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#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
/**
* Simple bump allocator that can be used for
* allocations with a frame lifetime.
*/
struct frame_allocator {
uint8_t *buf;
size_t offset;
size_t capacity;
};
/**
* Create a new frame allocator
*
* @param capacity The capacity in bytes of the frame allocator
* @returns The frame allocator
*/
struct frame_allocator frame_allocator_create(size_t capacity) {
return (struct frame_allocator){
.capacity = capacity, .offset = 0, .buf = (uint8_t *)malloc(capacity)};
}
/**
* Allocate memory in this @ref frame_allocator "frame allocator"
*
* @param alloc The allocator to allocate in
* @param sz The size in bytes to allocate.
* @returns void* representing the start of the allocated region on success,
* NULL on failure.
*/
void *frame_allocator_alloc(struct frame_allocator *alloc, size_t sz) {
if (alloc->offset + sz > alloc->capacity) {
return NULL;
}
void *mem = alloc->buf + alloc->offset;
alloc->offset += sz;
return mem;
}
/**
* Clear this @ref frame_allocator "frame allocator".
*
* This does not free any memory, but simply resets the offset to 0.
* @param alloc The frame allocator to clear
*/
void frame_allocator_clear(struct frame_allocator *alloc) { alloc->offset = 0; }
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