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 <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36
37 #include "g72x.h"
38 #include "g72x_priv.h"
39
40 static G72x_STATE * g72x_state_new (void) ;
41 static int unpack_bytes (int bits, int blocksize, const unsigned char * block, short * samples) ;
42 static int pack_bytes (int bits, const short * samples, unsigned char * block) ;
43
44 static
45 short power2 [15] =
46 { 1, 2, 4, 8, 0x10, 0x20, 0x40, 0x80,
47 0x100, 0x200, 0x400, 0x800, 0x1000, 0x2000, 0x4000
48 } ;
49
50 /*
51 * quan ()
52 *
53 * quantizes the input val against the table of size short integers.
54 * It returns i if table [i - 1] <= val < table [i].
55 *
56 * Using linear search for simple coding.
57 */
58 static
quan(int val,short * table,int size)59 int quan (int val, short *table, int size)
60 {
61 int i ;
62
63 for (i = 0 ; i < size ; i++)
64 if (val < *table++)
65 break ;
66 return i ;
67 }
68
69 /*
70 * fmult ()
71 *
72 * returns the integer product of the 14-bit integer "an" and
73 * "floating point" representation (4-bit exponent, 6-bit mantessa) "srn".
74 */
75 static
fmult(int an,int srn)76 int fmult (int an, int srn)
77 {
78 short anmag, anexp, anmant ;
79 short wanexp, wanmant ;
80 short retval ;
81
82 anmag = (an > 0) ? an : ((-an) & 0x1FFF) ;
83 anexp = quan (anmag, power2, 15) - 6 ;
84 anmant = (anmag == 0) ? 32 :
85 (anexp >= 0) ? anmag >> anexp : anmag << -anexp ;
86 wanexp = anexp + ((srn >> 6) & 0xF) - 13 ;
87
88 /*
89 ** The original was :
90 ** wanmant = (anmant * (srn & 0x3F) + 0x30) >> 4 ;
91 ** but could see no valid reason for the + 0x30.
92 ** Removed it and it improved the SNR of the codec.
93 */
94
95 wanmant = (anmant * (srn & 0x3F)) >> 4 ;
96
97 retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) : (wanmant >> -wanexp) ;
98
99 return (((an ^ srn) < 0) ? -retval : retval) ;
100 }
101
g72x_state_new(void)102 static G72x_STATE * g72x_state_new (void)
103 { return calloc (1, sizeof (G72x_STATE)) ;
104 }
105
106 /*
107 * private_init_state ()
108 *
109 * This routine initializes and/or resets the G72x_PRIVATE structure
110 * pointed to by 'state_ptr'.
111 * All the initial state values are specified in the CCITT G.721 document.
112 */
private_init_state(G72x_STATE * state_ptr)113 void private_init_state (G72x_STATE *state_ptr)
114 {
115 int cnta ;
116
117 state_ptr->yl = 34816 ;
118 state_ptr->yu = 544 ;
119 state_ptr->dms = 0 ;
120 state_ptr->dml = 0 ;
121 state_ptr->ap = 0 ;
122 for (cnta = 0 ; cnta < 2 ; cnta++)
123 { state_ptr->a [cnta] = 0 ;
124 state_ptr->pk [cnta] = 0 ;
125 state_ptr->sr [cnta] = 32 ;
126 }
127 for (cnta = 0 ; cnta < 6 ; cnta++)
128 { state_ptr->b [cnta] = 0 ;
129 state_ptr->dq [cnta] = 32 ;
130 }
131 state_ptr->td = 0 ;
132 } /* private_init_state */
133
g72x_reader_init(int codec,int * blocksize,int * samplesperblock)134 struct g72x_state * g72x_reader_init (int codec, int *blocksize, int *samplesperblock)
135 { G72x_STATE *pstate ;
136
137 if ((pstate = g72x_state_new ()) == NULL)
138 return NULL ;
139
140 private_init_state (pstate) ;
141
142 pstate->encoder = NULL ;
143
144 switch (codec)
145 { case G723_16_BITS_PER_SAMPLE : /* 2 bits per sample. */
146 pstate->decoder = g723_16_decoder ;
147 *blocksize = G723_16_BYTES_PER_BLOCK ;
148 *samplesperblock = G723_16_SAMPLES_PER_BLOCK ;
149 pstate->codec_bits = 2 ;
150 pstate->blocksize = G723_16_BYTES_PER_BLOCK ;
151 pstate->samplesperblock = G723_16_SAMPLES_PER_BLOCK ;
152 break ;
153
154 case G723_24_BITS_PER_SAMPLE : /* 3 bits per sample. */
155 pstate->decoder = g723_24_decoder ;
156 *blocksize = G723_24_BYTES_PER_BLOCK ;
157 *samplesperblock = G723_24_SAMPLES_PER_BLOCK ;
158 pstate->codec_bits = 3 ;
159 pstate->blocksize = G723_24_BYTES_PER_BLOCK ;
160 pstate->samplesperblock = G723_24_SAMPLES_PER_BLOCK ;
161 break ;
162
163 case G721_32_BITS_PER_SAMPLE : /* 4 bits per sample. */
164 pstate->decoder = g721_decoder ;
165 *blocksize = G721_32_BYTES_PER_BLOCK ;
166 *samplesperblock = G721_32_SAMPLES_PER_BLOCK ;
167 pstate->codec_bits = 4 ;
168 pstate->blocksize = G721_32_BYTES_PER_BLOCK ;
169 pstate->samplesperblock = G721_32_SAMPLES_PER_BLOCK ;
170 break ;
171
172 case G721_40_BITS_PER_SAMPLE : /* 5 bits per sample. */
173 pstate->decoder = g723_40_decoder ;
174 *blocksize = G721_40_BYTES_PER_BLOCK ;
175 *samplesperblock = G721_40_SAMPLES_PER_BLOCK ;
176 pstate->codec_bits = 5 ;
177 pstate->blocksize = G721_40_BYTES_PER_BLOCK ;
178 pstate->samplesperblock = G721_40_SAMPLES_PER_BLOCK ;
179 break ;
180
181 default :
182 free (pstate) ;
183 return NULL ;
184 } ;
185
186 return pstate ;
187 } /* g72x_reader_init */
188
g72x_writer_init(int codec,int * blocksize,int * samplesperblock)189 struct g72x_state * g72x_writer_init (int codec, int *blocksize, int *samplesperblock)
190 { G72x_STATE *pstate ;
191
192 if ((pstate = g72x_state_new ()) == NULL)
193 return NULL ;
194
195 private_init_state (pstate) ;
196 pstate->decoder = NULL ;
197
198 switch (codec)
199 { case G723_16_BITS_PER_SAMPLE : /* 2 bits per sample. */
200 pstate->encoder = g723_16_encoder ;
201 *blocksize = G723_16_BYTES_PER_BLOCK ;
202 *samplesperblock = G723_16_SAMPLES_PER_BLOCK ;
203 pstate->codec_bits = 2 ;
204 pstate->blocksize = G723_16_BYTES_PER_BLOCK ;
205 pstate->samplesperblock = G723_16_SAMPLES_PER_BLOCK ;
206 break ;
207
208 case G723_24_BITS_PER_SAMPLE : /* 3 bits per sample. */
209 pstate->encoder = g723_24_encoder ;
210 *blocksize = G723_24_BYTES_PER_BLOCK ;
211 *samplesperblock = G723_24_SAMPLES_PER_BLOCK ;
212 pstate->codec_bits = 3 ;
213 pstate->blocksize = G723_24_BYTES_PER_BLOCK ;
214 pstate->samplesperblock = G723_24_SAMPLES_PER_BLOCK ;
215 break ;
216
217 case G721_32_BITS_PER_SAMPLE : /* 4 bits per sample. */
218 pstate->encoder = g721_encoder ;
219 *blocksize = G721_32_BYTES_PER_BLOCK ;
220 *samplesperblock = G721_32_SAMPLES_PER_BLOCK ;
221 pstate->codec_bits = 4 ;
222 pstate->blocksize = G721_32_BYTES_PER_BLOCK ;
223 pstate->samplesperblock = G721_32_SAMPLES_PER_BLOCK ;
224 break ;
225
226 case G721_40_BITS_PER_SAMPLE : /* 5 bits per sample. */
227 pstate->encoder = g723_40_encoder ;
228 *blocksize = G721_40_BYTES_PER_BLOCK ;
229 *samplesperblock = G721_40_SAMPLES_PER_BLOCK ;
230 pstate->codec_bits = 5 ;
231 pstate->blocksize = G721_40_BYTES_PER_BLOCK ;
232 pstate->samplesperblock = G721_40_SAMPLES_PER_BLOCK ;
233 break ;
234
235 default :
236 free (pstate) ;
237 return NULL ;
238 } ;
239
240 return pstate ;
241 } /* g72x_writer_init */
242
g72x_decode_block(G72x_STATE * pstate,const unsigned char * block,short * samples)243 int g72x_decode_block (G72x_STATE *pstate, const unsigned char *block, short *samples)
244 { int k, count ;
245
246 count = unpack_bytes (pstate->codec_bits, pstate->blocksize, block, samples) ;
247
248 for (k = 0 ; k < count ; k++)
249 samples [k] = pstate->decoder (samples [k], pstate) ;
250
251 return 0 ;
252 } /* g72x_decode_block */
253
g72x_encode_block(G72x_STATE * pstate,short * samples,unsigned char * block)254 int g72x_encode_block (G72x_STATE *pstate, short *samples, unsigned char *block)
255 { int k, count ;
256
257 for (k = 0 ; k < pstate->samplesperblock ; k++)
258 samples [k] = pstate->encoder (samples [k], pstate) ;
259
260 count = pack_bytes (pstate->codec_bits, samples, block) ;
261
262 return count ;
263 } /* g72x_encode_block */
264
265 /*
266 * predictor_zero ()
267 *
268 * computes the estimated signal from 6-zero predictor.
269 *
270 */
predictor_zero(G72x_STATE * state_ptr)271 int predictor_zero (G72x_STATE *state_ptr)
272 {
273 int i ;
274 int sezi ;
275
276 sezi = fmult (state_ptr->b [0] >> 2, state_ptr->dq [0]) ;
277 for (i = 1 ; i < 6 ; i++) /* ACCUM */
278 sezi += fmult (state_ptr->b [i] >> 2, state_ptr->dq [i]) ;
279 return sezi ;
280 }
281 /*
282 * predictor_pole ()
283 *
284 * computes the estimated signal from 2-pole predictor.
285 *
286 */
predictor_pole(G72x_STATE * state_ptr)287 int predictor_pole (G72x_STATE *state_ptr)
288 {
289 return (fmult (state_ptr->a [1] >> 2, state_ptr->sr [1]) +
290 fmult (state_ptr->a [0] >> 2, state_ptr->sr [0])) ;
291 }
292 /*
293 * step_size ()
294 *
295 * computes the quantization step size of the adaptive quantizer.
296 *
297 */
step_size(G72x_STATE * state_ptr)298 int step_size (G72x_STATE *state_ptr)
299 {
300 int y ;
301 int dif ;
302 int al ;
303
304 if (state_ptr->ap >= 256)
305 return (state_ptr->yu) ;
306 else {
307 y = state_ptr->yl >> 6 ;
308 dif = state_ptr->yu - y ;
309 al = state_ptr->ap >> 2 ;
310 if (dif > 0)
311 y += (dif * al) >> 6 ;
312 else if (dif < 0)
313 y += (dif * al + 0x3F) >> 6 ;
314 return y ;
315 }
316 }
317
318 /*
319 * quantize ()
320 *
321 * Given a raw sample, 'd', of the difference signal and a
322 * quantization step size scale factor, 'y', this routine returns the
323 * ADPCM codeword to which that sample gets quantized. The step
324 * size scale factor division operation is done in the log base 2 domain
325 * as a subtraction.
326 */
quantize(int d,int y,short * table,int size)327 int quantize (
328 int d, /* Raw difference signal sample */
329 int y, /* Step size multiplier */
330 short *table, /* quantization table */
331 int size) /* table size of short integers */
332 {
333 short dqm ; /* Magnitude of 'd' */
334 short expon ; /* Integer part of base 2 log of 'd' */
335 short mant ; /* Fractional part of base 2 log */
336 short dl ; /* Log of magnitude of 'd' */
337 short dln ; /* Step size scale factor normalized log */
338 int i ;
339
340 /*
341 * LOG
342 *
343 * Compute base 2 log of 'd', and store in 'dl'.
344 */
345 dqm = abs (d) ;
346 expon = quan (dqm >> 1, power2, 15) ;
347 mant = ((dqm << 7) >> expon) & 0x7F ; /* Fractional portion. */
348 dl = (expon << 7) + mant ;
349
350 /*
351 * SUBTB
352 *
353 * "Divide" by step size multiplier.
354 */
355 dln = dl - (y >> 2) ;
356
357 /*
358 * QUAN
359 *
360 * Obtain codword i for 'd'.
361 */
362 i = quan (dln, table, size) ;
363 if (d < 0) /* take 1's complement of i */
364 return ((size << 1) + 1 - i) ;
365 else if (i == 0) /* take 1's complement of 0 */
366 return ((size << 1) + 1) ; /* new in 1988 */
367
368 return i ;
369 }
370 /*
371 * reconstruct ()
372 *
373 * Returns reconstructed difference signal 'dq' obtained from
374 * codeword 'i' and quantization step size scale factor 'y'.
375 * Multiplication is performed in log base 2 domain as addition.
376 */
377 int
reconstruct(int sign,int dqln,int y)378 reconstruct (
379 int sign, /* 0 for non-negative value */
380 int dqln, /* G.72x codeword */
381 int y) /* Step size multiplier */
382 {
383 short dql ; /* Log of 'dq' magnitude */
384 short dex ; /* Integer part of log */
385 short dqt ;
386 short dq ; /* Reconstructed difference signal sample */
387
388 dql = dqln + (y >> 2) ; /* ADDA */
389
390 if (dql < 0)
391 return ((sign) ? -0x8000 : 0) ;
392 else /* ANTILOG */
393 { dex = (dql >> 7) & 15 ;
394 dqt = 128 + (dql & 127) ;
395 dq = (dqt << 7) >> (14 - dex) ;
396 return ((sign) ? (dq - 0x8000) : dq) ;
397 }
398 }
399
400
401 /*
402 * update ()
403 *
404 * updates the state variables for each output code
405 */
406 void
update(int code_size,int y,int wi,int fi,int dq,int sr,int dqsez,G72x_STATE * state_ptr)407 update (
408 int code_size, /* distinguish 723_40 with others */
409 int y, /* quantizer step size */
410 int wi, /* scale factor multiplier */
411 int fi, /* for long/short term energies */
412 int dq, /* quantized prediction difference */
413 int sr, /* reconstructed signal */
414 int dqsez, /* difference from 2-pole predictor */
415 G72x_STATE *state_ptr) /* coder state pointer */
416 {
417 int cnt ;
418 short mag, expon ; /* Adaptive predictor, FLOAT A */
419 short a2p = 0 ; /* LIMC */
420 short a1ul ; /* UPA1 */
421 short pks1 ; /* UPA2 */
422 short fa1 ;
423 char tr ; /* tone/transition detector */
424 short ylint, thr2, dqthr ;
425 short ylfrac, thr1 ;
426 short pk0 ;
427
428 pk0 = (dqsez < 0) ? 1 : 0 ; /* needed in updating predictor poles */
429
430 mag = dq & 0x7FFF ; /* prediction difference magnitude */
431 /* TRANS */
432 ylint = state_ptr->yl >> 15 ; /* exponent part of yl */
433 ylfrac = (state_ptr->yl >> 10) & 0x1F ; /* fractional part of yl */
434 thr1 = (32 + ylfrac) << ylint ; /* threshold */
435 thr2 = (ylint > 9) ? 31 << 10 : thr1 ; /* limit thr2 to 31 << 10 */
436 dqthr = (thr2 + (thr2 >> 1)) >> 1 ; /* dqthr = 0.75 * thr2 */
437 if (state_ptr->td == 0) /* signal supposed voice */
438 tr = 0 ;
439 else if (mag <= dqthr) /* supposed data, but small mag */
440 tr = 0 ; /* treated as voice */
441 else /* signal is data (modem) */
442 tr = 1 ;
443
444 /*
445 * Quantizer scale factor adaptation.
446 */
447
448 /* FUNCTW & FILTD & DELAY */
449 /* update non-steady state step size multiplier */
450 state_ptr->yu = y + ((wi - y) >> 5) ;
451
452 /* LIMB */
453 if (state_ptr->yu < 544) /* 544 <= yu <= 5120 */
454 state_ptr->yu = 544 ;
455 else if (state_ptr->yu > 5120)
456 state_ptr->yu = 5120 ;
457
458 /* FILTE & DELAY */
459 /* update steady state step size multiplier */
460 state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6) ;
461
462 /*
463 * Adaptive predictor coefficients.
464 */
465 if (tr == 1) { /* reset a's and b's for modem signal */
466 state_ptr->a [0] = 0 ;
467 state_ptr->a [1] = 0 ;
468 state_ptr->b [0] = 0 ;
469 state_ptr->b [1] = 0 ;
470 state_ptr->b [2] = 0 ;
471 state_ptr->b [3] = 0 ;
472 state_ptr->b [4] = 0 ;
473 state_ptr->b [5] = 0 ;
474 }
475 else /* update a's and b's */
476 { pks1 = pk0 ^ state_ptr->pk [0] ; /* UPA2 */
477
478 /* update predictor pole a [1] */
479 a2p = state_ptr->a [1] - (state_ptr->a [1] >> 7) ;
480 if (dqsez != 0)
481 { fa1 = (pks1) ? state_ptr->a [0] : -state_ptr->a [0] ;
482 if (fa1 < -8191) /* a2p = function of fa1 */
483 a2p -= 0x100 ;
484 else if (fa1 > 8191)
485 a2p += 0xFF ;
486 else
487 a2p += fa1 >> 5 ;
488
489 if (pk0 ^ state_ptr->pk [1])
490 { /* LIMC */
491 if (a2p <= -12160)
492 a2p = -12288 ;
493 else if (a2p >= 12416)
494 a2p = 12288 ;
495 else
496 a2p -= 0x80 ;
497 }
498 else if (a2p <= -12416)
499 a2p = -12288 ;
500 else if (a2p >= 12160)
501 a2p = 12288 ;
502 else
503 a2p += 0x80 ;
504 }
505
506 /* TRIGB & DELAY */
507 state_ptr->a [1] = a2p ;
508
509 /* UPA1 */
510 /* update predictor pole a [0] */
511 state_ptr->a [0] -= state_ptr->a [0] >> 8 ;
512 if (dqsez != 0)
513 { if (pks1 == 0)
514 state_ptr->a [0] += 192 ;
515 else
516 state_ptr->a [0] -= 192 ;
517 } ;
518
519 /* LIMD */
520 a1ul = 15360 - a2p ;
521 if (state_ptr->a [0] < -a1ul)
522 state_ptr->a [0] = -a1ul ;
523 else if (state_ptr->a [0] > a1ul)
524 state_ptr->a [0] = a1ul ;
525
526 /* UPB : update predictor zeros b [6] */
527 for (cnt = 0 ; cnt < 6 ; cnt++)
528 { if (code_size == 5) /* for 40Kbps G.723 */
529 state_ptr->b [cnt] -= state_ptr->b [cnt] >> 9 ;
530 else /* for G.721 and 24Kbps G.723 */
531 state_ptr->b [cnt] -= state_ptr->b [cnt] >> 8 ;
532 if (dq & 0x7FFF) /* XOR */
533 { if ((dq ^ state_ptr->dq [cnt]) >= 0)
534 state_ptr->b [cnt] += 128 ;
535 else
536 state_ptr->b [cnt] -= 128 ;
537 }
538 }
539 }
540
541 for (cnt = 5 ; cnt > 0 ; cnt--)
542 state_ptr->dq [cnt] = state_ptr->dq [cnt - 1] ;
543 /* FLOAT A : convert dq [0] to 4-bit exp, 6-bit mantissa f.p. */
544 if (mag == 0)
545 state_ptr->dq [0] = (dq >= 0) ? 0x20 : 0xFC20 ;
546 else
547 { expon = quan (mag, power2, 15) ;
548 state_ptr->dq [0] = (dq >= 0) ?
549 (expon << 6) + ((mag << 6) >> expon) :
550 (expon << 6) + ((mag << 6) >> expon) - 0x400 ;
551 }
552
553 state_ptr->sr [1] = state_ptr->sr [0] ;
554 /* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
555 if (sr == 0)
556 state_ptr->sr [0] = 0x20 ;
557 else if (sr > 0)
558 { expon = quan (sr, power2, 15) ;
559 state_ptr->sr [0] = (expon << 6) + ((sr << 6) >> expon) ;
560 }
561 else if (sr > -32768)
562 { mag = -sr ;
563 expon = quan (mag, power2, 15) ;
564 state_ptr->sr [0] = (expon << 6) + ((mag << 6) >> expon) - 0x400 ;
565 }
566 else
567 state_ptr->sr [0] = (short) 0xFC20 ;
568
569 /* DELAY A */
570 state_ptr->pk [1] = state_ptr->pk [0] ;
571 state_ptr->pk [0] = pk0 ;
572
573 /* TONE */
574 if (tr == 1) /* this sample has been treated as data */
575 state_ptr->td = 0 ; /* next one will be treated as voice */
576 else if (a2p < -11776) /* small sample-to-sample correlation */
577 state_ptr->td = 1 ; /* signal may be data */
578 else /* signal is voice */
579 state_ptr->td = 0 ;
580
581 /*
582 * Adaptation speed control.
583 */
584 state_ptr->dms += (fi - state_ptr->dms) >> 5 ; /* FILTA */
585 state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7) ; /* FILTB */
586
587 if (tr == 1)
588 state_ptr->ap = 256 ;
589 else if (y < 1536) /* SUBTC */
590 state_ptr->ap += (0x200 - state_ptr->ap) >> 4 ;
591 else if (state_ptr->td == 1)
592 state_ptr->ap += (0x200 - state_ptr->ap) >> 4 ;
593 else if (abs ((state_ptr->dms << 2) - state_ptr->dml) >= (state_ptr->dml >> 3))
594 state_ptr->ap += (0x200 - state_ptr->ap) >> 4 ;
595 else
596 state_ptr->ap += (-state_ptr->ap) >> 4 ;
597
598 return ;
599 } /* update */
600
601 /*------------------------------------------------------------------------------
602 */
603
604 static int
unpack_bytes(int bits,int blocksize,const unsigned char * block,short * samples)605 unpack_bytes (int bits, int blocksize, const unsigned char * block, short * samples)
606 { unsigned int in_buffer = 0 ;
607 unsigned char in_byte ;
608 int k, in_bits = 0, bindex = 0 ;
609
610 for (k = 0 ; bindex <= blocksize && k < G72x_BLOCK_SIZE ; k++)
611 { if (in_bits < bits)
612 { in_byte = block [bindex++] ;
613
614 in_buffer |= (in_byte << in_bits) ;
615 in_bits += 8 ;
616 }
617 samples [k] = in_buffer & ((1 << bits) - 1) ;
618 in_buffer >>= bits ;
619 in_bits -= bits ;
620 } ;
621
622 return k ;
623 } /* unpack_bytes */
624
625 static int
pack_bytes(int bits,const short * samples,unsigned char * block)626 pack_bytes (int bits, const short * samples, unsigned char * block)
627 {
628 unsigned int out_buffer = 0 ;
629 int k, bindex = 0, out_bits = 0 ;
630 unsigned char out_byte ;
631
632 for (k = 0 ; k < G72x_BLOCK_SIZE ; k++)
633 { out_buffer |= (samples [k] << out_bits) ;
634 out_bits += bits ;
635 if (out_bits >= 8)
636 { out_byte = out_buffer & 0xFF ;
637 out_bits -= 8 ;
638 out_buffer >>= 8 ;
639 block [bindex++] = out_byte ;
640 }
641 } ;
642
643 return bindex ;
644 } /* pack_bytes */
645
646