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1 /* libFLAC - Free Lossless Audio Codec library
2  * Copyright (C) 2004-2009  Josh Coalson
3  * Copyright (C) 2011-2014  Xiph.Org Foundation
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * - Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  *
12  * - Redistributions in binary form must reproduce the above copyright
13  * notice, this list of conditions and the following disclaimer in the
14  * documentation and/or other materials provided with the distribution.
15  *
16  * - Neither the name of the Xiph.org Foundation nor the names of its
17  * contributors may be used to endorse or promote products derived from
18  * this software without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
24  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
26  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
27  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
28  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
29  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
30  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 #ifdef HAVE_CONFIG_H
34 #  include <config.h>
35 #endif
36 
37 #include "FLAC/assert.h"
38 #include "share/compat.h"
39 #include "private/float.h"
40 
41 #ifdef FLAC__INTEGER_ONLY_LIBRARY
42 
43 const FLAC__fixedpoint FLAC__FP_ZERO = 0;
44 const FLAC__fixedpoint FLAC__FP_ONE_HALF = 0x00008000;
45 const FLAC__fixedpoint FLAC__FP_ONE = 0x00010000;
46 const FLAC__fixedpoint FLAC__FP_LN2 = 45426;
47 const FLAC__fixedpoint FLAC__FP_E = 178145;
48 
49 /* Lookup tables for Knuth's logarithm algorithm */
50 #define LOG2_LOOKUP_PRECISION 16
51 static const FLAC__uint32 log2_lookup[][LOG2_LOOKUP_PRECISION] = {
52 	{
53 		/*
54 		 * 0 fraction bits
55 		 */
56 		/* undefined */ 0x00000000,
57 		/* lg(2/1) = */ 0x00000001,
58 		/* lg(4/3) = */ 0x00000000,
59 		/* lg(8/7) = */ 0x00000000,
60 		/* lg(16/15) = */ 0x00000000,
61 		/* lg(32/31) = */ 0x00000000,
62 		/* lg(64/63) = */ 0x00000000,
63 		/* lg(128/127) = */ 0x00000000,
64 		/* lg(256/255) = */ 0x00000000,
65 		/* lg(512/511) = */ 0x00000000,
66 		/* lg(1024/1023) = */ 0x00000000,
67 		/* lg(2048/2047) = */ 0x00000000,
68 		/* lg(4096/4095) = */ 0x00000000,
69 		/* lg(8192/8191) = */ 0x00000000,
70 		/* lg(16384/16383) = */ 0x00000000,
71 		/* lg(32768/32767) = */ 0x00000000
72 	},
73 	{
74 		/*
75 		 * 4 fraction bits
76 		 */
77 		/* undefined */ 0x00000000,
78 		/* lg(2/1) = */ 0x00000010,
79 		/* lg(4/3) = */ 0x00000007,
80 		/* lg(8/7) = */ 0x00000003,
81 		/* lg(16/15) = */ 0x00000001,
82 		/* lg(32/31) = */ 0x00000001,
83 		/* lg(64/63) = */ 0x00000000,
84 		/* lg(128/127) = */ 0x00000000,
85 		/* lg(256/255) = */ 0x00000000,
86 		/* lg(512/511) = */ 0x00000000,
87 		/* lg(1024/1023) = */ 0x00000000,
88 		/* lg(2048/2047) = */ 0x00000000,
89 		/* lg(4096/4095) = */ 0x00000000,
90 		/* lg(8192/8191) = */ 0x00000000,
91 		/* lg(16384/16383) = */ 0x00000000,
92 		/* lg(32768/32767) = */ 0x00000000
93 	},
94 	{
95 		/*
96 		 * 8 fraction bits
97 		 */
98 		/* undefined */ 0x00000000,
99 		/* lg(2/1) = */ 0x00000100,
100 		/* lg(4/3) = */ 0x0000006a,
101 		/* lg(8/7) = */ 0x00000031,
102 		/* lg(16/15) = */ 0x00000018,
103 		/* lg(32/31) = */ 0x0000000c,
104 		/* lg(64/63) = */ 0x00000006,
105 		/* lg(128/127) = */ 0x00000003,
106 		/* lg(256/255) = */ 0x00000001,
107 		/* lg(512/511) = */ 0x00000001,
108 		/* lg(1024/1023) = */ 0x00000000,
109 		/* lg(2048/2047) = */ 0x00000000,
110 		/* lg(4096/4095) = */ 0x00000000,
111 		/* lg(8192/8191) = */ 0x00000000,
112 		/* lg(16384/16383) = */ 0x00000000,
113 		/* lg(32768/32767) = */ 0x00000000
114 	},
115 	{
116 		/*
117 		 * 12 fraction bits
118 		 */
119 		/* undefined */ 0x00000000,
120 		/* lg(2/1) = */ 0x00001000,
121 		/* lg(4/3) = */ 0x000006a4,
122 		/* lg(8/7) = */ 0x00000315,
123 		/* lg(16/15) = */ 0x0000017d,
124 		/* lg(32/31) = */ 0x000000bc,
125 		/* lg(64/63) = */ 0x0000005d,
126 		/* lg(128/127) = */ 0x0000002e,
127 		/* lg(256/255) = */ 0x00000017,
128 		/* lg(512/511) = */ 0x0000000c,
129 		/* lg(1024/1023) = */ 0x00000006,
130 		/* lg(2048/2047) = */ 0x00000003,
131 		/* lg(4096/4095) = */ 0x00000001,
132 		/* lg(8192/8191) = */ 0x00000001,
133 		/* lg(16384/16383) = */ 0x00000000,
134 		/* lg(32768/32767) = */ 0x00000000
135 	},
136 	{
137 		/*
138 		 * 16 fraction bits
139 		 */
140 		/* undefined */ 0x00000000,
141 		/* lg(2/1) = */ 0x00010000,
142 		/* lg(4/3) = */ 0x00006a40,
143 		/* lg(8/7) = */ 0x00003151,
144 		/* lg(16/15) = */ 0x000017d6,
145 		/* lg(32/31) = */ 0x00000bba,
146 		/* lg(64/63) = */ 0x000005d1,
147 		/* lg(128/127) = */ 0x000002e6,
148 		/* lg(256/255) = */ 0x00000172,
149 		/* lg(512/511) = */ 0x000000b9,
150 		/* lg(1024/1023) = */ 0x0000005c,
151 		/* lg(2048/2047) = */ 0x0000002e,
152 		/* lg(4096/4095) = */ 0x00000017,
153 		/* lg(8192/8191) = */ 0x0000000c,
154 		/* lg(16384/16383) = */ 0x00000006,
155 		/* lg(32768/32767) = */ 0x00000003
156 	},
157 	{
158 		/*
159 		 * 20 fraction bits
160 		 */
161 		/* undefined */ 0x00000000,
162 		/* lg(2/1) = */ 0x00100000,
163 		/* lg(4/3) = */ 0x0006a3fe,
164 		/* lg(8/7) = */ 0x00031513,
165 		/* lg(16/15) = */ 0x00017d60,
166 		/* lg(32/31) = */ 0x0000bb9d,
167 		/* lg(64/63) = */ 0x00005d10,
168 		/* lg(128/127) = */ 0x00002e59,
169 		/* lg(256/255) = */ 0x00001721,
170 		/* lg(512/511) = */ 0x00000b8e,
171 		/* lg(1024/1023) = */ 0x000005c6,
172 		/* lg(2048/2047) = */ 0x000002e3,
173 		/* lg(4096/4095) = */ 0x00000171,
174 		/* lg(8192/8191) = */ 0x000000b9,
175 		/* lg(16384/16383) = */ 0x0000005c,
176 		/* lg(32768/32767) = */ 0x0000002e
177 	},
178 	{
179 		/*
180 		 * 24 fraction bits
181 		 */
182 		/* undefined */ 0x00000000,
183 		/* lg(2/1) = */ 0x01000000,
184 		/* lg(4/3) = */ 0x006a3fe6,
185 		/* lg(8/7) = */ 0x00315130,
186 		/* lg(16/15) = */ 0x0017d605,
187 		/* lg(32/31) = */ 0x000bb9ca,
188 		/* lg(64/63) = */ 0x0005d0fc,
189 		/* lg(128/127) = */ 0x0002e58f,
190 		/* lg(256/255) = */ 0x0001720e,
191 		/* lg(512/511) = */ 0x0000b8d8,
192 		/* lg(1024/1023) = */ 0x00005c61,
193 		/* lg(2048/2047) = */ 0x00002e2d,
194 		/* lg(4096/4095) = */ 0x00001716,
195 		/* lg(8192/8191) = */ 0x00000b8b,
196 		/* lg(16384/16383) = */ 0x000005c5,
197 		/* lg(32768/32767) = */ 0x000002e3
198 	},
199 	{
200 		/*
201 		 * 28 fraction bits
202 		 */
203 		/* undefined */ 0x00000000,
204 		/* lg(2/1) = */ 0x10000000,
205 		/* lg(4/3) = */ 0x06a3fe5c,
206 		/* lg(8/7) = */ 0x03151301,
207 		/* lg(16/15) = */ 0x017d6049,
208 		/* lg(32/31) = */ 0x00bb9ca6,
209 		/* lg(64/63) = */ 0x005d0fba,
210 		/* lg(128/127) = */ 0x002e58f7,
211 		/* lg(256/255) = */ 0x001720da,
212 		/* lg(512/511) = */ 0x000b8d87,
213 		/* lg(1024/1023) = */ 0x0005c60b,
214 		/* lg(2048/2047) = */ 0x0002e2d7,
215 		/* lg(4096/4095) = */ 0x00017160,
216 		/* lg(8192/8191) = */ 0x0000b8ad,
217 		/* lg(16384/16383) = */ 0x00005c56,
218 		/* lg(32768/32767) = */ 0x00002e2b
219 	}
220 };
221 
222 #if 0
223 static const FLAC__uint64 log2_lookup_wide[] = {
224 	{
225 		/*
226 		 * 32 fraction bits
227 		 */
228 		/* undefined */ 0x00000000,
229 		/* lg(2/1) = */ FLAC__U64L(0x100000000),
230 		/* lg(4/3) = */ FLAC__U64L(0x6a3fe5c6),
231 		/* lg(8/7) = */ FLAC__U64L(0x31513015),
232 		/* lg(16/15) = */ FLAC__U64L(0x17d60497),
233 		/* lg(32/31) = */ FLAC__U64L(0x0bb9ca65),
234 		/* lg(64/63) = */ FLAC__U64L(0x05d0fba2),
235 		/* lg(128/127) = */ FLAC__U64L(0x02e58f74),
236 		/* lg(256/255) = */ FLAC__U64L(0x01720d9c),
237 		/* lg(512/511) = */ FLAC__U64L(0x00b8d875),
238 		/* lg(1024/1023) = */ FLAC__U64L(0x005c60aa),
239 		/* lg(2048/2047) = */ FLAC__U64L(0x002e2d72),
240 		/* lg(4096/4095) = */ FLAC__U64L(0x00171600),
241 		/* lg(8192/8191) = */ FLAC__U64L(0x000b8ad2),
242 		/* lg(16384/16383) = */ FLAC__U64L(0x0005c55d),
243 		/* lg(32768/32767) = */ FLAC__U64L(0x0002e2ac)
244 	},
245 	{
246 		/*
247 		 * 48 fraction bits
248 		 */
249 		/* undefined */ 0x00000000,
250 		/* lg(2/1) = */ FLAC__U64L(0x1000000000000),
251 		/* lg(4/3) = */ FLAC__U64L(0x6a3fe5c60429),
252 		/* lg(8/7) = */ FLAC__U64L(0x315130157f7a),
253 		/* lg(16/15) = */ FLAC__U64L(0x17d60496cfbb),
254 		/* lg(32/31) = */ FLAC__U64L(0xbb9ca64ecac),
255 		/* lg(64/63) = */ FLAC__U64L(0x5d0fba187cd),
256 		/* lg(128/127) = */ FLAC__U64L(0x2e58f7441ee),
257 		/* lg(256/255) = */ FLAC__U64L(0x1720d9c06a8),
258 		/* lg(512/511) = */ FLAC__U64L(0xb8d8752173),
259 		/* lg(1024/1023) = */ FLAC__U64L(0x5c60aa252e),
260 		/* lg(2048/2047) = */ FLAC__U64L(0x2e2d71b0d8),
261 		/* lg(4096/4095) = */ FLAC__U64L(0x1716001719),
262 		/* lg(8192/8191) = */ FLAC__U64L(0xb8ad1de1b),
263 		/* lg(16384/16383) = */ FLAC__U64L(0x5c55d640d),
264 		/* lg(32768/32767) = */ FLAC__U64L(0x2e2abcf52)
265 	}
266 };
267 #endif
268 
FLAC__fixedpoint_log2(FLAC__uint32 x,unsigned fracbits,unsigned precision)269 FLAC__uint32 FLAC__fixedpoint_log2(FLAC__uint32 x, unsigned fracbits, unsigned precision)
270 {
271 	const FLAC__uint32 ONE = (1u << fracbits);
272 	const FLAC__uint32 *table = log2_lookup[fracbits >> 2];
273 
274 	FLAC__ASSERT(fracbits < 32);
275 	FLAC__ASSERT((fracbits & 0x3) == 0);
276 
277 	if(x < ONE)
278 		return 0;
279 
280 	if(precision > LOG2_LOOKUP_PRECISION)
281 		precision = LOG2_LOOKUP_PRECISION;
282 
283 	/* Knuth's algorithm for computing logarithms, optimized for base-2 with lookup tables */
284 	{
285 		FLAC__uint32 y = 0;
286 		FLAC__uint32 z = x >> 1, k = 1;
287 		while (x > ONE && k < precision) {
288 			if (x - z >= ONE) {
289 				x -= z;
290 				z = x >> k;
291 				y += table[k];
292 			}
293 			else {
294 				z >>= 1;
295 				k++;
296 			}
297 		}
298 		return y;
299 	}
300 }
301 
302 #endif /* defined FLAC__INTEGER_ONLY_LIBRARY */
303