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authorllornkcor <llornkcor>2004-04-22 09:31:57 (UTC)
committer llornkcor <llornkcor>2004-04-22 09:31:57 (UTC)
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-rw-r--r--core/applets/vmemo/adpcm.c8
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diff --git a/core/applets/vmemo/adpcm.c b/core/applets/vmemo/adpcm.c
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1/*********************************************************** 1/***********************************************************
2Copyright 1992 by Stichting Mathematisch Centrum, Amsterdam, The 2Copyright 1992 by Stichting Mathematisch Centrum, Amsterdam, The
3Netherlands. 3Netherlands.
4 4
5 All Rights Reserved 5 All Rights Reserved
6 6
7Permission to use, copy, modify, and distribute this software and its 7Permission to use, copy, modify, and distribute this software and its
8documentation for any purpose and without fee is hereby granted, 8documentation for any purpose and without fee is hereby granted,
9provided that the above copyright notice appear in all copies and that 9provided that the above copyright notice appear in all copies and that
10both that copyright notice and this permission notice appear in 10both that copyright notice and this permission notice appear in
11supporting documentation, and that the names of Stichting Mathematisch 11supporting documentation, and that the names of Stichting Mathematisch
12Centrum or CWI not be used in advertising or publicity pertaining to 12Centrum or CWI not be used in advertising or publicity pertaining to
13distribution of the software without specific, written prior permission. 13distribution of the software without specific, written prior permission.
14 14
15STICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO 15STICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO
16THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND 16THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
17FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLE 17FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLE
18FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 18FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
19WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 19WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
20ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 20ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
21OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 21OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
22 22
23******************************************************************/ 23******************************************************************/
24 24
25/* 25/*
26** Intel/DVI ADPCM coder/decoder. 26** Intel/DVI ADPCM coder/decoder.
27** 27**
28** The algorithm for this coder was taken from the IMA Compatability Project 28** The algorithm for this coder was taken from the IMA Compatability Project
29** proceedings, Vol 2, Number 2; May 1992. 29** proceedings, Vol 2, Number 2; May 1992.
30** 30**
31** Version 1.2, 18-Dec-92. 31** Version 1.2, 18-Dec-92.
32** 32**
33** Change log: 33** Change log:
34** - Fixed a stupid bug, where the delta was computed as 34** - Fixed a stupid bug, where the delta was computed as
35** stepsize*code/4 in stead of stepsize*(code+0.5)/4. 35** stepsize*code/4 in stead of stepsize*(code+0.5)/4.
36** - There was an off-by-one error causing it to pick 36** - There was an off-by-one error causing it to pick
37** an incorrect delta once in a blue moon. 37** an incorrect delta once in a blue moon.
38** - The NODIVMUL define has been removed. Computations are now always done 38** - The NODIVMUL define has been removed. Computations are now always done
39** using shifts, adds and subtracts. It turned out that, because the standard 39** using shifts, adds and subtracts. It turned out that, because the standard
40** is defined using shift/add/subtract, you needed bits of fixup code 40** is defined using shift/add/subtract, you needed bits of fixup code
41** (because the div/mul simulation using shift/add/sub made some rounding 41** (because the div/mul simulation using shift/add/sub made some rounding
42** errors that real div/mul don't make) and all together the resultant code 42** errors that real div/mul don't make) and all together the resultant code
43** ran slower than just using the shifts all the time. 43** ran slower than just using the shifts all the time.
44** - Changed some of the variable names to be more meaningful. 44** - Changed some of the variable names to be more meaningful.
45*/ 45*/
46 46
47#include "adpcm.h" 47#include "adpcm.h"
48#include <stdio.h> /*DBG*/ 48#include <stdio.h> /*DBG*/
49 49
50#ifndef __STDC__ 50#ifndef __STDC__
51#define signed 51#define signed
52#endif 52#endif
53 53
54/* Intel ADPCM step variation table */ 54/* Intel ADPCM step variation table */
55static int indexTable[16] = { 55static int indexTable[16] = {
56 -1, -1, -1, -1, 2, 4, 6, 8, 56 -1, -1, -1, -1, 2, 4, 6, 8,
57 -1, -1, -1, -1, 2, 4, 6, 8, 57 -1, -1, -1, -1, 2, 4, 6, 8,
58}; 58};
59 59
60static int stepsizeTable[89] = { 60static int stepsizeTable[89] = {
61 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 61 7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
62 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 62 19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
63 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 63 50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
64 130, 143, 157, 173, 190, 209, 230, 253, 279, 307, 64 130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
65 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 65 337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
66 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, 66 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
67 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358, 67 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
68 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899, 68 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
69 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 69 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
70}; 70};
71 71
72void 72void
73adpcm_coder(indata, outdata, len, state) 73adpcm_coder(indata, outdata, len, state)
74 short indata[]; 74 short indata[];
75 char outdata[]; 75 char outdata[];
76 int len; 76 int len;
77 struct adpcm_state *state; 77 struct adpcm_state *state;
78{ 78{
79 short *inp; /* Input buffer pointer */ 79 short *inp; /* Input buffer pointer */
80 signed char *outp; /* output buffer pointer */ 80 signed char *outp; /* output buffer pointer */
81 int val; /* Current input sample value */ 81 int val; /* Current input sample value */
82 int sign; /* Current adpcm sign bit */ 82 int sign; /* Current adpcm sign bit */
83 int delta; /* Current adpcm output value */ 83 int delta; /* Current adpcm output value */
84 int diff; /* Difference between val and valprev */ 84 int diff; /* Difference between val and valprev */
85 int step; /* Stepsize */ 85 int step; /* Stepsize */
86 int valpred; /* Predicted output value */ 86 int valpred; /* Predicted output value */
87 int vpdiff; /* Current change to valpred */ 87 int vpdiff; /* Current change to valpred */
88 int index; /* Current step change index */ 88 int index; /* Current step change index */
89 int outputbuffer; /* place to keep previous 4-bit value */ 89 int outputbuffer = 0; /* place to keep previous 4-bit value */
90 int bufferstep; /* toggle between outputbuffer/output */ 90 int bufferstep = 0; /* toggle between outputbuffer/output */
91 91
92 outp = (signed char *)outdata; 92 outp = (signed char *)outdata;
93 inp = indata; 93 inp = indata;
94 94
95 valpred = state->valprev; 95 valpred = state->valprev;
96 index = state->index; 96 index = state->index;
97 step = stepsizeTable[index]; 97 step = stepsizeTable[index];
98 98
99 bufferstep = 1; 99 bufferstep = 1;
100 100
101 for ( ; len > 0 ; len-- ) { 101 for ( ; len > 0 ; len-- ) {
102 val = *inp++; 102 val = *inp++;
103 103
104 /* Step 1 - compute difference with previous value */ 104 /* Step 1 - compute difference with previous value */
105 diff = val - valpred; 105 diff = val - valpred;
106 sign = (diff < 0) ? 8 : 0; 106 sign = (diff < 0) ? 8 : 0;
107 if ( sign ) diff = (-diff); 107 if ( sign ) diff = (-diff);
108 108
109 /* Step 2 - Divide and clamp */ 109 /* Step 2 - Divide and clamp */
110 /* Note: 110 /* Note:
111 ** This code *approximately* computes: 111 ** This code *approximately* computes:
112 ** delta = diff*4/step; 112 ** delta = diff*4/step;
113 ** vpdiff = (delta+0.5)*step/4; 113 ** vpdiff = (delta+0.5)*step/4;
114 ** but in shift step bits are dropped. The net result of this is 114 ** but in shift step bits are dropped. The net result of this is
115 ** that even if you have fast mul/div hardware you cannot put it to 115 ** that even if you have fast mul/div hardware you cannot put it to
116 ** good use since the fixup would be too expensive. 116 ** good use since the fixup would be too expensive.
117 */ 117 */
118 delta = 0; 118 delta = 0;
119 vpdiff = (step >> 3); 119 vpdiff = (step >> 3);
120 120
121 if ( diff >= step ) { 121 if ( diff >= step ) {
122 delta = 4; 122 delta = 4;
123 diff -= step; 123 diff -= step;
124 vpdiff += step; 124 vpdiff += step;
125 } 125 }
126 step >>= 1; 126 step >>= 1;
127 if ( diff >= step ) { 127 if ( diff >= step ) {
128 delta |= 2; 128 delta |= 2;
129 diff -= step; 129 diff -= step;
130 vpdiff += step; 130 vpdiff += step;
131 } 131 }
132 step >>= 1; 132 step >>= 1;
133 if ( diff >= step ) { 133 if ( diff >= step ) {
134 delta |= 1; 134 delta |= 1;
135 vpdiff += step; 135 vpdiff += step;
136 } 136 }
137 137
138 /* Step 3 - Update previous value */ 138 /* Step 3 - Update previous value */
139 if ( sign ) 139 if ( sign )
140 valpred -= vpdiff; 140 valpred -= vpdiff;
141 else 141 else
142 valpred += vpdiff; 142 valpred += vpdiff;
143 143
144 /* Step 4 - Clamp previous value to 16 bits */ 144 /* Step 4 - Clamp previous value to 16 bits */
145 if ( valpred > 32767 ) 145 if ( valpred > 32767 )
146 valpred = 32767; 146 valpred = 32767;
147 else if ( valpred < -32768 ) 147 else if ( valpred < -32768 )
148 valpred = -32768; 148 valpred = -32768;
149 149
150 /* Step 5 - Assemble value, update index and step values */ 150 /* Step 5 - Assemble value, update index and step values */
151 delta |= sign; 151 delta |= sign;
152 152
153 index += indexTable[delta]; 153 index += indexTable[delta];
154 if ( index < 0 ) index = 0; 154 if ( index < 0 ) index = 0;
155 if ( index > 88 ) index = 88; 155 if ( index > 88 ) index = 88;
156 step = stepsizeTable[index]; 156 step = stepsizeTable[index];
157 157
158 /* Step 6 - Output value */ 158 /* Step 6 - Output value */
159 if ( bufferstep ) { 159 if ( bufferstep ) {
160 outputbuffer = (delta << 4) & 0xf0; 160 outputbuffer = (delta << 4) & 0xf0;
161 } else { 161 } else {
162 *outp++ = (delta & 0x0f) | outputbuffer; 162 *outp++ = (delta & 0x0f) | outputbuffer;
163 } 163 }
164 bufferstep = !bufferstep; 164 bufferstep = !bufferstep;
165 } 165 }
166 166
167 /* Output last step, if needed */ 167 /* Output last step, if needed */
168 if ( !bufferstep ) 168 if ( !bufferstep )
169 *outp++ = outputbuffer; 169 *outp++ = outputbuffer;
170 170
171 state->valprev = valpred; 171 state->valprev = valpred;
172 state->index = index; 172 state->index = index;
173} 173}
174 174
175void 175void
176adpcm_decoder(indata, outdata, len, state) 176adpcm_decoder(indata, outdata, len, state)
177 char indata[]; 177 char indata[];
178 short outdata[]; 178 short outdata[];
179 int len; 179 int len;
180 struct adpcm_state *state; 180 struct adpcm_state *state;
181{ 181{
182 signed char *inp; /* Input buffer pointer */ 182 signed char *inp; /* Input buffer pointer */
183 short *outp; /* output buffer pointer */ 183 short *outp; /* output buffer pointer */
184 int sign; /* Current adpcm sign bit */ 184 int sign; /* Current adpcm sign bit */
185 int delta; /* Current adpcm output value */ 185 int delta; /* Current adpcm output value */
186 int step; /* Stepsize */ 186 int step; /* Stepsize */
187 int valpred; /* Predicted value */ 187 int valpred; /* Predicted value */
188 int vpdiff; /* Current change to valpred */ 188 int vpdiff; /* Current change to valpred */
189 int index; /* Current step change index */ 189 int index; /* Current step change index */
190 int inputbuffer; /* place to keep next 4-bit value */ 190 int inputbuffer = 0; /* place to keep next 4-bit value */
191 int bufferstep; /* toggle between inputbuffer/input */ 191 int bufferstep = 0; /* toggle between inputbuffer/input */
192 192
193 outp = outdata; 193 outp = outdata;
194 inp = (signed char *)indata; 194 inp = (signed char *)indata;
195 195
196 valpred = state->valprev; 196 valpred = state->valprev;
197 index = state->index; 197 index = state->index;
198 step = stepsizeTable[index]; 198 step = stepsizeTable[index];
199 199
200 bufferstep = 0; 200 bufferstep = 0;
201 201
202 for ( ; len > 0 ; len-- ) { 202 for ( ; len > 0 ; len-- ) {
203 203
204 /* Step 1 - get the delta value */ 204 /* Step 1 - get the delta value */
205 if ( bufferstep ) { 205 if ( bufferstep ) {
206 delta = inputbuffer & 0xf; 206 delta = inputbuffer & 0xf;
207 } else { 207 } else {
208 inputbuffer = *inp++; 208 inputbuffer = *inp++;
209 delta = (inputbuffer >> 4) & 0xf; 209 delta = (inputbuffer >> 4) & 0xf;
210 } 210 }
211 bufferstep = !bufferstep; 211 bufferstep = !bufferstep;
212 212
213 /* Step 2 - Find new index value (for later) */ 213 /* Step 2 - Find new index value (for later) */
214 index += indexTable[delta]; 214 index += indexTable[delta];
215 if ( index < 0 ) index = 0; 215 if ( index < 0 ) index = 0;
216 if ( index > 88 ) index = 88; 216 if ( index > 88 ) index = 88;
217 217
218 /* Step 3 - Separate sign and magnitude */ 218 /* Step 3 - Separate sign and magnitude */
219 sign = delta & 8; 219 sign = delta & 8;
220 delta = delta & 7; 220 delta = delta & 7;
221 221
222 /* Step 4 - Compute difference and new predicted value */ 222 /* Step 4 - Compute difference and new predicted value */
223 /* 223 /*
224 ** Computes 'vpdiff = (delta+0.5)*step/4', but see comment 224 ** Computes 'vpdiff = (delta+0.5)*step/4', but see comment
225 ** in adpcm_coder. 225 ** in adpcm_coder.
226 */ 226 */
227 vpdiff = step >> 3; 227 vpdiff = step >> 3;
228 if ( delta & 4 ) vpdiff += step; 228 if ( delta & 4 ) vpdiff += step;
229 if ( delta & 2 ) vpdiff += step>>1; 229 if ( delta & 2 ) vpdiff += step>>1;
230 if ( delta & 1 ) vpdiff += step>>2; 230 if ( delta & 1 ) vpdiff += step>>2;
231 231
232 if ( sign ) 232 if ( sign )
233 valpred -= vpdiff; 233 valpred -= vpdiff;
234 else 234 else
235 valpred += vpdiff; 235 valpred += vpdiff;
236 236
237 /* Step 5 - clamp output value */ 237 /* Step 5 - clamp output value */
238 if ( valpred > 32767 ) 238 if ( valpred > 32767 )
239 valpred = 32767; 239 valpred = 32767;
240 else if ( valpred < -32768 ) 240 else if ( valpred < -32768 )
241 valpred = -32768; 241 valpred = -32768;
242 242
243 /* Step 6 - Update step value */ 243 /* Step 6 - Update step value */
244 step = stepsizeTable[index]; 244 step = stepsizeTable[index];
245 245
246 /* Step 7 - Output value */ 246 /* Step 7 - Output value */
247 *outp++ = valpred; 247 *outp++ = valpred;
248 } 248 }
249 249
250 state->valprev = valpred; 250 state->valprev = valpred;
251 state->index = index; 251 state->index = index;
252} 252}