1 /*****************************************************************************
2 * bits.h : Bit handling helpers
3 *****************************************************************************
4 * Copyright (C) 2003 the VideoLAN team
7 * Authors: Laurent Aimar <fenrir@via.ecp.fr>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
22 *****************************************************************************/
24 #if !defined( __LIBVLC__ )
25 #error You are not libvlc or one of its plugins. You cannot include this file
37 int i_left; /* i_count number of available bits */
40 static inline void bs_init( bs_t *s, void *p_data, int i_data )
44 s->p_end = s->p + i_data;
47 static inline int bs_pos( bs_t *s )
49 return( 8 * ( s->p - s->p_start ) + 8 - s->i_left );
51 static inline int bs_eof( bs_t *s )
53 return( s->p >= s->p_end ? 1: 0 );
55 static inline uint32_t bs_read( bs_t *s, int i_count )
57 static uint32_t i_mask[33] =
59 0x01, 0x03, 0x07, 0x0f,
60 0x1f, 0x3f, 0x7f, 0xff,
61 0x1ff, 0x3ff, 0x7ff, 0xfff,
62 0x1fff, 0x3fff, 0x7fff, 0xffff,
63 0x1ffff, 0x3ffff, 0x7ffff, 0xfffff,
64 0x1fffff, 0x3fffff, 0x7fffff, 0xffffff,
65 0x1ffffff, 0x3ffffff, 0x7ffffff, 0xfffffff,
66 0x1fffffff,0x3fffffff,0x7fffffff,0xffffffff};
68 uint32_t i_result = 0;
72 if( s->p >= s->p_end )
77 if( ( i_shr = s->i_left - i_count ) >= 0 )
79 /* more in the buffer than requested */
80 i_result |= ( *s->p >> i_shr )&i_mask[i_count];
91 /* less in the buffer than requested */
92 i_result |= (*s->p&i_mask[s->i_left]) << -i_shr;
102 static inline uint32_t bs_read1( bs_t *s )
104 if( s->p < s->p_end )
106 unsigned int i_result;
109 i_result = ( *s->p >> s->i_left )&0x01;
121 static inline uint32_t bs_show( bs_t *s, int i_count )
124 return bs_read( &s_tmp, i_count );
127 static inline void bs_skip( bs_t *s, int i_count )
129 s->i_left -= i_count;
131 while( s->i_left <= 0 )
138 static inline void bs_write( bs_t *s, int i_count, uint32_t i_bits )
142 if( s->p >= s->p_end )
149 if( ( i_bits >> i_count )&0x01 )
151 *s->p |= 1 << ( s->i_left - 1 );
155 *s->p &= ~( 1 << ( s->i_left - 1 ) );
166 static inline void bs_align( bs_t *s )
174 static inline void bs_align_0( bs_t *s )
178 bs_write( s, s->i_left, 0 );
181 static inline void bs_align_1( bs_t *s )
183 while( s->i_left != 8 )