gstreamer/sys/shm/shmalloc.c

182 lines
4.2 KiB
C

/* GStreamer
* Copyright (C) <2009> Collabora Ltd
* @author: Olivier Crete <olivier.crete@collabora.co.uk
* Copyright (C) <2009> Nokia Inc
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "shmalloc.h"
#include <stdio.h>
#include <string.h>
#include <assert.h>
/* This is the allocated space to hold multiple blocks */
struct _ShmAllocSpace
{
/* The total size of this space */
size_t size;
/* chained list of the blocks contained in this space */
ShmAllocBlock *blocks;
};
/* A single block of data */
struct _ShmAllocBlock
{
int use_count;
/* Pointer back to the AllocSpace where this block is */
ShmAllocSpace *space;
/* The offset of this block in the alloc space */
unsigned long offset;
/* The size of the block */
unsigned long size;
/* Pointer to the next block in the chain */
ShmAllocBlock *next;
};
ShmAllocSpace *
shm_alloc_space_new (size_t size)
{
ShmAllocSpace *self = spalloc_new (ShmAllocSpace);
memset (self, 0, sizeof (ShmAllocSpace));
self->size = size;
return self;
}
void
shm_alloc_space_free (ShmAllocSpace * self)
{
assert (self && self->blocks == NULL);
spalloc_free (ShmAllocSpace, self);
}
ShmAllocBlock *
shm_alloc_space_alloc_block (ShmAllocSpace * self, unsigned long size)
{
ShmAllocBlock *block;
ShmAllocBlock *item = NULL;
ShmAllocBlock *prev_item = NULL;
unsigned long prev_end_offset = 0;
for (item = self->blocks; item; item = item->next) {
unsigned long max_size = 0;
max_size = item->offset - prev_end_offset;
if (max_size >= size)
break;
prev_end_offset = item->offset + item->size;
prev_item = item;
}
/* Return NULL if there is no big enough space, otherwise, there is space
* at the end */
assert (prev_end_offset <= self->size);
if (!item && self->size - prev_end_offset < size)
return NULL;
block = spalloc_new (ShmAllocBlock);
memset (block, 0, sizeof (ShmAllocBlock));
block->offset = prev_end_offset;
block->size = size;
block->use_count = 1;
block->space = self;
if (prev_item)
prev_item->next = block;
else
self->blocks = block;
block->next = item;
return block;
}
unsigned long
shm_alloc_space_alloc_block_get_offset (ShmAllocBlock * block)
{
return block->offset;
}
static void
shm_alloc_space_free_block (ShmAllocBlock * block)
{
ShmAllocBlock *item = NULL;
ShmAllocBlock *prev_item = NULL;
ShmAllocSpace *self = block->space;
for (item = self->blocks; item; item = item->next) {
if (item == block) {
if (prev_item)
prev_item->next = item->next;
else
self->blocks = item->next;
break;
}
prev_item = item;
}
spalloc_free (ShmAllocBlock, block);
}
ShmAllocBlock *
shm_alloc_space_block_get (ShmAllocSpace * self, unsigned long offset)
{
ShmAllocBlock *block = NULL;
for (block = self->blocks; block; block = block->next) {
if (block->offset <= offset && (block->offset + block->size) > offset)
return block;
}
return NULL;
}
void
shm_alloc_space_block_inc (ShmAllocBlock * block)
{
block->use_count++;
}
void
shm_alloc_space_block_dec (ShmAllocBlock * block)
{
block->use_count--;
if (block->use_count <= 0)
shm_alloc_space_free_block (block);
}