bgfx_alloc.cpp

#include "bgfx_alloc.h"
#include <bx/allocator.h>
#include <atomic>
#include <stdlib.h>

#ifndef BX_CONFIG_ALLOCATOR_NATURAL_ALIGNMENT
#    define BX_CONFIG_ALLOCATOR_NATURAL_ALIGNMENT 8
#endif

static bx::DefaultAllocator bx_alloc;
static std::atomic<int64_t> allocator_memory (0);

#if BX_PLATFORM_WINDOWS
#define bx_malloc_size _msize
#elif BX_PLATFORM_LINUX
#define bx_malloc_size malloc_usable_size
#elif BX_PLATFORM_OSX
#include <malloc/malloc.h>
#define bx_malloc_size malloc_size
#elif BX_PLATFORM_IOS
#include <malloc/malloc.h>
#define bx_malloc_size malloc_size
#else
#    error "Unknown PLATFORM!"
#endif

static void* originalPtr(void* _ptr, size_t _align) {
    if (BX_CONFIG_ALLOCATOR_NATURAL_ALIGNMENT >= _align) {
        return _ptr;
    }
    uint8_t* aligned = (uint8_t*)_ptr;
    uint32_t* header = (uint32_t*)aligned - 1;
    uint8_t* ptr = aligned - *header;
    return ptr;
}

static size_t bx_aligned_malloc_size(void* _ptr, size_t _align) {
#if BX_COMPILER_MSVC
    if (BX_CONFIG_ALLOCATOR_NATURAL_ALIGNMENT >= _align) {
        return _msize(_ptr);
    }
    return _aligned_msize(_ptr, _align, 0);
#else
    return bx_malloc_size(originalPtr(_ptr, _align));
#endif
}

static void* allocator_realloc(bgfx_allocator_interface_t* /*_this*/, void* _ptr, size_t _size, size_t _align, const char* _file, uint32_t _line) {
    if (_ptr) {
        allocator_memory -= bx_aligned_malloc_size(_ptr, _align);
    }
    void* newptr = bx_alloc.realloc(_ptr, _size, _align, _file, _line);
    if (newptr) {
        allocator_memory += bx_aligned_malloc_size(newptr, _align);
    }
    return newptr;
}

static bgfx_allocator_vtbl_t      allocator_vtbl = {.realloc=allocator_realloc};
static bgfx_allocator_interface_t allocator_impl = {.vtbl=&allocator_vtbl};

int luabgfx_getalloc(bgfx_allocator_interface_t** pinterface) {
    *pinterface = &allocator_impl;
    return 1;
}

int luabgfx_info(int64_t* psize) {
    *psize = allocator_memory;
    return 1;
}