entcode.h (5423B)
1 /* Copyright (c) 2001-2011 Timothy B. Terriberry 2 Copyright (c) 2008-2009 Xiph.Org Foundation */ 3 /* 4 Redistribution and use in source and binary forms, with or without 5 modification, are permitted provided that the following conditions 6 are met: 7 8 - Redistributions of source code must retain the above copyright 9 notice, this list of conditions and the following disclaimer. 10 11 - Redistributions in binary form must reproduce the above copyright 12 notice, this list of conditions and the following disclaimer in the 13 documentation and/or other materials provided with the distribution. 14 15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 18 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER 19 OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 20 EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21 PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 22 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 23 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 24 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 25 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "opus_types.h" 29 #include "opus_defines.h" 30 31 #if !defined(_entcode_H) 32 # define _entcode_H (1) 33 # include <limits.h> 34 # include <stddef.h> 35 # include "ecintrin.h" 36 37 extern const opus_uint32 SMALL_DIV_TABLE[129]; 38 39 #ifdef OPUS_ARM_ASM 40 #define USE_SMALL_DIV_TABLE 41 #endif 42 43 /*OPT: ec_window must be at least 32 bits, but if you have fast arithmetic on a 44 larger type, you can speed up the decoder by using it here.*/ 45 typedef opus_uint32 ec_window; 46 typedef struct ec_ctx ec_ctx; 47 typedef struct ec_ctx ec_enc; 48 typedef struct ec_ctx ec_dec; 49 50 # define EC_WINDOW_SIZE ((int)sizeof(ec_window)*CHAR_BIT) 51 52 /*The number of bits to use for the range-coded part of unsigned integers.*/ 53 # define EC_UINT_BITS (8) 54 55 /*The resolution of fractional-precision bit usage measurements, i.e., 56 3 => 1/8th bits.*/ 57 # define BITRES 3 58 59 /*The entropy encoder/decoder context. 60 We use the same structure for both, so that common functions like ec_tell() 61 can be used on either one.*/ 62 struct ec_ctx{ 63 /*Buffered input/output.*/ 64 unsigned char *buf; 65 /*The size of the buffer.*/ 66 opus_uint32 storage; 67 /*The offset at which the last byte containing raw bits was read/written.*/ 68 opus_uint32 end_offs; 69 /*Bits that will be read from/written at the end.*/ 70 ec_window end_window; 71 /*Number of valid bits in end_window.*/ 72 int nend_bits; 73 /*The total number of whole bits read/written. 74 This does not include partial bits currently in the range coder.*/ 75 int nbits_total; 76 /*The offset at which the next range coder byte will be read/written.*/ 77 opus_uint32 offs; 78 /*The number of values in the current range.*/ 79 opus_uint32 rng; 80 /*In the decoder: the difference between the top of the current range and 81 the input value, minus one. 82 In the encoder: the low end of the current range.*/ 83 opus_uint32 val; 84 /*In the decoder: the saved normalization factor from ec_decode(). 85 In the encoder: the number of outstanding carry propagating symbols.*/ 86 opus_uint32 ext; 87 /*A buffered input/output symbol, awaiting carry propagation.*/ 88 int rem; 89 /*Nonzero if an error occurred.*/ 90 int error; 91 }; 92 93 static OPUS_INLINE opus_uint32 ec_range_bytes(ec_ctx *_this){ 94 return _this->offs; 95 } 96 97 static OPUS_INLINE unsigned char *ec_get_buffer(ec_ctx *_this){ 98 return _this->buf; 99 } 100 101 static OPUS_INLINE int ec_get_error(ec_ctx *_this){ 102 return _this->error; 103 } 104 105 /*Returns the number of bits "used" by the encoded or decoded symbols so far. 106 This same number can be computed in either the encoder or the decoder, and is 107 suitable for making coding decisions. 108 Return: The number of bits. 109 This will always be slightly larger than the exact value (e.g., all 110 rounding error is in the positive direction).*/ 111 static OPUS_INLINE int ec_tell(ec_ctx *_this){ 112 return _this->nbits_total-EC_ILOG(_this->rng); 113 } 114 115 /*Returns the number of bits "used" by the encoded or decoded symbols so far. 116 This same number can be computed in either the encoder or the decoder, and is 117 suitable for making coding decisions. 118 Return: The number of bits scaled by 2**BITRES. 119 This will always be slightly larger than the exact value (e.g., all 120 rounding error is in the positive direction).*/ 121 opus_uint32 ec_tell_frac(ec_ctx *_this); 122 123 /* Tested exhaustively for all n and for 1<=d<=256 */ 124 static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) { 125 celt_sig_assert(d>0); 126 #ifdef USE_SMALL_DIV_TABLE 127 if (d>256) 128 return n/d; 129 else { 130 opus_uint32 t, q; 131 t = EC_ILOG(d&-d); 132 q = (opus_uint64)SMALL_DIV_TABLE[d>>t]*(n>>(t-1))>>32; 133 return q+(n-q*d >= d); 134 } 135 #else 136 return n/d; 137 #endif 138 } 139 140 static OPUS_INLINE opus_int32 celt_sudiv(opus_int32 n, opus_int32 d) { 141 celt_sig_assert(d>0); 142 #ifdef USE_SMALL_DIV_TABLE 143 if (n<0) 144 return -(opus_int32)celt_udiv(-n, d); 145 else 146 return celt_udiv(n, d); 147 #else 148 return n/d; 149 #endif 150 } 151 152 #endif