/***************************************************************************** * bits.h : Bit handling helpers ***************************************************************************** * Copyright (C) 2003 the VideoLAN team * $Id: 4dcfa2f1a37e577448a371dea8c56303551d48bf $ * * 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;    while( s->i_left <= 0 )    {        s->p++;        s->i_left += 8;    }}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