* block.c: Data blocks management functions
*****************************************************************************
* Copyright (C) 2003-2004 the VideoLAN team
- * $Id$
+ * Copyright (C) 2007-2009 Rémi Denis-Courmont
*
* Authors: Laurent Aimar <fenrir@videolan.org>
*
#include <vlc_common.h>
#include <sys/stat.h>
+#include <assert.h>
#include "vlc_block.h"
/**
b->i_dts = VLC_TS_INVALID;
b->i_length = 0;
b->i_rate = 0;
+ b->i_samples = 0;
b->p_buffer = buf;
b->i_buffer = size;
#ifndef NDEBUG
free( p_block );
}
+static void BlockMetaCopy( block_t *restrict out, const block_t *in )
+{
+ out->p_next = in->p_next;
+ out->i_dts = in->i_dts;
+ out->i_pts = in->i_pts;
+ out->i_flags = in->i_flags;
+ out->i_length = in->i_length;
+ out->i_rate = in->i_rate;
+ out->i_samples = in->i_samples;
+}
+
/* Memory alignment */
#define BLOCK_ALIGN 16
/* Initial size of reserved header and footer */
block_t *block_Realloc( block_t *p_block, ssize_t i_prebody, size_t i_body )
{
block_sys_t *p_sys = (block_sys_t *)p_block;
- ssize_t i_buffer_size = i_prebody + i_body;
+ size_t requested = i_prebody + i_body;
- if( i_buffer_size <= 0 )
+ /* Corner case: empty block requested */
+ if( i_prebody <= 0 && i_body <= (size_t)(-i_prebody) )
{
block_Release( p_block );
return NULL;
p_sys = (block_sys_t *)p_block;
}
- /* Adjust reserved header if there is enough room */
- if( p_block->p_buffer - i_prebody > p_sys->p_allocated_buffer &&
- p_block->p_buffer - i_prebody < p_sys->p_allocated_buffer +
- p_sys->i_allocated_buffer )
+ uint8_t *p_start = p_sys->p_allocated_buffer;
+ uint8_t *p_end = p_sys->p_allocated_buffer + p_sys->i_allocated_buffer;
+
+ assert( p_block->p_buffer + p_block->i_buffer <= p_end );
+ assert( p_block->p_buffer >= p_start );
+
+ /* Corner case: the current payload is discarded completely */
+ if( i_prebody <= 0 && p_block->i_buffer <= (size_t)-i_prebody )
+ p_block->i_buffer = 0; /* discard current payload */
+ if( p_block->i_buffer == 0 )
+ {
+ size_t available = p_end - p_start;
+
+ if( requested <= available )
+ { /* Enough room: recycle buffer */
+ size_t extra = available - requested;
+
+ p_block->p_buffer = p_start + (extra / 2);
+ p_block->i_buffer = requested;
+ return p_block;
+ }
+ /* Not enough room: allocate a new buffer */
+ block_t *p_rea = block_Alloc( requested );
+ if( p_rea )
+ BlockMetaCopy( p_rea, p_block );
+ block_Release( p_block );
+ return p_rea;
+ }
+
+ /* First, shrink payload */
+
+ /* Pull payload start */
+ if( i_prebody < 0 )
{
+ assert( p_block->i_buffer >= (size_t)-i_prebody );
p_block->p_buffer -= i_prebody;
p_block->i_buffer += i_prebody;
+ i_body += i_prebody;
i_prebody = 0;
}
- /* Adjust payload size if there is enough room */
- if( p_block->p_buffer + i_body < p_sys->p_allocated_buffer +
- p_sys->i_allocated_buffer )
- {
- p_block->i_buffer = i_buffer_size;
- i_body = 0;
- }
+ /* Trim payload end */
+ if( p_block->i_buffer > i_body )
+ p_block->i_buffer = i_body;
- /* Not enough room, reallocate the buffer */
- if( i_body > 0 || i_prebody > 0 )
+ /* Second, reallocate the buffer if we lack space. This is done now to
+ * minimize the payload size for memory copy. */
+ assert( i_prebody >= 0 );
+ if( (size_t)(p_block->p_buffer - p_start) < (size_t)i_prebody
+ || (size_t)(p_end - p_block->p_buffer) < i_body )
{
/* FIXME: this is really dumb, we should use realloc() */
- block_t *p_rea = block_New( NULL, i_buffer_size );
-
+ block_t *p_rea = block_Alloc( requested );
if( p_rea )
{
- p_rea->i_dts = p_block->i_dts;
- p_rea->i_pts = p_block->i_pts;
- p_rea->i_flags = p_block->i_flags;
- p_rea->i_length = p_block->i_length;
- p_rea->i_rate = p_block->i_rate;
- p_rea->i_samples = p_block->i_samples;
-
- memcpy( p_rea->p_buffer + i_prebody, p_block->p_buffer,
- __MIN( p_block->i_buffer, p_rea->i_buffer - i_prebody ) );
+ BlockMetaCopy( p_rea, p_block );
+ p_rea->p_buffer += i_prebody;
+ p_rea->i_buffer -= i_prebody;
+ memcpy( p_rea->p_buffer, p_block->p_buffer, p_block->i_buffer );
}
-
block_Release( p_block );
-
- return p_rea;
+ p_block = p_rea;
}
-
+ else
/* We have a very large reserved footer now? Release some of it.
- * XXX it may not keep the algniment of p_buffer */
- if( (p_sys->p_allocated_buffer + p_sys->i_allocated_buffer) -
- (p_block->p_buffer + p_block->i_buffer) > BLOCK_WASTE_SIZE )
+ * XXX it might not preserve the alignment of p_buffer */
+ if( p_end - (p_block->p_buffer + i_body) > BLOCK_WASTE_SIZE )
{
- const ptrdiff_t i_prebody = p_block->p_buffer - p_sys->p_allocated_buffer;
- const size_t i_new = i_prebody + p_block->i_buffer + 1 * BLOCK_PADDING_SIZE;
+ const ptrdiff_t i_prebody = p_block->p_buffer - p_start;
+ const size_t i_new = requested + 1 * BLOCK_PADDING_SIZE;
block_sys_t *p_new = realloc( p_sys, sizeof (*p_sys) + i_new );
if( p_new != NULL )
p_block->p_buffer = &p_sys->p_allocated_buffer[i_prebody];
}
}
+
+ /* NOTE: p_start and p_end are corrupted from this point */
+
+ /* Third, expand payload */
+
+ /* Push payload start */
+ if( i_prebody > 0 )
+ {
+ p_block->p_buffer -= i_prebody;
+ p_block->i_buffer += i_prebody;
+ i_body += i_prebody;
+ i_prebody = 0;
+ }
+
+ /* Expand payload to requested size */
+ p_block->i_buffer = i_body;
+
return p_block;
}
projects / vlc / blobdiff