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vlc/include/vlc_block_helper.h

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/*****************************************************************************
* vlc_block_helper.h: Helper functions for data blocks management.
*****************************************************************************
* Copyright (C) 2003-2017 VLC authors and VideoLAN
*
* Authors: Gildas Bazin <gbazin@netcourrier.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
*****************************************************************************/
#ifndef VLC_BLOCK_HELPER_H
#define VLC_BLOCK_HELPER_H 1
#include <vlc_block.h>
typedef struct block_bytestream_t
{
block_t *p_chain; /**< byte stream head block */
block_t **pp_last; /**< tail ppointer for appends */
block_t *p_block; /**< byte stream read pointer block */
size_t i_block_offset; /**< byte stream read pointer offset within block */
size_t i_base_offset; /**< block base offset (previous blocks total size) */
size_t i_total; /**< total bytes over all linked blocks */
} block_bytestream_t;
/*****************************************************************************
* block_bytestream_t management
*****************************************************************************/
static inline void block_BytestreamInit( block_bytestream_t *p_bytestream )
{
p_bytestream->p_chain = p_bytestream->p_block = NULL;
p_bytestream->pp_last = &p_bytestream->p_chain;
p_bytestream->i_block_offset = 0;
p_bytestream->i_base_offset = 0;
p_bytestream->i_total = 0;
}
static inline void block_BytestreamRelease( block_bytestream_t *p_bytestream )
{
block_ChainRelease( p_bytestream->p_chain );
}
/**
* It flush all data (read and unread) from a block_bytestream_t.
*/
static inline void block_BytestreamEmpty( block_bytestream_t *p_bytestream )
{
block_BytestreamRelease( p_bytestream );
block_BytestreamInit( p_bytestream );
}
/**
* It flushes all already read data from a block_bytestream_t.
*/
static inline void block_BytestreamFlush( block_bytestream_t *p_bytestream )
{
block_t *block = p_bytestream->p_chain;
while( block != p_bytestream->p_block )
{
block_t *p_next = block->p_next;
p_bytestream->i_total -= block->i_buffer;
p_bytestream->i_base_offset -= block->i_buffer;
block_Release( block );
block = p_next;
}
while( block != NULL && block->i_buffer == p_bytestream->i_block_offset )
{
block_t *p_next = block->p_next;
p_bytestream->i_total -= block->i_buffer;
block_Release( block );
block = p_next;
p_bytestream->i_block_offset = 0;
}
p_bytestream->p_chain = p_bytestream->p_block = block;
if( p_bytestream->p_chain == NULL )
p_bytestream->pp_last = &p_bytestream->p_chain;
}
static inline void block_BytestreamPush( block_bytestream_t *p_bytestream,
block_t *p_block )
{
block_ChainLastAppend( &p_bytestream->pp_last, p_block );
if( !p_bytestream->p_block ) p_bytestream->p_block = p_block;
for( ; p_block; p_block = p_block->p_next )
p_bytestream->i_total += p_block->i_buffer;
}
static inline size_t block_BytestreamRemaining( const block_bytestream_t *p_bytestream )
{
return ( p_bytestream->i_total > p_bytestream->i_base_offset + p_bytestream->i_block_offset ) ?
p_bytestream->i_total - p_bytestream->i_base_offset - p_bytestream->i_block_offset : 0;
}
VLC_USED
static inline block_t *block_BytestreamPop( block_bytestream_t *p_bytestream )
{
block_t *p_block;
block_BytestreamFlush( p_bytestream );
p_block = p_bytestream->p_block;
if( unlikely( p_block == NULL ) )
{
return NULL;
}
else if( !p_block->p_next )
{
p_block->p_buffer += p_bytestream->i_block_offset;
p_block->i_buffer -= p_bytestream->i_block_offset;
p_bytestream->i_block_offset = 0;
p_bytestream->i_total = 0;
p_bytestream->p_chain = p_bytestream->p_block = NULL;
p_bytestream->pp_last = &p_bytestream->p_chain;
return p_block;
}
while( p_block->p_next && p_block->p_next->p_next )
p_block = p_block->p_next;
block_t *p_block_old = p_block;
p_block = p_block->p_next;
p_block_old->p_next = NULL;
p_bytestream->pp_last = &p_block_old->p_next;
if( p_block )
p_bytestream->i_total -= p_block->i_buffer;
return p_block;
}
static inline int block_WaitBytes( block_bytestream_t *p_bytestream,
size_t i_data )
{
if( block_BytestreamRemaining( p_bytestream ) >= i_data )
return VLC_SUCCESS;
return VLC_EGENERIC;
}
static inline int block_PeekBytes( block_bytestream_t *p_bytestream,
uint8_t *p_data, size_t i_data )
{
if( block_BytestreamRemaining( p_bytestream ) < i_data )
return VLC_EGENERIC;
/* Copy the data */
size_t i_offset = p_bytestream->i_block_offset;
size_t i_size = i_data;
for( block_t *p_block = p_bytestream->p_block;
p_block != NULL; p_block = p_block->p_next )
{
size_t i_copy = __MIN( i_size, p_block->i_buffer - i_offset );
i_size -= i_copy;
if( i_copy )
{
memcpy( p_data, p_block->p_buffer + i_offset, i_copy );
p_data += i_copy;
}
i_offset = 0;
if( !i_size ) break;
}
return VLC_SUCCESS;
}
static inline int block_GetBytes( block_bytestream_t *p_bytestream,
uint8_t *p_data, size_t i_data )
{
if( block_BytestreamRemaining( p_bytestream ) < i_data )
return VLC_EGENERIC;
/* Copy the data */
size_t i_offset = p_bytestream->i_block_offset;
size_t i_size = i_data;
size_t i_copy = 0;
block_t *p_block;
for( p_block = p_bytestream->p_block;
p_block != NULL; p_block = p_block->p_next )
{
i_copy = __MIN( i_size, p_block->i_buffer - i_offset );
i_size -= i_copy;
if( i_copy && p_data != NULL )
{
memcpy( p_data, p_block->p_buffer + i_offset, i_copy );
p_data += i_copy;
}
if( i_size == 0 )
break;
p_bytestream->i_base_offset += p_block->i_buffer;
i_offset = 0;
}
p_bytestream->p_block = p_block;
p_bytestream->i_block_offset = i_offset + i_copy;
return VLC_SUCCESS;
}
static inline int block_SkipBytes( block_bytestream_t *p_bytestream,
size_t i_data )
{
return block_GetBytes( p_bytestream, NULL, i_data );
}
static inline int block_SkipByte( block_bytestream_t *p_bytestream )
{
return block_GetBytes( p_bytestream, NULL, 1 );
}
static inline int block_PeekOffsetBytes( block_bytestream_t *p_bytestream,
size_t i_peek_offset, uint8_t *p_data, size_t i_data )
{
const size_t i_remain = block_BytestreamRemaining( p_bytestream );
if( i_remain < i_data + i_peek_offset )
return VLC_EGENERIC;
/* Find the right place */
size_t i_offset = p_bytestream->i_block_offset;
size_t i_size = i_peek_offset;
size_t i_copy = 0;
block_t *p_block;
for( p_block = p_bytestream->p_block;
p_block != NULL; p_block = p_block->p_next )
{
i_copy = __MIN( i_size, p_block->i_buffer - i_offset );
i_size -= i_copy;
if( !i_size ) break;
i_offset = 0;
}
/* Copy the data */
i_offset += i_copy;
i_size = i_data;
for( ; p_block != NULL; p_block = p_block->p_next )
{
i_copy = __MIN( i_size, p_block->i_buffer - i_offset );
i_size -= i_copy;
if( i_copy )
{
memcpy( p_data, p_block->p_buffer + i_offset, i_copy );
p_data += i_copy;
}
i_offset = 0;
if( !i_size ) break;
}
return VLC_SUCCESS;
}
typedef const uint8_t * (*block_startcode_helper_t)( const uint8_t *, const uint8_t * );
typedef bool (*block_startcode_matcher_t)( uint8_t, size_t, const uint8_t * );
static inline int block_FindStartcodeFromOffset(
block_bytestream_t *p_bytestream, size_t *pi_offset,
const uint8_t *p_startcode, int i_startcode_length,
block_startcode_helper_t p_startcode_helper,
block_startcode_matcher_t p_startcode_matcher )
{
block_t *p_block, *p_block_backup = 0;
ssize_t i_size = 0;
size_t i_offset, i_offset_backup = 0;
int i_caller_offset_backup = 0, i_match;
/* Find the right place */
i_size = *pi_offset + p_bytestream->i_block_offset;
for( p_block = p_bytestream->p_block;
p_block != NULL; p_block = p_block->p_next )
{
i_size -= p_block->i_buffer;
if( i_size < 0 ) break;
}
if( unlikely( i_size >= 0 ) )
{
/* Not enough data, bail out */
return VLC_EGENERIC;
}
/* Begin the search.
* We first look for an occurrence of the 1st startcode byte and
* if found, we do a more thorough check. */
i_size += p_block->i_buffer;
*pi_offset -= i_size;
i_match = 0;
for( ; p_block != NULL; p_block = p_block->p_next )
{
for( i_offset = i_size; i_offset < p_block->i_buffer; i_offset++ )
{
/* Use optimized helper when possible */
if( p_startcode_helper && !i_match &&
(p_block->i_buffer - i_offset) > ((size_t)i_startcode_length - 1) )
{
const uint8_t *p_res = p_startcode_helper( &p_block->p_buffer[i_offset],
&p_block->p_buffer[p_block->i_buffer] );
if( p_res )
{
*pi_offset += i_offset + (p_res - &p_block->p_buffer[i_offset]);
return VLC_SUCCESS;
}
/* Then parsing boundary with legacy code */
i_offset = p_block->i_buffer - (i_startcode_length - 1);
}
bool b_matched = ( p_startcode_matcher )
? p_startcode_matcher( p_block->p_buffer[i_offset], i_match, p_startcode )
: p_block->p_buffer[i_offset] == p_startcode[i_match];
if( b_matched )
{
if( i_match == 0 )
{
p_block_backup = p_block;
i_offset_backup = i_offset;
i_caller_offset_backup = *pi_offset;
}
if( i_match + 1 == i_startcode_length )
{
/* We have it */
*pi_offset += i_offset - i_match;
return VLC_SUCCESS;
}
i_match++;
}
else if ( i_match > 0 )
{
/* False positive */
p_block = p_block_backup;
i_offset = i_offset_backup;
*pi_offset = i_caller_offset_backup;
i_match = 0;
}
}
i_size = 0;
*pi_offset += i_offset;
}
*pi_offset -= i_match;
return VLC_EGENERIC;
}
#endif /* VLC_BLOCK_HELPER_H */
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