vlc_bits.h
资源名称:vlc-1.0.5.zip [点击查看]
上传用户:kjfoods
上传日期:2020-07-06
资源大小:29949k
文件大小:4k
源码类别:
midi
开发平台:
Unix_Linux
- /*****************************************************************************
- * bits.h : Bit handling helpers
- *****************************************************************************
- * Copyright (C) 2003 the VideoLAN team
- * $Id: 778493cb3f7f7e46a8ae967b500300b52b77f846 $
- *
- * Authors: Laurent Aimar <fenrir@via.ecp.fr>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 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 General Public License for more details.
- *
- * You should have received a copy of the GNU 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_BITS_H
- #define VLC_BITS_H 1
- /**
- * file
- * This file defines functions, structures for handling streams of bits in vlc
- */
- typedef struct bs_s
- {
- uint8_t *p_start;
- uint8_t *p;
- uint8_t *p_end;
- int i_left; /* i_count number of available bits */
- } bs_t;
- static inline void bs_init( bs_t *s, void *p_data, int i_data )
- {
- s->p_start = p_data;
- s->p = p_data;
- s->p_end = s->p + i_data;
- s->i_left = 8;
- }
- static inline int bs_pos( bs_t *s )
- {
- return( 8 * ( s->p - s->p_start ) + 8 - s->i_left );
- }
- static inline int bs_eof( bs_t *s )
- {
- return( s->p >= s->p_end ? 1: 0 );
- }
- static inline uint32_t bs_read( bs_t *s, int i_count )
- {
- static const uint32_t i_mask[33] =
- { 0x00,
- 0x01, 0x03, 0x07, 0x0f,
- 0x1f, 0x3f, 0x7f, 0xff,
- 0x1ff, 0x3ff, 0x7ff, 0xfff,
- 0x1fff, 0x3fff, 0x7fff, 0xffff,
- 0x1ffff, 0x3ffff, 0x7ffff, 0xfffff,
- 0x1fffff, 0x3fffff, 0x7fffff, 0xffffff,
- 0x1ffffff, 0x3ffffff, 0x7ffffff, 0xfffffff,
- 0x1fffffff,0x3fffffff,0x7fffffff,0xffffffff};
- int i_shr;
- uint32_t i_result = 0;
- while( i_count > 0 )
- {
- if( s->p >= s->p_end )
- {
- break;
- }
- if( ( i_shr = s->i_left - i_count ) >= 0 )
- {
- /* more in the buffer than requested */
- i_result |= ( *s->p >> i_shr )&i_mask[i_count];
- s->i_left -= i_count;
- if( s->i_left == 0 )
- {
- s->p++;
- s->i_left = 8;
- }
- return( i_result );
- }
- else
- {
- /* less in the buffer than requested */
- i_result |= (*s->p&i_mask[s->i_left]) << -i_shr;
- i_count -= s->i_left;
- s->p++;
- s->i_left = 8;
- }
- }
- return( i_result );
- }
- static inline uint32_t bs_read1( bs_t *s )
- {
- if( s->p < s->p_end )
- {
- unsigned int i_result;
- s->i_left--;
- i_result = ( *s->p >> s->i_left )&0x01;
- if( s->i_left == 0 )
- {
- s->p++;
- s->i_left = 8;
- }
- return i_result;
- }
- return 0;
- }
- static inline uint32_t bs_show( bs_t *s, int i_count )
- {
- bs_t s_tmp = *s;
- return bs_read( &s_tmp, i_count );
- }
- static inline void bs_skip( bs_t *s, int i_count )
- {
- s->i_left -= i_count;
- if( s->i_left <= 0 )
- {
- const int i_bytes = ( -s->i_left + 8 ) / 8;
- s->p += i_bytes;
- s->i_left += 8 * i_bytes;
- }
- }
- static inline void bs_write( bs_t *s, int i_count, uint32_t i_bits )
- {
- while( i_count > 0 )
- {
- if( s->p >= s->p_end )
- {
- break;
- }
- i_count--;
- if( ( i_bits >> i_count )&0x01 )
- {
- *s->p |= 1 << ( s->i_left - 1 );
- }
- else
- {
- *s->p &= ~( 1 << ( s->i_left - 1 ) );
- }
- s->i_left--;
- if( s->i_left == 0 )
- {
- s->p++;
- s->i_left = 8;
- }
- }
- }
- static inline void bs_align( bs_t *s )
- {
- if( s->i_left != 8 )
- {
- s->i_left = 8;
- s->p++;
- }
- }
- static inline void bs_align_0( bs_t *s )
- {
- if( s->i_left != 8 )
- {
- bs_write( s, s->i_left, 0 );
- }
- }
- static inline void bs_align_1( bs_t *s )
- {
- while( s->i_left != 8 )
- {
- bs_write( s, 1, 1 );
- }
- }
- #endif