codecs/codec_g726.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 1999 - 2006, Digium, Inc.
   5  *
   6  * Mark Spencer <markster@digium.com>
   7  * Kevin P. Fleming <kpfleming@digium.com>
   8  *
   9  * Based on frompcm.c and topcm.c from the Emiliano MIPL browser/
  10  * interpreter.  See http://www.bsdtelephony.com.mx
  11  *
  12  * See http://www.asterisk.org for more information about
  13  * the Asterisk project. Please do not directly contact
  14  * any of the maintainers of this project for assistance;
  15  * the project provides a web site, mailing lists and IRC
  16  * channels for your use.
  17  *
  18  * This program is free software, distributed under the terms of
  19  * the GNU General Public License Version 2. See the LICENSE file
  20  * at the top of the source tree.
  21  */
  22
  23 /*! \file
  24  *
  25  * \brief codec_g726.c - translate between signed linear and ITU G.726-32kbps (both RFC3551 and AAL2 codeword packing)
  26  *
  27  * \ingroup codecs
  28  */
  29
  30 #include "asterisk.h"
  31
  32 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  33
  34 #include "asterisk/lock.h"
  35 #include "asterisk/linkedlists.h"
  36 #include "asterisk/module.h"
  37 #include "asterisk/config.h"
  38 #include "asterisk/translate.h"
  39 #include "asterisk/utils.h"
  40
  41 #define WANT_ASM
  42 #include "log2comp.h"
  43
  44 /* define NOT_BLI to use a faster but not bit-level identical version */
  45 /* #define NOT_BLI */
  46
  47 #if defined(NOT_BLI)
  48 #       if defined(_MSC_VER)
  49 typedef __int64 sint64;
  50 #       elif defined(__GNUC__)
  51 typedef long long sint64;
  52 #       else
  53 #               error 64-bit integer type is not defined for your compiler/platform
  54 #       endif
  55 #endif
  56
  57 #define BUFFER_SAMPLES   8096   /* size for the translation buffers */
  58 #define BUF_SHIFT       5
  59
  60 /* Sample frame data */
  61
  62 #include "slin_g726_ex.h"
  63 #include "g726_slin_ex.h"
  64
  65 /*
  66  * The following is the definition of the state structure
  67  * used by the G.726 encoder and decoder to preserve their internal
  68  * state between successive calls.  The meanings of the majority
  69  * of the state structure fields are explained in detail in the
  70  * CCITT Recommendation G.721.  The field names are essentially identical
  71  * to variable names in the bit level description of the coding algorithm
  72  * included in this Recommendation.
  73  */
  74 struct g726_state {
  75         long yl;        /* Locked or steady state step size multiplier. */
  76         int yu;         /* Unlocked or non-steady state step size multiplier. */
  77         int dms;        /* Short term energy estimate. */
  78         int dml;        /* Long term energy estimate. */
  79         int ap;         /* Linear weighting coefficient of 'yl' and 'yu'. */
  80         int a[2];       /* Coefficients of pole portion of prediction filter.
  81                          * stored as fixed-point 1==2^14 */
  82         int b[6];       /* Coefficients of zero portion of prediction filter.
  83                          * stored as fixed-point 1==2^14 */
  84         int pk[2];      /* Signs of previous two samples of a partially
  85                          * reconstructed signal. */
  86         int dq[6];      /* Previous 6 samples of the quantized difference signal
  87                          * stored as fixed point 1==2^12,
  88                          * or in internal floating point format */
  89         int sr[2];      /* Previous 2 samples of the quantized difference signal
  90                          * stored as fixed point 1==2^12,
  91                          * or in internal floating point format */
  92         int td;         /* delayed tone detect, new in 1988 version */
  93 };
  94
  95 static int qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400};
  96 /*
  97  * Maps G.721 code word to reconstructed scale factor normalized log
  98  * magnitude values.
  99  */
 100 static int _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425,
 101                                 425, 373, 323, 273, 213, 135, 4, -2048};
 102
 103 /* Maps G.721 code word to log of scale factor multiplier. */
 104 static int _witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122,
 105                                 1122, 355, 198, 112, 64, 41, 18, -12};
 106 /*
 107  * Maps G.721 code words to a set of values whose long and short
 108  * term averages are computed and then compared to give an indication
 109  * how stationary (steady state) the signal is.
 110  */
 111 static int _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
 112                                 0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};
 113
 114
 115 /*
 116  * g72x_init_state()
 117  *
 118  * This routine initializes and/or resets the g726_state structure
 119  * pointed to by 'state_ptr'.
 120  * All the initial state values are specified in the CCITT G.721 document.
 121  */
 122 static void g726_init_state(struct g726_state *state_ptr)
 123 {
 124         int             cnta;
 125
 126         state_ptr->yl = 34816;
 127         state_ptr->yu = 544;
 128         state_ptr->dms = 0;
 129         state_ptr->dml = 0;
 130         state_ptr->ap = 0;
 131         for (cnta = 0; cnta < 2; cnta++) {
 132                 state_ptr->a[cnta] = 0;
 133                 state_ptr->pk[cnta] = 0;
 134 #ifdef NOT_BLI
 135                 state_ptr->sr[cnta] = 1;
 136 #else
 137                 state_ptr->sr[cnta] = 32;
 138 #endif
 139         }
 140         for (cnta = 0; cnta < 6; cnta++) {
 141                 state_ptr->b[cnta] = 0;
 142 #ifdef NOT_BLI
 143                 state_ptr->dq[cnta] = 1;
 144 #else
 145                 state_ptr->dq[cnta] = 32;
 146 #endif
 147         }
 148         state_ptr->td = 0;
 149 }
 150
 151 /*
 152  * quan()
 153  *
 154  * quantizes the input val against the table of integers.
 155  * It returns i if table[i - 1] <= val < table[i].
 156  *
 157  * Using linear search for simple coding.
 158  */
 159 static int quan(int val, int *table, int size)
 160 {
 161         int             i;
 162
 163         for (i = 0; i < size && val >= *table; ++i, ++table)
 164                 ;
 165         return (i);
 166 }
 167
 168 #ifdef NOT_BLI /* faster non-identical version */
 169
 170 /*
 171  * predictor_zero()
 172  *
 173  * computes the estimated signal from 6-zero predictor.
 174  *
 175  */
 176 static int predictor_zero(struct g726_state *state_ptr)
 177 {       /* divide by 2 is necessary here to handle negative numbers correctly */
 178         int i;
 179         sint64 sezi;
 180         for (sezi = 0, i = 0; i < 6; i++)                       /* ACCUM */
 181                 sezi += (sint64)state_ptr->b[i] * state_ptr->dq[i];
 182         return (int)(sezi >> 13) / 2 /* 2^14 */;
 183 }
 184
 185 /*
 186  * predictor_pole()
 187  *
 188  * computes the estimated signal from 2-pole predictor.
 189  *
 190  */
 191 static int predictor_pole(struct g726_state *state_ptr)
 192 {       /* divide by 2 is necessary here to handle negative numbers correctly */
 193         return (int)(((sint64)state_ptr->a[1] * state_ptr->sr[1] +
 194                       (sint64)state_ptr->a[0] * state_ptr->sr[0]) >> 13) / 2 /* 2^14 */;
 195 }
 196
 197 #else /* NOT_BLI - identical version */
 198 /*
 199  * fmult()
 200  *
 201  * returns the integer product of the fixed-point number "an" (1==2^12) and
 202  * "floating point" representation (4-bit exponent, 6-bit mantessa) "srn".
 203  */
 204 static int fmult(int an, int srn)
 205 {
 206         int             anmag, anexp, anmant;
 207         int             wanexp, wanmant;
 208         int             retval;
 209
 210         anmag = (an > 0) ? an : ((-an) & 0x1FFF);
 211         anexp = ilog2(anmag) - 5;
 212         anmant = (anmag == 0) ? 32 :
 213             (anexp >= 0) ? anmag >> anexp : anmag << -anexp;
 214         wanexp = anexp + ((srn >> 6) & 0xF) - 13;
 215
 216         wanmant = (anmant * (srn & 077) + 0x30) >> 4;
 217         retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) :
 218             (wanmant >> -wanexp);
 219
 220         return (((an ^ srn) < 0) ? -retval : retval);
 221 }
 222
 223 static int predictor_zero(struct g726_state *state_ptr)
 224 {
 225         int             i;
 226         int             sezi;
 227         for (sezi = 0, i = 0; i < 6; i++)                       /* ACCUM */
 228                 sezi += fmult(state_ptr->b[i] >> 2, state_ptr->dq[i]);
 229         return sezi;
 230 }
 231
 232 static int predictor_pole(struct g726_state *state_ptr)
 233 {
 234         return (fmult(state_ptr->a[1] >> 2, state_ptr->sr[1]) +
 235                         fmult(state_ptr->a[0] >> 2, state_ptr->sr[0]));
 236 }
 237
 238 #endif /* NOT_BLI */
 239
 240 /*
 241  * step_size()
 242  *
 243  * computes the quantization step size of the adaptive quantizer.
 244  *
 245  */
 246 static int step_size(struct g726_state *state_ptr)
 247 {
 248         int             y;
 249         int             dif;
 250         int             al;
 251
 252         if (state_ptr->ap >= 256)
 253                 return (state_ptr->yu);
 254         else {
 255                 y = state_ptr->yl >> 6;
 256                 dif = state_ptr->yu - y;
 257                 al = state_ptr->ap >> 2;
 258                 if (dif > 0)
 259                         y += (dif * al) >> 6;
 260                 else if (dif < 0)
 261                         y += (dif * al + 0x3F) >> 6;
 262                 return (y);
 263         }
 264 }
 265
 266 /*
 267  * quantize()
 268  *
 269  * Given a raw sample, 'd', of the difference signal and a
 270  * quantization step size scale factor, 'y', this routine returns the
 271  * ADPCM codeword to which that sample gets quantized.  The step
 272  * size scale factor division operation is done in the log base 2 domain
 273  * as a subtraction.
 274  */
 275 static int quantize(
 276         int             d,      /* Raw difference signal sample */
 277         int             y,      /* Step size multiplier */
 278         int             *table, /* quantization table */
 279         int             size)   /* table size of integers */
 280 {
 281         int             dqm;    /* Magnitude of 'd' */
 282         int             exp;    /* Integer part of base 2 log of 'd' */
 283         int             mant;   /* Fractional part of base 2 log */
 284         int             dl;             /* Log of magnitude of 'd' */
 285         int             dln;    /* Step size scale factor normalized log */
 286         int             i;
 287
 288         /*
 289          * LOG
 290          *
 291          * Compute base 2 log of 'd', and store in 'dl'.
 292          */
 293         dqm = abs(d);
 294         exp = ilog2(dqm);
 295         if (exp < 0)
 296                 exp = 0;
 297         mant = ((dqm << 7) >> exp) & 0x7F;      /* Fractional portion. */
 298         dl = (exp << 7) | mant;
 299
 300         /*
 301          * SUBTB
 302          *
 303          * "Divide" by step size multiplier.
 304          */
 305         dln = dl - (y >> 2);
 306
 307         /*
 308          * QUAN
 309          *
 310          * Obtain codword i for 'd'.
 311          */
 312         i = quan(dln, table, size);
 313         if (d < 0)                      /* take 1's complement of i */
 314                 return ((size << 1) + 1 - i);
 315         else if (i == 0)                /* take 1's complement of 0 */
 316                 return ((size << 1) + 1); /* new in 1988 */
 317         else
 318                 return (i);
 319 }
 320
 321 /*
 322  * reconstruct()
 323  *
 324  * Returns reconstructed difference signal 'dq' obtained from
 325  * codeword 'i' and quantization step size scale factor 'y'.
 326  * Multiplication is performed in log base 2 domain as addition.
 327  */
 328 static int reconstruct(
 329         int             sign,   /* 0 for non-negative value */
 330         int             dqln,   /* G.72x codeword */
 331         int             y)      /* Step size multiplier */
 332 {
 333         int             dql;    /* Log of 'dq' magnitude */
 334         int             dex;    /* Integer part of log */
 335         int             dqt;
 336         int             dq;     /* Reconstructed difference signal sample */
 337
 338         dql = dqln + (y >> 2);  /* ADDA */
 339
 340         if (dql < 0) {
 341 #ifdef NOT_BLI
 342                 return (sign) ? -1 : 1;
 343 #else
 344                 return (sign) ? -0x8000 : 0;
 345 #endif
 346         } else {                /* ANTILOG */
 347                 dex = (dql >> 7) & 15;
 348                 dqt = 128 + (dql & 127);
 349 #ifdef NOT_BLI
 350                 dq = ((dqt << 19) >> (14 - dex));
 351                 return (sign) ? -dq : dq;
 352 #else
 353                 dq = (dqt << 7) >> (14 - dex);
 354                 return (sign) ? (dq - 0x8000) : dq;
 355 #endif
 356         }
 357 }
 358
 359 /*
 360  * update()
 361  *
 362  * updates the state variables for each output code
 363  */
 364 static void update(
 365         int             code_size,      /* distinguish 723_40 with others */
 366         int             y,              /* quantizer step size */
 367         int             wi,             /* scale factor multiplier */
 368         int             fi,             /* for long/short term energies */
 369         int             dq,             /* quantized prediction difference */
 370         int             sr,             /* reconstructed signal */
 371         int             dqsez,          /* difference from 2-pole predictor */
 372         struct g726_state *state_ptr)   /* coder state pointer */
 373 {
 374         int             cnt;
 375         int             mag;            /* Adaptive predictor, FLOAT A */
 376 #ifndef NOT_BLI
 377         int             exp;
 378 #endif
 379         int             a2p=0;          /* LIMC */
 380         int             a1ul;           /* UPA1 */
 381         int             pks1;           /* UPA2 */
 382         int             fa1;
 383         int             tr;                     /* tone/transition detector */
 384         int             ylint, thr2, dqthr;
 385         int             ylfrac, thr1;
 386         int             pk0;
 387
 388         pk0 = (dqsez < 0) ? 1 : 0;      /* needed in updating predictor poles */
 389
 390 #ifdef NOT_BLI
 391         mag = abs(dq / 0x1000); /* prediction difference magnitude */
 392 #else
 393         mag = dq & 0x7FFF;              /* prediction difference magnitude */
 394 #endif
 395         /* TRANS */
 396         ylint = state_ptr->yl >> 15;    /* exponent part of yl */
 397         ylfrac = (state_ptr->yl >> 10) & 0x1F;  /* fractional part of yl */
 398         thr1 = (32 + ylfrac) << ylint;          /* threshold */
 399         thr2 = (ylint > 9) ? 31 << 10 : thr1;   /* limit thr2 to 31 << 10 */
 400         dqthr = (thr2 + (thr2 >> 1)) >> 1;      /* dqthr = 0.75 * thr2 */
 401         if (state_ptr->td == 0)         /* signal supposed voice */
 402                 tr = 0;
 403         else if (mag <= dqthr)          /* supposed data, but small mag */
 404                 tr = 0;                 /* treated as voice */
 405         else                            /* signal is data (modem) */
 406                 tr = 1;
 407
 408         /*
 409          * Quantizer scale factor adaptation.
 410          */
 411
 412         /* FUNCTW & FILTD & DELAY */
 413         /* update non-steady state step size multiplier */
 414         state_ptr->yu = y + ((wi - y) >> 5);
 415
 416         /* LIMB */
 417         if (state_ptr->yu < 544)        /* 544 <= yu <= 5120 */
 418                 state_ptr->yu = 544;
 419         else if (state_ptr->yu > 5120)
 420                 state_ptr->yu = 5120;
 421
 422         /* FILTE & DELAY */
 423         /* update steady state step size multiplier */
 424         state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);
 425
 426         /*
 427          * Adaptive predictor coefficients.
 428          */
 429         if (tr == 1) {                  /* reset a's and b's for modem signal */
 430                 state_ptr->a[0] = 0;
 431                 state_ptr->a[1] = 0;
 432                 state_ptr->b[0] = 0;
 433                 state_ptr->b[1] = 0;
 434                 state_ptr->b[2] = 0;
 435                 state_ptr->b[3] = 0;
 436                 state_ptr->b[4] = 0;
 437                 state_ptr->b[5] = 0;
 438         } else {                        /* update a's and b's */
 439                 pks1 = pk0 ^ state_ptr->pk[0];          /* UPA2 */
 440
 441                 /* update predictor pole a[1] */
 442                 a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
 443                 if (dqsez != 0) {
 444                         fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
 445                         if (fa1 < -8191)        /* a2p = function of fa1 */
 446                                 a2p -= 0x100;
 447                         else if (fa1 > 8191)
 448                                 a2p += 0xFF;
 449                         else
 450                                 a2p += fa1 >> 5;
 451
 452                         if (pk0 ^ state_ptr->pk[1])
 453                                 /* LIMC */
 454                                 if (a2p <= -12160)
 455                                         a2p = -12288;
 456                                 else if (a2p >= 12416)
 457                                         a2p = 12288;
 458                                 else
 459                                         a2p -= 0x80;
 460                         else if (a2p <= -12416)
 461                                 a2p = -12288;
 462                         else if (a2p >= 12160)
 463                                 a2p = 12288;
 464                         else
 465                                 a2p += 0x80;
 466                 }
 467
 468                 /* TRIGB & DELAY */
 469                 state_ptr->a[1] = a2p;
 470
 471                 /* UPA1 */
 472                 /* update predictor pole a[0] */
 473                 state_ptr->a[0] -= state_ptr->a[0] >> 8;
 474                 if (dqsez != 0) {
 475                         if (pks1 == 0)
 476                                 state_ptr->a[0] += 192;
 477                         else
 478                                 state_ptr->a[0] -= 192;
 479                 }
 480                 /* LIMD */
 481                 a1ul = 15360 - a2p;
 482                 if (state_ptr->a[0] < -a1ul)
 483                         state_ptr->a[0] = -a1ul;
 484                 else if (state_ptr->a[0] > a1ul)
 485                         state_ptr->a[0] = a1ul;
 486
 487                 /* UPB : update predictor zeros b[6] */
 488                 for (cnt = 0; cnt < 6; cnt++) {
 489                         if (code_size == 5)             /* for 40Kbps G.723 */
 490                                 state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9;
 491                         else                    /* for G.721 and 24Kbps G.723 */
 492                                 state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
 493                         if (mag)
 494                         {       /* XOR */
 495                                 if ((dq ^ state_ptr->dq[cnt]) >= 0)
 496                                         state_ptr->b[cnt] += 128;
 497                                 else
 498                                         state_ptr->b[cnt] -= 128;
 499                         }
 500                 }
 501         }
 502
 503         for (cnt = 5; cnt > 0; cnt--)
 504                 state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
 505 #ifdef NOT_BLI
 506         state_ptr->dq[0] = dq;
 507 #else
 508         /* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
 509         if (mag == 0) {
 510                 state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0x20 - 0x400;
 511         } else {
 512                 exp = ilog2(mag) + 1;
 513                 state_ptr->dq[0] = (dq >= 0) ?
 514                     (exp << 6) + ((mag << 6) >> exp) :
 515                     (exp << 6) + ((mag << 6) >> exp) - 0x400;
 516         }
 517 #endif
 518
 519         state_ptr->sr[1] = state_ptr->sr[0];
 520 #ifdef NOT_BLI
 521         state_ptr->sr[0] = sr;
 522 #else
 523         /* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
 524         if (sr == 0) {
 525                 state_ptr->sr[0] = 0x20;
 526         } else if (sr > 0) {
 527                 exp = ilog2(sr) + 1;
 528                 state_ptr->sr[0] = (exp << 6) + ((sr << 6) >> exp);
 529         } else if (sr > -0x8000) {
 530                 mag = -sr;
 531                 exp = ilog2(mag) + 1;
 532                 state_ptr->sr[0] =  (exp << 6) + ((mag << 6) >> exp) - 0x400;
 533         } else
 534                 state_ptr->sr[0] = 0x20 - 0x400;
 535 #endif
 536
 537         /* DELAY A */
 538         state_ptr->pk[1] = state_ptr->pk[0];
 539         state_ptr->pk[0] = pk0;
 540
 541         /* TONE */
 542         if (tr == 1)            /* this sample has been treated as data */
 543                 state_ptr->td = 0;      /* next one will be treated as voice */
 544         else if (a2p < -11776)  /* small sample-to-sample correlation */
 545                 state_ptr->td = 1;      /* signal may be data */
 546         else                            /* signal is voice */
 547                 state_ptr->td = 0;
 548
 549         /*
 550          * Adaptation speed control.
 551          */
 552         state_ptr->dms += (fi - state_ptr->dms) >> 5;           /* FILTA */
 553         state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7);  /* FILTB */
 554
 555         if (tr == 1)
 556                 state_ptr->ap = 256;
 557         else if (y < 1536)                                      /* SUBTC */
 558                 state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
 559         else if (state_ptr->td == 1)
 560                 state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
 561         else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
 562             (state_ptr->dml >> 3))
 563                 state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
 564         else
 565                 state_ptr->ap += (-state_ptr->ap) >> 4;
 566 }
 567
 568 /*
 569  * g726_decode()
 570  *
 571  * Description:
 572  *
 573  * Decodes a 4-bit code of G.726-32 encoded data of i and
 574  * returns the resulting linear PCM, A-law or u-law value.
 575  * return -1 for unknown out_coding value.
 576  */
 577 static int g726_decode(int      i, struct g726_state *state_ptr)
 578 {
 579         int             sezi, sez, se;  /* ACCUM */
 580         int             y;                      /* MIX */
 581         int             sr;                     /* ADDB */
 582         int             dq;
 583         int             dqsez;
 584
 585         i &= 0x0f;                      /* mask to get proper bits */
 586 #ifdef NOT_BLI
 587         sezi = predictor_zero(state_ptr);
 588         sez = sezi;
 589         se = sezi + predictor_pole(state_ptr);  /* estimated signal */
 590 #else
 591         sezi = predictor_zero(state_ptr);
 592         sez = sezi >> 1;
 593         se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
 594 #endif
 595
 596         y = step_size(state_ptr);       /* dynamic quantizer step size */
 597
 598         dq = reconstruct(i & 8, _dqlntab[i], y); /* quantized diff. */
 599
 600 #ifdef NOT_BLI
 601         sr = se + dq;                           /* reconst. signal */
 602         dqsez = dq + sez;                       /* pole prediction diff. */
 603 #else
 604         sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
 605         dqsez = sr - se + sez;          /* pole prediction diff. */
 606 #endif
 607
 608         update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
 609
 610 #ifdef NOT_BLI
 611         return (sr >> 10);      /* sr was 26-bit dynamic range */
 612 #else
 613         return (sr << 2);       /* sr was 14-bit dynamic range */
 614 #endif
 615 }
 616
 617 /*
 618  * g726_encode()
 619  *
 620  * Encodes the input vale of linear PCM, A-law or u-law data sl and returns
 621  * the resulting code. -1 is returned for unknown input coding value.
 622  */
 623 static int g726_encode(int sl, struct g726_state *state_ptr)
 624 {
 625         int             sezi, se, sez;          /* ACCUM */
 626         int             d;                      /* SUBTA */
 627         int             sr;                     /* ADDB */
 628         int             y;                      /* MIX */
 629         int             dqsez;                  /* ADDC */
 630         int             dq, i;
 631
 632 #ifdef NOT_BLI
 633         sl <<= 10;                      /* 26-bit dynamic range */
 634
 635         sezi = predictor_zero(state_ptr);
 636         sez = sezi;
 637         se = sezi + predictor_pole(state_ptr);  /* estimated signal */
 638 #else
 639         sl >>= 2;                       /* 14-bit dynamic range */
 640
 641         sezi = predictor_zero(state_ptr);
 642         sez = sezi >> 1;
 643         se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
 644 #endif
 645
 646         d = sl - se;                            /* estimation difference */
 647
 648         /* quantize the prediction difference */
 649         y = step_size(state_ptr);               /* quantizer step size */
 650 #ifdef NOT_BLI
 651         d /= 0x1000;
 652 #endif
 653         i = quantize(d, y, qtab_721, 7);        /* i = G726 code */
 654
 655         dq = reconstruct(i & 8, _dqlntab[i], y);        /* quantized est diff */
 656
 657 #ifdef NOT_BLI
 658         sr = se + dq;                           /* reconst. signal */
 659         dqsez = dq + sez;                       /* pole prediction diff. */
 660 #else
 661         sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
 662         dqsez = sr - se + sez;                  /* pole prediction diff. */
 663 #endif
 664
 665         update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
 666
 667         return (i);
 668 }
 669
 670 /*
 671  * Private workspace for translating signed linear signals to G726.
 672  * Don't bother to define two distinct structs.
 673  */
 674
 675 struct g726_coder_pvt {
 676         /* buffer any odd byte in input - 0x80 + (value & 0xf) if present */
 677         unsigned char next_flag;
 678         struct g726_state g726;
 679 };
 680
 681 /*! \brief init a new instance of g726_coder_pvt. */
 682 static int lintog726_new(struct ast_trans_pvt *pvt)
 683 {
 684         struct g726_coder_pvt *tmp = pvt->pvt;
 685
 686         g726_init_state(&tmp->g726);
 687
 688         return 0;
 689 }
 690
 691 /*! \brief decode packed 4-bit G726 values (AAL2 packing) and store in buffer. */
 692 static int g726aal2tolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 693 {
 694         struct g726_coder_pvt *tmp = pvt->pvt;
 695         unsigned char *src = f->data.ptr;
 696         int16_t *dst = (int16_t *) pvt->outbuf + pvt->samples;
 697         unsigned int i;
 698
 699         for (i = 0; i < f->datalen; i++) {
 700                 *dst++ = g726_decode((src[i] >> 4) & 0xf, &tmp->g726);
 701                 *dst++ = g726_decode(src[i] & 0x0f, &tmp->g726);
 702         }
 703
 704         pvt->samples += f->samples;
 705         pvt->datalen += 2 * f->samples; /* 2 bytes/sample */
 706
 707         return 0;
 708 }
 709
 710 /*! \brief compress and store data (4-bit G726 samples, AAL2 packing) in outbuf */
 711 static int lintog726aal2_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
 712 {
 713         struct g726_coder_pvt *tmp = pvt->pvt;
 714         int16_t *src = f->data.ptr;
 715         unsigned int i;
 716
 717         for (i = 0; i < f->samples; i++) {
 718                 unsigned char d = g726_encode(src[i], &tmp->g726); /* this sample */
 719
 720                 if (tmp->next_flag & 0x80) {    /* merge with leftover sample */
 721                         pvt->outbuf[pvt->datalen++] = ((tmp->next_flag & 0xf)<< 4) | d;
 722                         pvt->samples += 2;      /* 2 samples per byte */
 723                         tmp->next_flag = 0;
 724                 } else {
 725                         tmp->next_flag = 0x80 | d;
 726                 }
 727         }
 728
 729         return 0;
 730 }
 731
 732 /*! \brief decode packed 4-bit G726 values (RFC3551 packing) and store in buffer. */
 733 static int g726tolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 734 {
 735         struct g726_coder_pvt *tmp = pvt->pvt;
 736         unsigned char *src = f->data.ptr;
 737         int16_t *dst = (int16_t *) pvt->outbuf + pvt->samples;
 738         unsigned int i;
 739
 740         for (i = 0; i < f->datalen; i++) {
 741                 *dst++ = g726_decode(src[i] & 0x0f, &tmp->g726);
 742                 *dst++ = g726_decode((src[i] >> 4) & 0xf, &tmp->g726);
 743         }
 744
 745         pvt->samples += f->samples;
 746         pvt->datalen += 2 * f->samples; /* 2 bytes/sample */
 747
 748         return 0;
 749 }
 750
 751 /*! \brief compress and store data (4-bit G726 samples, RFC3551 packing) in outbuf */
 752 static int lintog726_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
 753 {
 754         struct g726_coder_pvt *tmp = pvt->pvt;
 755         int16_t *src = f->data.ptr;
 756         unsigned int i;
 757
 758         for (i = 0; i < f->samples; i++) {
 759                 unsigned char d = g726_encode(src[i], &tmp->g726); /* this sample */
 760
 761                 if (tmp->next_flag & 0x80) {    /* merge with leftover sample */
 762                         pvt->outbuf[pvt->datalen++] = (d << 4) | (tmp->next_flag & 0xf);
 763                         pvt->samples += 2;      /* 2 samples per byte */
 764                         tmp->next_flag = 0;
 765                 } else {
 766                         tmp->next_flag = 0x80 | d;
 767                 }
 768         }
 769
 770         return 0;
 771 }
 772
 773 /*! \brief convert G726-32 RFC3551 packed data into AAL2 packed data (or vice-versa) */
 774 static int g726tog726aal2_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
 775 {
 776         unsigned char *src = f->data.ptr;
 777         unsigned char *dst = (unsigned char *) pvt->outbuf + pvt->samples;
 778         unsigned int i;
 779
 780         for (i = 0; i < f->datalen; i++)
 781                 *dst++ = ((src[i] & 0xf) << 4) | (src[i] >> 4);
 782
 783         pvt->samples += f->samples;
 784         pvt->datalen += f->samples; /* 1 byte/sample */
 785
 786         return 0;
 787 }
 788
 789 static struct ast_frame *g726tolin_sample(void)
 790 {
 791         static struct ast_frame f = {
 792                 .frametype = AST_FRAME_VOICE,
 793                 .subclass = AST_FORMAT_G726,
 794                 .datalen = sizeof(g726_slin_ex),
 795                 .samples = sizeof(g726_slin_ex) * 2,    /* 2 samples per byte */
 796                 .src = __PRETTY_FUNCTION__,
 797                 .data.ptr = g726_slin_ex,
 798         };
 799
 800         return &f;
 801 }
 802
 803 static struct ast_frame *lintog726_sample (void)
 804 {
 805         static struct ast_frame f = {
 806                 .frametype = AST_FRAME_VOICE,
 807                 .subclass = AST_FORMAT_SLINEAR,
 808                 .datalen = sizeof(slin_g726_ex),
 809                 .samples = sizeof(slin_g726_ex) / 2,    /* 1 sample per 2 bytes */
 810                 .src = __PRETTY_FUNCTION__,
 811                 .data.ptr = slin_g726_ex,
 812         };
 813
 814         return &f;
 815 }
 816
 817 static struct ast_translator g726tolin = {
 818         .name = "g726tolin",
 819         .srcfmt = AST_FORMAT_G726,
 820         .dstfmt = AST_FORMAT_SLINEAR,
 821         .newpvt = lintog726_new,        /* same for both directions */
 822         .framein = g726tolin_framein,
 823         .sample = g726tolin_sample,
 824         .desc_size = sizeof(struct g726_coder_pvt),
 825         .buffer_samples = BUFFER_SAMPLES,
 826         .buf_size = BUFFER_SAMPLES * 2,
 827         .plc_samples = 160,
 828 };
 829
 830 static struct ast_translator lintog726 = {
 831         .name = "lintog726",
 832         .srcfmt = AST_FORMAT_SLINEAR,
 833         .dstfmt = AST_FORMAT_G726,
 834         .newpvt = lintog726_new,        /* same for both directions */
 835         .framein = lintog726_framein,
 836         .sample = lintog726_sample,
 837         .desc_size = sizeof(struct g726_coder_pvt),
 838         .buffer_samples = BUFFER_SAMPLES,
 839         .buf_size = BUFFER_SAMPLES/2,
 840 };
 841
 842 static struct ast_translator g726aal2tolin = {
 843         .name = "g726aal2tolin",
 844         .srcfmt = AST_FORMAT_G726_AAL2,
 845         .dstfmt = AST_FORMAT_SLINEAR,
 846         .newpvt = lintog726_new,        /* same for both directions */
 847         .framein = g726aal2tolin_framein,
 848         .sample = g726tolin_sample,
 849         .desc_size = sizeof(struct g726_coder_pvt),
 850         .buffer_samples = BUFFER_SAMPLES,
 851         .buf_size = BUFFER_SAMPLES * 2,
 852         .plc_samples = 160,
 853 };
 854
 855 static struct ast_translator lintog726aal2 = {
 856         .name = "lintog726aal2",
 857         .srcfmt = AST_FORMAT_SLINEAR,
 858         .dstfmt = AST_FORMAT_G726_AAL2,
 859         .newpvt = lintog726_new,        /* same for both directions */
 860         .framein = lintog726aal2_framein,
 861         .sample = lintog726_sample,
 862         .desc_size = sizeof(struct g726_coder_pvt),
 863         .buffer_samples = BUFFER_SAMPLES,
 864         .buf_size = BUFFER_SAMPLES / 2,
 865 };
 866
 867 static struct ast_translator g726tog726aal2 = {
 868         .name = "g726tog726aal2",
 869         .srcfmt = AST_FORMAT_G726,
 870         .dstfmt = AST_FORMAT_G726_AAL2,
 871         .framein = g726tog726aal2_framein,      /* same for both directions */
 872         .sample = lintog726_sample,
 873         .buffer_samples = BUFFER_SAMPLES,
 874         .buf_size = BUFFER_SAMPLES,
 875 };
 876
 877 static struct ast_translator g726aal2tog726 = {
 878         .name = "g726aal2tog726",
 879         .srcfmt = AST_FORMAT_G726_AAL2,
 880         .dstfmt = AST_FORMAT_G726,
 881         .framein = g726tog726aal2_framein,      /* same for both directions */
 882         .sample = lintog726_sample,
 883         .buffer_samples = BUFFER_SAMPLES,
 884         .buf_size = BUFFER_SAMPLES,
 885 };
 886
 887 static int parse_config(int reload)
 888 {
 889         struct ast_variable *var;
 890         struct ast_flags config_flags = { reload ? CONFIG_FLAG_FILEUNCHANGED : 0 };
 891         struct ast_config *cfg = ast_config_load("codecs.conf", config_flags);
 892
 893         if (cfg == NULL)
 894                 return 0;
 895         if (cfg == CONFIG_STATUS_FILEUNCHANGED)
 896                 return 0;
 897         for (var = ast_variable_browse(cfg, "plc"); var; var = var->next) {
 898                 if (!strcasecmp(var->name, "genericplc")) {
 899                         g726tolin.useplc = ast_true(var->value) ? 1 : 0;
 900                         ast_verb(3, "codec_g726: %susing generic PLC\n",
 901                                         g726tolin.useplc ? "" : "not ");
 902                 }
 903         }
 904         ast_config_destroy(cfg);
 905         return 0;
 906 }
 907
 908 static int reload(void)
 909 {
 910         if (parse_config(1))
 911                 return AST_MODULE_LOAD_DECLINE;
 912         return AST_MODULE_LOAD_SUCCESS;
 913 }
 914
 915 static int unload_module(void)
 916 {
 917         int res = 0;
 918
 919         res |= ast_unregister_translator(&g726tolin);
 920         res |= ast_unregister_translator(&lintog726);
 921
 922         res |= ast_unregister_translator(&g726aal2tolin);
 923         res |= ast_unregister_translator(&lintog726aal2);
 924
 925         res |= ast_unregister_translator(&g726aal2tog726);
 926         res |= ast_unregister_translator(&g726tog726aal2);
 927
 928         return res;
 929 }
 930
 931 static int load_module(void)
 932 {
 933         int res = 0;
 934
 935
 936         if (parse_config(0))
 937                 return AST_MODULE_LOAD_DECLINE;
 938
 939         res |= ast_register_translator(&g726tolin);
 940         res |= ast_register_translator(&lintog726);
 941
 942         res |= ast_register_translator(&g726aal2tolin);
 943         res |= ast_register_translator(&lintog726aal2);
 944
 945         res |= ast_register_translator(&g726aal2tog726);
 946         res |= ast_register_translator(&g726tog726aal2);
 947
 948         if (res) {
 949                 unload_module();
 950                 return AST_MODULE_LOAD_FAILURE;
 951         }
 952
 953         return AST_MODULE_LOAD_SUCCESS;
 954 }
 955
 956 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "ITU G.726-32kbps G726 Transcoder",
 957                 .load = load_module,
 958                 .unload = unload_module,
 959                 .reload = reload,
 960                );