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1 /*
2 * This source code is a product of Sun Microsystems, Inc. and is provided
3 * for unrestricted use. Users may copy or modify this source code without
4 * charge.
5 *
6 * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
7 * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
8 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
9 *
10 * Sun source code is provided with no support and without any obligation on
11 * the part of Sun Microsystems, Inc. to assist in its use, correction,
12 * modification or enhancement.
13 *
14 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
15 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE
16 * OR ANY PART THEREOF.
17 *
18 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
19 * or profits or other special, indirect and consequential damages, even if
20 * Sun has been advised of the possibility of such damages.
21 *
22 * Sun Microsystems, Inc.
23 * 2550 Garcia Avenue
24 * Mountain View, California 94043
25 */
26
27 /*
28 * g72x.c
29 *
30 * Common routines for G.721 and G.723 conversions.
31 */
32
33 #include <stdlib.h>
34 #include "g72x.h"
35
36 static short power2[15] = {1, 2, 4, 8, 0x10, 0x20, 0x40, 0x80,
37 0x100, 0x200, 0x400, 0x800, 0x1000, 0x2000, 0x4000};
38
39 /*
40 * quan()
41 *
42 * quantizes the input val against the table of size short integers.
43 * It returns i if table[i - 1] <= val < table[i].
44 *
45 * Using linear search for simple coding.
46 */
47 static int
48 quan(
49 int val,
50 short *table,
51 int size)
52 {
53 int i;
54
55 for (i = 0; i < size; i++)
56 if (val < *table++)
57 break;
58 return (i);
59 }
60
61 static char quan2_tab[65536];
62 static short base2_tab[65536];
63 static int init_tabs_done = 0;
64
65 inline char quan2 (unsigned short val)
66 {
67 return quan2_tab[val];
68 }
69
70 inline short base2 (unsigned short val)
71 {
72 return base2_tab[val];
73 }
74
75 static void init_quan2_tab (void)
76 {
77 long i;
78
79 for (i = 0; i < 65536; i++) {
80 quan2_tab[i] = quan (i, power2, 15);
81 };
82 }
83
84 static void init_base2_tab (void)
85 {
86 long i;
87 short exp;
88
89 for (i = 0; i < 65536; i++) {
90 exp = quan2 (short (i));
91 base2_tab[i] = short ((exp << 6) + ((i << 6) >> exp));
92 };
93 }
94
95 static void init_tabs (void)
96 {
97 if (init_tabs_done) return;
98
99 init_quan2_tab();
100 init_base2_tab();
101
102 init_tabs_done = 1;
103 }
104
105 /*
106 * fmult()
107 *
108 * returns the integer product of the 14-bit integer "an" and
109 * "floating point" representation (4-bit exponent, 6-bit mantessa) "srn".
110 */
111 static int
112 fmult(
113 int an,
114 int srn)
115 {
116 short anmag, anexp, anmant;
117 short wanexp, wanmant;
118 short retval;
119
120 anmag = (an > 0) ? an : ((-an) & 0x1FFF);
121 anexp = quan2(anmag) - 6;
122 anmant = (anmag == 0) ? 32 :
123 (anexp >= 0) ? anmag >> anexp : anmag << -anexp;
124 wanexp = anexp + ((srn >> 6) & 0xF) - 13;
125
126 wanmant = (anmant * (srn & 077) + 0x30) >> 4;
127 retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) :
128 (wanmant >> -wanexp);
129
130 return (((an ^ srn) < 0) ? -retval : retval);
131 }
132
133 /*
134 * g72x_init_state()
135 *
136 * This routine initializes and/or resets the g72x_state structure
137 * pointed to by 'state_ptr'.
138 * All the initial state values are specified in the CCITT G.721 document.
139 */
140 void
141 g72x_init_state(
142 struct g72x_state *state_ptr)
143 {
144 int cnta;
145
146 init_tabs ();
147
148 state_ptr->yl = 34816;
149 state_ptr->yu = 544;
150 state_ptr->dms = 0;
151 state_ptr->dml = 0;
152 state_ptr->ap = 0;
153 for (cnta = 0; cnta < 2; cnta++) {
154 state_ptr->a[cnta] = 0;
155 state_ptr->pk[cnta] = 0;
156 state_ptr->sr[cnta] = 32;
157 }
158 for (cnta = 0; cnta < 6; cnta++) {
159 state_ptr->b[cnta] = 0;
160 state_ptr->dq[cnta] = 32;
161 }
162 state_ptr->td = 0;
163 }
164
165 /*
166 * predictor_zero()
167 *
168 * computes the estimated signal from 6-zero predictor.
169 *
170 */
171 int
172 predictor_zero(
173 struct g72x_state *state_ptr)
174 {
175 int i;
176 int sezi;
177
178 sezi = fmult(state_ptr->b[0] >> 2, state_ptr->dq[0]);
179 for (i = 1; i < 6; i++) /* ACCUM */
180 sezi += fmult(state_ptr->b[i] >> 2, state_ptr->dq[i]);
181 return (sezi);
182 }
183 /*
184 * predictor_pole()
185 *
186 * computes the estimated signal from 2-pole predictor.
187 *
188 */
189 int
190 predictor_pole(
191 struct g72x_state *state_ptr)
192 {
193 return (fmult(state_ptr->a[1] >> 2, state_ptr->sr[1]) +
194 fmult(state_ptr->a[0] >> 2, state_ptr->sr[0]));
195 }
196 /*
197 * step_size()
198 *
199 * computes the quantization step size of the adaptive quantizer.
200 *
201 */
202 int
203 step_size(
204 struct g72x_state *state_ptr)
205 {
206 int y;
207 int dif;
208 int al;
209
210 if (state_ptr->ap >= 256)
211 return (state_ptr->yu);
212 else {
213 y = state_ptr->yl >> 6;
214 dif = state_ptr->yu - y;
215 al = state_ptr->ap >> 2;
216 if (dif > 0)
217 y += (dif * al) >> 6;
218 else if (dif < 0)
219 y += (dif * al + 0x3F) >> 6;
220 return (y);
221 }
222 }
223
224 /*
225 * quantize()
226 *
227 * Given a raw sample, 'd', of the difference signal and a
228 * quantization step size scale factor, 'y', this routine returns the
229 * ADPCM codeword to which that sample gets quantized. The step
230 * size scale factor division operation is done in the log base 2 domain
231 * as a subtraction.
232 */
233 int
234 quantize(
235 int d, /* Raw difference signal sample */
236 int y, /* Step size multiplier */
237 short *table, /* quantization table */
238 int size) /* table size of short integers */
239 {
240 short dqm; /* Magnitude of 'd' */
241 short exp; /* Integer part of base 2 log of 'd' */
242 short mant; /* Fractional part of base 2 log */
243 short dl; /* Log of magnitude of 'd' */
244 short dln; /* Step size scale factor normalized log */
245 int i;
246
247 /*
248 * LOG
249 *
250 * Compute base 2 log of 'd', and store in 'dl'.
251 */
252 dqm = abs(d);
253 exp = quan2(dqm >> 1);
254 mant = ((dqm << 7) >> exp) & 0x7F; /* Fractional portion. */
255 dl = (exp << 7) + mant;
256
257 /*
258 * SUBTB
259 *
260 * "Divide" by step size multiplier.
261 */
262 dln = dl - (y >> 2);
263
264 /*
265 * QUAN
266 *
267 * Obtain codword i for 'd'.
268 */
269 i = quan(dln, table, size);
270 if (d < 0) /* take 1's complement of i */
271 return ((size << 1) + 1 - i);
272 else if (i == 0) /* take 1's complement of 0 */
273 return ((size << 1) + 1); /* new in 1988 */
274 else
275 return (i);
276 }
277 /*
278 * reconstruct()
279 *
280 * Returns reconstructed difference signal 'dq' obtained from
281 * codeword 'i' and quantization step size scale factor 'y'.
282 * Multiplication is performed in log base 2 domain as addition.
283 */
284 int
285 reconstruct(
286 int sign, /* 0 for non-negative value */
287 int dqln, /* G.72x codeword */
288 int y) /* Step size multiplier */
289 {
290 short dql; /* Log of 'dq' magnitude */
291 short dex; /* Integer part of log */
292 short dqt;
293 short dq; /* Reconstructed difference signal sample */
294
295 dql = dqln + (y >> 2); /* ADDA */
296
297 if (dql < 0) {
298 return ((sign) ? -0x8000 : 0);
299 } else { /* ANTILOG */
300 dex = (dql >> 7) & 15;
301 dqt = 128 + (dql & 127);
302 dq = (dqt << 7) >> (14 - dex);
303 return ((sign) ? (dq - 0x8000) : dq);
304 }
305 }
306
307
308 /*
309 * update()
310 *
311 * updates the state variables for each output code
312 */
313 void
314 update(
315 int code_size, /* distinguish 723_40 with others */
316 int y, /* quantizer step size */
317 int wi, /* scale factor multiplier */
318 int fi, /* for long/short term energies */
319 int dq, /* quantized prediction difference */
320 int sr, /* reconstructed signal */
321 int dqsez, /* difference from 2-pole predictor */
322 struct g72x_state *state_ptr) /* coder state pointer */
323 {
324 int cnt;
325 short mag; /* Adaptive predictor, FLOAT A */
326 short a2p; /* LIMC */
327 short a1ul; /* UPA1 */
328 short pks1; /* UPA2 */
329 short fa1;
330 char tr; /* tone/transition detector */
331 short ylint, thr2, dqthr;
332 short ylfrac, thr1;
333 short pk0;
334
335 pk0 = (dqsez < 0) ? 1 : 0; /* needed in updating predictor poles */
336
337 mag = dq & 0x7FFF; /* prediction difference magnitude */
338 /* TRANS */
339 ylint = short (state_ptr->yl >> 15); /* exponent part of yl */
340 ylfrac = (state_ptr->yl >> 10) & 0x1F; /* fractional part of yl */
341 thr1 = (32 + ylfrac) << ylint; /* threshold */
342 thr2 = (ylint > 9) ? 31 << 10 : thr1; /* limit thr2 to 31 << 10 */
343 dqthr = (thr2 + (thr2 >> 1)) >> 1; /* dqthr = 0.75 * thr2 */
344 if (state_ptr->td == 0) /* signal supposed voice */
345 tr = 0;
346 else if (mag <= dqthr) /* supposed data, but small mag */
347 tr = 0; /* treated as voice */
348 else /* signal is data (modem) */
349 tr = 1;
350
351 /*
352 * Quantizer scale factor adaptation.
353 */
354
355 /* FUNCTW & FILTD & DELAY */
356 /* update non-steady state step size multiplier */
357 state_ptr->yu = y + ((wi - y) >> 5);
358
359 /* LIMB */
360 if (state_ptr->yu < 544) /* 544 <= yu <= 5120 */
361 state_ptr->yu = 544;
362 else if (state_ptr->yu > 5120)
363 state_ptr->yu = 5120;
364
365 /* FILTE & DELAY */
366 /* update steady state step size multiplier */
367 state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);
368
369 /*
370 * Adaptive predictor coefficients.
371 */
372 if (tr == 1) { /* reset a's and b's for modem signal */
373 state_ptr->a[0] = 0;
374 state_ptr->a[1] = 0;
375 state_ptr->b[0] = 0;
376 state_ptr->b[1] = 0;
377 state_ptr->b[2] = 0;
378 state_ptr->b[3] = 0;
379 state_ptr->b[4] = 0;
380 state_ptr->b[5] = 0;
381
382 a2p = 0; /* eliminate Compiler Warnings */
383 } else { /* update a's and b's */
384 pks1 = pk0 ^ state_ptr->pk[0]; /* UPA2 */
385
386 /* update predictor pole a[1] */
387 a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
388 if (dqsez != 0) {
389 fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
390 if (fa1 < -8191) /* a2p = function of fa1 */
391 a2p -= 0x100;
392 else if (fa1 > 8191)
393 a2p += 0xFF;
394 else
395 a2p += fa1 >> 5;
396
397 if (pk0 ^ state_ptr->pk[1])
398 /* LIMC */
399 if (a2p <= -12160)
400 a2p = -12288;
401 else if (a2p >= 12416)
402 a2p = 12288;
403 else
404 a2p -= 0x80;
405 else if (a2p <= -12416)
406 a2p = -12288;
407 else if (a2p >= 12160)
408 a2p = 12288;
409 else
410 a2p += 0x80;
411 }
412
413 /* TRIGB & DELAY */
414 state_ptr->a[1] = a2p;
415
416 /* UPA1 */
417 /* update predictor pole a[0] */
418 state_ptr->a[0] -= state_ptr->a[0] >> 8;
419 if (dqsez != 0)
420 if (pks1 == 0)
421 state_ptr->a[0] += 192;
422 else
423 state_ptr->a[0] -= 192;
424
425 /* LIMD */
426 a1ul = 15360 - a2p;
427 if (state_ptr->a[0] < -a1ul)
428 state_ptr->a[0] = -a1ul;
429 else if (state_ptr->a[0] > a1ul)
430 state_ptr->a[0] = a1ul;
431
432 /* UPB : update predictor zeros b[6] */
433 for (cnt = 0; cnt < 6; cnt++) {
434 if (code_size == 5) /* for 40Kbps G.723 */
435 state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9;
436 else /* for G.721 and 24Kbps G.723 */
437 state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
438 if (dq & 0x7FFF) { /* XOR */
439 if ((dq ^ state_ptr->dq[cnt]) >= 0)
440 state_ptr->b[cnt] += 128;
441 else
442 state_ptr->b[cnt] -= 128;
443 }
444 }
445 }
446
447 for (cnt = 5; cnt > 0; cnt--)
448 state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
449 /* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
450 if (mag == 0) {
451 state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0xFC20;
452 } else {
453 state_ptr->dq[0] = (dq >= 0) ?
454 base2 (mag) : base2 (mag) - 0x400;
455 }
456
457 state_ptr->sr[1] = state_ptr->sr[0];
458 /* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
459 if (sr == 0) {
460 state_ptr->sr[0] = 0x20;
461 } else if (sr > 0) {
462 state_ptr->sr[0] = base2(sr);
463 } else if (sr > -32768) {
464 mag = -sr;
465 state_ptr->sr[0] = base2(mag) - 0x400;
466 } else
467 state_ptr->sr[0] = short (0xFC20);
468
469 /* DELAY A */
470 state_ptr->pk[1] = state_ptr->pk[0];
471 state_ptr->pk[0] = pk0;
472
473 /* TONE */
474 if (tr == 1) /* this sample has been treated as data */
475 state_ptr->td = 0; /* next one will be treated as voice */
476 else if (a2p < -11776) /* small sample-to-sample correlation */
477 state_ptr->td = 1; /* signal may be data */
478 else /* signal is voice */
479 state_ptr->td = 0;
480
481 /*
482 * Adaptation speed control.
483 */
484 state_ptr->dms += (fi - state_ptr->dms) >> 5; /* FILTA */
485 state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7); /* FILTB */
486
487 if (tr == 1)
488 state_ptr->ap = 256;
489 else if (y < 1536) /* SUBTC */
490 state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
491 else if (state_ptr->td == 1)
492 state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
493 else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
494 (state_ptr->dml >> 3))
495 state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
496 else
497 state_ptr->ap += (-state_ptr->ap) >> 4;
498 }
499
500 /*
501 * tandem_adjust(sr, se, y, i, sign)
502 *
503 * At the end of ADPCM decoding, it simulates an encoder which may be receiving
504 * the output of this decoder as a tandem process. If the output of the
505 * simulated encoder differs from the input to this decoder, the decoder output
506 * is adjusted by one level of A-law or u-law codes.
507 *
508 * Input:
509 * sr decoder output linear PCM sample,
510 * se predictor estimate sample,
511 * y quantizer step size,
512 * i decoder input code,
513 * sign sign bit of code i
514 *
515 * Return:
516 * adjusted A-law or u-law compressed sample.
517 */
518 int
519 tandem_adjust_alaw(
520 int sr, /* decoder output linear PCM sample */
521 int se, /* predictor estimate sample */
522 int y, /* quantizer step size */
523 int i, /* decoder input code */
524 int sign,
525 short *qtab)
526 {
527 unsigned char sp; /* A-law compressed 8-bit code */
528 short dx; /* prediction error */
529 char id; /* quantized prediction error */
530 int sd; /* adjusted A-law decoded sample value */
531 int im; /* biased magnitude of i */
532 int imx; /* biased magnitude of id */
533
534 if (sr <= -32768)
535 sr = -1;
536 sp = linear2alaw((sr >> 1) << 3); /* short to A-law compression */
537 dx = (alaw2linear(sp) >> 2) - se; /* 16-bit prediction error */
538 id = quantize(dx, y, qtab, sign - 1);
539
540 if (id == i) { /* no adjustment on sp */
541 return (sp);
542 } else { /* sp adjustment needed */
543 /* ADPCM codes : 8, 9, ... F, 0, 1, ... , 6, 7 */
544 im = i ^ sign; /* 2's complement to biased unsigned */
545 imx = id ^ sign;
546
547 if (imx > im) { /* sp adjusted to next lower value */
548 if (sp & 0x80) {
549 sd = (sp == 0xD5) ? 0x55 :
550 ((sp ^ 0x55) - 1) ^ 0x55;
551 } else {
552 sd = (sp == 0x2A) ? 0x2A :
553 ((sp ^ 0x55) + 1) ^ 0x55;
554 }
555 } else { /* sp adjusted to next higher value */
556 if (sp & 0x80)
557 sd = (sp == 0xAA) ? 0xAA :
558 ((sp ^ 0x55) + 1) ^ 0x55;
559 else
560 sd = (sp == 0x55) ? 0xD5 :
561 ((sp ^ 0x55) - 1) ^ 0x55;
562 }
563 return (sd);
564 }
565 }
566
567 int
568 tandem_adjust_ulaw(
569 int sr, /* decoder output linear PCM sample */
570 int se, /* predictor estimate sample */
571 int y, /* quantizer step size */
572 int i, /* decoder input code */
573 int sign,
574 short *qtab)
575 {
576 unsigned char sp; /* u-law compressed 8-bit code */
577 short dx; /* prediction error */
578 char id; /* quantized prediction error */
579 int sd; /* adjusted u-law decoded sample value */
580 int im; /* biased magnitude of i */
581 int imx; /* biased magnitude of id */
582
583 if (sr <= -32768)
584 sr = 0;
585 sp = linear2ulaw(sr << 2); /* short to u-law compression */
586 dx = (ulaw2linear(sp) >> 2) - se; /* 16-bit prediction error */
587 id = quantize(dx, y, qtab, sign - 1);
588 if (id == i) {
589 return (sp);
590 } else {
591 /* ADPCM codes : 8, 9, ... F, 0, 1, ... , 6, 7 */
592 im = i ^ sign; /* 2's complement to biased unsigned */
593 imx = id ^ sign;
594 if (imx > im) { /* sp adjusted to next lower value */
595 if (sp & 0x80)
596 sd = (sp == 0xFF) ? 0x7E : sp + 1;
597 else
598 sd = (sp == 0) ? 0 : sp - 1;
599
600 } else { /* sp adjusted to next higher value */
601 if (sp & 0x80)
602 sd = (sp == 0x80) ? 0x80 : sp - 1;
603 else
604 sd = (sp == 0x7F) ? 0xFE : sp + 1;
605 }
606 return (sd);
607 }
608 }
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