1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright (c) 1992-2001 by Sun Microsystems, Inc.
24 * All rights reserved.
25 */
26
27 /*
28 *
29 * Description:
30 *
31 * g721_encode(), g721_decode(), g721_set_law()
32 *
33 * These routines comprise an implementation of the CCITT G.721 ADPCM coding
34 * algorithm. Essentially, this implementation is identical to
35 * the bit level description except for a few deviations which
36 * take advantage of work station attributes, such as hardware 2's
37 * complement arithmetic and large memory. Specifically, certain time
38 * consuming operations such as multiplications are replaced
39 * with look up tables and software 2's complement operations are
40 * replaced with hardware 2's complement.
41 *
42 * The deviation (look up tables) from the bit level
43 * specification, preserves the bit level performance specifications.
44 *
45 * As outlined in the G.721 Recommendation, the algorithm is broken
46 * down into modules. Each section of code below is preceded by
47 * the name of the module which it is implementing.
48 *
49 */
50 #include <stdlib.h>
51 #include <libaudio.h>
52
53 /*
54 * Maps G.721 code word to reconstructed scale factor normalized log
55 * magnitude values.
56 */
57 static short _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425,
58 425, 373, 323, 273, 213, 135, 4, -2048};
59
60 /* Maps G.721 code word to log of scale factor multiplier. */
61 static long _witab[16] = {-384, 576, 1312, 2048, 3584, 6336, 11360, 35904,
62 35904, 11360, 6336, 3584, 2048, 1312, 576, -384};
63
64 /*
65 * Maps G.721 code words to a set of values whose long and short
66 * term averages are computed and then compared to give an indication
67 * how stationary (steady state) the signal is.
68 */
69 static short _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
70 0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};
71
72 /*
73 * g721_init_state()
74 *
75 * Description:
76 *
77 * This routine initializes and/or resets the audio_g72x_state structure
78 * pointed to by 'state_ptr'.
79 * All the initial state values are specified in the G.721 standard specs.
80 */
81 void
g721_init_state(struct audio_g72x_state * state_ptr)82 g721_init_state(
83 struct audio_g72x_state *state_ptr)
84 {
85 int cnta;
86
87 state_ptr->yl = 34816;
88 state_ptr->yu = 544;
89 state_ptr->dms = 0;
90 state_ptr->dml = 0;
91 state_ptr->ap = 0;
92 for (cnta = 0; cnta < 2; cnta++) {
93 state_ptr->a[cnta] = 0;
94 state_ptr->pk[cnta] = 0;
95 state_ptr->sr[cnta] = 32;
96 }
97 for (cnta = 0; cnta < 6; cnta++) {
98 state_ptr->b[cnta] = 0;
99 state_ptr->dq[cnta] = 32;
100 }
101 state_ptr->td = 0;
102 state_ptr->leftover_cnt = 0; /* no left over codes */
103 }
104
105 /*
106 * _g721_fmult()
107 *
108 * returns the integer product of the "floating point" an and srn
109 * by the lookup table _fmultwanmant[].
110 *
111 */
112 static int
_g721_fmult(int an,int srn)113 _g721_fmult(
114 int an,
115 int srn)
116 {
117 short anmag, anexp, anmant;
118 short wanexp;
119
120 if (an == 0) {
121 return ((srn >= 0) ?
122 ((srn & 077) + 1) >> (18 - (srn >> 6)) :
123 -(((srn & 077) + 1) >> (2 - (srn >> 6))));
124 } else if (an > 0) {
125 anexp = _fmultanexp[an] - 12;
126 anmant = ((anexp >= 0) ? an >> anexp : an << -anexp) & 07700;
127 if (srn >= 0) {
128 wanexp = anexp + (srn >> 6) - 7;
129 return ((wanexp >= 0) ?
130 (_fmultwanmant[(srn & 077) + anmant] << wanexp)
131 & 0x7FFF :
132 _fmultwanmant[(srn & 077) + anmant] >> -wanexp);
133 } else {
134 wanexp = anexp + (srn >> 6) - 0xFFF7;
135 return ((wanexp >= 0) ?
136 -((_fmultwanmant[(srn & 077) + anmant] << wanexp)
137 & 0x7FFF) :
138 -(_fmultwanmant[(srn & 077) + anmant] >> -wanexp));
139 }
140 } else {
141 anmag = (-an) & 0x1FFF;
142 anexp = _fmultanexp[anmag] - 12;
143 anmant = ((anexp >= 0) ? anmag >> anexp : anmag << -anexp)
144 & 07700;
145 if (srn >= 0) {
146 wanexp = anexp + (srn >> 6) - 7;
147 return ((wanexp >= 0) ?
148 -((_fmultwanmant[(srn & 077) + anmant] << wanexp)
149 & 0x7FFF) :
150 -(_fmultwanmant[(srn & 077) + anmant] >> -wanexp));
151 } else {
152 wanexp = anexp + (srn >> 6) - 0xFFF7;
153 return ((wanexp >= 0) ?
154 (_fmultwanmant[(srn & 077) + anmant] << wanexp)
155 & 0x7FFF :
156 _fmultwanmant[(srn & 077) + anmant] >> -wanexp);
157 }
158 }
159 }
160
161 /*
162 * _g721_update()
163 *
164 * updates the state variables for each output code
165 *
166 */
167 static void
_g721_update(int y,int i,int dq,int sr,int pk0,struct audio_g72x_state * state_ptr,int sigpk)168 _g721_update(
169 int y,
170 int i,
171 int dq,
172 int sr,
173 int pk0,
174 struct audio_g72x_state *state_ptr,
175 int sigpk)
176 {
177 int cnt;
178 long fi; /* FUNCTF */
179 short mag, exp; /* FLOAT A */
180 short a2p; /* LIMC */
181 short a1ul; /* UPA1 */
182 short pks1, fa1; /* UPA2 */
183 char tr; /* tone/transition detector */
184 short thr2;
185
186 mag = dq & 0x3FFF;
187 /* TRANS */
188 if (state_ptr->td == 0) {
189 tr = 0;
190 } else if (state_ptr->yl > 0x40000) {
191 tr = (mag <= 0x2F80) ? 0 : 1;
192 } else {
193 thr2 = (0x20 + ((state_ptr->yl >> 10) & 0x1F)) <<
194 (state_ptr->yl >> 15);
195 if (mag >= thr2) {
196 tr = 1;
197 } else {
198 tr = (mag <= (thr2 - (thr2 >> 2))) ? 0 : 1;
199 }
200 }
201
202 /*
203 * Quantizer scale factor adaptation.
204 */
205
206 /* FUNCTW & FILTD & DELAY */
207 state_ptr->yu = y + ((_witab[i] - y) >> 5);
208
209 /* LIMB */
210 if (state_ptr->yu < 544) {
211 state_ptr->yu = 544;
212 } else if (state_ptr->yu > 5120) {
213 state_ptr->yu = 5120;
214 }
215
216 /* FILTE & DELAY */
217 state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);
218
219 /*
220 * Adaptive predictor.
221 */
222 if (tr == 1) {
223 state_ptr->a[0] = 0;
224 state_ptr->a[1] = 0;
225 state_ptr->b[0] = 0;
226 state_ptr->b[1] = 0;
227 state_ptr->b[2] = 0;
228 state_ptr->b[3] = 0;
229 state_ptr->b[4] = 0;
230 state_ptr->b[5] = 0;
231 } else {
232
233 /* UPA2 */
234 pks1 = pk0 ^ state_ptr->pk[0];
235
236 a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
237 if (sigpk == 0) {
238 fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
239 if (fa1 < -8191) {
240 a2p -= 0x100;
241 } else if (fa1 > 8191) {
242 a2p += 0xFF;
243 } else {
244 a2p += fa1 >> 5;
245 }
246
247 if (pk0 ^ state_ptr->pk[1]) {
248 /* LIMC */
249 if (a2p <= -12160) {
250 a2p = -12288;
251 } else if (a2p >= 12416) {
252 a2p = 12288;
253 } else {
254 a2p -= 0x80;
255 }
256 } else if (a2p <= -12416) {
257 a2p = -12288;
258 } else if (a2p >= 12160) {
259 a2p = 12288;
260 } else {
261 a2p += 0x80;
262 }
263 }
264
265 /* TRIGB & DELAY */
266 state_ptr->a[1] = a2p;
267
268 /* UPA1 */
269 state_ptr->a[0] -= state_ptr->a[0] >> 8;
270 if (sigpk == 0) {
271 if (pks1 == 0) {
272 state_ptr->a[0] += 192;
273 } else {
274 state_ptr->a[0] -= 192;
275 }
276 }
277
278 /* LIMD */
279 a1ul = 15360 - a2p;
280 if (state_ptr->a[0] < -a1ul)
281 state_ptr->a[0] = -a1ul;
282 else if (state_ptr->a[0] > a1ul)
283 state_ptr->a[0] = a1ul;
284
285 /* UPB : update of b's */
286 for (cnt = 0; cnt < 6; cnt++) {
287 state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
288 if (dq & 0x3FFF) {
289 /* XOR */
290 if ((dq ^ state_ptr->dq[cnt]) >= 0)
291 state_ptr->b[cnt] += 128;
292 else
293 state_ptr->b[cnt] -= 128;
294 }
295 }
296 }
297
298 for (cnt = 5; cnt > 0; cnt--)
299 state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
300 /* FLOAT A */
301 if (mag == 0) {
302 state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0xFC20;
303 } else {
304 exp = _fmultanexp[mag];
305 state_ptr->dq[0] = (dq >= 0) ?
306 (exp << 6) + ((mag << 6) >> exp) :
307 (exp << 6) + ((mag << 6) >> exp) - 0x400;
308 }
309
310 state_ptr->sr[1] = state_ptr->sr[0];
311 /* FLOAT B */
312 if (sr == 0) {
313 state_ptr->sr[0] = 0x20;
314 } else if (sr > 0) {
315 exp = _fmultanexp[sr];
316 state_ptr->sr[0] = (exp << 6) + ((sr << 6) >> exp);
317 } else {
318 mag = -sr;
319 exp = _fmultanexp[mag];
320 state_ptr->sr[0] = (exp << 6) + ((mag << 6) >> exp) - 0x400;
321 }
322
323 /* DELAY A */
324 state_ptr->pk[1] = state_ptr->pk[0];
325 state_ptr->pk[0] = pk0;
326
327 /* TONE */
328 if (tr == 1)
329 state_ptr->td = 0;
330 else if (a2p < -11776)
331 state_ptr->td = 1;
332 else
333 state_ptr->td = 0;
334
335 /*
336 * Adaptation speed control.
337 */
338 fi = _fitab[i]; /* FUNCTF */
339 state_ptr->dms += (fi - state_ptr->dms) >> 5; /* FILTA */
340 state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7); /* FILTB */
341
342 if (tr == 1)
343 state_ptr->ap = 256;
344 else if (y < 1536) /* SUBTC */
345 state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
346 else if (state_ptr->td == 1)
347 state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
348 else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
349 (state_ptr->dml >> 3))
350 state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
351 else
352 state_ptr->ap += (-state_ptr->ap) >> 4;
353 }
354
355 /*
356 * _g721_quantize()
357 *
358 * Description:
359 *
360 * Given a raw sample, 'd', of the difference signal and a
361 * quantization step size scale factor, 'y', this routine returns the
362 * G.721 codeword to which that sample gets quantized. The step
363 * size scale factor division operation is done in the log base 2 domain
364 * as a subtraction.
365 */
366 static unsigned int
_g721_quantize(int d,int y)367 _g721_quantize(
368 int d, /* Raw difference signal sample. */
369 int y) /* Step size multiplier. */
370 {
371 /* LOG */
372 short dqm; /* Magnitude of 'd'. */
373 short exp; /* Integer part of base 2 log of magnitude of 'd'. */
374 short mant; /* Fractional part of base 2 log. */
375 short dl; /* Log of magnitude of 'd'. */
376
377 /* SUBTB */
378 short dln; /* Step size scale factor normalized log. */
379
380 /* QUAN */
381 char i; /* G.721 codeword. */
382
383 /*
384 * LOG
385 *
386 * Compute base 2 log of 'd', and store in 'dln'.
387 *
388 */
389 dqm = abs(d);
390 exp = _fmultanexp[dqm >> 1];
391 mant = ((dqm << 7) >> exp) & 0x7F; /* Fractional portion. */
392 dl = (exp << 7) + mant;
393
394 /*
395 * SUBTB
396 *
397 * "Divide" by step size multiplier.
398 */
399 dln = dl - (y >> 2);
400
401 /*
402 * QUAN
403 *
404 * Obtain codword for 'd'.
405 */
406 i = _quani[dln & 0xFFF];
407 if (d < 0)
408 i ^= 0xF; /* Stuff in sign of 'd'. */
409 else if (i == 0)
410 i = 0xF; /* New in 1988 revision */
411
412 return (i);
413 }
414
415 /*
416 * _g721_reconstr()
417 *
418 * Description:
419 *
420 * Returns reconstructed difference signal 'dq' obtained from
421 * G.721 codeword 'i' and quantization step size scale factor 'y'.
422 * Multiplication is performed in log base 2 domain as addition.
423 */
424 static unsigned long
_g721_reconstr(int i,unsigned long y)425 _g721_reconstr(
426 int i, /* G.721 codeword. */
427 unsigned long y) /* Step size multiplier. */
428 {
429 /* ADD A */
430 short dql; /* Log of 'dq' magnitude. */
431
432 /* ANTILOG */
433 short dex; /* Integer part of log. */
434 short dqt;
435 short dq; /* Reconstructed difference signal sample. */
436
437 dql = _dqlntab[i] + (y >> 2); /* ADDA */
438
439 if (dql < 0)
440 dq = 0;
441 else { /* ANTILOG */
442 dex = (dql >> 7) & 15;
443 dqt = 128 + (dql & 127);
444 dq = (dqt << 7) >> (14 - dex);
445 }
446 if (i & 8)
447 dq -= 0x4000;
448
449 return (dq);
450 }
451
452 /*
453 * _tandem_adjust(sr, se, y, i)
454 *
455 * Description:
456 *
457 * At the end of ADPCM decoding, it simulates an encoder which may be receiving
458 * the output of this decoder as a tandem process. If the output of the
459 * simulated encoder differs from the input to this decoder, the decoder output
460 * is adjusted by one level of A-law or u-law codes.
461 *
462 * Input:
463 * sr decoder output linear PCM sample,
464 * se predictor estimate sample,
465 * y quantizer step size,
466 * i decoder input code
467 *
468 * Return:
469 * adjusted A-law or u-law compressed sample.
470 */
471 static int
_tandem_adjust_alaw(int sr,int se,int y,int i)472 _tandem_adjust_alaw(
473 int sr, /* decoder output linear PCM sample */
474 int se, /* predictor estimate sample */
475 int y, /* quantizer step size */
476 int i) /* decoder input code */
477 {
478 unsigned char sp; /* A-law compressed 8-bit code */
479 short dx; /* prediction error */
480 char id; /* quantized prediction error */
481 int sd; /* adjusted A-law decoded sample value */
482 int im; /* biased magnitude of i */
483 int imx; /* biased magnitude of id */
484
485 sp = audio_s2a((sr <= -0x2000)? -0x8000 :
486 (sr >= 0x1FFF)? 0x7FFF : sr << 2); /* short to A-law compression */
487 dx = (audio_a2s(sp) >> 2) - se; /* 16-bit prediction error */
488 id = _g721_quantize(dx, y);
489
490 if (id == i) /* no adjustment on sp */
491 return (sp);
492 else { /* sp adjustment needed */
493 /* ADPCM codes : 8, 9, ... F, 0, 1, ... , 6, 7 */
494 im = i ^ 8; /* 2's complement to biased unsigned */
495 imx = id ^ 8;
496
497 if (imx > im) { /* sp adjusted to next lower value */
498 if (sp & 0x80)
499 sd = (sp == 0xD5)? 0x55 :
500 ((sp ^ 0x55) - 1) ^ 0x55;
501 else
502 sd = (sp == 0x2A)? 0x2A :
503 ((sp ^ 0x55) + 1) ^ 0x55;
504 } else { /* sp adjusted to next higher value */
505 if (sp & 0x80)
506 sd = (sp == 0xAA)? 0xAA :
507 ((sp ^ 0x55) + 1) ^ 0x55;
508 else
509 sd = (sp == 0x55)? 0xD5 :
510 ((sp ^ 0x55) - 1) ^ 0x55;
511 }
512 return (sd);
513 }
514 }
515
516 static int
_tandem_adjust_ulaw(int sr,int se,int y,int i)517 _tandem_adjust_ulaw(
518 int sr, /* decoder output linear PCM sample */
519 int se, /* predictor estimate sample */
520 int y, /* quantizer step size */
521 int i) /* decoder input code */
522 {
523 unsigned char sp; /* A-law compressed 8-bit code */
524 short dx; /* prediction error */
525 char id; /* quantized prediction error */
526 int sd; /* adjusted A-law decoded sample value */
527 int im; /* biased magnitude of i */
528 int imx; /* biased magnitude of id */
529
530 sp = audio_s2u((sr <= -0x2000)? -0x8000 :
531 (sr >= 0x1FFF)? 0x7FFF : sr << 2); /* short to u-law compression */
532 dx = (audio_u2s(sp) >> 2) - se; /* 16-bit prediction error */
533 id = _g721_quantize(dx, y);
534 if (id == i)
535 return (sp);
536 else {
537 /* ADPCM codes : 8, 9, ... F, 0, 1, ... , 6, 7 */
538 im = i ^ 8; /* 2's complement to biased unsigned */
539 imx = id ^ 8;
540 if (imx > im) { /* sp adjusted to next lower value */
541 if (sp & 0x80)
542 sd = (sp == 0xFF)? 0x7F : sp + 1;
543 else
544 sd = (sp == 0)? 0 : sp - 1;
545
546 } else { /* sp adjusted to next higher value */
547 if (sp & 0x80)
548 sd = (sp == 0x80)? 0x80 : sp - 1;
549 else
550 sd = (sp == 0x7F)? 0xFF : sp + 1;
551 }
552 return (sd);
553 }
554 }
555
556 /*
557 * g721_encode()
558 *
559 * Description:
560 *
561 * Encodes a buffer of linear PCM, A-law or u-law data pointed to by
562 * 'in_buf' according * the G.721 encoding algorithm and packs the
563 * resulting code words into bytes. The bytes of codeword pairs are
564 * written to a buffer pointed to by 'out_buf'.
565 *
566 * Notes:
567 *
568 * In the event that the total number of codewords which have to be
569 * written is odd, the last unpairable codeword is saved in the
570 * state structure till the next call. It is then paired off and
571 * packed with the first codeword of the new buffer. The number of
572 * valid bytes in 'out_buf' is returned in *out_size. Note that
573 * *out_size will not always be equal to half * of 'data_size' on input.
574 * On the final call to 'g721_encode()' the calling program might want to
575 * check if a codeword was left over. This can be
576 * done by calling 'g721_encode()' with data_size = 0, which returns in
577 * *out_size a 0 if nothing was leftover and 1 if a codeword was leftover
578 * which now is in out_buf[0].
579 *
580 * The 4 lower significant bits of an individual byte in the output byte
581 * stream is packed with a G.721 codeword first. Then the 4 higher order
582 * bits are packed with the next codeword.
583 */
584 int
g721_encode(void * in_buf,int data_size,Audio_hdr * in_header,unsigned char * out_buf,int * out_size,struct audio_g72x_state * state_ptr)585 g721_encode(
586 void *in_buf,
587 int data_size,
588 Audio_hdr *in_header,
589 unsigned char *out_buf,
590 int *out_size,
591 struct audio_g72x_state *state_ptr)
592 {
593 short sl; /* EXPAND */
594 short sei, sezi, se, sez; /* ACCUM */
595 short d; /* SUBTA */
596 float al; /* use floating point for faster multiply */
597 short y, dif; /* MIX */
598 short sr; /* ADDB */
599 short pk0, sigpk, dqsez; /* ADDC */
600 short dq, i;
601 int cnt, cnta;
602 int out_leng;
603 unsigned char *char_in;
604 unsigned char *char_out;
605 short *short_ptr;
606
607 if (data_size == 0) {
608 /* Actually, the leftover count will never be more than 4 */
609 for (i = 0; state_ptr->leftover_cnt > 0; i++) {
610 *out_buf++ = state_ptr->leftover[i];
611 state_ptr->leftover_cnt -= 8;
612 }
613 *out_size = i;
614 state_ptr->leftover_cnt = 0;
615 return (AUDIO_SUCCESS);
616 }
617
618 /* XXX - if linear, it had better be 16-bit! */
619 if (in_header->encoding == AUDIO_ENCODING_LINEAR) {
620 if (data_size & 1) {
621 return (AUDIO_ERR_BADFRAME);
622 } else {
623 data_size >>= 1; /* divide to get sample cnt */
624 short_ptr = (short *)in_buf;
625 }
626 } else {
627 char_in = (unsigned char *)in_buf;
628 }
629 char_out = (unsigned char *)out_buf;
630 if (state_ptr->leftover_cnt > 0) {
631 *char_out = state_ptr->leftover[0];
632 state_ptr->leftover_cnt = 0;
633 data_size += 1;
634 cnta = 1;
635 } else {
636 cnta = 0;
637 }
638 out_leng = (data_size & ~0x01); /* clear low order bit */
639 for (; cnta < data_size; cnta++) {
640 /* EXPAND */
641 switch (in_header->encoding) {
642 case AUDIO_ENCODING_LINEAR:
643 sl = *short_ptr++ >> 2;
644 break;
645 case AUDIO_ENCODING_ALAW:
646 sl = audio_a2s(*char_in++) >> 2;
647 break;
648 case AUDIO_ENCODING_ULAW:
649 sl = audio_u2s(*char_in++) >> 2; /* u-law to short */
650 break;
651 default:
652 return (AUDIO_ERR_ENCODING);
653 }
654
655 /* ACCUM */
656 sezi = _g721_fmult(state_ptr->b[0] >> 2, state_ptr->dq[0]);
657 for (cnt = 1; cnt < 6; cnt++)
658 sezi = sezi + _g721_fmult(state_ptr->b[cnt] >> 2,
659 state_ptr->dq[cnt]);
660 sei = sezi;
661 for (cnt = 1; cnt > -1; cnt--)
662 sei = sei + _g721_fmult(state_ptr->a[cnt] >> 2,
663 state_ptr->sr[cnt]);
664 sez = sezi >> 1;
665 se = sei >> 1;
666 d = sl - se; /* SUBTA */
667
668 if (state_ptr->ap >= 256)
669 y = state_ptr->yu;
670 else {
671 y = state_ptr->yl >> 6;
672 dif = state_ptr->yu - y;
673 al = state_ptr->ap >> 2;
674 if (dif > 0)
675 y += ((int)(dif * al)) >> 6;
676 else if (dif < 0)
677 y += ((int)(dif * al) + 0x3F) >> 6;
678 }
679
680 i = _g721_quantize(d, y);
681 dq = _g721_reconstr(i, y);
682 /* ADDB */
683 sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;
684
685 if (cnta & 1) {
686 *char_out++ += i << 4;
687 } else if (cnta < out_leng) {
688 *char_out = i;
689 } else {
690 /*
691 * save the last codeword which can not be paired into
692 * a byte in the state stucture and set leftover_flag.
693 */
694 state_ptr->leftover[0] = i;
695 state_ptr->leftover_cnt = 4;
696 }
697
698 dqsez = sr + sez - se; /* ADDC */
699 if (dqsez == 0) {
700 pk0 = 0;
701 sigpk = 1;
702 } else {
703 pk0 = (dqsez < 0) ? 1 : 0;
704 sigpk = 0;
705 }
706
707 _g721_update(y, i, dq, sr, pk0, state_ptr, sigpk);
708 }
709 *out_size = cnta >> 1;
710
711 return (AUDIO_SUCCESS);
712 }
713
714 /*
715 * g721_decode()
716 *
717 * Description:
718 *
719 * Decodes a buffer of G.721 encoded data pointed to by 'in_buf' and
720 * writes the resulting linear PCM, A-law or Mu-law bytes into a buffer
721 * pointed to by 'out_buf'.
722 */
723 int
g721_decode(unsigned char * in_buf,int data_size,Audio_hdr * out_header,void * out_buf,int * out_size,struct audio_g72x_state * state_ptr)724 g721_decode(
725 unsigned char *in_buf, /* Buffer of g721 encoded data. */
726 int data_size, /* Size in bytes of in_buf. */
727 Audio_hdr *out_header,
728 void *out_buf, /* Decoded data buffer. */
729 int *out_size,
730 struct audio_g72x_state *state_ptr) /* the decoder's state structure. */
731 {
732 short sezi, sei, sez, se; /* ACCUM */
733 float al; /* use floating point for faster multiply */
734 short y, dif; /* MIX */
735 short sr; /* ADDB */
736 char pk0, i; /* ADDC */
737 short dq;
738 char sigpk;
739 short dqsez;
740 unsigned char *char_in;
741 unsigned char *char_out;
742 int cnt, cnta;
743 short *linear_out;
744
745 *out_size = data_size << 1;
746 char_in = (unsigned char *)in_buf;
747 char_out = (unsigned char *)out_buf;
748 linear_out = (short *)out_buf;
749 for (cnta = 0; cnta < *out_size; cnta++) {
750 if (cnta & 1)
751 i = *char_in++ >> 4;
752 else
753 i = *char_in & 0xF;
754 /* ACCUM */
755 sezi = _g721_fmult(state_ptr->b[0] >> 2, state_ptr->dq[0]);
756 for (cnt = 1; cnt < 6; cnt++)
757 sezi = sezi + _g721_fmult(state_ptr->b[cnt] >> 2,
758 state_ptr->dq[cnt]);
759 sei = sezi;
760 for (cnt = 1; cnt >= 0; cnt--)
761 sei = sei + _g721_fmult(state_ptr->a[cnt] >> 2,
762 state_ptr->sr[cnt]);
763
764 sez = sezi >> 1;
765 se = sei >> 1;
766 if (state_ptr->ap >= 256)
767 y = state_ptr->yu;
768 else {
769 y = state_ptr->yl >> 6;
770 dif = state_ptr->yu - y;
771 al = state_ptr->ap >> 2;
772 if (dif > 0)
773 y += ((int)(dif * al)) >> 6;
774 else if (dif < 0)
775 y += ((int)(dif * al) + 0x3F) >> 6;
776 }
777
778 dq = _g721_reconstr(i, y);
779 /* ADDB */
780 if (dq < 0)
781 sr = se - (dq & 0x3FFF);
782 else
783 sr = se + dq;
784
785 switch (out_header->encoding) {
786 case AUDIO_ENCODING_LINEAR:
787 *linear_out++ = ((sr <= -0x2000) ? -0x8000 :
788 (sr >= 0x1FFF) ? 0x7FFF : sr << 2);
789 break;
790 case AUDIO_ENCODING_ALAW:
791 *char_out++ = _tandem_adjust_alaw(sr, se, y, i);
792 break;
793 case AUDIO_ENCODING_ULAW:
794 *char_out++ = _tandem_adjust_ulaw(sr, se, y, i);
795 break;
796 default:
797 return (AUDIO_ERR_ENCODING);
798 }
799 /* ADDC */
800 dqsez = sr - se + sez;
801 pk0 = (dqsez < 0) ? 1 : 0;
802 sigpk = (dqsez) ? 0 : 1;
803
804 _g721_update(y, i, dq, sr, pk0, state_ptr, sigpk);
805 }
806 *out_size = cnta;
807
808 return (AUDIO_SUCCESS);
809 }
810