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#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include "wv_mem.h"
#include "wv_err.h"
/* Detect alignment pre-C11 */
union wv_max_align { long l; double d; void *p; };
#define WV_ALIGNOF(type) offsetof(struct { char c; type member; }, member)
#define WV_ALIGNMENT WV_ALIGNOF(union wv_max_align)
#define WV_ALIGN_MASK (WV_ALIGNMENT - 1)
#define WV_ARENA_MIN_SIZE (256 * 1024)
#define WV_ARENA_RESERVED WV_ALIGNMENT /* Reserve 0 as the sentinel "null" ref */
struct wv_arena *wv_arena_create(size_t n)
{
struct wv_arena *arena;
if (n < WV_ARENA_MIN_SIZE)
n = WV_ARENA_MIN_SIZE;
arena = malloc(sizeof(struct wv_arena));
if (arena == NULL)
err(1, "malloc arena struct");
arena->buf = malloc(n);
if (arena->buf == NULL)
err(1, "malloc arena buffer");
arena->size = n;
arena->offset = WV_ARENA_RESERVED;
return arena;
}
wv_ref wv_alloc(struct wv_arena *arena, size_t n)
{
wv_ref ref;
unsigned char *new_buf;
size_t aligned_n, new_size;
if (n == 0)
errx(1, "wv_alloc: zero-size allocation");
if (n > SIZE_MAX - WV_ALIGN_MASK)
errx(1, "wv_alloc: allocation size overflow");
aligned_n = (n + WV_ALIGN_MASK) & ~WV_ALIGN_MASK;
if (aligned_n > SIZE_MAX - arena->offset)
errx(1, "wv_alloc: arena offset overflow");
if (arena->offset + aligned_n > arena->size) {
new_size = arena->size;
while (new_size < arena->offset + aligned_n) {
if (new_size > SIZE_MAX / 2)
errx(1, "wv_alloc: arena growth overflow");
new_size *= 2;
}
new_buf = realloc(arena->buf, new_size);
if (new_buf == NULL)
err(1, "realloc arena failed at %zu bytes", new_size);
arena->buf = new_buf;
arena->size = new_size;
}
ref = (wv_ref)arena->offset;
arena->offset += aligned_n;
return ref;
}
void wv_arena_reset(struct wv_arena *arena)
{
if (arena == NULL)
return;
memset(arena->buf, 0, arena->offset);
arena->offset = WV_ARENA_RESERVED;
}
void wv_arena_destroy(struct wv_arena *arena)
{
if (arena == NULL)
return;
free(arena->buf);
free(arena);
}
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