1 /* ------------------------------------------------------------------ 2 * Copyright (C) 1998-2009 PacketVideo 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either 13 * express or implied. 14 * See the License for the specific language governing permissions 15 * and limitations under the License. 16 * ------------------------------------------------------------------- 17 */ 18 /**************************************************************************************** 19 Portions of this file are derived from the following 3GPP standard: 20 21 3GPP TS 26.073 22 ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec 23 Available from http://www.3gpp.org 24 25 (C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC) 26 Permission to distribute, modify and use this file under the standard license 27 terms listed above has been obtained from the copyright holder. 28 ****************************************************************************************/ 29 /* 30 ------------------------------------------------------------------------------ 31 32 33 34 Pathname: ./audio/gsm-amr/c/src/levinson.c 35 Funtions: Levinson_init 36 Levinson_reset 37 Levinson_exit 38 Levinson 39 40 ------------------------------------------------------------------------------ 41 MODULE DESCRIPTION 42 43 This file contains the function the implements the Levinson-Durbin algorithm 44 using double-precision arithmetic. This file also includes functions to 45 initialize, allocate, and deallocate memory used by the Levinson function. 46 47 ------------------------------------------------------------------------------ 48 */ 49 50 /*---------------------------------------------------------------------------- 51 ; INCLUDES 52 ----------------------------------------------------------------------------*/ 53 #include <stdlib.h> 54 #include <string.h> 55 56 #include "levinson.h" 57 #include "basicop_malloc.h" 58 #include "basic_op.h" 59 #include "div_32.h" 60 #include "cnst.h" 61 62 /*---------------------------------------------------------------------------- 63 ; MACROS 64 ; Define module specific macros here 65 ----------------------------------------------------------------------------*/ 66 67 /*---------------------------------------------------------------------------- 68 ; DEFINES 69 ; Include all pre-processor statements here. Include conditional 70 ; compile variables also. 71 ----------------------------------------------------------------------------*/ 72 73 /*---------------------------------------------------------------------------- 74 ; LOCAL FUNCTION DEFINITIONS 75 ; Function Prototype declaration 76 ----------------------------------------------------------------------------*/ 77 78 /*---------------------------------------------------------------------------- 79 ; LOCAL VARIABLE DEFINITIONS 80 ; Variable declaration - defined here and used outside this module 81 ----------------------------------------------------------------------------*/ 82 83 84 /* 85 ------------------------------------------------------------------------------ 86 FUNCTION NAME: Levinson_init 87 ------------------------------------------------------------------------------ 88 INPUT AND OUTPUT DEFINITIONS 89 90 Inputs: 91 state = pointer to an array of pointers to structures of type 92 LevinsonState 93 94 Outputs: 95 pointer pointed to by state points to the newly allocated memory to 96 be used by Levinson function 97 98 Returns: 99 return_value = 0, if initialization was successful; -1, otherwise (int) 100 101 Global Variables Used: 102 None 103 104 Local Variables Needed: 105 None 106 107 ------------------------------------------------------------------------------ 108 FUNCTION DESCRIPTION 109 110 This function allocates and initializes the state memory used by the 111 Levinson function. 112 113 ------------------------------------------------------------------------------ 114 REQUIREMENTS 115 116 None 117 118 ------------------------------------------------------------------------------ 119 REFERENCES 120 121 levinson.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 122 123 ------------------------------------------------------------------------------ 124 PSEUDO-CODE 125 126 int Levinson_init (LevinsonState **state) 127 { 128 LevinsonState* s; 129 130 if (state == (LevinsonState **) NULL){ 131 //fprint(stderr, "Levinson_init: invalid parameter\n"); 132 return -1; 133 } 134 *state = NULL; 135 136 // allocate memory 137 if ((s= (LevinsonState *) malloc(sizeof(LevinsonState))) == NULL){ 138 //fprint(stderr, "Levinson_init: can not malloc state structure\n"); 139 return -1; 140 } 141 142 Levinson_reset(s); 143 *state = s; 144 145 return 0; 146 } 147 148 ------------------------------------------------------------------------------ 149 RESOURCES USED [optional] 150 151 When the code is written for a specific target processor the 152 the resources used should be documented below. 153 154 HEAP MEMORY USED: x bytes 155 156 STACK MEMORY USED: x bytes 157 158 CLOCK CYCLES: (cycle count equation for this function) + (variable 159 used to represent cycle count for each subroutine 160 called) 161 where: (cycle count variable) = cycle count for [subroutine 162 name] 163 164 ------------------------------------------------------------------------------ 165 CAUTION [optional] 166 [State any special notes, constraints or cautions for users of this function] 167 168 ------------------------------------------------------------------------------ 169 */ 170 171 Word16 Levinson_init(LevinsonState **state) 172 { 173 LevinsonState* s; 174 175 if (state == (LevinsonState **) NULL) 176 { 177 /* fprint(stderr, "Levinson_init: invalid parameter\n"); */ 178 return(-1); 179 } 180 *state = NULL; 181 182 /* allocate memory */ 183 if ((s = (LevinsonState *) malloc(sizeof(LevinsonState))) == NULL) 184 { 185 /* fprint(stderr, "Levinson_init: 186 can not malloc state structure\n"); */ 187 return(-1); 188 } 189 190 Levinson_reset(s); 191 *state = s; 192 193 return(0); 194 } 195 196 /****************************************************************************/ 197 198 199 /* 200 ------------------------------------------------------------------------------ 201 FUNCTION NAME: Levinson_reset 202 ------------------------------------------------------------------------------ 203 INPUT AND OUTPUT DEFINITIONS 204 205 Inputs: 206 state = pointer to structures of type LevinsonState 207 208 Outputs: 209 old_A field of structure pointed to by state is initialized to 4096 210 (first location) and the rest to zeros 211 212 Returns: 213 return_value = 0, if reset was successful; -1, otherwise (int) 214 215 Global Variables Used: 216 None 217 218 Local Variables Needed: 219 None 220 221 ------------------------------------------------------------------------------ 222 FUNCTION DESCRIPTION 223 224 This function initializes the state memory used by the Levinson function to 225 zero. 226 227 ------------------------------------------------------------------------------ 228 REQUIREMENTS 229 230 None 231 232 ------------------------------------------------------------------------------ 233 REFERENCES 234 235 levinson.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 236 237 ------------------------------------------------------------------------------ 238 PSEUDO-CODE 239 240 int Levinson_reset (LevinsonState *state) 241 { 242 Word16 i; 243 244 if (state == (LevinsonState *) NULL){ 245 fprint(stderr, "Levinson_reset: invalid parameter\n"); 246 return -1; 247 } 248 249 state->old_A[0] = 4096; 250 for(i = 1; i < M + 1; i++) 251 state->old_A[i] = 0; 252 253 return 0; 254 } 255 256 ------------------------------------------------------------------------------ 257 RESOURCES USED [optional] 258 259 When the code is written for a specific target processor the 260 the resources used should be documented below. 261 262 HEAP MEMORY USED: x bytes 263 264 STACK MEMORY USED: x bytes 265 266 CLOCK CYCLES: (cycle count equation for this function) + (variable 267 used to represent cycle count for each subroutine 268 called) 269 where: (cycle count variable) = cycle count for [subroutine 270 name] 271 272 ------------------------------------------------------------------------------ 273 CAUTION [optional] 274 [State any special notes, constraints or cautions for users of this function] 275 276 ------------------------------------------------------------------------------ 277 */ 278 279 Word16 Levinson_reset(LevinsonState *state) 280 { 281 Word16 i; 282 283 if (state == (LevinsonState *) NULL) 284 { 285 /* fprint(stderr, "Levinson_reset: invalid parameter\n"); */ 286 return(-1); 287 } 288 289 state->old_A[0] = 4096; 290 for (i = 1; i < M + 1; i++) 291 { 292 state->old_A[i] = 0; 293 } 294 295 return(0); 296 } 297 298 /****************************************************************************/ 299 300 /* 301 ------------------------------------------------------------------------------ 302 FUNCTION NAME: Levinson_exit 303 ------------------------------------------------------------------------------ 304 INPUT AND OUTPUT DEFINITIONS 305 306 Inputs: 307 state = pointer to an array of pointers to structures of type 308 LevinsonState 309 310 Outputs: 311 pointer pointed to by state is set to the NULL address 312 313 Returns: 314 None 315 316 Global Variables Used: 317 None 318 319 Local Variables Needed: 320 None 321 322 ------------------------------------------------------------------------------ 323 FUNCTION DESCRIPTION 324 325 This function deallocates the state memory used by the Levinson function. 326 327 ------------------------------------------------------------------------------ 328 REQUIREMENTS 329 330 None 331 332 ------------------------------------------------------------------------------ 333 REFERENCES 334 335 levinson.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 336 337 ------------------------------------------------------------------------------ 338 PSEUDO-CODE 339 340 void Levinson_exit (LevinsonState **state) 341 { 342 if (state == NULL || *state == NULL) 343 return; 344 345 // deallocate memory 346 free(*state); 347 *state = NULL; 348 349 return; 350 } 351 352 ------------------------------------------------------------------------------ 353 RESOURCES USED [optional] 354 355 When the code is written for a specific target processor the 356 the resources used should be documented below. 357 358 HEAP MEMORY USED: x bytes 359 360 STACK MEMORY USED: x bytes 361 362 CLOCK CYCLES: (cycle count equation for this function) + (variable 363 used to represent cycle count for each subroutine 364 called) 365 where: (cycle count variable) = cycle count for [subroutine 366 name] 367 368 ------------------------------------------------------------------------------ 369 CAUTION [optional] 370 [State any special notes, constraints or cautions for users of this function] 371 372 ------------------------------------------------------------------------------ 373 */ 374 375 void Levinson_exit(LevinsonState **state) 376 { 377 if (state == NULL || *state == NULL) 378 { 379 return; 380 } 381 382 /* deallocate memory */ 383 free(*state); 384 *state = NULL; 385 386 return; 387 } 388 389 /****************************************************************************/ 390 391 392 /* 393 ------------------------------------------------------------------------------ 394 FUNCTION NAME: Levinson 395 ------------------------------------------------------------------------------ 396 INPUT AND OUTPUT DEFINITIONS 397 398 Inputs: 399 st = pointer to structures of type LevinsonState 400 Rh = vector containing most significant byte of 401 autocorrelation values (Word16) 402 Rl = vector containing least significant byte of 403 autocorrelation values (Word16) 404 A = vector of LPC coefficients (10th order) (Word16) 405 rc = vector containing first four reflection coefficients (Word16) 406 pOverflow = pointer to overflow indicator (Flag) 407 408 Outputs: 409 A contains the newly calculated LPC coefficients 410 rc contains the newly calculated reflection coefficients 411 412 Returns: 413 return_value = 0 (int) 414 415 Global Variables Used: 416 None 417 418 Local Variables Needed: 419 None 420 421 ------------------------------------------------------------------------------ 422 FUNCTION DESCRIPTION 423 424 This function implements the Levinson-Durbin algorithm using double- 425 precision arithmetic. This is used to compute the Linear Predictive (LP) 426 filter parameters from the speech autocorrelation values. 427 428 The algorithm implemented is as follows: 429 A[0] = 1 430 K = -R[1]/R[0] 431 A[1] = K 432 Alpha = R[0] * (1-K**2] 433 434 FOR i = 2 to M 435 436 S = SUM ( R[j]*A[i-j] ,j=1,i-1 ) + R[i] 437 K = -S / Alpha 438 439 FOR j = 1 to i-1 440 An[j] = A[j] + K*A[i-j] where An[i] = new A[i] 441 ENDFOR 442 443 An[i]=K 444 Alpha=Alpha * (1-K**2) 445 446 END 447 448 where: 449 R[i] = autocorrelations 450 A[i] = filter coefficients 451 K = reflection coefficient 452 Alpha = prediction gain 453 454 ------------------------------------------------------------------------------ 455 REQUIREMENTS 456 457 None 458 459 ------------------------------------------------------------------------------ 460 REFERENCES 461 462 levinson.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 463 464 ------------------------------------------------------------------------------ 465 PSEUDO-CODE 466 467 int Levinson ( 468 LevinsonState *st, 469 Word16 Rh[], // i : Rh[m+1] Vector of autocorrelations (msb) 470 Word16 Rl[], // i : Rl[m+1] Vector of autocorrelations (lsb) 471 Word16 A[], // o : A[m] LPC coefficients (m = 10) 472 Word16 rc[] // o : rc[4] First 4 reflection coefficients 473 ) 474 { 475 Word16 i, j; 476 Word16 hi, lo; 477 Word16 Kh, Kl; // reflexion coefficient; hi and lo 478 Word16 alp_h, alp_l, alp_exp; // Prediction gain; hi lo and exponent 479 Word16 Ah[M + 1], Al[M + 1]; // LPC coef. in double prec. 480 Word16 Anh[M + 1], Anl[M + 1];// LPC coef.for next iteration in double 481 prec. 482 Word32 t0, t1, t2; // temporary variable 483 484 // K = A[1] = -R[1] / R[0] 485 486 t1 = L_Comp (Rh[1], Rl[1]); 487 t2 = L_abs (t1); // abs R[1] 488 t0 = Div_32 (t2, Rh[0], Rl[0]); // R[1]/R[0] 489 if (t1 > 0) 490 t0 = L_negate (t0); // -R[1]/R[0] 491 L_Extract (t0, &Kh, &Kl); // K in DPF 492 493 rc[0] = pv_round (t0); 494 495 t0 = L_shr (t0, 4); // A[1] in 496 L_Extract (t0, &Ah[1], &Al[1]); // A[1] in DPF 497 498 // Alpha = R[0] * (1-K**2) 499 500 t0 = Mpy_32 (Kh, Kl, Kh, Kl); // K*K 501 t0 = L_abs (t0); // Some case <0 !! 502 t0 = L_sub ((Word32) 0x7fffffffL, t0); // 1 - K*K 503 L_Extract (t0, &hi, &lo); // DPF format 504 t0 = Mpy_32 (Rh[0], Rl[0], hi, lo); // Alpha in 505 506 // Normalize Alpha 507 508 alp_exp = norm_l (t0); 509 t0 = L_shl (t0, alp_exp); 510 L_Extract (t0, &alp_h, &alp_l); // DPF format 511 512 *--------------------------------------* 513 * ITERATIONS I=2 to M * 514 *--------------------------------------* 515 516 for (i = 2; i <= M; i++) 517 { 518 // t0 = SUM ( R[j]*A[i-j] ,j=1,i-1 ) + R[i] 519 520 t0 = 0; 521 for (j = 1; j < i; j++) 522 { 523 t0 = L_add (t0, Mpy_32 (Rh[j], Rl[j], Ah[i - j], Al[i - j])); 524 } 525 t0 = L_shl (t0, 4); 526 527 t1 = L_Comp (Rh[i], Rl[i]); 528 t0 = L_add (t0, t1); // add R[i] 529 530 // K = -t0 / Alpha 531 532 t1 = L_abs (t0); 533 t2 = Div_32 (t1, alp_h, alp_l); // abs(t0)/Alpha 534 if (t0 > 0) 535 t2 = L_negate (t2); // K =-t0/Alpha 536 t2 = L_shl (t2, alp_exp); // denormalize; compare to Alpha 537 L_Extract (t2, &Kh, &Kl); // K in DPF 538 539 if (sub (i, 5) < 0) 540 { 541 rc[i - 1] = pv_round (t2); 542 } 543 // Test for unstable filter. If unstable keep old A(z) 544 545 if (sub (abs_s (Kh), 32750) > 0) 546 { 547 for (j = 0; j <= M; j++) 548 { 549 A[j] = st->old_A[j]; 550 } 551 552 for (j = 0; j < 4; j++) 553 { 554 rc[j] = 0; 555 } 556 557 return 0; 558 } 559 *------------------------------------------* 560 * Compute new LPC coeff. -> An[i] * 561 * An[j]= A[j] + K*A[i-j] , j=1 to i-1 * 562 * An[i]= K * 563 *------------------------------------------* 564 565 for (j = 1; j < i; j++) 566 { 567 t0 = Mpy_32 (Kh, Kl, Ah[i - j], Al[i - j]); 568 t0 = L_add(t0, L_Comp(Ah[j], Al[j])); 569 L_Extract (t0, &Anh[j], &Anl[j]); 570 } 571 t2 = L_shr (t2, 4); 572 L_Extract (t2, &Anh[i], &Anl[i]); 573 574 // Alpha = Alpha * (1-K**2) 575 576 t0 = Mpy_32 (Kh, Kl, Kh, Kl); // K*K 577 t0 = L_abs (t0); // Some case <0 !! 578 t0 = L_sub ((Word32) 0x7fffffffL, t0); // 1 - K*K 579 L_Extract (t0, &hi, &lo); // DPF format 580 t0 = Mpy_32 (alp_h, alp_l, hi, lo); 581 582 // Normalize Alpha 583 584 j = norm_l (t0); 585 t0 = L_shl (t0, j); 586 L_Extract (t0, &alp_h, &alp_l); // DPF format 587 alp_exp = add (alp_exp, j); // Add normalization to 588 alp_exp 589 590 // A[j] = An[j] 591 592 for (j = 1; j <= i; j++) 593 { 594 Ah[j] = Anh[j]; 595 Al[j] = Anl[j]; 596 } 597 } 598 599 A[0] = 4096; 600 for (i = 1; i <= M; i++) 601 { 602 t0 = L_Comp (Ah[i], Al[i]); 603 st->old_A[i] = A[i] = pv_round (L_shl (t0, 1)); 604 } 605 606 return 0; 607 } 608 609 ------------------------------------------------------------------------------ 610 RESOURCES USED [optional] 611 612 When the code is written for a specific target processor the 613 the resources used should be documented below. 614 615 HEAP MEMORY USED: x bytes 616 617 STACK MEMORY USED: x bytes 618 619 CLOCK CYCLES: (cycle count equation for this function) + (variable 620 used to represent cycle count for each subroutine 621 called) 622 where: (cycle count variable) = cycle count for [subroutine 623 name] 624 625 ------------------------------------------------------------------------------ 626 CAUTION [optional] 627 [State any special notes, constraints or cautions for users of this function] 628 629 ------------------------------------------------------------------------------ 630 */ 631 632 Word16 Levinson( 633 LevinsonState *st, 634 Word16 Rh[], /* i : Rh[m+1] Vector of autocorrelations (msb) */ 635 Word16 Rl[], /* i : Rl[m+1] Vector of autocorrelations (lsb) */ 636 Word16 A[], /* o : A[m] LPC coefficients (m = 10) */ 637 Word16 rc[], /* o : rc[4] First 4 reflection coefficients */ 638 Flag *pOverflow 639 ) 640 { 641 register Word16 i; 642 register Word16 j; 643 Word16 hi; 644 Word16 lo; 645 Word16 Kh; /* reflexion coefficient; hi and lo */ 646 Word16 Kl; 647 Word16 alp_h; /* Prediction gain; hi lo and exponent*/ 648 Word16 alp_l; 649 Word16 alp_exp; 650 Word16 Ah[M + 1]; /* LPC coef. in double prec. */ 651 Word16 Al[M + 1]; 652 Word16 Anh[M + 1]; /* LPC coef.for next iteration in */ 653 Word16 Anl[M + 1]; /* double prec. */ 654 register Word32 t0; /* temporary variable */ 655 register Word32 t1; /* temporary variable */ 656 register Word32 t2; /* temporary variable */ 657 658 Word16 *p_Rh; 659 Word16 *p_Rl; 660 Word16 *p_Ah; 661 Word16 *p_Al; 662 Word16 *p_Anh; 663 Word16 *p_Anl; 664 Word16 *p_A; 665 666 /* K = A[1] = -R[1] / R[0] */ 667 t1 = ((Word32) * (Rh + 1)) << 16; 668 t1 += *(Rl + 1) << 1; 669 670 t2 = L_abs(t1); /* abs R[1] - required by Div_32 */ 671 t0 = Div_32(t2, *Rh, *Rl, pOverflow); /* R[1]/R[0] */ 672 673 if (t1 > 0) 674 { 675 t0 = L_negate(t0); /* -R[1]/R[0] */ 676 } 677 678 /* K in DPF */ 679 Kh = (Word16)(t0 >> 16); 680 Kl = (Word16)((t0 >> 1) - ((Word32)(Kh) << 15)); 681 682 *rc = pv_round(t0, pOverflow); 683 684 t0 = t0 >> 4; 685 686 /* A[1] in DPF */ 687 *(Ah + 1) = (Word16)(t0 >> 16); 688 689 *(Al + 1) = (Word16)((t0 >> 1) - ((Word32)(*(Ah + 1)) << 15)); 690 691 /* Alpha = R[0] * (1-K**2) */ 692 t0 = Mpy_32(Kh, Kl, Kh, Kl, pOverflow); /* K*K */ 693 t0 = L_abs(t0); /* Some case <0 !! */ 694 t0 = 0x7fffffffL - t0; /* 1 - K*K */ 695 696 /* DPF format */ 697 hi = (Word16)(t0 >> 16); 698 lo = (Word16)((t0 >> 1) - ((Word32)(hi) << 15)); 699 700 t0 = Mpy_32(*Rh, *Rl, hi, lo, pOverflow); /* Alpha in */ 701 702 /* Normalize Alpha */ 703 704 alp_exp = norm_l(t0); 705 t0 = t0 << alp_exp; 706 707 /* DPF format */ 708 alp_h = (Word16)(t0 >> 16); 709 alp_l = (Word16)((t0 >> 1) - ((Word32)(alp_h) << 15)); 710 711 /*--------------------------------------* 712 * ITERATIONS I=2 to M * 713 *--------------------------------------*/ 714 715 for (i = 2; i <= M; i++) 716 { 717 /* t0 = SUM ( R[j]*A[i-j] ,j=1,i-1 ) + R[i] */ 718 719 t0 = 0; 720 p_Rh = &Rh[1]; 721 p_Rl = &Rl[1]; 722 p_Ah = &Ah[i-1]; 723 p_Al = &Al[i-1]; 724 for (j = 1; j < i; j++) 725 { 726 t0 += (((Word32) * (p_Rh)* *(p_Al--)) >> 15); 727 t0 += (((Word32) * (p_Rl++)* *(p_Ah)) >> 15); 728 t0 += ((Word32) * (p_Rh++)* *(p_Ah--)); 729 } 730 731 t0 = t0 << 5; 732 733 t1 = ((Word32) * (Rh + i) << 16) + ((Word32)(*(Rl + i)) << 1); 734 t0 += t1; 735 736 /* K = -t0 / Alpha */ 737 738 t1 = L_abs(t0); 739 t2 = Div_32(t1, alp_h, alp_l, pOverflow); /* abs(t0)/Alpha */ 740 741 if (t0 > 0) 742 { 743 t2 = L_negate(t2); /* K =-t0/Alpha */ 744 } 745 746 t2 = L_shl(t2, alp_exp, pOverflow); /* denormalize; compare to Alpha */ 747 Kh = (Word16)(t2 >> 16); 748 Kl = (Word16)((t2 >> 1) - ((Word32)(Kh) << 15)); 749 750 if (i < 5) 751 { 752 *(rc + i - 1) = (Word16)((t2 + 0x00008000L) >> 16); 753 } 754 /* Test for unstable filter. If unstable keep old A(z) */ 755 if ((abs_s(Kh)) > 32750) 756 { 757 memcpy(A, &(st->old_A[0]), sizeof(Word16)*(M + 1)); 758 memset(rc, 0, sizeof(Word16)*4); 759 return(0); 760 } 761 /*------------------------------------------* 762 * Compute new LPC coeff. -> An[i] * 763 * An[j]= A[j] + K*A[i-j] , j=1 to i-1 * 764 * An[i]= K * 765 *------------------------------------------*/ 766 p_Ah = &Ah[i-1]; 767 p_Al = &Al[i-1]; 768 p_Anh = &Anh[1]; 769 p_Anl = &Anl[1]; 770 for (j = 1; j < i; j++) 771 { 772 t0 = (((Word32)Kh* *(p_Al--)) >> 15); 773 t0 += (((Word32)Kl* *(p_Ah)) >> 15); 774 t0 += ((Word32)Kh* *(p_Ah--)); 775 776 t0 += (Ah[j] << 15) + Al[j]; 777 778 *(p_Anh) = (Word16)(t0 >> 15); 779 *(p_Anl++) = (Word16)(t0 - ((Word32)(*(p_Anh++)) << 15)); 780 } 781 782 *(p_Anh) = (Word16)(t2 >> 20); 783 *(p_Anl) = (Word16)((t2 >> 5) - ((Word32)(*(Anh + i)) << 15)); 784 785 /* Alpha = Alpha * (1-K**2) */ 786 787 t0 = Mpy_32(Kh, Kl, Kh, Kl, pOverflow); /* K*K */ 788 t0 = L_abs(t0); /* Some case <0 !! */ 789 t0 = 0x7fffffffL - t0; /* 1 - K*K */ 790 791 hi = (Word16)(t0 >> 16); 792 lo = (Word16)((t0 >> 1) - ((Word32)(hi) << 15)); 793 794 t0 = (((Word32)alp_h * lo) >> 15); 795 t0 += (((Word32)alp_l * hi) >> 15); 796 t0 += ((Word32)alp_h * hi); 797 798 t0 <<= 1; 799 /* Normalize Alpha */ 800 801 j = norm_l(t0); 802 t0 <<= j; 803 alp_h = (Word16)(t0 >> 16); 804 alp_l = (Word16)((t0 >> 1) - ((Word32)(alp_h) << 15)); 805 alp_exp += j; /* Add normalization to alp_exp */ 806 807 /* A[j] = An[j] */ 808 memcpy(&Ah[1], &Anh[1], sizeof(Word16)*i); 809 memcpy(&Al[1], &Anl[1], sizeof(Word16)*i); 810 } 811 812 p_A = &A[0]; 813 *(p_A++) = 4096; 814 p_Ah = &Ah[1]; 815 p_Al = &Al[1]; 816 817 for (i = 1; i <= M; i++) 818 { 819 t0 = ((Word32) * (p_Ah++) << 15) + *(p_Al++); 820 st->old_A[i] = *(p_A++) = (Word16)((t0 + 0x00002000) >> 14); 821 } 822 823 return(0); 824 } 825
