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path: root/core/applets/vmemo/adpcm.c
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-rw-r--r--core/applets/vmemo/adpcm.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/core/applets/vmemo/adpcm.c b/core/applets/vmemo/adpcm.c
index c4dfa50..a123249 100644
--- a/core/applets/vmemo/adpcm.c
+++ b/core/applets/vmemo/adpcm.c
@@ -41,98 +41,98 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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 */
@@ -142,98 +142,98 @@ adpcm_coder(indata, outdata, len, state)
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;