Alexandre Lision | d204ea5 | 2013-10-15 10:16:25 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische |
| 3 | * Universitaet Berlin. See the accompanying file "COPYRIGHT" for |
| 4 | * details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE. |
| 5 | */ |
| 6 | |
| 7 | /* $Header: /tmp_amd/presto/export/kbs/jutta/src/gsm/RCS/rpe.c,v 1.3 1994/05/10 20:18:46 jutta Exp $ */ |
| 8 | |
| 9 | #include <stdio.h> |
| 10 | #include <assert.h> |
| 11 | |
| 12 | #include "private.h" |
| 13 | |
| 14 | #include "gsm.h" |
| 15 | #include "proto.h" |
| 16 | |
| 17 | /* 4.2.13 .. 4.2.17 RPE ENCODING SECTION |
| 18 | */ |
| 19 | |
| 20 | /* 4.2.13 */ |
| 21 | |
| 22 | static void Weighting_filter P2((e, x), |
| 23 | register word * e, /* signal [-5..0.39.44] IN */ |
| 24 | word * x /* signal [0..39] OUT */ |
| 25 | ) |
| 26 | /* |
| 27 | * The coefficients of the weighting filter are stored in a table |
| 28 | * (see table 4.4). The following scaling is used: |
| 29 | * |
| 30 | * H[0..10] = integer( real_H[ 0..10] * 8192 ); |
| 31 | */ |
| 32 | { |
| 33 | /* word wt[ 50 ]; */ |
| 34 | |
| 35 | register longword L_result; |
| 36 | register int k /* , i */ ; |
| 37 | |
| 38 | /* Initialization of a temporary working array wt[0...49] |
| 39 | */ |
| 40 | |
| 41 | /* for (k = 0; k <= 4; k++) wt[k] = 0; |
| 42 | * for (k = 5; k <= 44; k++) wt[k] = *e++; |
| 43 | * for (k = 45; k <= 49; k++) wt[k] = 0; |
| 44 | * |
| 45 | * (e[-5..-1] and e[40..44] are allocated by the caller, |
| 46 | * are initially zero and are not written anywhere.) |
| 47 | */ |
| 48 | e -= 5; |
| 49 | |
| 50 | /* Compute the signal x[0..39] |
| 51 | */ |
| 52 | for (k = 0; k <= 39; k++) { |
| 53 | |
| 54 | L_result = 8192 >> 1; |
| 55 | |
| 56 | /* for (i = 0; i <= 10; i++) { |
| 57 | * L_temp = GSM_L_MULT( wt[k+i], gsm_H[i] ); |
| 58 | * L_result = GSM_L_ADD( L_result, L_temp ); |
| 59 | * } |
| 60 | */ |
| 61 | |
| 62 | #undef STEP |
| 63 | #define STEP( i, H ) (e[ k + i ] * (longword)H) |
| 64 | |
| 65 | /* Every one of these multiplications is done twice -- |
| 66 | * but I don't see an elegant way to optimize this. |
| 67 | * Do you? |
| 68 | */ |
| 69 | |
| 70 | #ifdef STUPID_COMPILER |
| 71 | L_result += STEP( 0, -134 ) ; |
| 72 | L_result += STEP( 1, -374 ) ; |
| 73 | /* + STEP( 2, 0 ) */ |
| 74 | L_result += STEP( 3, 2054 ) ; |
| 75 | L_result += STEP( 4, 5741 ) ; |
| 76 | L_result += STEP( 5, 8192 ) ; |
| 77 | L_result += STEP( 6, 5741 ) ; |
| 78 | L_result += STEP( 7, 2054 ) ; |
| 79 | /* + STEP( 8, 0 ) */ |
| 80 | L_result += STEP( 9, -374 ) ; |
| 81 | L_result += STEP( 10, -134 ) ; |
| 82 | #else |
| 83 | L_result += |
| 84 | STEP( 0, -134 ) |
| 85 | + STEP( 1, -374 ) |
| 86 | /* + STEP( 2, 0 ) */ |
| 87 | + STEP( 3, 2054 ) |
| 88 | + STEP( 4, 5741 ) |
| 89 | + STEP( 5, 8192 ) |
| 90 | + STEP( 6, 5741 ) |
| 91 | + STEP( 7, 2054 ) |
| 92 | /* + STEP( 8, 0 ) */ |
| 93 | + STEP( 9, -374 ) |
| 94 | + STEP(10, -134 ) |
| 95 | ; |
| 96 | #endif |
| 97 | |
| 98 | /* L_result = GSM_L_ADD( L_result, L_result ); (* scaling(x2) *) |
| 99 | * L_result = GSM_L_ADD( L_result, L_result ); (* scaling(x4) *) |
| 100 | * |
| 101 | * x[k] = SASR( L_result, 16 ); |
| 102 | */ |
| 103 | |
| 104 | /* 2 adds vs. >>16 => 14, minus one shift to compensate for |
| 105 | * those we lost when replacing L_MULT by '*'. |
| 106 | */ |
| 107 | |
| 108 | L_result = SASR( L_result, 13 ); |
| 109 | x[k] = ( L_result < MIN_WORD ? MIN_WORD |
| 110 | : (L_result > MAX_WORD ? MAX_WORD : L_result )); |
| 111 | } |
| 112 | } |
| 113 | |
| 114 | /* 4.2.14 */ |
| 115 | |
| 116 | static void RPE_grid_selection P3((x,xM,Mc_out), |
| 117 | word * x, /* [0..39] IN */ |
| 118 | word * xM, /* [0..12] OUT */ |
| 119 | word * Mc_out /* OUT */ |
| 120 | ) |
| 121 | /* |
| 122 | * The signal x[0..39] is used to select the RPE grid which is |
| 123 | * represented by Mc. |
| 124 | */ |
| 125 | { |
| 126 | /* register word temp1; */ |
| 127 | register int /* m, */ i; |
| 128 | register longword L_result, L_temp; |
| 129 | longword EM; /* xxx should be L_EM? */ |
| 130 | word Mc; |
| 131 | |
| 132 | longword L_common_0_3; |
| 133 | |
| 134 | EM = 0; |
| 135 | Mc = 0; |
| 136 | |
| 137 | /* for (m = 0; m <= 3; m++) { |
| 138 | * L_result = 0; |
| 139 | * |
| 140 | * |
| 141 | * for (i = 0; i <= 12; i++) { |
| 142 | * |
| 143 | * temp1 = SASR( x[m + 3*i], 2 ); |
| 144 | * |
| 145 | * assert(temp1 != MIN_WORD); |
| 146 | * |
| 147 | * L_temp = GSM_L_MULT( temp1, temp1 ); |
| 148 | * L_result = GSM_L_ADD( L_temp, L_result ); |
| 149 | * } |
| 150 | * |
| 151 | * if (L_result > EM) { |
| 152 | * Mc = m; |
| 153 | * EM = L_result; |
| 154 | * } |
| 155 | * } |
| 156 | */ |
| 157 | |
| 158 | #undef STEP |
| 159 | #define STEP( m, i ) L_temp = SASR( x[m + 3 * i], 2 ); \ |
| 160 | L_result += L_temp * L_temp; |
| 161 | |
| 162 | /* common part of 0 and 3 */ |
| 163 | |
| 164 | L_result = 0; |
| 165 | STEP( 0, 1 ); STEP( 0, 2 ); STEP( 0, 3 ); STEP( 0, 4 ); |
| 166 | STEP( 0, 5 ); STEP( 0, 6 ); STEP( 0, 7 ); STEP( 0, 8 ); |
| 167 | STEP( 0, 9 ); STEP( 0, 10); STEP( 0, 11); STEP( 0, 12); |
| 168 | L_common_0_3 = L_result; |
| 169 | |
| 170 | /* i = 0 */ |
| 171 | |
| 172 | STEP( 0, 0 ); |
| 173 | L_result <<= 1; /* implicit in L_MULT */ |
| 174 | EM = L_result; |
| 175 | |
| 176 | /* i = 1 */ |
| 177 | |
| 178 | L_result = 0; |
| 179 | STEP( 1, 0 ); |
| 180 | STEP( 1, 1 ); STEP( 1, 2 ); STEP( 1, 3 ); STEP( 1, 4 ); |
| 181 | STEP( 1, 5 ); STEP( 1, 6 ); STEP( 1, 7 ); STEP( 1, 8 ); |
| 182 | STEP( 1, 9 ); STEP( 1, 10); STEP( 1, 11); STEP( 1, 12); |
| 183 | L_result <<= 1; |
| 184 | if (L_result > EM) { |
| 185 | Mc = 1; |
| 186 | EM = L_result; |
| 187 | } |
| 188 | |
| 189 | /* i = 2 */ |
| 190 | |
| 191 | L_result = 0; |
| 192 | STEP( 2, 0 ); |
| 193 | STEP( 2, 1 ); STEP( 2, 2 ); STEP( 2, 3 ); STEP( 2, 4 ); |
| 194 | STEP( 2, 5 ); STEP( 2, 6 ); STEP( 2, 7 ); STEP( 2, 8 ); |
| 195 | STEP( 2, 9 ); STEP( 2, 10); STEP( 2, 11); STEP( 2, 12); |
| 196 | L_result <<= 1; |
| 197 | if (L_result > EM) { |
| 198 | Mc = 2; |
| 199 | EM = L_result; |
| 200 | } |
| 201 | |
| 202 | /* i = 3 */ |
| 203 | |
| 204 | L_result = L_common_0_3; |
| 205 | STEP( 3, 12 ); |
| 206 | L_result <<= 1; |
| 207 | if (L_result > EM) { |
| 208 | Mc = 3; |
| 209 | EM = L_result; |
| 210 | } |
| 211 | |
| 212 | /**/ |
| 213 | |
| 214 | /* Down-sampling by a factor 3 to get the selected xM[0..12] |
| 215 | * RPE sequence. |
| 216 | */ |
| 217 | for (i = 0; i <= 12; i ++) xM[i] = x[Mc + 3*i]; |
| 218 | *Mc_out = Mc; |
| 219 | } |
| 220 | |
| 221 | /* 4.12.15 */ |
| 222 | |
| 223 | static void APCM_quantization_xmaxc_to_exp_mant P3((xmaxc,exp_out,mant_out), |
| 224 | word xmaxc, /* IN */ |
| 225 | word * exp_out, /* OUT */ |
| 226 | word * mant_out ) /* OUT */ |
| 227 | { |
| 228 | word exp, mant; |
| 229 | |
| 230 | /* Compute exponent and mantissa of the decoded version of xmaxc |
| 231 | */ |
| 232 | |
| 233 | exp = 0; |
| 234 | if (xmaxc > 15) exp = SASR(xmaxc, 3) - 1; |
| 235 | mant = xmaxc - (exp << 3); |
| 236 | |
| 237 | if (mant == 0) { |
| 238 | exp = -4; |
| 239 | mant = 7; |
| 240 | } |
| 241 | else { |
| 242 | while (mant <= 7) { |
| 243 | mant = mant << 1 | 1; |
| 244 | exp--; |
| 245 | } |
| 246 | mant -= 8; |
| 247 | } |
| 248 | |
| 249 | assert( exp >= -4 && exp <= 6 ); |
| 250 | assert( mant >= 0 && mant <= 7 ); |
| 251 | |
| 252 | *exp_out = exp; |
| 253 | *mant_out = mant; |
| 254 | } |
| 255 | |
| 256 | static void APCM_quantization P5((xM,xMc,mant_out,exp_out,xmaxc_out), |
| 257 | word * xM, /* [0..12] IN */ |
| 258 | |
| 259 | word * xMc, /* [0..12] OUT */ |
| 260 | word * mant_out, /* OUT */ |
| 261 | word * exp_out, /* OUT */ |
| 262 | word * xmaxc_out /* OUT */ |
| 263 | ) |
| 264 | { |
| 265 | int i, itest; |
| 266 | |
| 267 | word xmax, xmaxc, temp, temp1, temp2; |
| 268 | word exp, mant; |
| 269 | |
| 270 | |
| 271 | /* Find the maximum absolute value xmax of xM[0..12]. |
| 272 | */ |
| 273 | |
| 274 | xmax = 0; |
| 275 | for (i = 0; i <= 12; i++) { |
| 276 | temp = xM[i]; |
| 277 | temp = GSM_ABS(temp); |
| 278 | if (temp > xmax) xmax = temp; |
| 279 | } |
| 280 | |
| 281 | /* Qantizing and coding of xmax to get xmaxc. |
| 282 | */ |
| 283 | |
| 284 | exp = 0; |
| 285 | temp = SASR( xmax, 9 ); |
| 286 | itest = 0; |
| 287 | |
| 288 | for (i = 0; i <= 5; i++) { |
| 289 | |
| 290 | itest |= (temp <= 0); |
| 291 | temp = SASR( temp, 1 ); |
| 292 | |
| 293 | assert(exp <= 5); |
| 294 | if (itest == 0) exp++; /* exp = add (exp, 1) */ |
| 295 | } |
| 296 | |
| 297 | assert(exp <= 6 && exp >= 0); |
| 298 | temp = exp + 5; |
| 299 | |
| 300 | assert(temp <= 11 && temp >= 0); |
| 301 | xmaxc = gsm_add( SASR(xmax, temp), exp << 3 ); |
| 302 | |
| 303 | /* Quantizing and coding of the xM[0..12] RPE sequence |
| 304 | * to get the xMc[0..12] |
| 305 | */ |
| 306 | |
| 307 | APCM_quantization_xmaxc_to_exp_mant( xmaxc, &exp, &mant ); |
| 308 | |
| 309 | /* This computation uses the fact that the decoded version of xmaxc |
| 310 | * can be calculated by using the exponent and the mantissa part of |
| 311 | * xmaxc (logarithmic table). |
| 312 | * So, this method avoids any division and uses only a scaling |
| 313 | * of the RPE samples by a function of the exponent. A direct |
| 314 | * multiplication by the inverse of the mantissa (NRFAC[0..7] |
| 315 | * found in table 4.5) gives the 3 bit coded version xMc[0..12] |
| 316 | * of the RPE samples. |
| 317 | */ |
| 318 | |
| 319 | |
| 320 | /* Direct computation of xMc[0..12] using table 4.5 |
| 321 | */ |
| 322 | |
| 323 | assert( exp <= 4096 && exp >= -4096); |
| 324 | assert( mant >= 0 && mant <= 7 ); |
| 325 | |
| 326 | temp1 = 6 - exp; /* normalization by the exponent */ |
| 327 | temp2 = gsm_NRFAC[ mant ]; /* inverse mantissa */ |
| 328 | |
| 329 | for (i = 0; i <= 12; i++) { |
| 330 | |
| 331 | assert(temp1 >= 0 && temp1 < 16); |
| 332 | |
| 333 | temp = xM[i] << temp1; |
| 334 | temp = GSM_MULT( temp, temp2 ); |
| 335 | temp = SASR(temp, 12); |
| 336 | xMc[i] = temp + 4; /* see note below */ |
| 337 | } |
| 338 | |
| 339 | /* NOTE: This equation is used to make all the xMc[i] positive. |
| 340 | */ |
| 341 | |
| 342 | *mant_out = mant; |
| 343 | *exp_out = exp; |
| 344 | *xmaxc_out = xmaxc; |
| 345 | } |
| 346 | |
| 347 | /* 4.2.16 */ |
| 348 | |
| 349 | static void APCM_inverse_quantization P4((xMc,mant,exp,xMp), |
| 350 | register word * xMc, /* [0..12] IN */ |
| 351 | word mant, |
| 352 | word exp, |
| 353 | register word * xMp) /* [0..12] OUT */ |
| 354 | /* |
| 355 | * This part is for decoding the RPE sequence of coded xMc[0..12] |
| 356 | * samples to obtain the xMp[0..12] array. Table 4.6 is used to get |
| 357 | * the mantissa of xmaxc (FAC[0..7]). |
| 358 | */ |
| 359 | { |
| 360 | int i; |
| 361 | word temp, temp1, temp2, temp3; |
| 362 | longword ltmp; |
| 363 | |
| 364 | assert( mant >= 0 && mant <= 7 ); |
| 365 | |
| 366 | temp1 = gsm_FAC[ mant ]; /* see 4.2-15 for mant */ |
| 367 | temp2 = gsm_sub( 6, exp ); /* see 4.2-15 for exp */ |
| 368 | temp3 = gsm_asl( 1, gsm_sub( temp2, 1 )); |
| 369 | |
| 370 | for (i = 13; i--;) { |
| 371 | |
| 372 | assert( *xMc <= 7 && *xMc >= 0 ); /* 3 bit unsigned */ |
| 373 | |
| 374 | /* temp = gsm_sub( *xMc++ << 1, 7 ); */ |
| 375 | temp = (*xMc++ << 1) - 7; /* restore sign */ |
| 376 | assert( temp <= 7 && temp >= -7 ); /* 4 bit signed */ |
| 377 | |
| 378 | temp <<= 12; /* 16 bit signed */ |
| 379 | temp = GSM_MULT_R( temp1, temp ); |
| 380 | temp = GSM_ADD( temp, temp3 ); |
| 381 | *xMp++ = gsm_asr( temp, temp2 ); |
| 382 | } |
| 383 | } |
| 384 | |
| 385 | /* 4.2.17 */ |
| 386 | |
| 387 | static void RPE_grid_positioning P3((Mc,xMp,ep), |
| 388 | word Mc, /* grid position IN */ |
| 389 | register word * xMp, /* [0..12] IN */ |
| 390 | register word * ep /* [0..39] OUT */ |
| 391 | ) |
| 392 | /* |
| 393 | * This procedure computes the reconstructed long term residual signal |
| 394 | * ep[0..39] for the LTP analysis filter. The inputs are the Mc |
| 395 | * which is the grid position selection and the xMp[0..12] decoded |
| 396 | * RPE samples which are upsampled by a factor of 3 by inserting zero |
| 397 | * values. |
| 398 | */ |
| 399 | { |
| 400 | int i = 13; |
| 401 | |
| 402 | assert(0 <= Mc && Mc <= 3); |
| 403 | |
| 404 | switch (Mc) { |
| 405 | case 3: *ep++ = 0; |
| 406 | case 2: do { |
| 407 | *ep++ = 0; |
| 408 | case 1: *ep++ = 0; |
| 409 | case 0: *ep++ = *xMp++; |
| 410 | } while (--i); |
| 411 | } |
| 412 | while (++Mc < 4) *ep++ = 0; |
| 413 | |
| 414 | /* |
| 415 | |
| 416 | int i, k; |
| 417 | for (k = 0; k <= 39; k++) ep[k] = 0; |
| 418 | for (i = 0; i <= 12; i++) { |
| 419 | ep[ Mc + (3*i) ] = xMp[i]; |
| 420 | } |
| 421 | */ |
| 422 | } |
| 423 | |
| 424 | /* 4.2.18 */ |
| 425 | |
| 426 | /* This procedure adds the reconstructed long term residual signal |
| 427 | * ep[0..39] to the estimated signal dpp[0..39] from the long term |
| 428 | * analysis filter to compute the reconstructed short term residual |
| 429 | * signal dp[-40..-1]; also the reconstructed short term residual |
| 430 | * array dp[-120..-41] is updated. |
| 431 | */ |
| 432 | |
| 433 | #if 0 /* Has been inlined in code.c */ |
| 434 | void Gsm_Update_of_reconstructed_short_time_residual_signal P3((dpp, ep, dp), |
| 435 | word * dpp, /* [0...39] IN */ |
| 436 | word * ep, /* [0...39] IN */ |
| 437 | word * dp) /* [-120...-1] IN/OUT */ |
| 438 | { |
| 439 | int k; |
| 440 | |
| 441 | for (k = 0; k <= 79; k++) |
| 442 | dp[ -120 + k ] = dp[ -80 + k ]; |
| 443 | |
| 444 | for (k = 0; k <= 39; k++) |
| 445 | dp[ -40 + k ] = gsm_add( ep[k], dpp[k] ); |
| 446 | } |
| 447 | #endif /* Has been inlined in code.c */ |
| 448 | |
| 449 | void Gsm_RPE_Encoding P5((S,e,xmaxc,Mc,xMc), |
| 450 | |
| 451 | struct gsm_state * S, |
| 452 | |
| 453 | word * e, /* -5..-1][0..39][40..44 IN/OUT */ |
| 454 | word * xmaxc, /* OUT */ |
| 455 | word * Mc, /* OUT */ |
| 456 | word * xMc) /* [0..12] OUT */ |
| 457 | { |
| 458 | word x[40]; |
| 459 | word xM[13], xMp[13]; |
| 460 | word mant, exp; |
| 461 | |
| 462 | Weighting_filter(e, x); |
| 463 | RPE_grid_selection(x, xM, Mc); |
| 464 | |
| 465 | APCM_quantization( xM, xMc, &mant, &exp, xmaxc); |
| 466 | APCM_inverse_quantization( xMc, mant, exp, xMp); |
| 467 | |
| 468 | RPE_grid_positioning( *Mc, xMp, e ); |
| 469 | |
| 470 | } |
| 471 | |
| 472 | void Gsm_RPE_Decoding P5((S, xmaxcr, Mcr, xMcr, erp), |
| 473 | struct gsm_state * S, |
| 474 | |
| 475 | word xmaxcr, |
| 476 | word Mcr, |
| 477 | word * xMcr, /* [0..12], 3 bits IN */ |
| 478 | word * erp /* [0..39] OUT */ |
| 479 | ) |
| 480 | { |
| 481 | word exp, mant; |
| 482 | word xMp[ 13 ]; |
| 483 | |
| 484 | APCM_quantization_xmaxc_to_exp_mant( xmaxcr, &exp, &mant ); |
| 485 | APCM_inverse_quantization( xMcr, mant, exp, xMp ); |
| 486 | RPE_grid_positioning( Mcr, xMp, erp ); |
| 487 | |
| 488 | } |