| /* |
| * Common bit i/o utils |
| * Copyright (c) 2000, 2001 Fabrice Bellard. |
| * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> |
| * |
| * This library 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 of the License, or (at your option) any later version. |
| * |
| * This library 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 library; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| * |
| * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at> |
| */ |
| |
| /** |
| * @file common.c |
| * common internal api. |
| */ |
| |
| #include "avcodec.h" |
| |
| const uint8_t ff_sqrt_tab[128]={ |
| 0, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, |
| 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, |
| 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, |
| 9, 9, 9, 9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11 |
| }; |
| |
| const uint8_t ff_log2_tab[256]={ |
| 0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4, |
| 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5, |
| 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6, |
| 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6, |
| 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, |
| 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, |
| 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, |
| 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 |
| }; |
| |
| /** |
| * init GetBitContext. |
| * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits |
| * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end |
| * @param bit_size the size of the buffer in bits |
| */ |
| void init_get_bits(GetBitContext *s, |
| const uint8_t *buffer, int bit_size) |
| { |
| const int buffer_size= (bit_size+7)>>3; |
| |
| s->buffer= buffer; |
| s->size_in_bits= bit_size; |
| s->buffer_end= buffer + buffer_size; |
| s->index=0; |
| { |
| OPEN_READER(re, s) |
| UPDATE_CACHE(re, s) |
| UPDATE_CACHE(re, s) |
| CLOSE_READER(re, s) |
| } |
| } |
| |
| /** |
| * reads 0-32 bits. |
| */ |
| unsigned int get_bits_long(GetBitContext *s, int n){ |
| if(n<=17) return get_bits(s, n); |
| else{ |
| int ret= get_bits(s, 16) << (n-16); |
| return ret | get_bits(s, n-16); |
| } |
| } |
| |
| /** |
| * shows 0-32 bits. |
| */ |
| unsigned int show_bits_long(GetBitContext *s, int n){ |
| if(n<=17) return show_bits(s, n); |
| else{ |
| GetBitContext gb= *s; |
| int ret= get_bits_long(s, n); |
| *s= gb; |
| return ret; |
| } |
| } |
| |
| void align_get_bits(GetBitContext *s) |
| { |
| int n= (-get_bits_count(s)) & 7; |
| if(n) skip_bits(s, n); |
| } |
| |
| int check_marker(GetBitContext *s, const char *msg) |
| { |
| (void)msg; |
| int bit= get_bits1(s); |
| return bit; |
| } |
| |