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#include <assert.h>
#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
struct arena {
void *buffer;
size_t offset;
size_t size;
};
void arena_create(struct arena *arena)
{
unsigned long const init_size = 4ul * 1024ul;
*arena = (struct arena){
.buffer = malloc(init_size),
.size = init_size,
};
}
void arena_destroy(struct arena *arena)
{
free(arena->buffer);
*arena = (struct arena){0};
}
size_t arena_add(struct arena *arena, void const *data, size_t const size)
{
size_t const offset = arena->offset;
if (size + offset > arena->size) {
arena->size = (size + offset) * 1.5;
arena->buffer = realloc(arena->buffer, arena->size);
assert(arena->buffer);
}
if (data) {
memcpy(arena->buffer + offset, data, size);
}
arena->offset += size;
return offset;
}
static inline void *arena_get(struct arena const *arena, size_t offset)
{
return arena->buffer + offset;
}
int main(int argc, char * const argv[])
{
(void)argc;
(void)argv;
struct arena arena;
arena_create(&arena);
unsigned data[4] = {1u, 2u, 3u, 4u};
for (size_t i = 0; i < 50000000lu; i++) {
size_t const offset = arena_add(&arena, data, sizeof(data));
data[0] = (uintptr_t)arena_get(&arena, offset);
}
arena_destroy(&arena);
}
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