Line data Source code
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 oustanding 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 0 : static OPUS_INLINE opus_uint32 ec_range_bytes(ec_ctx *_this){
94 0 : return _this->offs;
95 : }
96 :
97 0 : static OPUS_INLINE unsigned char *ec_get_buffer(ec_ctx *_this){
98 0 : return _this->buf;
99 : }
100 :
101 0 : static OPUS_INLINE int ec_get_error(ec_ctx *_this){
102 0 : 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 0 : static OPUS_INLINE int ec_tell(ec_ctx *_this){
112 0 : 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 0 : static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) {
125 0 : celt_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 0 : return n/d;
137 : #endif
138 : }
139 :
140 0 : static OPUS_INLINE opus_int32 celt_sudiv(opus_int32 n, opus_int32 d) {
141 0 : celt_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 0 : return n/d;
149 : #endif
150 : }
151 :
152 : #endif
|
