diff options
Diffstat (limited to 'apps/codecs/libwavpack/words.c')
-rw-r--r-- | apps/codecs/libwavpack/words.c | 503 |
1 files changed, 503 insertions, 0 deletions
diff --git a/apps/codecs/libwavpack/words.c b/apps/codecs/libwavpack/words.c new file mode 100644 index 0000000000..35061b69a9 --- /dev/null +++ b/apps/codecs/libwavpack/words.c | |||
@@ -0,0 +1,503 @@ | |||
1 | //////////////////////////////////////////////////////////////////////////// | ||
2 | // **** WAVPACK **** // | ||
3 | // Hybrid Lossless Wavefile Compressor // | ||
4 | // Copyright (c) 1998 - 2004 Conifer Software. // | ||
5 | // All Rights Reserved. // | ||
6 | //////////////////////////////////////////////////////////////////////////// | ||
7 | |||
8 | // words.c | ||
9 | |||
10 | // This module provides entropy word encoding and decoding functions using | ||
11 | // a variation on the Rice method. This was introduced in version 3.93 | ||
12 | // because it allows splitting the data into a "lossy" stream and a | ||
13 | // "correction" stream in a very efficient manner and is therefore ideal | ||
14 | // for the "hybrid" mode. For 4.0, the efficiency of this method was | ||
15 | // significantly improved by moving away from the normal Rice restriction of | ||
16 | // using powers of two for the modulus divisions and now the method can be | ||
17 | // used for both hybrid and pure lossless encoding. | ||
18 | |||
19 | // Samples are divided by median probabilities at 5/7 (71.43%), 10/49 (20.41%), | ||
20 | // and 20/343 (5.83%). Each zone has 3.5 times fewer samples than the | ||
21 | // previous. Using standard Rice coding on this data would result in 1.4 | ||
22 | // bits per sample average (not counting sign bit). However, there is a | ||
23 | // very simple encoding that is over 99% efficient with this data and | ||
24 | // results in about 1.22 bits per sample. | ||
25 | |||
26 | #include "wavpack.h" | ||
27 | |||
28 | #include <string.h> | ||
29 | |||
30 | //////////////////////////////// local macros ///////////////////////////////// | ||
31 | |||
32 | #define LIMIT_ONES 16 // maximum consecutive 1s sent for "div" data | ||
33 | |||
34 | // these control the time constant "slow_level" which is used for hybrid mode | ||
35 | // that controls bitrate as a function of residual level (HYBRID_BITRATE). | ||
36 | #define SLS 8 | ||
37 | #define SLO ((1 << (SLS - 1))) | ||
38 | |||
39 | // these control the time constant of the 3 median level breakpoints | ||
40 | #define DIV0 128 // 5/7 of samples | ||
41 | #define DIV1 64 // 10/49 of samples | ||
42 | #define DIV2 32 // 20/343 of samples | ||
43 | |||
44 | // this macro retrieves the specified median breakpoint (without frac; min = 1) | ||
45 | #define GET_MED(med) (((wps->w.median [med] [chan]) >> 4) + 1) | ||
46 | |||
47 | // These macros update the specified median breakpoints. Note that the median | ||
48 | // is incremented when the sample is higher than the median, else decremented. | ||
49 | // They are designed so that the median will never drop below 1 and the value | ||
50 | // is essentially stationary if there are 2 increments for every 5 decrements. | ||
51 | |||
52 | #define INC_MED0() (wps->w.median [0] [chan] += ((wps->w.median [0] [chan] + DIV0) / DIV0) * 5) | ||
53 | #define DEC_MED0() (wps->w.median [0] [chan] -= ((wps->w.median [0] [chan] + (DIV0-2)) / DIV0) * 2) | ||
54 | #define INC_MED1() (wps->w.median [1] [chan] += ((wps->w.median [1] [chan] + DIV1) / DIV1) * 5) | ||
55 | #define DEC_MED1() (wps->w.median [1] [chan] -= ((wps->w.median [1] [chan] + (DIV1-2)) / DIV1) * 2) | ||
56 | #define INC_MED2() (wps->w.median [2] [chan] += ((wps->w.median [2] [chan] + DIV2) / DIV2) * 5) | ||
57 | #define DEC_MED2() (wps->w.median [2] [chan] -= ((wps->w.median [2] [chan] + (DIV2-2)) / DIV2) * 2) | ||
58 | |||
59 | #define count_bits(av) ( \ | ||
60 | (av) < (1 << 8) ? nbits_table [av] : \ | ||
61 | ( \ | ||
62 | (av) < (1L << 16) ? nbits_table [(av) >> 8] + 8 : \ | ||
63 | ((av) < (1L << 24) ? nbits_table [(av) >> 16] + 16 : nbits_table [(av) >> 24] + 24) \ | ||
64 | ) \ | ||
65 | ) | ||
66 | |||
67 | ///////////////////////////// local table storage //////////////////////////// | ||
68 | |||
69 | const char nbits_table [] = { | ||
70 | 0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, // 0 - 15 | ||
71 | 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, // 16 - 31 | ||
72 | 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, // 32 - 47 | ||
73 | 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, // 48 - 63 | ||
74 | 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // 64 - 79 | ||
75 | 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // 80 - 95 | ||
76 | 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // 96 - 111 | ||
77 | 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // 112 - 127 | ||
78 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 128 - 143 | ||
79 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 144 - 159 | ||
80 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 160 - 175 | ||
81 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 176 - 191 | ||
82 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 192 - 207 | ||
83 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 208 - 223 | ||
84 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, // 224 - 239 | ||
85 | 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 // 240 - 255 | ||
86 | }; | ||
87 | |||
88 | static const uchar log2_table [] = { | ||
89 | 0x00, 0x01, 0x03, 0x04, 0x06, 0x07, 0x09, 0x0a, 0x0b, 0x0d, 0x0e, 0x10, 0x11, 0x12, 0x14, 0x15, | ||
90 | 0x16, 0x18, 0x19, 0x1a, 0x1c, 0x1d, 0x1e, 0x20, 0x21, 0x22, 0x24, 0x25, 0x26, 0x28, 0x29, 0x2a, | ||
91 | 0x2c, 0x2d, 0x2e, 0x2f, 0x31, 0x32, 0x33, 0x34, 0x36, 0x37, 0x38, 0x39, 0x3b, 0x3c, 0x3d, 0x3e, | ||
92 | 0x3f, 0x41, 0x42, 0x43, 0x44, 0x45, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4d, 0x4e, 0x4f, 0x50, 0x51, | ||
93 | 0x52, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, | ||
94 | 0x64, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x74, 0x75, | ||
95 | 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, | ||
96 | 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, | ||
97 | 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, | ||
98 | 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb2, | ||
99 | 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc0, | ||
100 | 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcb, 0xcc, 0xcd, 0xce, | ||
101 | 0xcf, 0xd0, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd8, 0xd9, 0xda, 0xdb, | ||
102 | 0xdc, 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe4, 0xe5, 0xe6, 0xe7, 0xe7, | ||
103 | 0xe8, 0xe9, 0xea, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xee, 0xef, 0xf0, 0xf1, 0xf1, 0xf2, 0xf3, 0xf4, | ||
104 | 0xf4, 0xf5, 0xf6, 0xf7, 0xf7, 0xf8, 0xf9, 0xf9, 0xfa, 0xfb, 0xfc, 0xfc, 0xfd, 0xfe, 0xff, 0xff | ||
105 | }; | ||
106 | |||
107 | static const uchar exp2_table [] = { | ||
108 | 0x00, 0x01, 0x01, 0x02, 0x03, 0x03, 0x04, 0x05, 0x06, 0x06, 0x07, 0x08, 0x08, 0x09, 0x0a, 0x0b, | ||
109 | 0x0b, 0x0c, 0x0d, 0x0e, 0x0e, 0x0f, 0x10, 0x10, 0x11, 0x12, 0x13, 0x13, 0x14, 0x15, 0x16, 0x16, | ||
110 | 0x17, 0x18, 0x19, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1d, 0x1e, 0x1f, 0x20, 0x20, 0x21, 0x22, 0x23, | ||
111 | 0x24, 0x24, 0x25, 0x26, 0x27, 0x28, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, | ||
112 | 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3a, 0x3b, 0x3c, 0x3d, | ||
113 | 0x3e, 0x3f, 0x40, 0x41, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x48, 0x49, 0x4a, 0x4b, | ||
114 | 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, | ||
115 | 0x5b, 0x5c, 0x5d, 0x5e, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, | ||
116 | 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, | ||
117 | 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x87, 0x88, 0x89, 0x8a, | ||
118 | 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, | ||
119 | 0x9c, 0x9d, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, | ||
120 | 0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, | ||
121 | 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc8, 0xc9, 0xca, 0xcb, 0xcd, 0xce, 0xcf, 0xd0, 0xd2, 0xd3, 0xd4, | ||
122 | 0xd6, 0xd7, 0xd8, 0xd9, 0xdb, 0xdc, 0xdd, 0xde, 0xe0, 0xe1, 0xe2, 0xe4, 0xe5, 0xe6, 0xe8, 0xe9, | ||
123 | 0xea, 0xec, 0xed, 0xee, 0xf0, 0xf1, 0xf2, 0xf4, 0xf5, 0xf6, 0xf8, 0xf9, 0xfa, 0xfc, 0xfd, 0xff | ||
124 | }; | ||
125 | |||
126 | ///////////////////////////// executable code //////////////////////////////// | ||
127 | |||
128 | static int log2 (unsigned long avalue); | ||
129 | |||
130 | // Read the median log2 values from the specifed metadata structure, convert | ||
131 | // them back to 32-bit unsigned values and store them. If length is not | ||
132 | // exactly correct then we flag and return an error. | ||
133 | |||
134 | int read_entropy_vars (WavpackStream *wps, WavpackMetadata *wpmd) | ||
135 | { | ||
136 | uchar *byteptr = wpmd->data; | ||
137 | |||
138 | if (wpmd->byte_length != ((wps->wphdr.flags & MONO_FLAG) ? 6 : 12)) | ||
139 | return FALSE; | ||
140 | |||
141 | wps->w.median [0] [0] = exp2s (byteptr [0] + (byteptr [1] << 8)); | ||
142 | wps->w.median [1] [0] = exp2s (byteptr [2] + (byteptr [3] << 8)); | ||
143 | wps->w.median [2] [0] = exp2s (byteptr [4] + (byteptr [5] << 8)); | ||
144 | |||
145 | if (!(wps->wphdr.flags & MONO_FLAG)) { | ||
146 | wps->w.median [0] [1] = exp2s (byteptr [6] + (byteptr [7] << 8)); | ||
147 | wps->w.median [1] [1] = exp2s (byteptr [8] + (byteptr [9] << 8)); | ||
148 | wps->w.median [2] [1] = exp2s (byteptr [10] + (byteptr [11] << 8)); | ||
149 | } | ||
150 | |||
151 | return TRUE; | ||
152 | } | ||
153 | |||
154 | // Read the hybrid related values from the specifed metadata structure, convert | ||
155 | // them back to their internal formats and store them. The extended profile | ||
156 | // stuff is not implemented yet, so return an error if we get more data than | ||
157 | // we know what to do with. | ||
158 | |||
159 | int read_hybrid_profile (WavpackStream *wps, WavpackMetadata *wpmd) | ||
160 | { | ||
161 | uchar *byteptr = wpmd->data; | ||
162 | uchar *endptr = byteptr + wpmd->byte_length; | ||
163 | |||
164 | if (wps->wphdr.flags & HYBRID_BITRATE) { | ||
165 | wps->w.slow_level [0] = exp2s (byteptr [0] + (byteptr [1] << 8)); | ||
166 | byteptr += 2; | ||
167 | |||
168 | if (!(wps->wphdr.flags & MONO_FLAG)) { | ||
169 | wps->w.slow_level [1] = exp2s (byteptr [0] + (byteptr [1] << 8)); | ||
170 | byteptr += 2; | ||
171 | } | ||
172 | } | ||
173 | |||
174 | wps->w.bitrate_acc [0] = (long)(byteptr [0] + (byteptr [1] << 8)) << 16; | ||
175 | byteptr += 2; | ||
176 | |||
177 | if (!(wps->wphdr.flags & MONO_FLAG)) { | ||
178 | wps->w.bitrate_acc [1] = (long)(byteptr [0] + (byteptr [1] << 8)) << 16; | ||
179 | byteptr += 2; | ||
180 | } | ||
181 | |||
182 | if (byteptr < endptr) { | ||
183 | wps->w.bitrate_delta [0] = exp2s ((short)(byteptr [0] + (byteptr [1] << 8))); | ||
184 | byteptr += 2; | ||
185 | |||
186 | if (!(wps->wphdr.flags & MONO_FLAG)) { | ||
187 | wps->w.bitrate_delta [1] = exp2s ((short)(byteptr [0] + (byteptr [1] << 8))); | ||
188 | byteptr += 2; | ||
189 | } | ||
190 | |||
191 | if (byteptr < endptr) | ||
192 | return FALSE; | ||
193 | } | ||
194 | else | ||
195 | wps->w.bitrate_delta [0] = wps->w.bitrate_delta [1] = 0; | ||
196 | |||
197 | return TRUE; | ||
198 | } | ||
199 | |||
200 | // This function is called during both encoding and decoding of hybrid data to | ||
201 | // update the "error_limit" variable which determines the maximum sample error | ||
202 | // allowed in the main bitstream. In the HYBRID_BITRATE mode (which is the only | ||
203 | // currently implemented) this is calculated from the slow_level values and the | ||
204 | // bitrate accumulators. Note that the bitrate accumulators can be changing. | ||
205 | |||
206 | static void update_error_limit (WavpackStream *wps) | ||
207 | { | ||
208 | int bitrate_0 = (wps->w.bitrate_acc [0] += wps->w.bitrate_delta [0]) >> 16; | ||
209 | |||
210 | if (wps->wphdr.flags & MONO_FLAG) { | ||
211 | if (wps->wphdr.flags & HYBRID_BITRATE) { | ||
212 | int slow_log_0 = (wps->w.slow_level [0] + SLO) >> SLS; | ||
213 | |||
214 | if (slow_log_0 - bitrate_0 > -0x100) | ||
215 | wps->w.error_limit [0] = exp2s (slow_log_0 - bitrate_0 + 0x100); | ||
216 | else | ||
217 | wps->w.error_limit [0] = 0; | ||
218 | } | ||
219 | else | ||
220 | wps->w.error_limit [0] = exp2s (bitrate_0); | ||
221 | } | ||
222 | else { | ||
223 | int bitrate_1 = (wps->w.bitrate_acc [1] += wps->w.bitrate_delta [1]) >> 16; | ||
224 | |||
225 | if (wps->wphdr.flags & HYBRID_BITRATE) { | ||
226 | int slow_log_0 = (wps->w.slow_level [0] + SLO) >> SLS; | ||
227 | int slow_log_1 = (wps->w.slow_level [1] + SLO) >> SLS; | ||
228 | |||
229 | if (wps->wphdr.flags & HYBRID_BALANCE) { | ||
230 | int balance = (slow_log_1 - slow_log_0 + bitrate_1 + 1) >> 1; | ||
231 | |||
232 | if (balance > bitrate_0) { | ||
233 | bitrate_1 = bitrate_0 * 2; | ||
234 | bitrate_0 = 0; | ||
235 | } | ||
236 | else if (-balance > bitrate_0) { | ||
237 | bitrate_0 = bitrate_0 * 2; | ||
238 | bitrate_1 = 0; | ||
239 | } | ||
240 | else { | ||
241 | bitrate_1 = bitrate_0 + balance; | ||
242 | bitrate_0 = bitrate_0 - balance; | ||
243 | } | ||
244 | } | ||
245 | |||
246 | if (slow_log_0 - bitrate_0 > -0x100) | ||
247 | wps->w.error_limit [0] = exp2s (slow_log_0 - bitrate_0 + 0x100); | ||
248 | else | ||
249 | wps->w.error_limit [0] = 0; | ||
250 | |||
251 | if (slow_log_1 - bitrate_1 > -0x100) | ||
252 | wps->w.error_limit [1] = exp2s (slow_log_1 - bitrate_1 + 0x100); | ||
253 | else | ||
254 | wps->w.error_limit [1] = 0; | ||
255 | } | ||
256 | else { | ||
257 | wps->w.error_limit [0] = exp2s (bitrate_0); | ||
258 | wps->w.error_limit [1] = exp2s (bitrate_1); | ||
259 | } | ||
260 | } | ||
261 | } | ||
262 | |||
263 | static ulong read_code (Bitstream *bs, ulong maxcode); | ||
264 | |||
265 | // Read the next word from the bitstream "wvbits" and return the value. This | ||
266 | // function can be used for hybrid or lossless streams, but since an | ||
267 | // optimized version is available for lossless this function would normally | ||
268 | // be used for hybrid only. If a hybrid lossless stream is being read then | ||
269 | // the "correction" offset is written at the specified pointer. A return value | ||
270 | // of WORD_EOF indicates that the end of the bitstream was reached (all 1s) or | ||
271 | // some other error occurred. | ||
272 | |||
273 | long get_word (WavpackStream *wps, int chan) | ||
274 | { | ||
275 | ulong ones_count, low, mid, high; | ||
276 | int sign; | ||
277 | |||
278 | if (wps->w.zeros_acc) { | ||
279 | if (--wps->w.zeros_acc) { | ||
280 | wps->w.slow_level [chan] -= (wps->w.slow_level [chan] + SLO) >> SLS; | ||
281 | return 0; | ||
282 | } | ||
283 | } | ||
284 | else if (!wps->w.holding_zero && !wps->w.holding_one && !(wps->w.median [0] [0] & ~1) && !(wps->w.median [0] [1] & ~1)) { | ||
285 | ulong mask; | ||
286 | int cbits; | ||
287 | |||
288 | for (cbits = 0; cbits < 33 && getbit (&wps->wvbits); ++cbits); | ||
289 | |||
290 | if (cbits == 33) | ||
291 | return WORD_EOF; | ||
292 | |||
293 | if (cbits < 2) | ||
294 | wps->w.zeros_acc = cbits; | ||
295 | else { | ||
296 | for (mask = 1, wps->w.zeros_acc = 0; --cbits; mask <<= 1) | ||
297 | if (getbit (&wps->wvbits)) | ||
298 | wps->w.zeros_acc |= mask; | ||
299 | |||
300 | wps->w.zeros_acc |= mask; | ||
301 | } | ||
302 | |||
303 | if (wps->w.zeros_acc) { | ||
304 | wps->w.slow_level [chan] -= (wps->w.slow_level [chan] + SLO) >> SLS; | ||
305 | CLEAR (wps->w.median); | ||
306 | return 0; | ||
307 | } | ||
308 | } | ||
309 | |||
310 | if (wps->w.holding_zero) | ||
311 | ones_count = wps->w.holding_zero = 0; | ||
312 | else { | ||
313 | #ifdef LIMIT_ONES | ||
314 | for (ones_count = 0; ones_count < (LIMIT_ONES + 1) && getbit (&wps->wvbits); ++ones_count); | ||
315 | |||
316 | if (ones_count == (LIMIT_ONES + 1)) | ||
317 | return WORD_EOF; | ||
318 | |||
319 | if (ones_count == LIMIT_ONES) { | ||
320 | ulong mask; | ||
321 | int cbits; | ||
322 | |||
323 | for (cbits = 0; cbits < 33 && getbit (&wps->wvbits); ++cbits); | ||
324 | |||
325 | if (cbits == 33) | ||
326 | return WORD_EOF; | ||
327 | |||
328 | if (cbits < 2) | ||
329 | ones_count = cbits; | ||
330 | else { | ||
331 | for (mask = 1, ones_count = 0; --cbits; mask <<= 1) | ||
332 | if (getbit (&wps->wvbits)) | ||
333 | ones_count |= mask; | ||
334 | |||
335 | ones_count |= mask; | ||
336 | } | ||
337 | |||
338 | ones_count += LIMIT_ONES; | ||
339 | } | ||
340 | #else | ||
341 | for (ones_count = 0; getbit (&wps->wvbits); ++ones_count); | ||
342 | #endif | ||
343 | |||
344 | if (wps->w.holding_one) { | ||
345 | wps->w.holding_one = ones_count & 1; | ||
346 | ones_count = (ones_count >> 1) + 1; | ||
347 | } | ||
348 | else { | ||
349 | wps->w.holding_one = ones_count & 1; | ||
350 | ones_count >>= 1; | ||
351 | } | ||
352 | |||
353 | wps->w.holding_zero = ~wps->w.holding_one & 1; | ||
354 | } | ||
355 | |||
356 | if ((wps->wphdr.flags & HYBRID_FLAG) && !chan) | ||
357 | update_error_limit (wps); | ||
358 | |||
359 | if (ones_count == 0) { | ||
360 | low = 0; | ||
361 | high = GET_MED (0) - 1; | ||
362 | DEC_MED0 (); | ||
363 | } | ||
364 | else { | ||
365 | low = GET_MED (0); | ||
366 | INC_MED0 (); | ||
367 | |||
368 | if (ones_count == 1) { | ||
369 | high = low + GET_MED (1) - 1; | ||
370 | DEC_MED1 (); | ||
371 | } | ||
372 | else { | ||
373 | low += GET_MED (1); | ||
374 | INC_MED1 (); | ||
375 | |||
376 | if (ones_count == 2) { | ||
377 | high = low + GET_MED (2) - 1; | ||
378 | DEC_MED2 (); | ||
379 | } | ||
380 | else { | ||
381 | low += (ones_count - 2) * GET_MED (2); | ||
382 | high = low + GET_MED (2) - 1; | ||
383 | INC_MED2 (); | ||
384 | } | ||
385 | } | ||
386 | } | ||
387 | |||
388 | mid = (high + low + 1) >> 1; | ||
389 | |||
390 | if (!wps->w.error_limit [chan]) | ||
391 | mid = read_code (&wps->wvbits, high - low) + low; | ||
392 | else while (high - low > wps->w.error_limit [chan]) { | ||
393 | if (getbit (&wps->wvbits)) | ||
394 | mid = (high + (low = mid) + 1) >> 1; | ||
395 | else | ||
396 | mid = ((high = mid - 1) + low + 1) >> 1; | ||
397 | } | ||
398 | |||
399 | sign = getbit (&wps->wvbits); | ||
400 | |||
401 | if (wps->wphdr.flags & HYBRID_BITRATE) { | ||
402 | wps->w.slow_level [chan] -= (wps->w.slow_level [chan] + SLO) >> SLS; | ||
403 | wps->w.slow_level [chan] += log2 (mid); | ||
404 | } | ||
405 | |||
406 | return sign ? ~mid : mid; | ||
407 | } | ||
408 | |||
409 | // Read a single unsigned value from the specified bitstream with a value | ||
410 | // from 0 to maxcode. If there are exactly a power of two number of possible | ||
411 | // codes then this will read a fixed number of bits; otherwise it reads the | ||
412 | // minimum number of bits and then determines whether another bit is needed | ||
413 | // to define the code. | ||
414 | |||
415 | static ulong read_code (Bitstream *bs, ulong maxcode) | ||
416 | { | ||
417 | int bitcount = count_bits (maxcode); | ||
418 | ulong extras = (1L << bitcount) - maxcode - 1, code; | ||
419 | |||
420 | if (!bitcount) | ||
421 | return 0; | ||
422 | |||
423 | getbits (&code, bitcount - 1, bs); | ||
424 | code &= (1L << (bitcount - 1)) - 1; | ||
425 | |||
426 | if (code >= extras) { | ||
427 | code = (code << 1) - extras; | ||
428 | |||
429 | if (getbit (bs)) | ||
430 | ++code; | ||
431 | } | ||
432 | |||
433 | return code; | ||
434 | } | ||
435 | |||
436 | // The concept of a base 2 logarithm is used in many parts of WavPack. It is | ||
437 | // a way of sufficiently accurately representing 32-bit signed and unsigned | ||
438 | // values storing only 16 bits (actually fewer). It is also used in the hybrid | ||
439 | // mode for quickly comparing the relative magnitude of large values (i.e. | ||
440 | // division) and providing smooth exponentials using only addition. | ||
441 | |||
442 | // These are not strict logarithms in that they become linear around zero and | ||
443 | // can therefore represent both zero and negative values. They have 8 bits | ||
444 | // of precision and in "roundtrip" conversions the total error never exceeds 1 | ||
445 | // part in 225 except for the cases of +/-115 and +/-195 (which error by 1). | ||
446 | |||
447 | |||
448 | // This function returns the log2 for the specified 32-bit unsigned value. | ||
449 | // The maximum value allowed is about 0xff800000 and returns 8447. | ||
450 | |||
451 | static int log2 (unsigned long avalue) | ||
452 | { | ||
453 | int dbits; | ||
454 | |||
455 | if ((avalue += avalue >> 9) < (1 << 8)) { | ||
456 | dbits = nbits_table [avalue]; | ||
457 | return (dbits << 8) + log2_table [(avalue << (9 - dbits)) & 0xff]; | ||
458 | } | ||
459 | else { | ||
460 | if (avalue < (1L << 16)) | ||
461 | dbits = nbits_table [avalue >> 8] + 8; | ||
462 | else if (avalue < (1L << 24)) | ||
463 | dbits = nbits_table [avalue >> 16] + 16; | ||
464 | else | ||
465 | dbits = nbits_table [avalue >> 24] + 24; | ||
466 | |||
467 | return (dbits << 8) + log2_table [(avalue >> (dbits - 9)) & 0xff]; | ||
468 | } | ||
469 | } | ||
470 | |||
471 | // This function returns the original integer represented by the supplied | ||
472 | // logarithm (at least within the provided accuracy). The log is signed, | ||
473 | // but since a full 32-bit value is returned this can be used for unsigned | ||
474 | // conversions as well (i.e. the input range is -8192 to +8447). | ||
475 | |||
476 | long exp2s (int log) | ||
477 | { | ||
478 | ulong value; | ||
479 | |||
480 | if (log < 0) | ||
481 | return -exp2s (-log); | ||
482 | |||
483 | value = exp2_table [log & 0xff] | 0x100; | ||
484 | |||
485 | if ((log >>= 8) <= 9) | ||
486 | return value >> (9 - log); | ||
487 | else | ||
488 | return value << (log - 9); | ||
489 | } | ||
490 | |||
491 | // These two functions convert internal weights (which are normally +/-1024) | ||
492 | // to and from an 8-bit signed character version for storage in metadata. The | ||
493 | // weights are clipped here in the case that they are outside that range. | ||
494 | |||
495 | int restore_weight (char weight) | ||
496 | { | ||
497 | int result; | ||
498 | |||
499 | if ((result = (int) weight << 3) > 0) | ||
500 | result += (result + 64) >> 7; | ||
501 | |||
502 | return result; | ||
503 | } | ||