e74e23d672
Storing the size of the blocks is now only activated when DEBUG__MEMFILL has been defined.
87 lines
2 KiB
C
87 lines
2 KiB
C
#include <string.h>
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#include <stdlib.h>
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#include "internal.h"
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// NOTE(uucidl): undefine to automatically fill up newly allocated block
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// with this byte:
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// #define DEBUG__MEMFILL 0xFF
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#if defined(DEBUG__MEMFILL)
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/**
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* Blocks allocated by the system_allocator start with this header.
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* I.e. the user part of the allocation directly follows.
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*/
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typedef struct HDebugBlockHeader_
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{
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size_t size; /** size of the user allocation */
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} HDebugBlockHeader;
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#define BLOCK_HEADER_SIZE (sizeof(HDebugBlockHeader))
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#else
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#define BLOCK_HEADER_SIZE (0)
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#endif
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/**
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* Compute the total size needed for a given allocation size.
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*/
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static inline size_t block_size(size_t alloc_size) {
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return BLOCK_HEADER_SIZE + alloc_size;
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}
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/**
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* Obtain the block containing the user pointer `uptr`
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*/
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static inline void* block_for_user_ptr(void *uptr) {
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return ((char*)uptr) - BLOCK_HEADER_SIZE;
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}
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/**
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* Obtain the user area of the allocation from a given block
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*/
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static inline void* user_ptr(void *block) {
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return ((char*)block) + BLOCK_HEADER_SIZE;
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}
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static void* system_alloc(HAllocator *allocator, size_t size) {
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void *block = malloc(block_size(size));
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if (!block) {
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return NULL;
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}
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void *uptr = user_ptr(block);
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#ifdef DEBUG__MEMFILL
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memset(uptr, DEBUG__MEMFILL, size);
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((HDebugBlockHeader*)block)->size = size;
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#endif
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return uptr;
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}
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static void* system_realloc(HAllocator *allocator, void* uptr, size_t size) {
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if (!uptr) {
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return system_alloc(allocator, size);
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}
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void* block = realloc(block_for_user_ptr(uptr), block_size(size));
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if (!block) {
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return NULL;
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}
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uptr = user_ptr(block);
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#ifdef DEBUG__MEMFILL
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size_t old_size = ((HDebugBlockHeader*)block)->size;
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if (size > old_size)
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memset((char*)uptr+old_size, DEBUG__MEMFILL, size - old_size);
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((HDebugBlockHeader*)block)->size = size;
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#endif
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return uptr;
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}
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static void system_free(HAllocator *allocator, void* uptr) {
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if (uptr) {
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free(block_for_user_ptr(uptr));
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}
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}
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HAllocator system_allocator = {
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.alloc = system_alloc,
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.realloc = system_realloc,
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.free = system_free,
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};
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