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