucrt-x86_64-clang  
+or:  
+pacman -S mingw-w64-ucrt-x86_64-gcc  
+
 pacman -Syu  
 And add to path:  
 C:\msys64\ucrt64\bin  
 
-gcc -O3 file_hasher.c xxhash.c xxh_x86dispatch.c -o file_hasher  
+Additionally, to use clang-cl install the latest version of Windows SDK and MSVC, or at least select these in Visual Studio Installer:  
-clang -O3 file_hasher.c xxhash.c xxh_x86dispatch.c -o file_hasher  
+  * MSVC Build tools fo x64/86.  
+  * C++ Build tools core features.  
+  * MSBuild support for LLVM (clang-cl) toolset.  
+  * Windows Universal C runtime.  
+  * Windows Universal CRT SDK.  
+  * Windows 11 SDK.  
+
+And use the MSVC command prompt or run a script to add MSVC environment variables to current session.  
+Ex: for PowerShell Terminal save as .ps1 (not persistent):
+```ps1
+# Add MS visual studio environment variables
+cmd /c '"C:\Program Files (x86)\Microsoft Visual Studio\18\BuildTools\VC\Auxiliary\Build\vcvarsall.bat" x64 && set' |
+ForEach-Object {
+    if ($_ -match "^(.*?)=(.*)$") {
+        Set-Item -Path "Env:$($matches[1])" -Value $matches[2]
+    }
+}
+```
+
+Optional: to use the build system  
+pacman -S mingw-w64-ucrt-x86_64-cmake  
+The build system uses Ninja and fallsback to make, in Windows it prefers clang-cl > gcc > clang, and in Linux gcc > clang.  
+
+### Using a build system  
+| Command | Description|
+| :--- | :--- |
+| ./build.bat | Build Release with best available compiler |
+| ./build.bat Debug | Build Debug |
+| ./build.bat clean | Clean and build Release |
+| ./build.bat Debug clean | Clean and build Debug |
+
+### Release  
+gcc -O3 file_hasher.c xxhash.c xxh_x86dispatch.c -o filehasher  
+clang -O3 file_hasher.c xxhash.c xxh_x86dispatch.c -o filehasher  
 clang-cl /O2 file_hasher.c xxhash.c xxh_x86dispatch.c  
 
 ### Debug  
-gcc -g -O0 file_hasher.c xxhash.c xxh_x86dispatch.c -o file_hasher  
+gcc -g -O0 file_hasher.c xxhash.c xxh_x86dispatch.c -o filehasher  
-clang -g -O0 file_hasher.c xxhash.c xxh_x86dispatch.c -o file_hasher  
+clang -g -O0 file_hasher.c xxhash.c xxh_x86dispatch.c -o filehasher  
 clang-cl /Zi /Od file_hasher.c xxhash.c xxh_x86dispatch.c  
 
 ## Linux  
+**Requirements**: GCC or clang, optional CMake, Ninja or make.
+
+### Using a build system  
+| Command | Description|
+| :--- | :--- |
+| ./build.sh | Build Release with best available compiler |
+| ./build.sh Debug | Build Debug |
+| ./build.sh clean | Clean and build Release |
+| ./build.sh Debug clean | Clean and build Debug |
+
 ### Release  
-gcc -O3 file_hasher.c xxhash.c xxh_x86dispatch.c -pthread -luring -o file_hasher  
+gcc -O3 file_hasher.c xxhash.c xxh_x86dispatch.c -pthread -luring -o filehasher  
-clang -O3 file_hasher.c xxhash.c xxh_x86dispatch.c -pthread -luring -o file_hasher  
+clang -O3 file_hasher.c xxhash.c xxh_x86dispatch.c -pthread -luring -o filehasher  
 
 ### Debug  
-gcc -g -O0 file_hasher.c xxhash.c xxh_x86dispatch.c -pthread -luring -o file_hasher  
+gcc -g -O0 file_hasher.c xxhash.c xxh_x86dispatch.c -pthread -luring -o filehasher  
-clang -g -O0 file_hasher.c xxhash.c xxh_x86dispatch.c -pthread -luring -o file_hasher  
+clang -g -O0 file_hasher.c xxhash.c xxh_x86dispatch.c -pthread -luring -o filehasher  
 
 # Notes about the IO Ring implementations  
 ## IO Ring  
@@ -88,16 +132,18 @@ While both systems share the same core concept, their APIs and management styles
 | **API Call** | `io_uring_register` | `BuildIoRingRegisterFileHandles` |
 | **Registration Method** | Synchronous system call; blocks until the table is set up. | Asynchronous request submitted to the ring like a read/write operation. |
 | **Partial Updates** | Supports `IORING_REGISTER_FILES_UPDATE` to swap specific indices. | No partial updates; a new registration replaces the entire table. |
-| **Memory Mapping** | User must manually `mmap()` queues into their address space. | Kernel handles memory mapping automatically when the ring is created. |
 | **Scope of Operations** | Extremely broad (files, sockets, timers, signals, etc.). | Primarily focused on file storage (read, write, flush). |
 
-### Completion Wait count  
+### Completion Wait count and peek  
 To avoid busy waiting when receiving CQEs, we can use io_uring_submit_and_wait() in Linux by entering a wait count, 
-the threads sleeps until the count of CQEs are received, in windows the wait_count is present in SubmitIoRing() 
+the threads sleep until the count of CQEs are received, in windows the wait_count is present in SubmitIoRing() 
 but is not implemented yet, so we wait with a completion event for a single completion. Another limitation on the completion 
 event is that the kernel will waik up the thread only when receiving the first CQE, after that we need to drain the completion
-queue completely before sleeping again, or we enter an eternal slumber. And my config, each time the thread wakes up 
+queue completely before sleeping again, or we enter an eternal slumber.  
-it receives rarely more than 3 to 5 CQEs and most of the time only one CQE.
+In the other hand, in Linux we can batch pop completions with io_uring_peek_batch_cqe() + io_uring_cq_advance(), 
+in Windows we can only pop one completion at a time with PopIoRingCompletion() (equivalent to io_uring_peek_cqe() + io_uring_cqe_seen()).  
+To simulate the same behavior as the Linux functions we use a double loop, an outer loop to control how much we wait
+and in inner loop to drain all the available completions.
 
 ### Filtering CQEs  
 
@@ -131,12 +177,15 @@ IO Ring implementation.
      "Increase the limit to solve this warning.\n");
 ```
 
-The Memlock limit in Linux restricts the amount of memory a process can
+The Memlock limit in Linux restricts the amount of memory that can be
-"lock" into physical RAM using the mlock() family of system calls. This
+"locked" into physical RAM using the mlock() family of system calls. This
 prevents the operating system from swapping that memory out to disk.  
 And registering buffers will lock the buffers memory so the hardware
 can access it directly without kernel intervention and prevents the kernel from 
-swapping it to the SSD or HDD. Increase the limit to be able to register the buffers.  
+swapping it to the SSD or HDD.  
+This limit does not apply to a single process, but it applies to what all the runnig processes can lock, so in order 
+to be able to register the buffers, we need to set it to unlimited or increase it to at least:  
+  num_hash_threads * NUM_BUFFERS_PER_THREAD * IORING_BUFFER_SIZE + extra memory reserved for other processes.  
 
 #### *Modifying the Limit*  
 The method for changing the memlock limit depends on whether you are
@@ -148,7 +197,7 @@ the /etc/security/limits.conf file. Add the following lines:
 ```conf
  # Example for a specific user (replace 'username'), unlimited or a custom value in KB
  username   soft    memlock    unlimited
- username   hard    memlock    unlimited
+ username   hard    memlock    unlimitedhttps://wiki.postgresql.org/wiki/AIO
 ```
 ```conf
  # Example for all users

arena.c

@@ -83,8 +83,7 @@ u64 arena_pos_from_ptr(mem_arena *arena, void *ptr) {
 
 void *arena_ptr_from_pos(mem_arena *arena, u64 global_pos) {
   ASSERT(arena);
-  ASSERT(global_pos >= 0);
+  if (!arena) {
-  if (!arena || global_pos < 0) {
     return NULL;
   }
 
@@ -197,7 +196,7 @@ mem_arena *arena_create(arena_params *params) { // mk create
       arena->free_list = arena_create(&(arena_params){
           .reserve_size = MiB(1),
           .commit_size = MiB(1),
-          .align = ARENA_ALIGN,
+          .align = ARENA_CACHE_ALIGN,
           .push_size = sizeof(arena_free_node),
           .allow_free_list = false,
           .free_list = NULL,
@@ -488,7 +487,6 @@ void *arena_free(mem_arena **arena_ptr, u8 **ptr, u64 size) { // mk free
      Find owning block
      ------------------------------------------------------------ */
 
-  mem_arena *selected = arena;
   mem_arena *owner = arena_block_from_ptr(arena, *ptr);
   ASSERT(owner);
   if (!owner) {
@@ -500,7 +498,7 @@ void *arena_free(mem_arena **arena_ptr, u8 **ptr, u64 size) { // mk free
      ------------------------------------------------------------ */
 
   u64 global_offset = arena_pos_from_ptr(arena, *ptr);
-  if (global_offset == -1) {
+  if (global_offset == UINT64_MAX) {
     return NULL;
   }
 
@@ -607,9 +605,6 @@ void *arena_swapback_pop(mem_arena **arena_ptr, u64 index) { // mk swapback
     fprintf(stderr, "ERROR: Swapback pop failed, index out of range");
     return NULL;
   }
-  u8 *owner_base = (u8 *)owner + ALIGN_UP_POW2(sizeof(mem_arena), owner->align);
-  u8 *arena_base = (u8 *)arena + ALIGN_UP_POW2(sizeof(mem_arena), arena->align);
-
   u8 *dst = arena_ptr_from_index(arena, index);
   u8 *src = arena_ptr_from_index(arena, count);
 
@@ -625,6 +620,119 @@ void *arena_swapback_pop(mem_arena **arena_ptr, u64 index) { // mk swapback
 /* ============================================================
    Utilities
    ============================================================ */
+typedef enum arena_trim_flags {
+  ARENA_TRIM_NONE = 0,
+
+  ARENA_TRIM_SPACE = 1 << 0,
+  ARENA_TRIM_TAB = 1 << 1,
+  ARENA_TRIM_LF = 1 << 2,
+  ARENA_TRIM_CR = 1 << 3,
+  ARENA_TRIM_NUL = 1 << 4,
+
+} arena_trim_flags;
+
+u64 arena_trim_string(mem_arena **arena_ptr, char *str, u8 termination_flags) {
+  ASSERT(arena_ptr);
+  ASSERT(*arena_ptr);
+  ASSERT(str);
+
+  if (!arena_ptr || !*arena_ptr || !str) {
+    return 0;
+  }
+
+  mem_arena *arena = *arena_ptr;
+
+  /* ------------------------------------------------------------
+     Find owning block
+     ------------------------------------------------------------ */
+
+  mem_arena *owner = arena_block_from_ptr(arena, (u8 *)str);
+
+  ASSERT(owner);
+  if (!owner) {
+    return 0;
+  }
+
+  /* ------------------------------------------------------------
+     Must be current block
+     ------------------------------------------------------------ */
+
+  if (owner != arena) {
+    fprintf(stderr, "arena_trim_string(): string is not "
+                    "in current arena block.\n");
+    return 0;
+  }
+
+  /* ------------------------------------------------------------
+     Compute string position
+     ------------------------------------------------------------ */
+
+  u64 str_pos = arena_pos_from_ptr(arena, str);
+
+  /* ------------------------------------------------------------
+     Original reserved size
+     ------------------------------------------------------------ */
+
+  u64 allocated_size = arena->pos - str_pos;
+
+  /* ------------------------------------------------------------
+     Compute sizes
+     ------------------------------------------------------------ */
+
+  u64 str_size = strlen(str);
+
+  char *dst = str + str_size;
+  u64 termination_size = 0;
+
+  if (termination_flags & ARENA_TRIM_SPACE) {
+    *dst++ = ' ';
+    termination_size++;
+  }
+
+  if (termination_flags & ARENA_TRIM_TAB) {
+    *dst++ = '\t';
+    termination_size++;
+  }
+
+  if (termination_flags & ARENA_TRIM_CR) {
+    *dst++ = '\r';
+    termination_size++;
+  }
+
+  if (termination_flags & ARENA_TRIM_LF) {
+    *dst++ = '\n';
+    termination_size++;
+  }
+
+  if (termination_flags & ARENA_TRIM_NUL) {
+    *dst++ = '\0';
+    termination_size++;
+  }
+  /* ------------------------------------------------------------
+     Final used size
+     ------------------------------------------------------------ */
+
+  u64 used_size = str_size + termination_size;
+
+  used_size = ALIGN_UP_POW2(used_size, arena->align);
+
+  /* ------------------------------------------------------------
+     Overflow detection
+     ------------------------------------------------------------ */
+
+  if (used_size > allocated_size) {
+    fprintf(stderr, "arena_trim_string(): string overflow "
+                    "detected.\n");
+  }
+
+  /* ------------------------------------------------------------
+     Update arena position
+     ------------------------------------------------------------ */
+
+  arena->pos = str_pos + used_size;
+
+  return used_size;
+}
 
 void *arena_clear(mem_arena **arena_ptr) { // mk clear
 
@@ -806,7 +914,7 @@ mem_arena_temp arena_scratch_get(mem_arena **conflicts, u32 num_conflicts) {
     arena_params params = {
         .reserve_size = MiB(64),
         .commit_size = MiB(1),
-        .align = ARENA_ALIGN,
+        .align = ARENA_CACHE_ALIGN,
         .push_size = 8,
         .allow_free_list = false,
         .allow_swapback = true,

arena.h

@@ -239,7 +239,7 @@ void *arena_ptr_from_index(mem_arena *arena, u64 index);
 */
 
 #define ARENA_HEADER_SIZE (sizeof(mem_arena))
-#define ARENA_ALIGN (sizeof(void *))
+#define ARENA_CACHE_ALIGN (sizeof(void *))
 
 // arena config
 typedef enum arena_growth_policy {

base.h

@@ -35,6 +35,7 @@
 #include <sys/stat.h>
 #include <sys/vfs.h>
 #include <unistd.h>
+#include <sys/mman.h>
 #endif
 
 #include <assert.h>
@@ -104,16 +105,16 @@ typedef double f64;
 #define ASSERT(x) assert(x)
 #endif
 
-#define NDEBUG // Comment to enable asserts
+#ifndef NDEBUG
+#define NDEBUG 1 // 0 to enable asserts
+#endif
 
 /* ------------------------------------------------------------
    Some helper functions
    ------------------------------------------------------------ */
 
 #if defined(_WIN32) || defined(_WIN64)
-
 // Memory allocation
-
 static u32 plat_get_pagesize(void) {
   SYSTEM_INFO sysinfo = {0};
   GetSystemInfo(&sysinfo);
@@ -130,58 +131,23 @@ static b32 plat_mem_commit(void *ptr, u64 size) {
   return ret != NULL;
 }
 
-static b32 plat_mem_decommit(void *ptr, u64 size) {
+// static b32 plat_mem_decommit(void *ptr, u64 size) { // Comment to prevent warning: unused function
-  return VirtualFree(ptr, size, MEM_DECOMMIT);
+//   return VirtualFree(ptr, size, MEM_DECOMMIT);
-}
+// }
 
 static b32 plat_mem_release(void *ptr, u64 size) {
   return VirtualFree(ptr, size, MEM_RELEASE);
 }
 
-// Semaphores
-typedef struct plat_sem {
-  HANDLE handle;
-} plat_sem;
-
-static b32 plat_sem_init(plat_sem *s, u32 initial) {
-  s->handle = CreateSemaphore(NULL, initial, LONG_MAX, NULL);
-  return s->handle != NULL;
-}
-
-static void plat_sem_wait(plat_sem *s) {
-  WaitForSingleObject(s->handle, INFINITE);
-}
-
-static b32 plat_sem_trywait(HANDLE sem) {
-  DWORD r = WaitForSingleObject(sem, 0);
-  return r == WAIT_OBJECT_0;
-}
-
-static void plat_sem_post(plat_sem *s, u32 count) {
-  ReleaseSemaphore(s->handle, count, NULL);
-}
-
-static void plat_sem_destroy(plat_sem *s) {
-  if (s->handle) {
-    CloseHandle(s->handle);
-    s->handle = NULL;
-  }
-}
-
 // Sleep
 static void sleep_ms(int ms) { Sleep(ms); }
 
 #elif defined(__linux__)
-
 // Memory allocation
-
 #ifndef _DEFAULT_SOURCE
 #define _DEFAULT_SOURCE
 #endif
 
-#include <sys/mman.h>
-#include <unistd.h>
-
 static u32 plat_get_pagesize(void) { return (u32)sysconf(_SC_PAGESIZE); }
 
 static void *plat_mem_reserve(u64 size) {
@@ -197,46 +163,19 @@ static b32 plat_mem_commit(void *ptr, u64 size) {
   return ret == 0;
 }
 
-static b32 plat_mem_decommit(void *ptr, u64 size) {
+// static b32 plat_mem_decommit(void *ptr, u64 size) { // Comment to prevent warning: unused function
-  i32 ret = mprotect(ptr, size, PROT_NONE);
+//   i32 ret = mprotect(ptr, size, PROT_NONE);
-  if (ret != 0)
+//   if (ret != 0)
-    return false;
+//     return false;
-  ret = madvise(ptr, size, MADV_DONTNEED);
+//   ret = madvise(ptr, size, MADV_DONTNEED);
-  return ret == 0;
+//   return ret == 0;
-}
+// }
 
 static b32 plat_mem_release(void *ptr, u64 size) {
   i32 ret = munmap(ptr, size);
   return ret == 0;
 }
 
-// Semaphores
-#include <semaphore.h>
-
-typedef struct plat_sem {
-  sem_t sem;
-} plat_sem;
-
-static b32 plat_sem_init(plat_sem *s, u32 initial) {
-  return sem_init(&s->sem, 0, initial) == 0;
-}
-
-static void plat_sem_wait(plat_sem *s) {
-  while (sem_wait(&s->sem) == -1 && errno == EINTR) {
-  }
-}
-
-static b32 plat_sem_trywait(sem_t *sem) { return sem_trywait(sem) == 0; }
-
-static void plat_sem_post(plat_sem *s, u32 count) {
-  for (u32 i = 0; i < count; i++) {
-    sem_post(&s->sem);
-  }
-}
-
-static void plat_sem_destroy(plat_sem *s) { sem_destroy(&s->sem); }
-
 // Sleep
 static void sleep_ms(int ms) { usleep(ms * 1000); }
-
 #endif

build.bat

@@ -0,0 +1,172 @@
+@echo off
+setlocal enabledelayedexpansion
+
+set PROJECT_NAME=dfin
+
+:: ============================================================================
+:: build.bat
+:: ============================================================================
+
+:: Get script directory (project root)
+set SCRIPT_DIR=%~dp0
+set SCRIPT_DIR=%SCRIPT_DIR:~0,-1%
+
+:: ---------------------------------------------------------------------------
+:: Default values
+:: ---------------------------------------------------------------------------
+
+set BUILD_TYPE=Release
+set CLEAN_BUILD=0
+
+:: --------------------------------------------------------------------------
+:: Parse arguments
+:: --------------------------------------------------------------------------
+:parse_args
+if "%~1"=="" goto :main
+
+if /i "%~1"=="Release" (
+    set BUILD_TYPE=Release
+    shift
+    goto :parse_args
+)
+if /i "%~1"=="Debug" (
+    set BUILD_TYPE=Debug
+    shift
+    goto :parse_args
+)
+if /i "%~1"=="clean" (
+    set CLEAN_BUILD=1
+    shift
+    goto :parse_args
+)
+
+echo Unknown argument: %~1
+echo Usage: build [Release^|Debug] [clean]
+exit /b 1
+
+:main
+set BUILD_DIR=%SCRIPT_DIR%\build\windows\%BUILD_TYPE%
+
+echo === Building %PROJECT_NAME% (%BUILD_TYPE%) ===
+
+:: --------------------------------------------------------------------------
+:: Clean if requested
+:: --------------------------------------------------------------------------
+if %CLEAN_BUILD%==1 (
+    echo Cleaning...
+    if exist "%BUILD_DIR%" rmdir /s /q "%BUILD_DIR%" 2>nul
+)
+
+:: --------------------------------------------------------------------------
+:: Create build directory
+:: --------------------------------------------------------------------------
+if not exist "%BUILD_DIR%" mkdir "%BUILD_DIR%"
+pushd "%BUILD_DIR%"
+
+:: --------------------------------------------------------------------------
+:: Compiler selection
+:: --------------------------------------------------------------------------
+set CC=
+
+where clang-cl >nul 2>&1
+if !ERRORLEVEL! equ 0 (
+    echo Compiler: clang-cl ^(preferred^)
+    set "CC=-DCMAKE_C_COMPILER=clang-cl"
+    goto :find_generator
+)
+
+where gcc >nul 2>&1
+if !ERRORLEVEL! equ 0 (
+    echo Compiler: gcc ^(fallback^)
+    set "CC=-DCMAKE_C_COMPILER=gcc"
+    goto :find_generator
+)
+
+where clang >nul 2>&1
+if !ERRORLEVEL! equ 0 (
+    echo Compiler: clang ^(last resort^)
+    set "CC=-DCMAKE_C_COMPILER=clang"
+    goto :find_generator
+)
+
+echo ERROR: No suitable compiler found!
+popd
+exit /b 1
+
+:: --------------------------------------------------------------------------
+:: Generator selection (prefer ninja)
+:: --------------------------------------------------------------------------
+:find_generator
+set GEN=
+where ninja >nul 2>&1
+if !ERRORLEVEL! equ 0 (
+    echo Generator: Ninja
+    set "GEN=-G Ninja"
+) else (
+    echo Generator: Default
+)
+
+:: --------------------------------------------------------------------------
+:: Configure
+:: --------------------------------------------------------------------------
+echo.
+echo Configuring CMake...
+
+:: --------------------------------------------------------------------------
+:: compile_commands.json logic
+:: --------------------------------------------------------------------------
+set EXPORT_COMPILE_COMMANDS=OFF
+
+if /i "%BUILD_TYPE%"=="Release" (
+    if exist "%SCRIPT_DIR%\compile_commands.json" (
+        echo compile_commands.json already exists - skipping generation
+    ) else (
+        echo compile_commands.json will be generated
+        set EXPORT_COMPILE_COMMANDS=ON
+    )
+)
+
+set CMD=cmake "%SCRIPT_DIR%" %GEN% %CC% -DCMAKE_BUILD_TYPE=%BUILD_TYPE% -DCMAKE_EXPORT_COMPILE_COMMANDS=%EXPORT_COMPILE_COMMANDS%
+
+echo !CMD!
+!CMD!
+if !ERRORLEVEL! neq 0 (
+    echo ERROR: Configuration failed
+    popd
+    exit /b 1
+)
+
+:: --------------------------------------------------------------------------
+:: Build
+:: --------------------------------------------------------------------------
+echo.
+echo Building...
+cmake --build . --config %BUILD_TYPE%
+if !ERRORLEVEL! neq 0 (
+    echo ERROR: Build failed
+    popd
+    exit /b 1
+)
+
+:: --------------------------------------------------------------------------
+:: Copy compile_commands.json (only if generated)
+:: --------------------------------------------------------------------------
+if /i "%EXPORT_COMPILE_COMMANDS%"=="ON" (
+    if exist "compile_commands.json" (
+        echo.
+        echo clangd: compile_commands.json generated
+
+        copy /Y "compile_commands.json" "%SCRIPT_DIR%\compile_commands.json" >nul 2>&1
+        if !ERRORLEVEL! equ 0 (
+            echo clangd: Copied to project root
+        ) else (
+            echo clangd: Copy failed
+        )
+    )
+)
+
+popd
+
+echo.
+echo === Build Complete ===
+echo Executable: %BUILD_DIR%\%PROJECT_NAME%.exe

build.sh

@@ -0,0 +1,274 @@
+#!/usr/bin/env bash
+# ============================================================================
+# build.sh - Build script (Linux)
+# Usage: ./build.sh [Release|Debug] [clean]
+#
+# Compiler preference: gcc > clang
+# Build system: Ninja (fallback to Make)
+# ============================================================================
+
+set -euo pipefail
+
+PROJECT_NAME="dfin"
+
+# ---------------------------------------------------------------------------
+# Colors
+# ---------------------------------------------------------------------------
+readonly RED='\033[0;31m'
+readonly GREEN='\033[0;32m'
+readonly YELLOW='\033[1;33m'
+readonly CYAN='\033[0;36m'
+readonly NC='\033[0m'
+
+# ---------------------------------------------------------------------------
+# Default values
+# ---------------------------------------------------------------------------
+BUILD_TYPE="Release"
+CLEAN_BUILD=0
+
+# ---------------------------------------------------------------------------
+# Parse arguments
+# ---------------------------------------------------------------------------
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        Release|release)
+            BUILD_TYPE="Release"
+            shift
+            ;;
+        Debug|debug)
+            BUILD_TYPE="Debug"
+            shift
+            ;;
+        clean|-clean|--clean)
+            CLEAN_BUILD=1
+            shift
+            ;;
+        *)
+            echo -e "${RED}Unknown argument: $1${NC}"
+            echo "Usage: $0 [Release|Debug] [clean]"
+            exit 1
+            ;;
+    esac
+done
+
+# ---------------------------------------------------------------------------
+# Setup
+# ---------------------------------------------------------------------------
+readonly BUILD_DIR="build/linux/${BUILD_TYPE}"
+readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+echo -e "${GREEN}=== Building ${PROJECT_NAME} (${BUILD_TYPE}) ===${NC}"
+echo "Project: ${SCRIPT_DIR}"
+
+# ---------------------------------------------------------------------------
+# Clean if requested
+# ---------------------------------------------------------------------------
+if [[ $CLEAN_BUILD -eq 1 ]]; then
+    echo -e "${YELLOW}Cleaning build directory...${NC}"
+    rm -rf "${BUILD_DIR}"
+    echo
+fi
+
+# ---------------------------------------------------------------------------
+# Create build directory
+# ---------------------------------------------------------------------------
+mkdir -p "${BUILD_DIR}"
+cd "${BUILD_DIR}"
+
+# ---------------------------------------------------------------------------
+# Compiler selection (prefer gcc, fallback to clang)
+# ---------------------------------------------------------------------------
+echo -e "${YELLOW}Detecting compiler...${NC}"
+
+CC_BINARY=""
+CC_NAME=""
+
+if command -v gcc &> /dev/null; then
+    CC_BINARY="gcc"
+    CC_VERSION=$(gcc --version | head -n1)
+    CC_NAME="GCC (${CC_VERSION})"
+    echo -e "  ${GREEN}[OK]${NC} Found GCC (preferred): ${CC_VERSION}"
+elif command -v clang &> /dev/null; then
+    CC_BINARY="clang"
+    CC_VERSION=$(clang --version | head -n1)
+    CC_NAME="Clang (${CC_VERSION})"
+    echo -e "  ${YELLOW}[OK]${NC} Found Clang (fallback): ${CC_VERSION}"
+else
+    echo -e "${RED}[FAIL] No suitable compiler found!${NC}"
+    echo "Please install gcc or clang:"
+    echo "  Ubuntu/Debian:  sudo apt install build-essential"
+    echo "  Fedora/RHEL:    sudo dnf install gcc"
+    echo "  Arch:           sudo pacman -S gcc"
+    exit 1
+fi
+
+# ---------------------------------------------------------------------------
+# Check dependencies
+# ---------------------------------------------------------------------------
+echo -e "${YELLOW}Checking dependencies...${NC}"
+
+# Check for liburing
+HAVE_LIBURING=0
+if ldconfig -p | grep -q liburing 2>/dev/null; then
+    HAVE_LIBURING=1
+    echo -e "  ${GREEN}[OK]${NC} Found liburing"
+elif pkg-config --exists liburing 2>/dev/null; then
+    HAVE_LIBURING=1
+    echo -e "  ${GREEN}[OK]${NC} Found liburing (pkg-config)"
+elif [[ -f /usr/lib/liburing.so ]] || [[ -f /usr/lib64/liburing.so ]] || [[ -f /usr/local/lib/liburing.so ]]; then
+    HAVE_LIBURING=1
+    echo -e "  ${GREEN}[OK]${NC} Found liburing (manual detection)"
+else
+    echo -e "${RED}[FAIL] liburing not found!${NC}"
+    echo "Please install liburing-dev:"
+    echo "  Ubuntu/Debian:  sudo apt install liburing-dev"
+    echo "  Fedora/RHEL:    sudo dnf install liburing-devel"
+    echo "  Arch:           sudo pacman -S liburing"
+    exit 1
+fi
+
+# Check for pthreads
+# Check if pthreads is available (either in ldconfig or merged into libc)
+if ldconfig -p | grep -q libpthread 2>/dev/null || ldd --version | grep -qP '2\.(3[4-9]|[4-9][0-9])'; then
+    echo -e "  ${GREEN}[OK]${NC} Found pthreads (merged or standalone)"
+else
+    echo -e "  ${YELLOW}[NOTE]${NC} pthreads not found, attempting link"
+fi
+echo
+
+# ---------------------------------------------------------------------------
+# Generator selection (prefer ninja)
+# ---------------------------------------------------------------------------
+echo -e "${YELLOW}Selecting build system...${NC}"
+
+GENERATOR=""
+GENERATOR_NAME=""
+
+if command -v ninja &> /dev/null; then
+    GENERATOR="Ninja"
+    GENERATOR_NAME="Ninja"
+    echo -e "  ${GREEN}[OK]${NC} Using Ninja"
+elif command -v make &> /dev/null; then
+    GENERATOR="Unix Makefiles"
+    GENERATOR_NAME="Make"
+    echo -e "  ${YELLOW}[OK]${NC} Ninja not found, using Make"
+else
+    echo -e "${RED}[FAIL] No build system found!${NC}"
+    echo "Please install ninja or make:"
+    echo "  Ubuntu/Debian:  sudo apt install ninja-build"
+    echo "  Fedora/RHEL:    sudo dnf install ninja-build"
+    echo "  Arch:           sudo pacman -S ninja"
+    exit 1
+fi
+
+echo
+
+# ---------------------------------------------------------------------------
+# Configure
+# ---------------------------------------------------------------------------
+echo -e "${YELLOW}Configuring CMake...${NC}"
+
+# --------------------------------------------------------------------------
+# compile_commands.json logic
+# --------------------------------------------------------------------------
+
+EXPORT_COMPILE_COMMANDS=OFF
+
+if [[ "$BUILD_TYPE" == "Release" ]]; then
+    if [[ -f "${SCRIPT_DIR}/compile_commands.json" ]]; then
+        echo -e "  compile_commands.json already exists - skipping generation"
+    else
+        echo -e "  compile_commands.json will be generated"
+        EXPORT_COMPILE_COMMANDS=ON
+    fi
+fi
+
+echo -e "  Build type: ${BUILD_TYPE}"
+echo -e "  Compiler:   ${CC_NAME}"
+echo -e "  Generator:  ${GENERATOR_NAME}"
+
+cmake "${SCRIPT_DIR}" \
+    -G "${GENERATOR}" \
+    -DCMAKE_BUILD_TYPE="${BUILD_TYPE}" \
+    -DCMAKE_C_COMPILER="${CC_BINARY}" \
+    -DCMAKE_EXPORT_COMPILE_COMMANDS=${EXPORT_COMPILE_COMMANDS}
+
+if [[ $? -ne 0 ]]; then
+    echo -e "${RED}CMake configuration failed!${NC}"
+    exit 1
+fi
+
+echo -e "${GREEN}Configuration successful!${NC}"
+echo
+
+# ---------------------------------------------------------------------------
+# Build
+# ---------------------------------------------------------------------------
+echo -e "${YELLOW}Building...${NC}"
+
+# Get number of CPU cores
+if command -v nproc &> /dev/null; then
+    CORES=$(nproc)
+else
+    CORES=4
+fi
+
+cmake --build . --config "${BUILD_TYPE}" --parallel "${CORES}"
+
+if [[ $? -ne 0 ]]; then
+    echo -e "${RED}Build failed!${NC}"
+    exit 1
+fi
+
+echo -e "${GREEN}Build successful!${NC}"
+echo
+
+# ---------------------------------------------------------------------------
+# Verify output
+# ---------------------------------------------------------------------------
+cd "${SCRIPT_DIR}"
+
+if [[ -f "${BUILD_DIR}/${PROJECT_NAME}" ]]; then
+    echo -e "${GREEN}Executable: ${BUILD_DIR}/${PROJECT_NAME}${NC}"
+
+    if command -v file &> /dev/null; then
+        echo -e "  Type: $(file -b ${BUILD_DIR}/${PROJECT_NAME})"
+    fi
+
+    if command -v du &> /dev/null; then
+        echo -e "  Size: $(du -h ${BUILD_DIR}/${PROJECT_NAME} | cut -f1)"
+    fi
+elif [[ -f "${BUILD_DIR}/${PROJECT_NAME}.exe" ]]; then
+    echo -e "${GREEN}Executable: ${BUILD_DIR}/${PROJECT_NAME}.exe${NC}"
+else
+    echo -e "${YELLOW}Note: Could not locate executable${NC}"
+    echo "Checking build directory:"
+    find "${BUILD_DIR}" -type f -executable 2>/dev/null || echo "  No executables found"
+fi
+
+# ---------------------------------------------------------------------------
+# Summary
+# ---------------------------------------------------------------------------
+echo
+echo -e "${CYAN}=== Build Complete ===${NC}"
+echo
+echo -e "${YELLOW}Build Information:${NC}"
+echo -e "  Configuration: ${BUILD_TYPE}"
+echo -e "  Compiler:      ${CC_NAME}"
+echo -e "  Generator:     ${GENERATOR_NAME}"
+echo -e "  Output:        ${BUILD_DIR}/"
+
+# ---------------------------------------------------------------------------
+# Copy compile_commands.json for clangd
+# ---------------------------------------------------------------------------
+if [[ "${EXPORT_COMPILE_COMMANDS}" == "ON" ]]; then
+    if [[ -f "${BUILD_DIR}/compile_commands.json" ]]; then
+        echo -e "  clangd:        compile_commands.json generated"
+
+        cp "${BUILD_DIR}/compile_commands.json" "${SCRIPT_DIR}/compile_commands.json"
+        echo -e "  clangd:        Copied to project root"
+    fi
+fi
+
+echo
+echo -e "${GREEN}Ready to run: ./${BUILD_DIR}/${PROJECT_NAME}${NC}"

config.h

@@ -15,6 +15,7 @@
 #define IORING_BUFFER_SIZE KiB(256)
 #define NUM_BUFFERS_PER_THREAD 32
 #define MAX_ACTIVE_FILES 16
+#define MAX_WAIT_COUNT (NUM_BUFFERS_PER_THREAD / 2)
 
 #define SUBMIT_TIMEOUT_MS 10000
 #define IORING_DEBUG_PRINTS 0

duplicate_finder.c

@@ -32,7 +32,11 @@ int main(int argc, char **argv) {
     buf[strcspn(buf, "\r\n")] = 0;
 
     if (buf[0] == 0) {
-      strcpy(folders[0], ".");
+      if (!platform_get_current_directory(folders[0], sizeof(folders[0]))) {
+        fprintf(stderr, "Failed to get current directory\n");
+        return 1;
+      }
+      normalize_path(folders[0]);
       folder_count = 1;
     } else {
       folder_count = parse_paths(buf, folders, 64);
@@ -71,20 +75,32 @@ int main(int argc, char **argv) {
       .max_nbre_blocks = 1,
   };
 
-  mem_arena *gp_arena = arena_create(&params);
+  arena_params params_caligned = {
+      .reserve_size = GiB(1),
+      .commit_size = MiB(16),
+      .align = ARENA_CACHE_ALIGN,
+      .push_size = 0,
+      .allow_free_list = true,
+      .allow_swapback = false,
+      .growth_policy = ARENA_GROWTH_NORMAL,
+      .commit_policy = ARENA_COMMIT_LAZY,
+      .max_nbre_blocks = 1,
+  };
+
+  mem_arena *gp_arena = arena_create(&params_caligned);
 
   // -------------------------------
   // Detect hardware
   // -------------------------------
   // --- Windows: detect PHYSICAL cores (not logical threads) ---
-  uint32_t cpu_cores = platform_physical_cores();
+  uint8_t cpu_cores = platform_physical_cores();
 
   // Logical threads = CPU cores * 2
-  uint32_t cpu_threads = cpu_cores * 2;
+  uint8_t cpu_threads = cpu_cores * 2;
 
 #if MULTI_THREADING
-  uint32_t num_scan_threads = cpu_threads;
+  uint8_t num_scan_threads = cpu_threads;
-  uint32_t num_hash_threads = cpu_threads;
+  uint8_t num_hash_threads = cpu_threads;
 
   printf("%d cores %d threads CPU detected with %s instruction set\n"
          "Starting thread pool: %d scanning and %d hashing threads\n",
@@ -119,11 +135,11 @@ int main(int argc, char **argv) {
   mpmc_init(&file_queue, MiB(1));
 
   // Starting hash threads
-  WorkerContext workers[num_hash_threads];
+  HasherContext workers[num_hash_threads];
   Thread *hash_threads =
       arena_push(&gp_arena, sizeof(Thread) * num_hash_threads, true);
 
-  for (size_t i = 0; i < num_hash_threads; ++i) {
+  for (uint8_t i = 0; i < num_hash_threads; ++i) {
     workers[i].arena = arena_create(&params);
     workers[i].file_queue = &file_queue;
 
@@ -135,7 +151,7 @@ int main(int argc, char **argv) {
         0)
 #endif
     {
-      fprintf(stderr, "Failed to create hash thread %zu\n", i);
+      fprintf(stderr, "Failed to create hash thread %d\n", i);
       exit(1);
     }
   }
@@ -153,16 +169,15 @@ int main(int argc, char **argv) {
   Thread *scan_threads =
       arena_push(&gp_arena, sizeof(Thread) * num_scan_threads, true);
 
-  for (size_t i = 0; i < num_scan_threads; i++) {
+  for (uint8_t i = 0; i < num_scan_threads; i++) {
     scanners[i].num_threads = num_scan_threads;
-    scanners[i].path_arena = arena_create(&params);
+    scanners[i].meta_arena = arena_create(&params_caligned);
-    scanners[i].meta_arena = arena_create(&params);
     scanners[i].dir_queue = &dir_queue;
     scanners[i].file_queue = &file_queue;
 
     if (thread_create(&scan_threads[i], (ThreadFunc)scan_worker,
                       &scanners[i]) != 0) {
-      fprintf(stderr, "Failed to create scan thread %zu\n", i);
+      fprintf(stderr, "Failed to create scan thread %d\n", i);
       exit(1);
     }
   }
@@ -170,7 +185,7 @@ int main(int argc, char **argv) {
   // Initial folder push
   for (int i = 0; i < folder_count; i++) {
     size_t len = strlen(folders[i]) + 1;
-    char *path = arena_push(&scanners[0].path_arena, len, false);
+    char *path = arena_push(&scanners[0].meta_arena, len, false);
     memcpy(path, folders[i], len);
     mpmc_push_work(&dir_queue, path);
   }
@@ -178,7 +193,7 @@ int main(int argc, char **argv) {
   // Stop scan threads
   thread_wait_multiple(scan_threads, num_scan_threads);
 
-  for (size_t i = 0; i < num_scan_threads; ++i) {
+  for (uint8_t i = 0; i < num_scan_threads; ++i) {
     thread_close(&scan_threads[i]);
   }
 
@@ -205,7 +220,7 @@ int main(int argc, char **argv) {
   // Stop hashing threads
   thread_wait_multiple(hash_threads, num_hash_threads);
 
-  for (size_t i = 0; i < num_hash_threads; ++i) {
+  for (uint8_t i = 0; i < num_hash_threads; ++i) {
     thread_close(&hash_threads[i]);
   }
 
@@ -222,7 +237,7 @@ int main(int argc, char **argv) {
 
   FILE *f = fopen(FILE_HASHES_TXT, "wb");
 
-  for (int i = 0; i < num_hash_threads; i++) {
+  for (uint8_t i = 0; i < num_hash_threads; i++) {
     mem_arena *arena = workers[i].arena;
     u8 *arena_base =
         (u8 *)arena + ALIGN_UP_POW2(sizeof(mem_arena), arena->align);

experiments/io_uring_test.c

@@ -0,0 +1,721 @@
+/*
+# Compile
+gcc -o io_uring_test io_uring_test.c -luring
+
+# Run
+./io_uring_test
+   */
+#include "base.h"
+#include <stdint.h>
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <liburing.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#define TEST_FILE "test_io_uring.txt"
+#define BUFFER_SIZE 4096
+#define NUM_BUFFERS 4
+#define NUM_REGISTERED_FILES 8 // Maximum number of files to register
+
+// Colors for output
+#define COLOR_GREEN "\033[0;32m"
+#define COLOR_RED "\033[0;31m"
+#define COLOR_YELLOW "\033[0;33m"
+#define COLOR_BLUE "\033[0;34m"
+#define COLOR_RESET "\033[0m"
+
+// Test result tracking
+typedef struct {
+  int passed;
+  int failed;
+} TestResults;
+
+static void print_success(const char *step) {
+  printf(COLOR_GREEN "[✓] SUCCESS: %s" COLOR_RESET "\n", step);
+}
+
+static void print_failure(const char *step, const char *error) {
+  printf(COLOR_RED "[✗] FAILED: %s - %s" COLOR_RESET "\n", step, error);
+}
+
+static void print_info(const char *msg) {
+  printf(COLOR_BLUE "[i] INFO: %s" COLOR_RESET "\n", msg);
+}
+
+static void print_step(const char *step) {
+  printf(COLOR_YELLOW "\n>>> Testing: %s" COLOR_RESET "\n", step);
+}
+
+// Create a test file with known content
+static int create_test_file(const char *filename, const char *content) {
+  FILE *f = fopen(filename, "w");
+  if (!f) {
+    perror("Failed to create test file");
+    return -1;
+  }
+
+  fprintf(f, "%s", content);
+  fclose(f);
+
+  printf("  Created test file: %s\n", filename);
+  return 0;
+}
+
+// Test 1: Create io_uring instance
+static int test_io_uring_create(struct io_uring *ring, TestResults *results) {
+  print_step("io_uring creation");
+
+  int ret = io_uring_queue_init(256, ring, 0);
+  if (ret < 0) {
+    print_failure("io_uring_queue_init", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("io_uring instance created");
+  results->passed++;
+  return 0;
+}
+
+// Test 2: Register buffers
+static int test_register_buffers(struct io_uring *ring, void **buffers,
+                                 struct iovec *iovs, TestResults *results) {
+  print_step("Buffer registration");
+
+  // Allocate and prepare buffers
+  size_t total_size = BUFFER_SIZE * NUM_BUFFERS;
+  *buffers = aligned_alloc(4096, total_size); // Page-aligned for O_DIRECT
+  if (!*buffers) {
+    print_failure("Buffer allocation", strerror(errno));
+    results->failed++;
+    return -1;
+  }
+
+  // Initialize iovecs
+  for (int i = 0; i < NUM_BUFFERS; i++) {
+    iovs[i].iov_base = (char *)*buffers + (i * BUFFER_SIZE);
+    iovs[i].iov_len = BUFFER_SIZE;
+    memset(iovs[i].iov_base, 0, BUFFER_SIZE);
+  }
+
+  int ret = io_uring_register_buffers(ring, iovs, NUM_BUFFERS);
+  if (ret < 0) {
+    print_failure("io_uring_register_buffers", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Buffers registered successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 2b: Register files
+static int test_register_files(struct io_uring *ring, int *fds, int num_fds,
+                               TestResults *results) {
+  print_step("File registration");
+
+  if (num_fds == 0) {
+    print_info("No files to register");
+    results->passed++;
+    return 0;
+  }
+
+  int ret = io_uring_register_files(ring, fds, num_fds);
+  if (ret < 0) {
+    // File registration might not be supported on all kernels
+    if (ret == -EOPNOTSUPP || ret == -EINVAL) {
+      print_info("File registration not supported on this kernel, skipping");
+      results->passed++;
+      return 0;
+    }
+    print_failure("io_uring_register_files", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  printf("  Registered %d files\n", num_fds);
+  print_success("Files registered successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 3: Open file
+static int test_open_file(const char *filename, int *fd, bool use_direct,
+                          TestResults *results) {
+  print_step("File opening");
+
+  // Get file size
+  struct stat st;
+  if (stat(filename, &st) != 0) {
+    print_failure("stat", strerror(errno));
+    results->failed++;
+    return -1;
+  }
+
+  int page_size = plat_get_pagesize();
+  size_t file_size = st.st_size;
+
+  printf("  File: %s\n", filename);
+  printf("  File size: %zu bytes\n", file_size);
+  printf("  Page size: %d bytes\n", page_size);
+
+  if (file_size % page_size != 0) {
+    printf("  Extending read size from %zu to %zu bytes\n", file_size,
+           ALIGN_UP_POW2(file_size, page_size));
+  }
+
+  // Try to open with specified flags
+  int flags = O_RDONLY;
+  if (use_direct) {
+    flags |= O_DIRECT;
+  }
+
+  *fd = open(filename, flags);
+  if (*fd < 0) {
+    if (use_direct) {
+      print_info("O_DIRECT failed, trying without it");
+      *fd = open(filename, O_RDONLY);
+      if (*fd < 0) {
+        print_failure("open", strerror(errno));
+        results->failed++;
+        return -1;
+      }
+      print_info("Using buffered I/O (O_DIRECT not available)");
+    } else {
+      print_failure("open", strerror(errno));
+      results->failed++;
+      return -1;
+    }
+  } else {
+    const char *io_type = use_direct ? "O_DIRECT" : "buffered I/O";
+    printf("  File opened with %s\n", io_type);
+    print_success("File opened successfully");
+  }
+
+  results->passed++;
+  return 0;
+}
+
+// Test 4: Build and submit read operation (using registered file)
+static int test_submit_read_registered(struct io_uring *ring, int file_index,
+                                       struct iovec *iovs, int buffer_id,
+                                       uint64_t user_data, size_t file_size,
+                                       TestResults *results) {
+  print_step("Building and submitting read operation (registered file)");
+
+  u32 page_size = plat_get_pagesize();
+  size_t read_size = BUFFER_SIZE;
+
+  // For O_DIRECT, ensure read size is sector-aligned
+  if (read_size > file_size) {
+    read_size = ALIGN_UP_POW2(file_size, page_size);
+    printf("  Adjusted read size to %zu bytes for O_DIRECT alignment\n",
+           read_size);
+  }
+
+  struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
+  if (!sqe) {
+    print_failure("io_uring_get_sqe", "No available SQE");
+    results->failed++;
+    return -1;
+  }
+
+  // Use fixed file descriptor
+  io_uring_prep_read_fixed(sqe, file_index, iovs[buffer_id].iov_base, read_size,
+                           0, buffer_id);
+  io_uring_sqe_set_data64(sqe, user_data);
+
+  int ret = io_uring_submit(ring);
+  if (ret < 0) {
+    print_failure("io_uring_submit", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  printf("  Using registered file index: %d\n", file_index);
+  print_success("Read operation submitted successfully (registered file)");
+  results->passed++;
+  return 0;
+}
+
+// Test 4b: Build and submit read operation (using fd directly)
+static int test_submit_read(struct io_uring *ring, int fd, struct iovec *iovs,
+                            int buffer_id, uint64_t user_data,
+                            TestResults *results) {
+  print_step("Building and submitting read operation");
+
+  // Get file size for proper alignment
+  struct stat st;
+  if (fstat(fd, &st) != 0) {
+    print_failure("fstat", strerror(errno));
+    results->failed++;
+    return -1;
+  }
+
+  u32 page_size = plat_get_pagesize();
+  size_t file_size = st.st_size;
+  size_t read_size = BUFFER_SIZE;
+
+  // For O_DIRECT, ensure read size is sector-aligned
+  if (read_size > file_size) {
+    read_size = ALIGN_UP_POW2(file_size, page_size);
+    printf("  Adjusted read size to %zu bytes for O_DIRECT alignment\n",
+           read_size);
+  }
+
+  struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
+  if (!sqe) {
+    print_failure("io_uring_get_sqe", "No available SQE");
+    results->failed++;
+    return -1;
+  }
+
+  // Prepare read operation using registered buffer
+  io_uring_prep_read_fixed(sqe, fd, iovs[buffer_id].iov_base, read_size, 0,
+                           buffer_id);
+  io_uring_sqe_set_data64(sqe, user_data);
+
+  int ret = io_uring_submit(ring);
+  if (ret < 0) {
+    print_failure("io_uring_submit", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Read operation submitted successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 5: Wait for completion
+static int test_wait_completion(struct io_uring *ring,
+                                struct io_uring_cqe **cqe,
+                                TestResults *results) {
+  print_step("Waiting for completion");
+
+  int ret = io_uring_wait_cqe(ring, cqe);
+  if (ret < 0) {
+    print_failure("io_uring_wait_cqe", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Completion received");
+  results->passed++;
+  return 0;
+}
+
+// Test 6: Process completion
+static int test_process_completion(struct io_uring_cqe *cqe,
+                                   uint64_t expected_user_data,
+                                   TestResults *results) {
+  print_step("Processing completion");
+
+  uint64_t user_data = io_uring_cqe_get_data64(cqe);
+  int res = cqe->res;
+
+  printf("  Completion data:\n");
+  printf("    User data: %lu (expected: %lu)\n", user_data, expected_user_data);
+  printf("    Result: %d bytes read\n", res);
+
+  if (user_data != expected_user_data) {
+    print_failure("User data mismatch",
+                  "User data doesn't match expected value");
+    results->failed++;
+    return -1;
+  }
+
+  if (res < 0) {
+    print_failure("Read operation", strerror(-res));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Completion processed successfully");
+  results->passed++;
+  return res; // Return number of bytes read
+}
+
+// Test 7: Verify read data
+static int test_verify_data(struct iovec *iovs, int buffer_id, int bytes_read,
+                            const char *expected_content,
+                            TestResults *results) {
+  print_step("Data verification");
+
+  char *data = (char *)iovs[buffer_id].iov_base;
+
+  printf("  Read data (first 200 chars):\n");
+  printf("  ---\n");
+  for (int i = 0; i < bytes_read && i < 200; i++) {
+    putchar(data[i]);
+  }
+  if (bytes_read > 200)
+    printf("...");
+  printf("\n  ---\n");
+
+  // Check if data is not empty
+  if (bytes_read == 0) {
+    print_failure("Data verification", "No data read");
+    results->failed++;
+    return -1;
+  }
+
+  // Check if data contains expected content
+  if (expected_content && strstr(data, expected_content) == NULL) {
+    print_failure("Data verification", "Expected content not found");
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Data verified successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 8: Test multiple concurrent reads
+static int test_concurrent_reads(struct io_uring *ring, int fd,
+                                 struct iovec *iovs, TestResults *results) {
+  print_step("Concurrent reads test");
+
+  int num_reads = 3;
+  int submitted = 0;
+
+  // Submit multiple reads
+  for (int i = 0; i < num_reads; i++) {
+    struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
+    if (!sqe) {
+      print_failure("Getting SQE for concurrent read", "No available SQE");
+      results->failed++;
+      return -1;
+    }
+
+    off_t offset = i * 100; // Read from different offsets
+    io_uring_prep_read_fixed(sqe, fd, iovs[i].iov_base, BUFFER_SIZE, offset, i);
+    io_uring_sqe_set_data64(sqe, i);
+    submitted++;
+  }
+
+  int ret = io_uring_submit(ring);
+  if (ret != submitted) {
+    char msg[64];
+    snprintf(msg, sizeof(msg), "Expected %d, got %d", submitted, ret);
+
+    print_failure("Submitting concurrent reads", msg);
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Concurrent reads submitted");
+
+  // Wait for and process completions
+  for (int i = 0; i < submitted; i++) {
+    struct io_uring_cqe *cqe;
+    ret = io_uring_wait_cqe(ring, &cqe);
+    if (ret < 0) {
+      print_failure("Waiting for concurrent read completion", strerror(-ret));
+      results->failed++;
+      return -1;
+    }
+
+    uint64_t user_data = io_uring_cqe_get_data64(cqe);
+    int res = cqe->res;
+
+    printf("  Concurrent read %lu completed: %d bytes read\n", user_data, res);
+    io_uring_cqe_seen(ring, cqe);
+  }
+
+  print_success("Concurrent reads completed successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 9: Test file registration with multiple files
+static int test_file_registration(struct io_uring *ring, TestResults *results) {
+  print_step("File registration with multiple files");
+
+  // Create multiple test files
+  const char *filenames[] = {"test_file1.txt", "test_file2.txt",
+                             "test_file3.txt"};
+  const char *contents[] = {"Content of file 1: Hello World!",
+                            "Content of file 2: io_uring is fast!",
+                            "Content of file 3: Registered files test."};
+
+  int fds[3];
+  int num_files = 3;
+
+  // Create and open files
+  for (int i = 0; i < num_files; i++) {
+    if (create_test_file(filenames[i], contents[i]) != 0) {
+      results->failed++;
+      return -1;
+    }
+
+    fds[i] = open(filenames[i], O_RDONLY);
+    if (fds[i] < 0) {
+      print_failure("Opening file for registration", strerror(errno));
+      // Close previously opened files
+      for (int j = 0; j < i; j++)
+        close(fds[j]);
+      results->failed++;
+      return -1;
+    }
+  }
+
+  // Register files
+  int ret = io_uring_register_files(ring, fds, num_files);
+  if (ret < 0) {
+    if (ret == -EOPNOTSUPP || ret == -EINVAL) {
+      print_info("File registration not supported, skipping test");
+      results->passed++;
+    } else {
+      print_failure("io_uring_register_files", strerror(-ret));
+      results->failed++;
+    }
+    // Cleanup
+    for (int i = 0; i < num_files; i++) {
+      close(fds[i]);
+      remove(filenames[i]);
+    }
+    return (ret == -EOPNOTSUPP || ret == -EINVAL) ? 0 : -1;
+  }
+
+  print_success("Multiple files registered successfully");
+
+  // Read from each registered file using fixed operations
+  for (int i = 0; i < num_files; i++) {
+    struct iovec iov;
+    char buf[256] = {0};
+    iov.iov_base = buf;
+    iov.iov_len = sizeof(buf);
+
+    // Register a single buffer for this test
+    ret = io_uring_register_buffers(ring, &iov, 1);
+    if (ret < 0) {
+      print_failure("Registering buffer for file test", strerror(-ret));
+      break;
+    }
+
+    struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
+    if (!sqe) {
+      print_failure("Getting SQE for registered file", "No available SQE");
+      break;
+    }
+
+    // Use fixed file and fixed buffer
+    io_uring_prep_read_fixed(sqe, i, iov.iov_base, strlen(contents[i]), 0, 0);
+    io_uring_sqe_set_data64(sqe, i);
+
+    ret = io_uring_submit(ring);
+    if (ret < 0) {
+      print_failure("Submitting read for registered file", strerror(-ret));
+      break;
+    }
+
+    struct io_uring_cqe *cqe;
+    ret = io_uring_wait_cqe(ring, &cqe);
+    if (ret < 0) {
+      print_failure("Waiting for registered file read", strerror(-ret));
+      break;
+    }
+
+    if (cqe->res < 0) {
+      print_failure("Reading registered file", strerror(-cqe->res));
+      io_uring_cqe_seen(ring, cqe);
+      break;
+    }
+
+    printf("  File %d: Read %d bytes: %.*s\n", i, cqe->res, cqe->res, buf);
+    io_uring_cqe_seen(ring, cqe);
+
+    // Unregister buffer for next iteration
+    io_uring_unregister_buffers(ring);
+  }
+
+  // Cleanup files
+  io_uring_unregister_files(ring);
+  for (int i = 0; i < num_files; i++) {
+    close(fds[i]);
+    remove(filenames[i]);
+  }
+
+  print_success("File registration test completed");
+  results->passed++;
+  return 0;
+}
+
+// Cleanup function
+static void cleanup(struct io_uring *ring, int *fds, int num_fds,
+                    void *buffers) {
+  if (fds) {
+    io_uring_unregister_files(ring);
+    for (int i = 0; i < num_fds; i++) {
+      if (fds[i] >= 0)
+        close(fds[i]);
+    }
+  }
+  if (buffers) {
+    io_uring_unregister_buffers(ring);
+    free(buffers);
+  }
+  io_uring_queue_exit(ring);
+  remove(TEST_FILE);
+}
+
+int main() {
+  TestResults results = {0, 0};
+  struct io_uring ring;
+  int fd = -1;
+  int registered_fds[1] = {-1}; // For registered file test
+  void *buffers = NULL;
+  struct iovec iovs[NUM_BUFFERS];
+
+  printf(COLOR_BLUE "\n========================================\n");
+  printf("    io_uring Test Suite with File Registration\n");
+  printf("========================================\n" COLOR_RESET);
+
+  // Create main test file
+  const char *test_content =
+      "Hello, io_uring! This is a test file for async I/O operations.\n"
+      "Line 2: Testing reads with registered buffers.\n"
+      "Line 3: The quick brown fox jumps over the lazy dog.\n"
+      "Line 4: ABCDEFGHIJKLMNOPQRSTUVWXYZ\n"
+      "Line 5: 0123456789\n";
+
+  if (create_test_file(TEST_FILE, test_content) != 0) {
+    return 1;
+  }
+
+  // Test 1: Create io_uring
+  if (test_io_uring_create(&ring, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 2: Register buffers
+  if (test_register_buffers(&ring, &buffers, iovs, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 3: Open file
+  if (test_open_file(TEST_FILE, &fd, true, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 4: Submit read with direct fd
+  uint64_t test_user_data = 12345;
+  if (test_submit_read(&ring, fd, iovs, 0, test_user_data, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 5: Wait for completion
+  struct io_uring_cqe *cqe;
+  if (test_wait_completion(&ring, &cqe, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 6: Process completion
+  int bytes_read = test_process_completion(cqe, test_user_data, &results);
+  if (bytes_read < 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+  io_uring_cqe_seen(&ring, cqe);
+
+  // Test 7: Verify data
+  if (test_verify_data(iovs, 0, bytes_read, "io_uring", &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Close the file for file registration test
+  close(fd);
+
+  // Reopen and register the file
+  registered_fds[0] = open(TEST_FILE, O_RDONLY);
+  if (registered_fds[0] < 0) {
+    print_failure("Reopening file for registration", strerror(errno));
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 2b: Register files
+  if (test_register_files(&ring, registered_fds, 1, &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  // Get file size for the registered read test
+  struct stat st;
+  stat(TEST_FILE, &st);
+
+  // Test 4b: Submit read using registered file
+  test_user_data = 67890;
+  if (test_submit_read_registered(&ring, 0, iovs, 0, test_user_data, st.st_size,
+                                  &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  // Wait for and process completion
+  if (test_wait_completion(&ring, &cqe, &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  bytes_read = test_process_completion(cqe, test_user_data, &results);
+  if (bytes_read < 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+  io_uring_cqe_seen(&ring, cqe);
+
+  // Verify data from registered file read
+  if (test_verify_data(iovs, 0, bytes_read, "io_uring", &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  // Test 8: Concurrent reads
+  if (test_concurrent_reads(&ring, registered_fds[0], iovs, &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  // Test 9: File registration with multiple files (requires new ring)
+  cleanup(&ring, registered_fds, 1, buffers);
+  buffers = NULL;
+  registered_fds[0] = -1;
+
+  if (test_io_uring_create(&ring, &results) != 0) {
+    return 1;
+  }
+
+  test_file_registration(&ring, &results);
+
+  // Cleanup the second ring
+  io_uring_queue_exit(&ring);
+
+  // Print summary
+  printf(COLOR_BLUE "\n========================================\n");
+  printf("           TEST SUMMARY\n");
+  printf("========================================\n" COLOR_RESET);
+  printf("  Total tests: %d\n", results.passed + results.failed);
+  printf(COLOR_GREEN "  Passed: %d\n" COLOR_RESET, results.passed);
+  if (results.failed > 0) {
+    printf(COLOR_RED "  Failed: %d\n" COLOR_RESET, results.failed);
+  } else {
+    printf(COLOR_GREEN "  ✓ ALL TESTS PASSED!\n" COLOR_RESET);
+  }
+
+  return results.failed > 0 ? 1 : 0;
+}

experiments/io_uring_test2.c

@@ -1,6 +1,6 @@
 /*
 # Compile
-gcc -o io_uring_test io_uring_test.c -luring
+gcc -o io_uring_test io_uring_test2.c -luring
 
 # Run
 ./io_uring_test

lf_mpmc.h

@@ -23,9 +23,6 @@ static void cpu_pause(void) {
   _mm_pause();
 #endif
 }
-
-typedef struct plat_sem plat_sem;
-
 typedef struct CACHE_ALIGN {
   atomic_size_t seq;
   void *data;
@@ -45,8 +42,6 @@ typedef struct {
   size_t commit_step;
   atomic_flag commit_lock;
 
-  plat_sem items_sem;
-
   MPMCSlot *slots;
 } MPMCQueue;
 
@@ -94,8 +89,6 @@ static void mpmc_init(MPMCQueue *q, size_t max_capacity) {
   atomic_init(&q->head, 0);
   atomic_init(&q->tail, 0);
   atomic_init(&q->work_count, 0);
-
-  plat_sem_init(&q->items_sem, 0);
 }
 
 /* ----------------------------------------------------------- */
@@ -141,7 +134,6 @@ static void mpmc_commit_more(MPMCQueue *q) {
 /* ----------------------------------------------------------- */
 /* PUSH */
 /* ----------------------------------------------------------- */
-// Does not increment work
 static void mpmc_push(MPMCQueue *q, void *item) {
   MPMCSlot *slot;
   size_t pos;
@@ -184,8 +176,6 @@ static void mpmc_push(MPMCQueue *q, void *item) {
   slot->data = item;
 
   atomic_store_explicit(&slot->seq, pos + 1, memory_order_release);
-
-  plat_sem_post(&q->items_sem, 1);
 }
 
 // Increment work
@@ -233,15 +223,11 @@ static void mpmc_push_work(MPMCQueue *q, void *item) {
   atomic_store_explicit(&slot->seq, pos + 1, memory_order_release);
 
   atomic_fetch_add(&q->work_count, 1);
-  plat_sem_post(&q->items_sem, 1);
 }
 /* ----------------------------------------------------------- */
 /* POP */
 /* ----------------------------------------------------------- */
 static void *mpmc_pop(MPMCQueue *q) {
-
-  plat_sem_wait(&q->items_sem);
-
   MPMCSlot *slot;
   size_t pos;
 
@@ -262,9 +248,14 @@ static void *mpmc_pop(MPMCQueue *q) {
                                                 memory_order_relaxed))
         break;
 
+    } else if (diff < 0) { // queue is empty
+
+      Sleep(500);
+
     } else { // slot is still transitioning (written by another thread)
+
       if (++spins > 10) {
-        sleep_ms(0); // yield CPU
+        SwitchToThread(); // yield CPU
         spins = 0;
       } else {
         cpu_pause();
@@ -306,21 +297,19 @@ static void mpmc_task_done(MPMCQueue *q, u8 consumer_count) {
 /* ----------------------------------------------------------- */
 /* MPMC Cleanup */
 /* ----------------------------------------------------------- */
-static void mpmc_finish(MPMCQueue *q) {
+// static void mpmc_finish(MPMCQueue *q) { // Comment to prevent warning: unused function
-  if (!q)
+//   if (!q)
-    return;
+//     return;
-
+//
-  if (q->slots) {
+//   if (q->slots) {
-    plat_mem_release(q->slots, 0);
+//     plat_mem_release(q->slots, 0);
-    q->slots = NULL;
+//     q->slots = NULL;
-  }
+//   }
-
+//
-  plat_sem_destroy(&q->items_sem);
+//   q->capacity = 0;
-
+//   q->mask = 0;
-  q->capacity = 0;
+//
-  q->mask = 0;
+//   atomic_store_explicit(&q->head, 0, memory_order_relaxed);
-
+//   atomic_store_explicit(&q->tail, 0, memory_order_relaxed);
-  atomic_store_explicit(&q->head, 0, memory_order_relaxed);
+//   atomic_store_explicit(&q->committed, 0, memory_order_relaxed);
-  atomic_store_explicit(&q->tail, 0, memory_order_relaxed);
+// }
-  atomic_store_explicit(&q->committed, 0, memory_order_relaxed);
-}

mt_mpmc.h

@@ -0,0 +1,254 @@
+#pragma once
+
+#include "base.h"
+
+// Cache align abstraction
+#define CACHELINE 64
+
+#if defined(_MSC_VER)
+#define CACHE_ALIGN __declspec(align(CACHELINE))
+#else
+#define CACHE_ALIGN __attribute__((aligned(CACHELINE)))
+#endif
+
+// Mutex/Critical section abstraction
+#if defined(_WIN32)
+#include <windows.h>
+typedef CRITICAL_SECTION mtx_t;
+typedef CONDITION_VARIABLE cond_t;
+
+#define mtx_init(m) InitializeCriticalSection(m)
+#define mtx_lock(m) EnterCriticalSection(m)
+#define mtx_unlock(m) LeaveCriticalSection(m)
+#define mtx_destroy(m) DeleteCriticalSection(m)
+
+#define cond_init(c) InitializeConditionVariable(c)
+#define cond_wait(c, m) SleepConditionVariableCS(c, m, INFINITE)
+#define cond_signal(c) WakeConditionVariable(c)
+#define cond_broadcast(c) WakeAllConditionVariable(c)
+
+#else
+#include <pthread.h>
+typedef pthread_mutex_t mtx_t;
+typedef pthread_cond_t cond_t;
+
+#define mtx_init(m) pthread_mutex_init(m, NULL)
+#define mtx_lock(m) pthread_mutex_lock(m)
+#define mtx_unlock(m) pthread_mutex_unlock(m)
+#define mtx_destroy(m) pthread_mutex_destroy(m)
+
+#define cond_init(c) pthread_cond_init(c, NULL)
+#define cond_wait(c, m) pthread_cond_wait(c, m)
+#define cond_signal(c) pthread_cond_signal(c)
+#define cond_broadcast(c) pthread_cond_broadcast(c)
+
+#endif
+
+typedef struct CACHE_ALIGN {
+  void *data;
+  char pad[64 - sizeof(void *)];
+} MPMCSlot;
+
+typedef struct {
+  CACHE_ALIGN size_t head;
+  CACHE_ALIGN size_t tail;
+
+  CACHE_ALIGN size_t count;
+  CACHE_ALIGN size_t work_count;
+
+  size_t capacity;
+  size_t mask;
+
+  size_t committed;
+  size_t commit_step;
+
+  mtx_t lock;
+  cond_t not_empty;
+  cond_t not_full;
+
+  MPMCSlot *slots;
+} MPMCQueue;
+
+/* ----------------------------------------------------------- */
+/* INIT */
+/* ----------------------------------------------------------- */
+static void mpmc_init(MPMCQueue *q, size_t max_capacity) {
+  q->capacity = max_capacity;
+  q->mask = max_capacity - 1;
+
+  size_t pagesize = plat_get_pagesize();
+  size_t bytes = ALIGN_UP_POW2(sizeof(MPMCSlot) * max_capacity, pagesize);
+
+  q->slots = (MPMCSlot *)plat_mem_reserve(bytes);
+  if (!q->slots) {
+    fprintf(stderr, "plat_mem_reserve failed\n");
+    exit(1);
+  }
+
+  size_t commit_bytes = ALIGN_UP_POW2(pagesize, pagesize);
+  q->commit_step = commit_bytes / sizeof(MPMCSlot);
+
+  q->committed = q->commit_step;
+  plat_mem_commit(q->slots, commit_bytes);
+
+  for (size_t i = 0; i < q->committed; i++) {
+    q->slots[i].data = NULL;
+  }
+
+  q->head = 0;
+  q->tail = 0;
+  q->count = 0;
+  q->work_count = 0;
+
+  mtx_init(&q->lock);
+  cond_init(&q->not_empty);
+  cond_init(&q->not_full);
+}
+
+/* ----------------------------------------------------------- */
+/* COMMIT MORE MEMORY */
+/* ----------------------------------------------------------- */
+static void mpmc_commit_more(MPMCQueue *q) {
+  size_t start = q->committed;
+
+  if (start >= q->capacity)
+    return;
+
+  size_t new_commit = start + q->commit_step;
+  if (new_commit > q->capacity)
+    new_commit = q->capacity;
+
+  size_t count = new_commit - start;
+
+  plat_mem_commit(&q->slots[start], count * sizeof(MPMCSlot));
+
+  for (size_t i = start; i < new_commit; i++) {
+    q->slots[i].data = NULL;
+  }
+
+  q->committed = new_commit;
+}
+
+/* ----------------------------------------------------------- */
+/* PUSH */
+/* ----------------------------------------------------------- */
+// Does not increment work
+static void mpmc_push(MPMCQueue *q, void *item) {
+  mtx_lock(&q->lock);
+
+  while (q->count == q->capacity) {
+    cond_wait(&q->not_full, &q->lock);
+  }
+
+  // Ensure committed
+  if (q->tail >= q->committed) {
+    mpmc_commit_more(q);
+  }
+
+  size_t pos = q->tail & q->mask;
+
+  q->slots[pos].data = item;
+  q->tail++;
+  q->count++;
+
+  cond_signal(&q->not_empty);
+  mtx_unlock(&q->lock);
+}
+
+// Increment work
+static void mpmc_push_work(MPMCQueue *q, void *item) {
+  mtx_lock(&q->lock);
+
+  while (q->count == q->capacity) {
+    cond_wait(&q->not_full, &q->lock);
+  }
+
+  if (q->tail >= q->committed) {
+    mpmc_commit_more(q);
+  }
+
+  size_t pos = q->tail & q->mask;
+
+  q->slots[pos].data = item;
+  q->tail++;
+  q->count++;
+  q->work_count++;
+
+  cond_signal(&q->not_empty);
+  mtx_unlock(&q->lock);
+}
+
+/* ----------------------------------------------------------- */
+/* POP */
+/* ----------------------------------------------------------- */
+static void *mpmc_pop(MPMCQueue *q) {
+  mtx_lock(&q->lock);
+
+  while (q->count == 0) {
+    cond_wait(&q->not_empty, &q->lock);
+  }
+
+  size_t pos = q->head & q->mask;
+
+  void *data = q->slots[pos].data;
+
+  q->head++;
+  q->count--;
+
+  cond_signal(&q->not_full);
+  mtx_unlock(&q->lock);
+
+  return data;
+}
+
+/* ----------------------------------------------------------- */
+/* PUSH POISON */
+/* ----------------------------------------------------------- */
+static void mpmc_producers_finished(MPMCQueue *q, u8 consumer_count) {
+  for (u8 i = 0; i < consumer_count; i++) {
+    mpmc_push(q, NULL);
+  }
+}
+
+/* ----------------------------------------------------------- */
+/* Done */
+/* ----------------------------------------------------------- */
+static void mpmc_task_done(MPMCQueue *q, u8 consumer_count) {
+
+  bool finished = false;
+
+  mtx_lock(&q->lock);
+
+  if (--q->work_count == 0) {
+    finished = true;
+  }
+
+  mtx_unlock(&q->lock);
+
+  if (finished) {
+    mpmc_producers_finished(q, consumer_count);
+  }
+}
+
+/* ----------------------------------------------------------- */
+/* MPMC Cleanup */
+/* ----------------------------------------------------------- */
+// static void mpmc_finish(MPMCQueue *q) { // Comment to prevent warning: unused
+// function
+//   if (!q) return;
+//
+//   if (q->slots) {
+//     plat_mem_release(q->slots, 0);
+//     q->slots = NULL;
+//   }
+//
+//   mtx_destroy(&q->lock);
+//
+// #if !defined(_WIN32)
+//   pthread_cond_destroy(&q->not_empty);
+//   pthread_cond_destroy(&q->not_full);
+// #endif
+//
+//   q->capacity = 0;
+//   q->mask = 0;
+// }

sm_mpmc.h

@@ -0,0 +1,388 @@
+#pragma once
+
+#include "base.h"
+
+// Cache align abstraction
+#define CACHELINE 64
+
+#if defined(_MSC_VER)
+#define CACHE_ALIGN __declspec(align(CACHELINE))
+#else
+#define CACHE_ALIGN __attribute__((aligned(CACHELINE)))
+#endif
+
+// Compiler hints
+#if defined(__GNUC__) || defined(__clang__)
+#define likely(x) __builtin_expect((x), 1)
+#define unlikely(x) __builtin_expect((x), 0)
+#else
+#define likely(x) (x)
+#define unlikely(x) (x)
+#endif
+
+static void cpu_pause(void) {
+#if defined(_MSC_VER) || defined(__x86_64__) || defined(__i386__)
+  _mm_pause();
+#endif
+}
+
+// Semaphores
+#if defined(_WIN32) || defined(_WIN64)
+typedef struct plat_sem {
+  HANDLE handle;
+} plat_sem;
+
+static b32 plat_sem_init(plat_sem *s, u32 initial) {
+  s->handle = CreateSemaphore(NULL, initial, LONG_MAX, NULL);
+  return s->handle != NULL;
+}
+
+static void plat_sem_wait(plat_sem *s) {
+  WaitForSingleObject(s->handle, INFINITE);
+}
+
+// static b32 plat_sem_trywait(HANDLE sem) { // Comment to prevent warning: unused function
+//   DWORD r = WaitForSingleObject(sem, 0);
+//   return r == WAIT_OBJECT_0;
+// }
+
+static void plat_sem_post(plat_sem *s, u32 count) {
+  ReleaseSemaphore(s->handle, count, NULL);
+}
+
+// static void plat_sem_destroy(plat_sem *s) { // Comment to prevent warning: unused function
+//   if (s->handle) {
+//     CloseHandle(s->handle);
+//     s->handle = NULL;
+//   }
+// }
+
+#elif defined(__linux__)
+#include <semaphore.h>
+
+typedef struct plat_sem {
+  sem_t sem;
+} plat_sem;
+
+static b32 plat_sem_init(plat_sem *s, u32 initial) {
+  return sem_init(&s->sem, 0, initial) == 0;
+}
+
+static void plat_sem_wait(plat_sem *s) {
+  while (sem_wait(&s->sem) == -1 && errno == EINTR) {
+  }
+}
+
+// static b32 plat_sem_trywait(sem_t *sem) { return sem_trywait(sem) == 0; } // Comment to prevent warning: unused function
+
+static void plat_sem_post(plat_sem *s, u32 count) {
+  for (u32 i = 0; i < count; i++) {
+    sem_post(&s->sem);
+  }
+}
+
+// static void plat_sem_destroy(plat_sem *s) { sem_destroy(&s->sem); } // Comment to prevent warning: unused function
+
+#endif
+
+typedef struct plat_sem plat_sem;
+
+typedef struct CACHE_ALIGN {
+  atomic_size_t seq;
+  void *data;
+  char pad[64 - sizeof(atomic_size_t) - sizeof(void *)];
+} MPMCSlot;
+
+typedef struct {
+  CACHE_ALIGN atomic_size_t head;
+  CACHE_ALIGN atomic_size_t tail;
+
+  CACHE_ALIGN atomic_size_t work_count;
+
+  size_t capacity;
+  size_t mask;
+
+  atomic_size_t committed;
+  size_t commit_step;
+  atomic_flag commit_lock;
+
+  plat_sem items_sem;
+
+  MPMCSlot *slots;
+} MPMCQueue;
+
+// --------------- functions ----------------
+// static: each translation unit gets its own private copy this will solve the
+// error:  Function defined in a header file; function definitions in header
+// files can lead to ODR violations (multiple definition errors if included in
+// more than one file)
+
+/* ----------------------------------------------------------- */
+/* INIT */
+/* ----------------------------------------------------------- */
+static void mpmc_init(MPMCQueue *q, size_t max_capacity) {
+
+  q->capacity = max_capacity;
+  q->mask = max_capacity - 1;
+
+  u32 pagesize = plat_get_pagesize();
+
+  size_t bytes = ALIGN_UP_POW2(sizeof(MPMCSlot) * max_capacity, pagesize);
+
+  q->slots = (MPMCSlot *)plat_mem_reserve(bytes);
+
+  if (!q->slots) {
+    fprintf(stderr, "VirtualAlloc reserve failed\n");
+    exit(1);
+  }
+
+  u64 commit_bytes = pagesize;
+  commit_bytes = ALIGN_UP_POW2(commit_bytes, pagesize);
+
+  q->commit_step = commit_bytes / sizeof(MPMCSlot);
+
+  atomic_flag_clear(&q->commit_lock);
+
+  q->committed = q->commit_step;
+
+  plat_mem_commit(q->slots, commit_bytes);
+
+  for (size_t i = 0; i < q->committed; i++) {
+    atomic_init(&q->slots[i].seq, i);
+    q->slots[i].data = NULL;
+  }
+
+  atomic_init(&q->head, 0);
+  atomic_init(&q->tail, 0);
+  atomic_init(&q->work_count, 0);
+
+  plat_sem_init(&q->items_sem, 0);
+}
+
+/* ----------------------------------------------------------- */
+/* COMMIT MORE MEMORY */
+/* ----------------------------------------------------------- */
+static void mpmc_commit_more(MPMCQueue *q) {
+
+  if (atomic_flag_test_and_set(&q->commit_lock))
+    return;
+
+  size_t start = atomic_load_explicit(&q->committed, memory_order_acquire);
+  size_t tail = atomic_load_explicit(&q->tail, memory_order_relaxed);
+
+  // another thread already committed enough
+  if (tail < start) {
+    atomic_flag_clear(&q->commit_lock);
+    return;
+  }
+
+  if (start >= q->capacity) {
+    atomic_flag_clear(&q->commit_lock);
+    return;
+  }
+
+  size_t new_commit = start + q->commit_step;
+  if (new_commit > q->capacity)
+    new_commit = q->capacity;
+
+  size_t count = new_commit - start;
+
+  plat_mem_commit(&q->slots[start], count * sizeof(MPMCSlot));
+
+  for (size_t i = start; i < new_commit; i++) {
+    atomic_init(&q->slots[i].seq, i);
+    q->slots[i].data = NULL;
+  }
+
+  atomic_store_explicit(&q->committed, new_commit, memory_order_release);
+
+  atomic_flag_clear(&q->commit_lock);
+}
+
+/* ----------------------------------------------------------- */
+/* PUSH */
+/* ----------------------------------------------------------- */
+// Does not increment work
+static void mpmc_push(MPMCQueue *q, void *item) {
+  MPMCSlot *slot;
+  size_t pos;
+
+  for (;;) {
+
+    pos = atomic_load_explicit(&q->tail, memory_order_relaxed);
+
+    // ensure the slot is committed BEFORE accessing it
+    size_t committed =
+        atomic_load_explicit(&q->committed, memory_order_relaxed);
+
+    if (unlikely(pos >= committed)) {
+      mpmc_commit_more(q);
+      continue;
+    }
+
+    slot = &q->slots[pos & q->mask];
+
+    size_t seq = atomic_load_explicit(&slot->seq, memory_order_acquire);
+    intptr_t diff = (intptr_t)seq - (intptr_t)pos;
+
+    if (likely(diff == 0)) {
+
+      if (atomic_compare_exchange_weak_explicit(&q->tail, &pos, pos + 1,
+                                                memory_order_relaxed,
+                                                memory_order_relaxed))
+        break;
+
+    } else if (diff < 0) { // queue actually full
+
+      sleep_ms(1000);
+
+    } else { // waiting to grow
+
+      sleep_ms(0);
+    }
+  }
+
+  slot->data = item;
+
+  atomic_store_explicit(&slot->seq, pos + 1, memory_order_release);
+
+  plat_sem_post(&q->items_sem, 1);
+}
+
+// Increment work
+static void mpmc_push_work(MPMCQueue *q, void *item) {
+  MPMCSlot *slot;
+  size_t pos;
+
+  for (;;) {
+
+    pos = atomic_load_explicit(&q->tail, memory_order_relaxed);
+
+    // ensure the slot is committed BEFORE accessing it
+    size_t committed =
+        atomic_load_explicit(&q->committed, memory_order_relaxed);
+
+    if (unlikely(pos >= committed)) {
+      mpmc_commit_more(q);
+      continue;
+    }
+
+    slot = &q->slots[pos & q->mask];
+
+    size_t seq = atomic_load_explicit(&slot->seq, memory_order_acquire);
+    intptr_t diff = (intptr_t)seq - (intptr_t)pos;
+
+    if (likely(diff == 0)) {
+
+      if (atomic_compare_exchange_weak_explicit(&q->tail, &pos, pos + 1,
+                                                memory_order_relaxed,
+                                                memory_order_relaxed))
+        break;
+
+    } else if (diff < 0) { // queue actually full
+
+      sleep_ms(1000);
+
+    } else { // waiting to grow
+
+      sleep_ms(0);
+    }
+  }
+
+  slot->data = item;
+
+  atomic_store_explicit(&slot->seq, pos + 1, memory_order_release);
+
+  atomic_fetch_add(&q->work_count, 1);
+  plat_sem_post(&q->items_sem, 1);
+}
+
+/* ----------------------------------------------------------- */
+/* POP */
+/* ----------------------------------------------------------- */
+static void *mpmc_pop(MPMCQueue *q) {
+
+  plat_sem_wait(&q->items_sem);
+
+  MPMCSlot *slot;
+  size_t pos;
+
+  int spins = 0;
+
+  for (;;) {
+
+    pos = atomic_load_explicit(&q->head, memory_order_relaxed);
+    slot = &q->slots[pos & q->mask];
+
+    size_t seq = atomic_load_explicit(&slot->seq, memory_order_acquire);
+    intptr_t diff = (intptr_t)seq - (intptr_t)(pos + 1);
+
+    if (likely(diff == 0)) {
+
+      if (atomic_compare_exchange_weak_explicit(&q->head, &pos, pos + 1,
+                                                memory_order_relaxed,
+                                                memory_order_relaxed))
+        break;
+
+    } else { // slot is still transitioning (written by another thread)
+      if (++spins > 10) {
+        sleep_ms(0); // yield CPU
+        spins = 0;
+      } else {
+        cpu_pause();
+      }
+    }
+  }
+
+  void *data = slot->data;
+
+  atomic_store_explicit(&slot->seq, pos + q->capacity, memory_order_release);
+
+  return data;
+}
+
+/* ----------------------------------------------------------- */
+/* PUSH POISON */
+/* ----------------------------------------------------------- */
+/*note:
+ After producers finishes, push N poison pills where N = number of consumer
+threads, this is necessary to stop the consumers.
+*/
+
+static void mpmc_producers_finished(MPMCQueue *q, u8 consumer_count) {
+  for (u8 i = 0; i < consumer_count; i++) {
+    mpmc_push(q, NULL);
+  }
+}
+
+/* ----------------------------------------------------------- */
+/* Done */
+/* ----------------------------------------------------------- */
+static void mpmc_task_done(MPMCQueue *q, u8 consumer_count) {
+  size_t prev = atomic_fetch_sub(&q->work_count, 1);
+  if (prev == 1) {
+    mpmc_producers_finished(q, consumer_count);
+  }
+}
+
+/* ----------------------------------------------------------- */
+/* MPMC Cleanup */
+/* ----------------------------------------------------------- */
+// static void mpmc_finish(MPMCQueue *q) { // Comment to prevent warning: unused function
+//   if (!q)
+//     return;
+//
+//   if (q->slots) {
+//     plat_mem_release(q->slots, 0);
+//     q->slots = NULL;
+//   }
+//
+//   plat_sem_destroy(&q->items_sem);
+//
+//   q->capacity = 0;
+//   q->mask = 0;
+//
+//   atomic_store_explicit(&q->head, 0, memory_order_relaxed);
+//   atomic_store_explicit(&q->tail, 0, memory_order_relaxed);
+//   atomic_store_explicit(&q->committed, 0, memory_order_relaxed);
+// }