gstreamer/subprojects/gst-plugins-bad/gst/dvbsubenc/libimagequant/mempool.c

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#include "libimagequant.h"
#include "mempool.h"
#include <stdlib.h>
#include <stdint.h>
#include <assert.h>
#define ALIGN_MASK 15UL
#define MEMPOOL_RESERVED ((sizeof(struct mempool)+ALIGN_MASK) & ~ALIGN_MASK)
struct mempool
{
unsigned int used, size;
void *(*malloc) (size_t);
void (*free) (void *);
struct mempool *next;
};
LIQ_PRIVATE void *
mempool_create (mempool * mptr, const unsigned int size, unsigned int max_size,
void *(*malloc) (size_t), void (*free) (void *))
{
mempool old;
uintptr_t mptr_used_start;
if (*mptr && ((*mptr)->used + size) <= (*mptr)->size) {
unsigned int prevused = (*mptr)->used;
(*mptr)->used += (size + 15UL) & ~0xFUL;
return ((char *) (*mptr)) + prevused;
}
old = *mptr;
if (!max_size)
max_size = (1 << 17);
max_size = size + ALIGN_MASK > max_size ? size + ALIGN_MASK : max_size;
*mptr = malloc (MEMPOOL_RESERVED + max_size);
if (!*mptr)
return NULL;
**mptr = (struct mempool) {
.malloc = malloc,.free = free,.size = MEMPOOL_RESERVED + max_size,.used =
sizeof (struct mempool),.next = old,
};
mptr_used_start = (uintptr_t) (*mptr) + (*mptr)->used;
(*mptr)->used += (ALIGN_MASK + 1 - (mptr_used_start & ALIGN_MASK)) & ALIGN_MASK; // reserve bytes required to make subsequent allocations aligned
assert (!(((uintptr_t) (*mptr) + (*mptr)->used) & ALIGN_MASK));
return mempool_alloc (mptr, size, size);
}
LIQ_PRIVATE void *
mempool_alloc (mempool * mptr, unsigned int size, unsigned int max_size)
{
if (((*mptr)->used + size) <= (*mptr)->size) {
unsigned int prevused = (*mptr)->used;
(*mptr)->used += (size + ALIGN_MASK) & ~ALIGN_MASK;
return ((char *) (*mptr)) + prevused;
}
return mempool_create (mptr, size, max_size, (*mptr)->malloc, (*mptr)->free);
}
LIQ_PRIVATE void
mempool_destroy (mempool m)
{
while (m) {
mempool next = m->next;
m->free (m);
m = next;
}
}