unary.h (1883B)
1 /* 2 * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at> 3 * 4 * This file is part of FFmpeg. 5 * 6 * FFmpeg is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU Lesser General Public 8 * License as published by the Free Software Foundation; either 9 * version 2.1 of the License, or (at your option) any later version. 10 * 11 * FFmpeg is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * Lesser General Public License for more details. 15 * 16 * You should have received a copy of the GNU Lesser General Public 17 * License along with FFmpeg; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 19 */ 20 21 #ifndef AVCODEC_UNARY_H 22 #define AVCODEC_UNARY_H 23 24 #include "get_bits.h" 25 26 /** 27 * Get unary code of limited length 28 * @param gb GetBitContext 29 * @param[in] stop The bitstop value (unary code of 1's or 0's) 30 * @param[in] len Maximum length 31 * @return unary 0 based code index. This is also the length in bits of the 32 * code excluding the stop bit. 33 * (in case len=1) 34 * 1 0 35 * 0 1 36 * (in case len=2) 37 * 1 0 38 * 01 1 39 * 00 2 40 * (in case len=3) 41 * 1 0 42 * 01 1 43 * 001 2 44 * 000 3 45 */ 46 static inline int get_unary(GetBitContext *gb, int stop, int len) 47 { 48 int i; 49 50 for(i = 0; i < len && get_bits1(gb) != stop; i++); 51 return i; 52 } 53 54 /** 55 * Get unary code terminated by a 0 with a maximum length of 33 56 * @param gb GetBitContext 57 * @return Unary length/index 58 */ 59 static inline int get_unary_0_33(GetBitContext *gb) 60 { 61 return get_unary(gb, 0, 33); 62 } 63 64 static inline int get_unary_0_9(GetBitContext *gb) 65 { 66 return get_unary(gb, 0, 9); 67 } 68 69 #endif /* AVCODEC_UNARY_H */