FLAC/src/lpc.c

   1 /* libFLAC - Free Lossless Audio Codec library
   2  * Copyright (C) 2000-2009  Josh Coalson
   3  * Copyright (C) 2011-2016  Xiph.Org Foundation
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * - Redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer.
  11  *
  12  * - Redistributions in binary form must reproduce the above copyright
  13  * notice, this list of conditions and the following disclaimer in the
  14  * documentation and/or other materials provided with the distribution.
  15  *
  16  * - Neither the name of the Xiph.org Foundation nor the names of its
  17  * contributors may be used to endorse or promote products derived from
  18  * this software without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  23  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
  24  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  25  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  26  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  27  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  28  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  29  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  30  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 #ifdef HAVE_CONFIG_H
  34 #  include <config.h>
  35 #endif
  36
  37 #include <math.h>
  38
  39 #include "FLAC/assert.h"
  40 #include "FLAC/format.h"
  41 #include "share/compat.h"
  42 #include "private/bitmath.h"
  43 #include "private/lpc.h"
  44 #include "private/macros.h"
  45 #if !defined(NDEBUG) || defined FLAC__OVERFLOW_DETECT || defined FLAC__OVERFLOW_DETECT_VERBOSE
  46 #include <stdio.h>
  47 #endif
  48
  49 /* OPT: #undef'ing this may improve the speed on some architectures */
  50 #define FLAC__LPC_UNROLLED_FILTER_LOOPS
  51
  52 #ifndef FLAC__INTEGER_ONLY_LIBRARY
  53
  54 #if defined(_MSC_VER) && (_MSC_VER < 1800)
  55 #include <float.h>
  56 static inline long int lround(double x) {
  57         return (long)(x + _copysign(0.5, x));
  58 }
  59 #elif !defined(HAVE_LROUND) && defined(__GNUC__)
  60 static inline long int lround(double x) {
  61         return (long)(x + __builtin_copysign(0.5, x));
  62 }
  63 /* If this fails, we are in the presence of a mid 90's compiler, move along... */
  64 #endif
  65
  66 void FLAC__lpc_window_data(const FLAC__int32 in[], const FLAC__real window[], FLAC__real out[], uint32_t data_len)
  67 {
  68         uint32_t i;
  69         for(i = 0; i < data_len; i++)
  70                 out[i] = in[i] * window[i];
  71 }
  72
  73 void FLAC__lpc_compute_autocorrelation(const FLAC__real data[], uint32_t data_len, uint32_t lag, FLAC__real autoc[])
  74 {
  75         /* a readable, but slower, version */
  76 #if 0
  77         FLAC__real d;
  78         uint32_t i;
  79
  80         FLAC__ASSERT(lag > 0);
  81         FLAC__ASSERT(lag <= data_len);
  82
  83         /*
  84          * Technically we should subtract the mean first like so:
  85          *   for(i = 0; i < data_len; i++)
  86          *     data[i] -= mean;
  87          * but it appears not to make enough of a difference to matter, and
  88          * most signals are already closely centered around zero
  89          */
  90         while(lag--) {
  91                 for(i = lag, d = 0.0; i < data_len; i++)
  92                         d += data[i] * data[i - lag];
  93                 autoc[lag] = d;
  94         }
  95 #endif
  96
  97         /*
  98          * this version tends to run faster because of better data locality
  99          * ('data_len' is usually much larger than 'lag')
 100          */
 101         FLAC__real d;
 102         uint32_t sample, coeff;
 103         const uint32_t limit = data_len - lag;
 104
 105         FLAC__ASSERT(lag > 0);
 106         FLAC__ASSERT(lag <= data_len);
 107
 108         for(coeff = 0; coeff < lag; coeff++)
 109                 autoc[coeff] = 0.0;
 110         for(sample = 0; sample <= limit; sample++) {
 111                 d = data[sample];
 112                 for(coeff = 0; coeff < lag; coeff++)
 113                         autoc[coeff] += d * data[sample+coeff];
 114         }
 115         for(; sample < data_len; sample++) {
 116                 d = data[sample];
 117                 for(coeff = 0; coeff < data_len - sample; coeff++)
 118                         autoc[coeff] += d * data[sample+coeff];
 119         }
 120 }
 121
 122 void FLAC__lpc_compute_lp_coefficients(const FLAC__real autoc[], uint32_t *max_order, FLAC__real lp_coeff[][FLAC__MAX_LPC_ORDER], double error[])
 123 {
 124         uint32_t i, j;
 125         double r, err, lpc[FLAC__MAX_LPC_ORDER];
 126
 127         FLAC__ASSERT(0 != max_order);
 128         FLAC__ASSERT(0 < *max_order);
 129         FLAC__ASSERT(*max_order <= FLAC__MAX_LPC_ORDER);
 130         FLAC__ASSERT(autoc[0] != 0.0);
 131
 132         err = autoc[0];
 133
 134         for(i = 0; i < *max_order; i++) {
 135                 /* Sum up this iteration's reflection coefficient. */
 136                 r = -autoc[i+1];
 137                 for(j = 0; j < i; j++)
 138                         r -= lpc[j] * autoc[i-j];
 139                 r /= err;
 140
 141                 /* Update LPC coefficients and total error. */
 142                 lpc[i]=r;
 143                 for(j = 0; j < (i>>1); j++) {
 144                         double tmp = lpc[j];
 145                         lpc[j] += r * lpc[i-1-j];
 146                         lpc[i-1-j] += r * tmp;
 147                 }
 148                 if(i & 1)
 149                         lpc[j] += lpc[j] * r;
 150
 151                 err *= (1.0 - r * r);
 152
 153                 /* save this order */
 154                 for(j = 0; j <= i; j++)
 155                         lp_coeff[i][j] = (FLAC__real)(-lpc[j]); /* negate FIR filter coeff to get predictor coeff */
 156                 error[i] = err;
 157
 158                 /* see SF bug https://sourceforge.net/p/flac/bugs/234/ */
 159                 if(err == 0.0) {
 160                         *max_order = i+1;
 161                         return;
 162                 }
 163         }
 164 }
 165
 166 int FLAC__lpc_quantize_coefficients(const FLAC__real lp_coeff[], uint32_t order, uint32_t precision, FLAC__int32 qlp_coeff[], int *shift)
 167 {
 168         uint32_t i;
 169         double cmax;
 170         FLAC__int32 qmax, qmin;
 171
 172         FLAC__ASSERT(precision > 0);
 173         FLAC__ASSERT(precision >= FLAC__MIN_QLP_COEFF_PRECISION);
 174
 175         /* drop one bit for the sign; from here on out we consider only |lp_coeff[i]| */
 176         precision--;
 177         qmax = 1 << precision;
 178         qmin = -qmax;
 179         qmax--;
 180
 181         /* calc cmax = max( |lp_coeff[i]| ) */
 182         cmax = 0.0;
 183         for(i = 0; i < order; i++) {
 184                 const double d = fabs(lp_coeff[i]);
 185                 if(d > cmax)
 186                         cmax = d;
 187         }
 188
 189         if(cmax <= 0.0) {
 190                 /* => coefficients are all 0, which means our constant-detect didn't work */
 191                 return 2;
 192         }
 193         else {
 194                 const int max_shiftlimit = (1 << (FLAC__SUBFRAME_LPC_QLP_SHIFT_LEN-1)) - 1;
 195                 const int min_shiftlimit = -max_shiftlimit - 1;
 196                 int log2cmax;
 197
 198                 (void)frexp(cmax, &log2cmax);
 199                 log2cmax--;
 200                 *shift = (int)precision - log2cmax - 1;
 201
 202                 if(*shift > max_shiftlimit)
 203                         *shift = max_shiftlimit;
 204                 else if(*shift < min_shiftlimit)
 205                         return 1;
 206         }
 207
 208         if(*shift >= 0) {
 209                 double error = 0.0;
 210                 FLAC__int32 q;
 211                 for(i = 0; i < order; i++) {
 212                         error += lp_coeff[i] * (1 << *shift);
 213                         q = lround(error);
 214
 215 #ifdef FLAC__OVERFLOW_DETECT
 216                         if(q > qmax+1) /* we expect q==qmax+1 occasionally due to rounding */
 217                                 fprintf(stderr,"FLAC__lpc_quantize_coefficients: quantizer overflow: q>qmax %d>%d shift=%d cmax=%f precision=%u lpc[%u]=%f\n",q,qmax,*shift,cmax,precision+1,i,lp_coeff[i]);
 218                         else if(q < qmin)
 219                                 fprintf(stderr,"FLAC__lpc_quantize_coefficients: quantizer overflow: q<qmin %d<%d shift=%d cmax=%f precision=%u lpc[%u]=%f\n",q,qmin,*shift,cmax,precision+1,i,lp_coeff[i]);
 220 #endif
 221                         if(q > qmax)
 222                                 q = qmax;
 223                         else if(q < qmin)
 224                                 q = qmin;
 225                         error -= q;
 226                         qlp_coeff[i] = q;
 227                 }
 228         }
 229         /* negative shift is very rare but due to design flaw, negative shift is
 230          * not allowed in the decoder, so it must be handled specially by scaling
 231          * down coeffs
 232          */
 233         else {
 234                 const int nshift = -(*shift);
 235                 double error = 0.0;
 236                 FLAC__int32 q;
 237 #ifndef NDEBUG
 238                 fprintf(stderr,"FLAC__lpc_quantize_coefficients: negative shift=%d order=%u cmax=%f\n", *shift, order, cmax);
 239 #endif
 240                 for(i = 0; i < order; i++) {
 241                         error += lp_coeff[i] / (1 << nshift);
 242                         q = lround(error);
 243 #ifdef FLAC__OVERFLOW_DETECT
 244                         if(q > qmax+1) /* we expect q==qmax+1 occasionally due to rounding */
 245                                 fprintf(stderr,"FLAC__lpc_quantize_coefficients: quantizer overflow: q>qmax %d>%d shift=%d cmax=%f precision=%u lpc[%u]=%f\n",q,qmax,*shift,cmax,precision+1,i,lp_coeff[i]);
 246                         else if(q < qmin)
 247                                 fprintf(stderr,"FLAC__lpc_quantize_coefficients: quantizer overflow: q<qmin %d<%d shift=%d cmax=%f precision=%u lpc[%u]=%f\n",q,qmin,*shift,cmax,precision+1,i,lp_coeff[i]);
 248 #endif
 249                         if(q > qmax)
 250                                 q = qmax;
 251                         else if(q < qmin)
 252                                 q = qmin;
 253                         error -= q;
 254                         qlp_coeff[i] = q;
 255                 }
 256                 *shift = 0;
 257         }
 258
 259         return 0;
 260 }
 261
 262 #if defined(_MSC_VER)
 263 // silence MSVC warnings about __restrict modifier
 264 #pragma warning ( disable : 4028 )
 265 #endif
 266
 267 void FLAC__lpc_compute_residual_from_qlp_coefficients(const FLAC__int32 * flac_restrict data, uint32_t data_len, const FLAC__int32 * flac_restrict qlp_coeff, uint32_t order, int lp_quantization, FLAC__int32 * flac_restrict residual)
 268 #if defined(FLAC__OVERFLOW_DETECT) || !defined(FLAC__LPC_UNROLLED_FILTER_LOOPS)
 269 {
 270         FLAC__int64 sumo;
 271         uint32_t i, j;
 272         FLAC__int32 sum;
 273         const FLAC__int32 *history;
 274
 275 #ifdef FLAC__OVERFLOW_DETECT_VERBOSE
 276         fprintf(stderr,"FLAC__lpc_compute_residual_from_qlp_coefficients: data_len=%d, order=%u, lpq=%d",data_len,order,lp_quantization);
 277         for(i=0;i<order;i++)
 278                 fprintf(stderr,", q[%u]=%d",i,qlp_coeff[i]);
 279         fprintf(stderr,"\n");
 280 #endif
 281         FLAC__ASSERT(order > 0);
 282
 283         for(i = 0; i < data_len; i++) {
 284                 sumo = 0;
 285                 sum = 0;
 286                 history = data;
 287                 for(j = 0; j < order; j++) {
 288                         sum += qlp_coeff[j] * (*(--history));
 289                         sumo += (FLAC__int64)qlp_coeff[j] * (FLAC__int64)(*history);
 290                         if(sumo > 2147483647ll || sumo < -2147483648ll)
 291                                 fprintf(stderr,"FLAC__lpc_compute_residual_from_qlp_coefficients: OVERFLOW, i=%u, j=%u, c=%d, d=%d, sumo=%" PRId64 "\n",i,j,qlp_coeff[j],*history,sumo);
 292                 }
 293                 *(residual++) = *(data++) - (sum >> lp_quantization);
 294         }
 295
 296         /* Here's a slower but clearer version:
 297         for(i = 0; i < data_len; i++) {
 298                 sum = 0;
 299                 for(j = 0; j < order; j++)
 300                         sum += qlp_coeff[j] * data[i-j-1];
 301                 residual[i] = data[i] - (sum >> lp_quantization);
 302         }
 303         */
 304 }
 305 #else /* fully unrolled version for normal use */
 306 {
 307         int i;
 308         FLAC__int32 sum;
 309
 310         FLAC__ASSERT(order > 0);
 311         FLAC__ASSERT(order <= 32);
 312
 313         /*
 314          * We do unique versions up to 12th order since that's the subset limit.
 315          * Also they are roughly ordered to match frequency of occurrence to
 316          * minimize branching.
 317          */
 318         if(order <= 12) {
 319                 if(order > 8) {
 320                         if(order > 10) {
 321                                 if(order == 12) {
 322                                         for(i = 0; i < (int)data_len; i++) {
 323                                                 sum = 0;
 324                                                 sum += qlp_coeff[11] * data[i-12];
 325                                                 sum += qlp_coeff[10] * data[i-11];
 326                                                 sum += qlp_coeff[9] * data[i-10];
 327                                                 sum += qlp_coeff[8] * data[i-9];
 328                                                 sum += qlp_coeff[7] * data[i-8];
 329                                                 sum += qlp_coeff[6] * data[i-7];
 330                                                 sum += qlp_coeff[5] * data[i-6];
 331                                                 sum += qlp_coeff[4] * data[i-5];
 332                                                 sum += qlp_coeff[3] * data[i-4];
 333                                                 sum += qlp_coeff[2] * data[i-3];
 334                                                 sum += qlp_coeff[1] * data[i-2];
 335                                                 sum += qlp_coeff[0] * data[i-1];
 336                                                 residual[i] = data[i] - (sum >> lp_quantization);
 337                                         }
 338                                 }
 339                                 else { /* order == 11 */
 340                                         for(i = 0; i < (int)data_len; i++) {
 341                                                 sum = 0;
 342                                                 sum += qlp_coeff[10] * data[i-11];
 343                                                 sum += qlp_coeff[9] * data[i-10];
 344                                                 sum += qlp_coeff[8] * data[i-9];
 345                                                 sum += qlp_coeff[7] * data[i-8];
 346                                                 sum += qlp_coeff[6] * data[i-7];
 347                                                 sum += qlp_coeff[5] * data[i-6];
 348                                                 sum += qlp_coeff[4] * data[i-5];
 349                                                 sum += qlp_coeff[3] * data[i-4];
 350                                                 sum += qlp_coeff[2] * data[i-3];
 351                                                 sum += qlp_coeff[1] * data[i-2];
 352                                                 sum += qlp_coeff[0] * data[i-1];
 353                                                 residual[i] = data[i] - (sum >> lp_quantization);
 354                                         }
 355                                 }
 356                         }
 357                         else {
 358                                 if(order == 10) {
 359                                         for(i = 0; i < (int)data_len; i++) {
 360                                                 sum = 0;
 361                                                 sum += qlp_coeff[9] * data[i-10];
 362                                                 sum += qlp_coeff[8] * data[i-9];
 363                                                 sum += qlp_coeff[7] * data[i-8];
 364                                                 sum += qlp_coeff[6] * data[i-7];
 365                                                 sum += qlp_coeff[5] * data[i-6];
 366                                                 sum += qlp_coeff[4] * data[i-5];
 367                                                 sum += qlp_coeff[3] * data[i-4];
 368                                                 sum += qlp_coeff[2] * data[i-3];
 369                                                 sum += qlp_coeff[1] * data[i-2];
 370                                                 sum += qlp_coeff[0] * data[i-1];
 371                                                 residual[i] = data[i] - (sum >> lp_quantization);
 372                                         }
 373                                 }
 374                                 else { /* order == 9 */
 375                                         for(i = 0; i < (int)data_len; i++) {
 376                                                 sum = 0;
 377                                                 sum += qlp_coeff[8] * data[i-9];
 378                                                 sum += qlp_coeff[7] * data[i-8];
 379                                                 sum += qlp_coeff[6] * data[i-7];
 380                                                 sum += qlp_coeff[5] * data[i-6];
 381                                                 sum += qlp_coeff[4] * data[i-5];
 382                                                 sum += qlp_coeff[3] * data[i-4];
 383                                                 sum += qlp_coeff[2] * data[i-3];
 384                                                 sum += qlp_coeff[1] * data[i-2];
 385                                                 sum += qlp_coeff[0] * data[i-1];
 386                                                 residual[i] = data[i] - (sum >> lp_quantization);
 387                                         }
 388                                 }
 389                         }
 390                 }
 391                 else if(order > 4) {
 392                         if(order > 6) {
 393                                 if(order == 8) {
 394                                         for(i = 0; i < (int)data_len; i++) {
 395                                                 sum = 0;
 396                                                 sum += qlp_coeff[7] * data[i-8];
 397                                                 sum += qlp_coeff[6] * data[i-7];
 398                                                 sum += qlp_coeff[5] * data[i-6];
 399                                                 sum += qlp_coeff[4] * data[i-5];
 400                                                 sum += qlp_coeff[3] * data[i-4];
 401                                                 sum += qlp_coeff[2] * data[i-3];
 402                                                 sum += qlp_coeff[1] * data[i-2];
 403                                                 sum += qlp_coeff[0] * data[i-1];
 404                                                 residual[i] = data[i] - (sum >> lp_quantization);
 405                                         }
 406                                 }
 407                                 else { /* order == 7 */
 408                                         for(i = 0; i < (int)data_len; i++) {
 409                                                 sum = 0;
 410                                                 sum += qlp_coeff[6] * data[i-7];
 411                                                 sum += qlp_coeff[5] * data[i-6];
 412                                                 sum += qlp_coeff[4] * data[i-5];
 413                                                 sum += qlp_coeff[3] * data[i-4];
 414                                                 sum += qlp_coeff[2] * data[i-3];
 415                                                 sum += qlp_coeff[1] * data[i-2];
 416                                                 sum += qlp_coeff[0] * data[i-1];
 417                                                 residual[i] = data[i] - (sum >> lp_quantization);
 418                                         }
 419                                 }
 420                         }
 421                         else {
 422                                 if(order == 6) {
 423                                         for(i = 0; i < (int)data_len; i++) {
 424                                                 sum = 0;
 425                                                 sum += qlp_coeff[5] * data[i-6];
 426                                                 sum += qlp_coeff[4] * data[i-5];
 427                                                 sum += qlp_coeff[3] * data[i-4];
 428                                                 sum += qlp_coeff[2] * data[i-3];
 429                                                 sum += qlp_coeff[1] * data[i-2];
 430                                                 sum += qlp_coeff[0] * data[i-1];
 431                                                 residual[i] = data[i] - (sum >> lp_quantization);
 432                                         }
 433                                 }
 434                                 else { /* order == 5 */
 435                                         for(i = 0; i < (int)data_len; i++) {
 436                                                 sum = 0;
 437                                                 sum += qlp_coeff[4] * data[i-5];
 438                                                 sum += qlp_coeff[3] * data[i-4];
 439                                                 sum += qlp_coeff[2] * data[i-3];
 440                                                 sum += qlp_coeff[1] * data[i-2];
 441                                                 sum += qlp_coeff[0] * data[i-1];
 442                                                 residual[i] = data[i] - (sum >> lp_quantization);
 443                                         }
 444                                 }
 445                         }
 446                 }
 447                 else {
 448                         if(order > 2) {
 449                                 if(order == 4) {
 450                                         for(i = 0; i < (int)data_len; i++) {
 451                                                 sum = 0;
 452                                                 sum += qlp_coeff[3] * data[i-4];
 453                                                 sum += qlp_coeff[2] * data[i-3];
 454                                                 sum += qlp_coeff[1] * data[i-2];
 455                                                 sum += qlp_coeff[0] * data[i-1];
 456                                                 residual[i] = data[i] - (sum >> lp_quantization);
 457                                         }
 458                                 }
 459                                 else { /* order == 3 */
 460                                         for(i = 0; i < (int)data_len; i++) {
 461                                                 sum = 0;
 462                                                 sum += qlp_coeff[2] * data[i-3];
 463                                                 sum += qlp_coeff[1] * data[i-2];
 464                                                 sum += qlp_coeff[0] * data[i-1];
 465                                                 residual[i] = data[i] - (sum >> lp_quantization);
 466                                         }
 467                                 }
 468                         }
 469                         else {
 470                                 if(order == 2) {
 471                                         for(i = 0; i < (int)data_len; i++) {
 472                                                 sum = 0;
 473                                                 sum += qlp_coeff[1] * data[i-2];
 474                                                 sum += qlp_coeff[0] * data[i-1];
 475                                                 residual[i] = data[i] - (sum >> lp_quantization);
 476                                         }
 477                                 }
 478                                 else { /* order == 1 */
 479                                         for(i = 0; i < (int)data_len; i++)
 480                                                 residual[i] = data[i] - ((qlp_coeff[0] * data[i-1]) >> lp_quantization);
 481                                 }
 482                         }
 483                 }
 484         }
 485         else { /* order > 12 */
 486                 for(i = 0; i < (int)data_len; i++) {
 487                         sum = 0;
 488                         switch(order) {
 489                                 case 32: sum += qlp_coeff[31] * data[i-32]; /* Falls through. */
 490                                 case 31: sum += qlp_coeff[30] * data[i-31]; /* Falls through. */
 491                                 case 30: sum += qlp_coeff[29] * data[i-30]; /* Falls through. */
 492                                 case 29: sum += qlp_coeff[28] * data[i-29]; /* Falls through. */
 493                                 case 28: sum += qlp_coeff[27] * data[i-28]; /* Falls through. */
 494                                 case 27: sum += qlp_coeff[26] * data[i-27]; /* Falls through. */
 495                                 case 26: sum += qlp_coeff[25] * data[i-26]; /* Falls through. */
 496                                 case 25: sum += qlp_coeff[24] * data[i-25]; /* Falls through. */
 497                                 case 24: sum += qlp_coeff[23] * data[i-24]; /* Falls through. */
 498                                 case 23: sum += qlp_coeff[22] * data[i-23]; /* Falls through. */
 499                                 case 22: sum += qlp_coeff[21] * data[i-22]; /* Falls through. */
 500                                 case 21: sum += qlp_coeff[20] * data[i-21]; /* Falls through. */
 501                                 case 20: sum += qlp_coeff[19] * data[i-20]; /* Falls through. */
 502                                 case 19: sum += qlp_coeff[18] * data[i-19]; /* Falls through. */
 503                                 case 18: sum += qlp_coeff[17] * data[i-18]; /* Falls through. */
 504                                 case 17: sum += qlp_coeff[16] * data[i-17]; /* Falls through. */
 505                                 case 16: sum += qlp_coeff[15] * data[i-16]; /* Falls through. */
 506                                 case 15: sum += qlp_coeff[14] * data[i-15]; /* Falls through. */
 507                                 case 14: sum += qlp_coeff[13] * data[i-14]; /* Falls through. */
 508                                 case 13: sum += qlp_coeff[12] * data[i-13];
 509                                          sum += qlp_coeff[11] * data[i-12];
 510                                          sum += qlp_coeff[10] * data[i-11];
 511                                          sum += qlp_coeff[ 9] * data[i-10];
 512                                          sum += qlp_coeff[ 8] * data[i- 9];
 513                                          sum += qlp_coeff[ 7] * data[i- 8];
 514                                          sum += qlp_coeff[ 6] * data[i- 7];
 515                                          sum += qlp_coeff[ 5] * data[i- 6];
 516                                          sum += qlp_coeff[ 4] * data[i- 5];
 517                                          sum += qlp_coeff[ 3] * data[i- 4];
 518                                          sum += qlp_coeff[ 2] * data[i- 3];
 519                                          sum += qlp_coeff[ 1] * data[i- 2];
 520                                          sum += qlp_coeff[ 0] * data[i- 1];
 521                         }
 522                         residual[i] = data[i] - (sum >> lp_quantization);
 523                 }
 524         }
 525 }
 526 #endif
 527
 528 void FLAC__lpc_compute_residual_from_qlp_coefficients_wide(const FLAC__int32 * flac_restrict data, uint32_t data_len, const FLAC__int32 * flac_restrict qlp_coeff, uint32_t order, int lp_quantization, FLAC__int32 * flac_restrict residual)
 529 #if defined(FLAC__OVERFLOW_DETECT) || !defined(FLAC__LPC_UNROLLED_FILTER_LOOPS)
 530 {
 531         uint32_t i, j;
 532         FLAC__int64 sum;
 533         const FLAC__int32 *history;
 534
 535 #ifdef FLAC__OVERFLOW_DETECT_VERBOSE
 536         fprintf(stderr,"FLAC__lpc_compute_residual_from_qlp_coefficients_wide: data_len=%d, order=%u, lpq=%d",data_len,order,lp_quantization);
 537         for(i=0;i<order;i++)
 538                 fprintf(stderr,", q[%u]=%d",i,qlp_coeff[i]);
 539         fprintf(stderr,"\n");
 540 #endif
 541         FLAC__ASSERT(order > 0);
 542
 543         for(i = 0; i < data_len; i++) {
 544                 sum = 0;
 545                 history = data;
 546                 for(j = 0; j < order; j++)
 547                         sum += (FLAC__int64)qlp_coeff[j] * (FLAC__int64)(*(--history));
 548                 if(FLAC__bitmath_silog2(sum >> lp_quantization) > 32) {
 549                         fprintf(stderr,"FLAC__lpc_compute_residual_from_qlp_coefficients_wide: OVERFLOW, i=%u, sum=%" PRId64 "\n", i, (sum >> lp_quantization));
 550                         break;
 551                 }
 552                 if(FLAC__bitmath_silog2((FLAC__int64)(*data) - (sum >> lp_quantization)) > 32) {
 553                         fprintf(stderr,"FLAC__lpc_compute_residual_from_qlp_coefficients_wide: OVERFLOW, i=%u, data=%d, sum=%" PRId64 ", residual=%" PRId64 "\n", i, *data, (int64_t)(sum >> lp_quantization), ((FLAC__int64)(*data) - (sum >> lp_quantization)));
 554                         break;
 555                 }
 556                 *(residual++) = *(data++) - (FLAC__int32)(sum >> lp_quantization);
 557         }
 558 }
 559 #else /* fully unrolled version for normal use */
 560 {
 561         int i;
 562         FLAC__int64 sum;
 563
 564         FLAC__ASSERT(order > 0);
 565         FLAC__ASSERT(order <= 32);
 566
 567         /*
 568          * We do unique versions up to 12th order since that's the subset limit.
 569          * Also they are roughly ordered to match frequency of occurrence to
 570          * minimize branching.
 571          */
 572         if(order <= 12) {
 573                 if(order > 8) {
 574                         if(order > 10) {
 575                                 if(order == 12) {
 576                                         for(i = 0; i < (int)data_len; i++) {
 577                                                 sum = 0;
 578                                                 sum += qlp_coeff[11] * (FLAC__int64)data[i-12];
 579                                                 sum += qlp_coeff[10] * (FLAC__int64)data[i-11];
 580                                                 sum += qlp_coeff[9] * (FLAC__int64)data[i-10];
 581                                                 sum += qlp_coeff[8] * (FLAC__int64)data[i-9];
 582                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
 583                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
 584                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
 585                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
 586                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
 587                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 588                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 589                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 590                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 591                                         }
 592                                 }
 593                                 else { /* order == 11 */
 594                                         for(i = 0; i < (int)data_len; i++) {
 595                                                 sum = 0;
 596                                                 sum += qlp_coeff[10] * (FLAC__int64)data[i-11];
 597                                                 sum += qlp_coeff[9] * (FLAC__int64)data[i-10];
 598                                                 sum += qlp_coeff[8] * (FLAC__int64)data[i-9];
 599                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
 600                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
 601                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
 602                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
 603                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
 604                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 605                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 606                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 607                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 608                                         }
 609                                 }
 610                         }
 611                         else {
 612                                 if(order == 10) {
 613                                         for(i = 0; i < (int)data_len; i++) {
 614                                                 sum = 0;
 615                                                 sum += qlp_coeff[9] * (FLAC__int64)data[i-10];
 616                                                 sum += qlp_coeff[8] * (FLAC__int64)data[i-9];
 617                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
 618                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
 619                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
 620                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
 621                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
 622                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 623                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 624                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 625                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 626                                         }
 627                                 }
 628                                 else { /* order == 9 */
 629                                         for(i = 0; i < (int)data_len; i++) {
 630                                                 sum = 0;
 631                                                 sum += qlp_coeff[8] * (FLAC__int64)data[i-9];
 632                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
 633                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
 634                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
 635                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
 636                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
 637                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 638                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 639                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 640                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 641                                         }
 642                                 }
 643                         }
 644                 }
 645                 else if(order > 4) {
 646                         if(order > 6) {
 647                                 if(order == 8) {
 648                                         for(i = 0; i < (int)data_len; i++) {
 649                                                 sum = 0;
 650                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
 651                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
 652                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
 653                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
 654                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
 655                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 656                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 657                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 658                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 659                                         }
 660                                 }
 661                                 else { /* order == 7 */
 662                                         for(i = 0; i < (int)data_len; i++) {
 663                                                 sum = 0;
 664                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
 665                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
 666                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
 667                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
 668                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 669                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 670                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 671                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 672                                         }
 673                                 }
 674                         }
 675                         else {
 676                                 if(order == 6) {
 677                                         for(i = 0; i < (int)data_len; i++) {
 678                                                 sum = 0;
 679                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
 680                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
 681                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
 682                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 683                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 684                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 685                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 686                                         }
 687                                 }
 688                                 else { /* order == 5 */
 689                                         for(i = 0; i < (int)data_len; i++) {
 690                                                 sum = 0;
 691                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
 692                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
 693                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 694                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 695                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 696                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 697                                         }
 698                                 }
 699                         }
 700                 }
 701                 else {
 702                         if(order > 2) {
 703                                 if(order == 4) {
 704                                         for(i = 0; i < (int)data_len; i++) {
 705                                                 sum = 0;
 706                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
 707                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 708                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 709                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 710                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 711                                         }
 712                                 }
 713                                 else { /* order == 3 */
 714                                         for(i = 0; i < (int)data_len; i++) {
 715                                                 sum = 0;
 716                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
 717                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 718                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 719                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 720                                         }
 721                                 }
 722                         }
 723                         else {
 724                                 if(order == 2) {
 725                                         for(i = 0; i < (int)data_len; i++) {
 726                                                 sum = 0;
 727                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
 728                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
 729                                                 residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 730                                         }
 731                                 }
 732                                 else { /* order == 1 */
 733                                         for(i = 0; i < (int)data_len; i++)
 734                                                 residual[i] = data[i] - (FLAC__int32)((qlp_coeff[0] * (FLAC__int64)data[i-1]) >> lp_quantization);
 735                                 }
 736                         }
 737                 }
 738         }
 739         else { /* order > 12 */
 740                 for(i = 0; i < (int)data_len; i++) {
 741                         sum = 0;
 742                         switch(order) {
 743                                 case 32: sum += qlp_coeff[31] * (FLAC__int64)data[i-32]; /* Falls through. */
 744                                 case 31: sum += qlp_coeff[30] * (FLAC__int64)data[i-31]; /* Falls through. */
 745                                 case 30: sum += qlp_coeff[29] * (FLAC__int64)data[i-30]; /* Falls through. */
 746                                 case 29: sum += qlp_coeff[28] * (FLAC__int64)data[i-29]; /* Falls through. */
 747                                 case 28: sum += qlp_coeff[27] * (FLAC__int64)data[i-28]; /* Falls through. */
 748                                 case 27: sum += qlp_coeff[26] * (FLAC__int64)data[i-27]; /* Falls through. */
 749                                 case 26: sum += qlp_coeff[25] * (FLAC__int64)data[i-26]; /* Falls through. */
 750                                 case 25: sum += qlp_coeff[24] * (FLAC__int64)data[i-25]; /* Falls through. */
 751                                 case 24: sum += qlp_coeff[23] * (FLAC__int64)data[i-24]; /* Falls through. */
 752                                 case 23: sum += qlp_coeff[22] * (FLAC__int64)data[i-23]; /* Falls through. */
 753                                 case 22: sum += qlp_coeff[21] * (FLAC__int64)data[i-22]; /* Falls through. */
 754                                 case 21: sum += qlp_coeff[20] * (FLAC__int64)data[i-21]; /* Falls through. */
 755                                 case 20: sum += qlp_coeff[19] * (FLAC__int64)data[i-20]; /* Falls through. */
 756                                 case 19: sum += qlp_coeff[18] * (FLAC__int64)data[i-19]; /* Falls through. */
 757                                 case 18: sum += qlp_coeff[17] * (FLAC__int64)data[i-18]; /* Falls through. */
 758                                 case 17: sum += qlp_coeff[16] * (FLAC__int64)data[i-17]; /* Falls through. */
 759                                 case 16: sum += qlp_coeff[15] * (FLAC__int64)data[i-16]; /* Falls through. */
 760                                 case 15: sum += qlp_coeff[14] * (FLAC__int64)data[i-15]; /* Falls through. */
 761                                 case 14: sum += qlp_coeff[13] * (FLAC__int64)data[i-14]; /* Falls through. */
 762                                 case 13: sum += qlp_coeff[12] * (FLAC__int64)data[i-13];
 763                                          sum += qlp_coeff[11] * (FLAC__int64)data[i-12];
 764                                          sum += qlp_coeff[10] * (FLAC__int64)data[i-11];
 765                                          sum += qlp_coeff[ 9] * (FLAC__int64)data[i-10];
 766                                          sum += qlp_coeff[ 8] * (FLAC__int64)data[i- 9];
 767                                          sum += qlp_coeff[ 7] * (FLAC__int64)data[i- 8];
 768                                          sum += qlp_coeff[ 6] * (FLAC__int64)data[i- 7];
 769                                          sum += qlp_coeff[ 5] * (FLAC__int64)data[i- 6];
 770                                          sum += qlp_coeff[ 4] * (FLAC__int64)data[i- 5];
 771                                          sum += qlp_coeff[ 3] * (FLAC__int64)data[i- 4];
 772                                          sum += qlp_coeff[ 2] * (FLAC__int64)data[i- 3];
 773                                          sum += qlp_coeff[ 1] * (FLAC__int64)data[i- 2];
 774                                          sum += qlp_coeff[ 0] * (FLAC__int64)data[i- 1];
 775                         }
 776                         residual[i] = data[i] - (FLAC__int32)(sum >> lp_quantization);
 777                 }
 778         }
 779 }
 780 #endif
 781
 782 #endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */
 783
 784 void FLAC__lpc_restore_signal(const FLAC__int32 * flac_restrict residual, uint32_t data_len, const FLAC__int32 * flac_restrict qlp_coeff, uint32_t order, int lp_quantization, FLAC__int32 * flac_restrict data)
 785 #if defined(FLAC__OVERFLOW_DETECT) || !defined(FLAC__LPC_UNROLLED_FILTER_LOOPS)
 786 {
 787         FLAC__int64 sumo;
 788         uint32_t i, j;
 789         FLAC__int32 sum;
 790         const FLAC__int32 *r = residual, *history;
 791
 792 #ifdef FLAC__OVERFLOW_DETECT_VERBOSE
 793         fprintf(stderr,"FLAC__lpc_restore_signal: data_len=%d, order=%u, lpq=%d",data_len,order,lp_quantization);
 794         for(i=0;i<order;i++)
 795                 fprintf(stderr,", q[%u]=%d",i,qlp_coeff[i]);
 796         fprintf(stderr,"\n");
 797 #endif
 798         FLAC__ASSERT(order > 0);
 799
 800         for(i = 0; i < data_len; i++) {
 801                 sumo = 0;
 802                 sum = 0;
 803                 history = data;
 804                 for(j = 0; j < order; j++) {
 805                         sum += qlp_coeff[j] * (*(--history));
 806                         sumo += (FLAC__int64)qlp_coeff[j] * (FLAC__int64)(*history);
 807                         if(sumo > 2147483647ll || sumo < -2147483648ll)
 808                                 fprintf(stderr,"FLAC__lpc_restore_signal: OVERFLOW, i=%u, j=%u, c=%d, d=%d, sumo=%" PRId64 "\n",i,j,qlp_coeff[j],*history,sumo);
 809                 }
 810                 *(data++) = *(r++) + (sum >> lp_quantization);
 811         }
 812
 813         /* Here's a slower but clearer version:
 814         for(i = 0; i < data_len; i++) {
 815                 sum = 0;
 816                 for(j = 0; j < order; j++)
 817                         sum += qlp_coeff[j] * data[i-j-1];
 818                 data[i] = residual[i] + (sum >> lp_quantization);
 819         }
 820         */
 821 }
 822 #else /* fully unrolled version for normal use */
 823 {
 824         int i;
 825         FLAC__int32 sum;
 826
 827         FLAC__ASSERT(order > 0);
 828         FLAC__ASSERT(order <= 32);
 829
 830         /*
 831          * We do unique versions up to 12th order since that's the subset limit.
 832          * Also they are roughly ordered to match frequency of occurrence to
 833          * minimize branching.
 834          */
 835         if(order <= 12) {
 836                 if(order > 8) {
 837                         if(order > 10) {
 838                                 if(order == 12) {
 839                                         for(i = 0; i < (int)data_len; i++) {
 840                                                 sum = 0;
 841                                                 sum += qlp_coeff[11] * data[i-12];
 842                                                 sum += qlp_coeff[10] * data[i-11];
 843                                                 sum += qlp_coeff[9] * data[i-10];
 844                                                 sum += qlp_coeff[8] * data[i-9];
 845                                                 sum += qlp_coeff[7] * data[i-8];
 846                                                 sum += qlp_coeff[6] * data[i-7];
 847                                                 sum += qlp_coeff[5] * data[i-6];
 848                                                 sum += qlp_coeff[4] * data[i-5];
 849                                                 sum += qlp_coeff[3] * data[i-4];
 850                                                 sum += qlp_coeff[2] * data[i-3];
 851                                                 sum += qlp_coeff[1] * data[i-2];
 852                                                 sum += qlp_coeff[0] * data[i-1];
 853                                                 data[i] = residual[i] + (sum >> lp_quantization);
 854                                         }
 855                                 }
 856                                 else { /* order == 11 */
 857                                         for(i = 0; i < (int)data_len; i++) {
 858                                                 sum = 0;
 859                                                 sum += qlp_coeff[10] * data[i-11];
 860                                                 sum += qlp_coeff[9] * data[i-10];
 861                                                 sum += qlp_coeff[8] * data[i-9];
 862                                                 sum += qlp_coeff[7] * data[i-8];
 863                                                 sum += qlp_coeff[6] * data[i-7];
 864                                                 sum += qlp_coeff[5] * data[i-6];
 865                                                 sum += qlp_coeff[4] * data[i-5];
 866                                                 sum += qlp_coeff[3] * data[i-4];
 867                                                 sum += qlp_coeff[2] * data[i-3];
 868                                                 sum += qlp_coeff[1] * data[i-2];
 869                                                 sum += qlp_coeff[0] * data[i-1];
 870                                                 data[i] = residual[i] + (sum >> lp_quantization);
 871                                         }
 872                                 }
 873                         }
 874                         else {
 875                                 if(order == 10) {
 876                                         for(i = 0; i < (int)data_len; i++) {
 877                                                 sum = 0;
 878                                                 sum += qlp_coeff[9] * data[i-10];
 879                                                 sum += qlp_coeff[8] * data[i-9];
 880                                                 sum += qlp_coeff[7] * data[i-8];
 881                                                 sum += qlp_coeff[6] * data[i-7];
 882                                                 sum += qlp_coeff[5] * data[i-6];
 883                                                 sum += qlp_coeff[4] * data[i-5];
 884                                                 sum += qlp_coeff[3] * data[i-4];
 885                                                 sum += qlp_coeff[2] * data[i-3];
 886                                                 sum += qlp_coeff[1] * data[i-2];
 887                                                 sum += qlp_coeff[0] * data[i-1];
 888                                                 data[i] = residual[i] + (sum >> lp_quantization);
 889                                         }
 890                                 }
 891                                 else { /* order == 9 */
 892                                         for(i = 0; i < (int)data_len; i++) {
 893                                                 sum = 0;
 894                                                 sum += qlp_coeff[8] * data[i-9];
 895                                                 sum += qlp_coeff[7] * data[i-8];
 896                                                 sum += qlp_coeff[6] * data[i-7];
 897                                                 sum += qlp_coeff[5] * data[i-6];
 898                                                 sum += qlp_coeff[4] * data[i-5];
 899                                                 sum += qlp_coeff[3] * data[i-4];
 900                                                 sum += qlp_coeff[2] * data[i-3];
 901                                                 sum += qlp_coeff[1] * data[i-2];
 902                                                 sum += qlp_coeff[0] * data[i-1];
 903                                                 data[i] = residual[i] + (sum >> lp_quantization);
 904                                         }
 905                                 }
 906                         }
 907                 }
 908                 else if(order > 4) {
 909                         if(order > 6) {
 910                                 if(order == 8) {
 911                                         for(i = 0; i < (int)data_len; i++) {
 912                                                 sum = 0;
 913                                                 sum += qlp_coeff[7] * data[i-8];
 914                                                 sum += qlp_coeff[6] * data[i-7];
 915                                                 sum += qlp_coeff[5] * data[i-6];
 916                                                 sum += qlp_coeff[4] * data[i-5];
 917                                                 sum += qlp_coeff[3] * data[i-4];
 918                                                 sum += qlp_coeff[2] * data[i-3];
 919                                                 sum += qlp_coeff[1] * data[i-2];
 920                                                 sum += qlp_coeff[0] * data[i-1];
 921                                                 data[i] = residual[i] + (sum >> lp_quantization);
 922                                         }
 923                                 }
 924                                 else { /* order == 7 */
 925                                         for(i = 0; i < (int)data_len; i++) {
 926                                                 sum = 0;
 927                                                 sum += qlp_coeff[6] * data[i-7];
 928                                                 sum += qlp_coeff[5] * data[i-6];
 929                                                 sum += qlp_coeff[4] * data[i-5];
 930                                                 sum += qlp_coeff[3] * data[i-4];
 931                                                 sum += qlp_coeff[2] * data[i-3];
 932                                                 sum += qlp_coeff[1] * data[i-2];
 933                                                 sum += qlp_coeff[0] * data[i-1];
 934                                                 data[i] = residual[i] + (sum >> lp_quantization);
 935                                         }
 936                                 }
 937                         }
 938                         else {
 939                                 if(order == 6) {
 940                                         for(i = 0; i < (int)data_len; i++) {
 941                                                 sum = 0;
 942                                                 sum += qlp_coeff[5] * data[i-6];
 943                                                 sum += qlp_coeff[4] * data[i-5];
 944                                                 sum += qlp_coeff[3] * data[i-4];
 945                                                 sum += qlp_coeff[2] * data[i-3];
 946                                                 sum += qlp_coeff[1] * data[i-2];
 947                                                 sum += qlp_coeff[0] * data[i-1];
 948                                                 data[i] = residual[i] + (sum >> lp_quantization);
 949                                         }
 950                                 }
 951                                 else { /* order == 5 */
 952                                         for(i = 0; i < (int)data_len; i++) {
 953                                                 sum = 0;
 954                                                 sum += qlp_coeff[4] * data[i-5];
 955                                                 sum += qlp_coeff[3] * data[i-4];
 956                                                 sum += qlp_coeff[2] * data[i-3];
 957                                                 sum += qlp_coeff[1] * data[i-2];
 958                                                 sum += qlp_coeff[0] * data[i-1];
 959                                                 data[i] = residual[i] + (sum >> lp_quantization);
 960                                         }
 961                                 }
 962                         }
 963                 }
 964                 else {
 965                         if(order > 2) {
 966                                 if(order == 4) {
 967                                         for(i = 0; i < (int)data_len; i++) {
 968                                                 sum = 0;
 969                                                 sum += qlp_coeff[3] * data[i-4];
 970                                                 sum += qlp_coeff[2] * data[i-3];
 971                                                 sum += qlp_coeff[1] * data[i-2];
 972                                                 sum += qlp_coeff[0] * data[i-1];
 973                                                 data[i] = residual[i] + (sum >> lp_quantization);
 974                                         }
 975                                 }
 976                                 else { /* order == 3 */
 977                                         for(i = 0; i < (int)data_len; i++) {
 978                                                 sum = 0;
 979                                                 sum += qlp_coeff[2] * data[i-3];
 980                                                 sum += qlp_coeff[1] * data[i-2];
 981                                                 sum += qlp_coeff[0] * data[i-1];
 982                                                 data[i] = residual[i] + (sum >> lp_quantization);
 983                                         }
 984                                 }
 985                         }
 986                         else {
 987                                 if(order == 2) {
 988                                         for(i = 0; i < (int)data_len; i++) {
 989                                                 sum = 0;
 990                                                 sum += qlp_coeff[1] * data[i-2];
 991                                                 sum += qlp_coeff[0] * data[i-1];
 992                                                 data[i] = residual[i] + (sum >> lp_quantization);
 993                                         }
 994                                 }
 995                                 else { /* order == 1 */
 996                                         for(i = 0; i < (int)data_len; i++)
 997                                                 data[i] = residual[i] + ((qlp_coeff[0] * data[i-1]) >> lp_quantization);
 998                                 }
 999                         }
1000                 }
1001         }
1002         else { /* order > 12 */
1003                 for(i = 0; i < (int)data_len; i++) {
1004                         sum = 0;
1005                         switch(order) {
1006                                 case 32: sum += qlp_coeff[31] * data[i-32]; /* Falls through. */
1007                                 case 31: sum += qlp_coeff[30] * data[i-31]; /* Falls through. */
1008                                 case 30: sum += qlp_coeff[29] * data[i-30]; /* Falls through. */
1009                                 case 29: sum += qlp_coeff[28] * data[i-29]; /* Falls through. */
1010                                 case 28: sum += qlp_coeff[27] * data[i-28]; /* Falls through. */
1011                                 case 27: sum += qlp_coeff[26] * data[i-27]; /* Falls through. */
1012                                 case 26: sum += qlp_coeff[25] * data[i-26]; /* Falls through. */
1013                                 case 25: sum += qlp_coeff[24] * data[i-25]; /* Falls through. */
1014                                 case 24: sum += qlp_coeff[23] * data[i-24]; /* Falls through. */
1015                                 case 23: sum += qlp_coeff[22] * data[i-23]; /* Falls through. */
1016                                 case 22: sum += qlp_coeff[21] * data[i-22]; /* Falls through. */
1017                                 case 21: sum += qlp_coeff[20] * data[i-21]; /* Falls through. */
1018                                 case 20: sum += qlp_coeff[19] * data[i-20]; /* Falls through. */
1019                                 case 19: sum += qlp_coeff[18] * data[i-19]; /* Falls through. */
1020                                 case 18: sum += qlp_coeff[17] * data[i-18]; /* Falls through. */
1021                                 case 17: sum += qlp_coeff[16] * data[i-17]; /* Falls through. */
1022                                 case 16: sum += qlp_coeff[15] * data[i-16]; /* Falls through. */
1023                                 case 15: sum += qlp_coeff[14] * data[i-15]; /* Falls through. */
1024                                 case 14: sum += qlp_coeff[13] * data[i-14]; /* Falls through. */
1025                                 case 13: sum += qlp_coeff[12] * data[i-13];
1026                                          sum += qlp_coeff[11] * data[i-12];
1027                                          sum += qlp_coeff[10] * data[i-11];
1028                                          sum += qlp_coeff[ 9] * data[i-10];
1029                                          sum += qlp_coeff[ 8] * data[i- 9];
1030                                          sum += qlp_coeff[ 7] * data[i- 8];
1031                                          sum += qlp_coeff[ 6] * data[i- 7];
1032                                          sum += qlp_coeff[ 5] * data[i- 6];
1033                                          sum += qlp_coeff[ 4] * data[i- 5];
1034                                          sum += qlp_coeff[ 3] * data[i- 4];
1035                                          sum += qlp_coeff[ 2] * data[i- 3];
1036                                          sum += qlp_coeff[ 1] * data[i- 2];
1037                                          sum += qlp_coeff[ 0] * data[i- 1];
1038                         }
1039                         data[i] = residual[i] + (sum >> lp_quantization);
1040                 }
1041         }
1042 }
1043 #endif
1044
1045 void FLAC__lpc_restore_signal_wide(const FLAC__int32 * flac_restrict residual, uint32_t data_len, const FLAC__int32 * flac_restrict qlp_coeff, uint32_t order, int lp_quantization, FLAC__int32 * flac_restrict data)
1046 #if defined(FLAC__OVERFLOW_DETECT) || !defined(FLAC__LPC_UNROLLED_FILTER_LOOPS)
1047 {
1048         uint32_t i, j;
1049         FLAC__int64 sum;
1050         const FLAC__int32 *r = residual, *history;
1051
1052 #ifdef FLAC__OVERFLOW_DETECT_VERBOSE
1053         fprintf(stderr,"FLAC__lpc_restore_signal_wide: data_len=%d, order=%u, lpq=%d",data_len,order,lp_quantization);
1054         for(i=0;i<order;i++)
1055                 fprintf(stderr,", q[%u]=%d",i,qlp_coeff[i]);
1056         fprintf(stderr,"\n");
1057 #endif
1058         FLAC__ASSERT(order > 0);
1059
1060         for(i = 0; i < data_len; i++) {
1061                 sum = 0;
1062                 history = data;
1063                 for(j = 0; j < order; j++)
1064                         sum += (FLAC__int64)qlp_coeff[j] * (FLAC__int64)(*(--history));
1065                 if(FLAC__bitmath_silog2(sum >> lp_quantization) > 32) {
1066                         fprintf(stderr,"FLAC__lpc_restore_signal_wide: OVERFLOW, i=%u, sum=%" PRId64 "\n", i, (sum >> lp_quantization));
1067                         break;
1068                 }
1069                 if(FLAC__bitmath_silog2((FLAC__int64)(*r) + (sum >> lp_quantization)) > 32) {
1070                         fprintf(stderr,"FLAC__lpc_restore_signal_wide: OVERFLOW, i=%u, residual=%d, sum=%" PRId64 ", data=%" PRId64 "\n", i, *r, (sum >> lp_quantization), ((FLAC__int64)(*r) + (sum >> lp_quantization)));
1071                         break;
1072                 }
1073                 *(data++) = *(r++) + (FLAC__int32)(sum >> lp_quantization);
1074         }
1075 }
1076 #else /* fully unrolled version for normal use */
1077 {
1078         int i;
1079         FLAC__int64 sum;
1080
1081         FLAC__ASSERT(order > 0);
1082         FLAC__ASSERT(order <= 32);
1083
1084         /*
1085          * We do unique versions up to 12th order since that's the subset limit.
1086          * Also they are roughly ordered to match frequency of occurrence to
1087          * minimize branching.
1088          */
1089         if(order <= 12) {
1090                 if(order > 8) {
1091                         if(order > 10) {
1092                                 if(order == 12) {
1093                                         for(i = 0; i < (int)data_len; i++) {
1094                                                 sum = 0;
1095                                                 sum += qlp_coeff[11] * (FLAC__int64)data[i-12];
1096                                                 sum += qlp_coeff[10] * (FLAC__int64)data[i-11];
1097                                                 sum += qlp_coeff[9] * (FLAC__int64)data[i-10];
1098                                                 sum += qlp_coeff[8] * (FLAC__int64)data[i-9];
1099                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
1100                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
1101                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
1102                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
1103                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
1104                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1105                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1106                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1107                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1108                                         }
1109                                 }
1110                                 else { /* order == 11 */
1111                                         for(i = 0; i < (int)data_len; i++) {
1112                                                 sum = 0;
1113                                                 sum += qlp_coeff[10] * (FLAC__int64)data[i-11];
1114                                                 sum += qlp_coeff[9] * (FLAC__int64)data[i-10];
1115                                                 sum += qlp_coeff[8] * (FLAC__int64)data[i-9];
1116                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
1117                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
1118                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
1119                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
1120                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
1121                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1122                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1123                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1124                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1125                                         }
1126                                 }
1127                         }
1128                         else {
1129                                 if(order == 10) {
1130                                         for(i = 0; i < (int)data_len; i++) {
1131                                                 sum = 0;
1132                                                 sum += qlp_coeff[9] * (FLAC__int64)data[i-10];
1133                                                 sum += qlp_coeff[8] * (FLAC__int64)data[i-9];
1134                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
1135                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
1136                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
1137                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
1138                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
1139                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1140                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1141                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1142                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1143                                         }
1144                                 }
1145                                 else { /* order == 9 */
1146                                         for(i = 0; i < (int)data_len; i++) {
1147                                                 sum = 0;
1148                                                 sum += qlp_coeff[8] * (FLAC__int64)data[i-9];
1149                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
1150                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
1151                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
1152                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
1153                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
1154                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1155                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1156                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1157                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1158                                         }
1159                                 }
1160                         }
1161                 }
1162                 else if(order > 4) {
1163                         if(order > 6) {
1164                                 if(order == 8) {
1165                                         for(i = 0; i < (int)data_len; i++) {
1166                                                 sum = 0;
1167                                                 sum += qlp_coeff[7] * (FLAC__int64)data[i-8];
1168                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
1169                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
1170                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
1171                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
1172                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1173                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1174                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1175                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1176                                         }
1177                                 }
1178                                 else { /* order == 7 */
1179                                         for(i = 0; i < (int)data_len; i++) {
1180                                                 sum = 0;
1181                                                 sum += qlp_coeff[6] * (FLAC__int64)data[i-7];
1182                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
1183                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
1184                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
1185                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1186                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1187                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1188                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1189                                         }
1190                                 }
1191                         }
1192                         else {
1193                                 if(order == 6) {
1194                                         for(i = 0; i < (int)data_len; i++) {
1195                                                 sum = 0;
1196                                                 sum += qlp_coeff[5] * (FLAC__int64)data[i-6];
1197                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
1198                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
1199                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1200                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1201                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1202                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1203                                         }
1204                                 }
1205                                 else { /* order == 5 */
1206                                         for(i = 0; i < (int)data_len; i++) {
1207                                                 sum = 0;
1208                                                 sum += qlp_coeff[4] * (FLAC__int64)data[i-5];
1209                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
1210                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1211                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1212                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1213                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1214                                         }
1215                                 }
1216                         }
1217                 }
1218                 else {
1219                         if(order > 2) {
1220                                 if(order == 4) {
1221                                         for(i = 0; i < (int)data_len; i++) {
1222                                                 sum = 0;
1223                                                 sum += qlp_coeff[3] * (FLAC__int64)data[i-4];
1224                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1225                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1226                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1227                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1228                                         }
1229                                 }
1230                                 else { /* order == 3 */
1231                                         for(i = 0; i < (int)data_len; i++) {
1232                                                 sum = 0;
1233                                                 sum += qlp_coeff[2] * (FLAC__int64)data[i-3];
1234                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1235                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1236                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1237                                         }
1238                                 }
1239                         }
1240                         else {
1241                                 if(order == 2) {
1242                                         for(i = 0; i < (int)data_len; i++) {
1243                                                 sum = 0;
1244                                                 sum += qlp_coeff[1] * (FLAC__int64)data[i-2];
1245                                                 sum += qlp_coeff[0] * (FLAC__int64)data[i-1];
1246                                                 data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1247                                         }
1248                                 }
1249                                 else { /* order == 1 */
1250                                         for(i = 0; i < (int)data_len; i++)
1251                                                 data[i] = residual[i] + (FLAC__int32)((qlp_coeff[0] * (FLAC__int64)data[i-1]) >> lp_quantization);
1252                                 }
1253                         }
1254                 }
1255         }
1256         else { /* order > 12 */
1257                 for(i = 0; i < (int)data_len; i++) {
1258                         sum = 0;
1259                         switch(order) {
1260                                 case 32: sum += qlp_coeff[31] * (FLAC__int64)data[i-32]; /* Falls through. */
1261                                 case 31: sum += qlp_coeff[30] * (FLAC__int64)data[i-31]; /* Falls through. */
1262                                 case 30: sum += qlp_coeff[29] * (FLAC__int64)data[i-30]; /* Falls through. */
1263                                 case 29: sum += qlp_coeff[28] * (FLAC__int64)data[i-29]; /* Falls through. */
1264                                 case 28: sum += qlp_coeff[27] * (FLAC__int64)data[i-28]; /* Falls through. */
1265                                 case 27: sum += qlp_coeff[26] * (FLAC__int64)data[i-27]; /* Falls through. */
1266                                 case 26: sum += qlp_coeff[25] * (FLAC__int64)data[i-26]; /* Falls through. */
1267                                 case 25: sum += qlp_coeff[24] * (FLAC__int64)data[i-25]; /* Falls through. */
1268                                 case 24: sum += qlp_coeff[23] * (FLAC__int64)data[i-24]; /* Falls through. */
1269                                 case 23: sum += qlp_coeff[22] * (FLAC__int64)data[i-23]; /* Falls through. */
1270                                 case 22: sum += qlp_coeff[21] * (FLAC__int64)data[i-22]; /* Falls through. */
1271                                 case 21: sum += qlp_coeff[20] * (FLAC__int64)data[i-21]; /* Falls through. */
1272                                 case 20: sum += qlp_coeff[19] * (FLAC__int64)data[i-20]; /* Falls through. */
1273                                 case 19: sum += qlp_coeff[18] * (FLAC__int64)data[i-19]; /* Falls through. */
1274                                 case 18: sum += qlp_coeff[17] * (FLAC__int64)data[i-18]; /* Falls through. */
1275                                 case 17: sum += qlp_coeff[16] * (FLAC__int64)data[i-17]; /* Falls through. */
1276                                 case 16: sum += qlp_coeff[15] * (FLAC__int64)data[i-16]; /* Falls through. */
1277                                 case 15: sum += qlp_coeff[14] * (FLAC__int64)data[i-15]; /* Falls through. */
1278                                 case 14: sum += qlp_coeff[13] * (FLAC__int64)data[i-14]; /* Falls through. */
1279                                 case 13: sum += qlp_coeff[12] * (FLAC__int64)data[i-13];
1280                                          sum += qlp_coeff[11] * (FLAC__int64)data[i-12];
1281                                          sum += qlp_coeff[10] * (FLAC__int64)data[i-11];
1282                                          sum += qlp_coeff[ 9] * (FLAC__int64)data[i-10];
1283                                          sum += qlp_coeff[ 8] * (FLAC__int64)data[i- 9];
1284                                          sum += qlp_coeff[ 7] * (FLAC__int64)data[i- 8];
1285                                          sum += qlp_coeff[ 6] * (FLAC__int64)data[i- 7];
1286                                          sum += qlp_coeff[ 5] * (FLAC__int64)data[i- 6];
1287                                          sum += qlp_coeff[ 4] * (FLAC__int64)data[i- 5];
1288                                          sum += qlp_coeff[ 3] * (FLAC__int64)data[i- 4];
1289                                          sum += qlp_coeff[ 2] * (FLAC__int64)data[i- 3];
1290                                          sum += qlp_coeff[ 1] * (FLAC__int64)data[i- 2];
1291                                          sum += qlp_coeff[ 0] * (FLAC__int64)data[i- 1];
1292                         }
1293                         data[i] = residual[i] + (FLAC__int32)(sum >> lp_quantization);
1294                 }
1295         }
1296 }
1297 #endif
1298
1299 #if defined(_MSC_VER)
1300 #pragma warning ( default : 4028 )
1301 #endif
1302
1303 #ifndef FLAC__INTEGER_ONLY_LIBRARY
1304
1305 double FLAC__lpc_compute_expected_bits_per_residual_sample(double lpc_error, uint32_t total_samples)
1306 {
1307         double error_scale;
1308
1309         FLAC__ASSERT(total_samples > 0);
1310
1311         error_scale = 0.5 / (double)total_samples;
1312
1313         return FLAC__lpc_compute_expected_bits_per_residual_sample_with_error_scale(lpc_error, error_scale);
1314 }
1315
1316 double FLAC__lpc_compute_expected_bits_per_residual_sample_with_error_scale(double lpc_error, double error_scale)
1317 {
1318         if(lpc_error > 0.0) {
1319                 double bps = (double)0.5 * log(error_scale * lpc_error) / M_LN2;
1320                 if(bps >= 0.0)
1321                         return bps;
1322                 else
1323                         return 0.0;
1324         }
1325         else if(lpc_error < 0.0) { /* error should not be negative but can happen due to inadequate floating-point resolution */
1326                 return 1e32;
1327         }
1328         else {
1329                 return 0.0;
1330         }
1331 }
1332
1333 uint32_t FLAC__lpc_compute_best_order(const double lpc_error[], uint32_t max_order, uint32_t total_samples, uint32_t overhead_bits_per_order)
1334 {
1335         uint32_t order, indx, best_index; /* 'index' the index into lpc_error; index==order-1 since lpc_error[0] is for order==1, lpc_error[1] is for order==2, etc */
1336         double bits, best_bits, error_scale;
1337
1338         FLAC__ASSERT(max_order > 0);
1339         FLAC__ASSERT(total_samples > 0);
1340
1341         error_scale = 0.5 / (double)total_samples;
1342
1343         best_index = 0;
1344         best_bits = (uint32_t)(-1);
1345
1346         for(indx = 0, order = 1; indx < max_order; indx++, order++) {
1347                 bits = FLAC__lpc_compute_expected_bits_per_residual_sample_with_error_scale(lpc_error[indx], error_scale) * (double)(total_samples - order) + (double)(order * overhead_bits_per_order);
1348                 if(bits < best_bits) {
1349                         best_index = indx;
1350                         best_bits = bits;
1351                 }
1352         }
1353
1354         return best_index+1; /* +1 since indx of lpc_error[] is order-1 */
1355 }
1356
1357 #endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */