Alexandre Lision | 7c6f4a6 | 2013-09-05 13:27:01 -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 | #include <stdio.h> |
| 8 | #include <assert.h> |
| 9 | |
| 10 | #include "gsm610_priv.h" |
| 11 | |
| 12 | /* 4.2.13 .. 4.2.17 RPE ENCODING SECTION |
| 13 | */ |
| 14 | |
| 15 | /* 4.2.13 */ |
| 16 | |
| 17 | static void Weighting_filter ( |
| 18 | register word * e, /* signal [-5..0.39.44] IN */ |
| 19 | word * x /* signal [0..39] OUT */ |
| 20 | ) |
| 21 | /* |
| 22 | * The coefficients of the weighting filter are stored in a table |
| 23 | * (see table 4.4). The following scaling is used: |
| 24 | * |
| 25 | * H[0..10] = integer( real_H[ 0..10] * 8192 ); |
| 26 | */ |
| 27 | { |
| 28 | /* word wt[ 50 ]; */ |
| 29 | |
| 30 | register longword L_result; |
| 31 | register int k /* , i */ ; |
| 32 | |
| 33 | /* Initialization of a temporary working array wt[0...49] |
| 34 | */ |
| 35 | |
| 36 | /* for (k = 0; k <= 4; k++) wt[k] = 0; |
| 37 | * for (k = 5; k <= 44; k++) wt[k] = *e++; |
| 38 | * for (k = 45; k <= 49; k++) wt[k] = 0; |
| 39 | * |
| 40 | * (e[-5..-1] and e[40..44] are allocated by the caller, |
| 41 | * are initially zero and are not written anywhere.) |
| 42 | */ |
| 43 | e -= 5; |
| 44 | |
| 45 | /* Compute the signal x[0..39] |
| 46 | */ |
| 47 | for (k = 0; k <= 39; k++) { |
| 48 | |
| 49 | L_result = 8192 >> 1; |
| 50 | |
| 51 | /* for (i = 0; i <= 10; i++) { |
| 52 | * L_temp = GSM_L_MULT( wt[k+i], gsm_H[i] ); |
| 53 | * L_result = GSM_L_ADD( L_result, L_temp ); |
| 54 | * } |
| 55 | */ |
| 56 | |
| 57 | #undef STEP |
| 58 | #define STEP( i, H ) (e[ k + i ] * (longword)H) |
| 59 | |
| 60 | /* Every one of these multiplications is done twice -- |
| 61 | * but I don't see an elegant way to optimize this. |
| 62 | * Do you? |
| 63 | */ |
| 64 | |
| 65 | #ifdef STUPID_COMPILER |
| 66 | L_result += STEP( 0, -134 ) ; |
| 67 | L_result += STEP( 1, -374 ) ; |
| 68 | /* + STEP( 2, 0 ) */ |
| 69 | L_result += STEP( 3, 2054 ) ; |
| 70 | L_result += STEP( 4, 5741 ) ; |
| 71 | L_result += STEP( 5, 8192 ) ; |
| 72 | L_result += STEP( 6, 5741 ) ; |
| 73 | L_result += STEP( 7, 2054 ) ; |
| 74 | /* + STEP( 8, 0 ) */ |
| 75 | L_result += STEP( 9, -374 ) ; |
| 76 | L_result += STEP( 10, -134 ) ; |
| 77 | #else |
| 78 | L_result += |
| 79 | STEP( 0, -134 ) |
| 80 | + STEP( 1, -374 ) |
| 81 | /* + STEP( 2, 0 ) */ |
| 82 | + STEP( 3, 2054 ) |
| 83 | + STEP( 4, 5741 ) |
| 84 | + STEP( 5, 8192 ) |
| 85 | + STEP( 6, 5741 ) |
| 86 | + STEP( 7, 2054 ) |
| 87 | /* + STEP( 8, 0 ) */ |
| 88 | + STEP( 9, -374 ) |
| 89 | + STEP(10, -134 ) |
| 90 | ; |
| 91 | #endif |
| 92 | |
| 93 | /* L_result = GSM_L_ADD( L_result, L_result ); (* scaling(x2) *) |
| 94 | * L_result = GSM_L_ADD( L_result, L_result ); (* scaling(x4) *) |
| 95 | * |
| 96 | * x[k] = SASR( L_result, 16 ); |
| 97 | */ |
| 98 | |
| 99 | /* 2 adds vs. >>16 => 14, minus one shift to compensate for |
| 100 | * those we lost when replacing L_MULT by '*'. |
| 101 | */ |
| 102 | |
| 103 | L_result = SASR_L( L_result, 13 ); |
| 104 | x[k] = ( L_result < MIN_WORD ? MIN_WORD |
| 105 | : (L_result > MAX_WORD ? MAX_WORD : L_result )); |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | /* 4.2.14 */ |
| 110 | |
| 111 | static void RPE_grid_selection ( |
| 112 | word * x, /* [0..39] IN */ |
| 113 | word * xM, /* [0..12] OUT */ |
| 114 | word * Mc_out /* OUT */ |
| 115 | ) |
| 116 | /* |
| 117 | * The signal x[0..39] is used to select the RPE grid which is |
| 118 | * represented by Mc. |
| 119 | */ |
| 120 | { |
| 121 | /* register word temp1; */ |
| 122 | register int /* m, */ i; |
| 123 | register longword L_result, L_temp; |
| 124 | longword EM; /* xxx should be L_EM? */ |
| 125 | word Mc; |
| 126 | |
| 127 | longword L_common_0_3; |
| 128 | |
| 129 | EM = 0; |
| 130 | Mc = 0; |
| 131 | |
| 132 | /* for (m = 0; m <= 3; m++) { |
| 133 | * L_result = 0; |
| 134 | * |
| 135 | * |
| 136 | * for (i = 0; i <= 12; i++) { |
| 137 | * |
| 138 | * temp1 = SASR_W( x[m + 3*i], 2 ); |
| 139 | * |
| 140 | * assert(temp1 != MIN_WORD); |
| 141 | * |
| 142 | * L_temp = GSM_L_MULT( temp1, temp1 ); |
| 143 | * L_result = GSM_L_ADD( L_temp, L_result ); |
| 144 | * } |
| 145 | * |
| 146 | * if (L_result > EM) { |
| 147 | * Mc = m; |
| 148 | * EM = L_result; |
| 149 | * } |
| 150 | * } |
| 151 | */ |
| 152 | |
| 153 | #undef STEP |
| 154 | #define STEP( m, i ) L_temp = SASR_W( x[m + 3 * i], 2 ); \ |
| 155 | L_result += L_temp * L_temp; |
| 156 | |
| 157 | /* common part of 0 and 3 */ |
| 158 | |
| 159 | L_result = 0; |
| 160 | STEP( 0, 1 ); STEP( 0, 2 ); STEP( 0, 3 ); STEP( 0, 4 ); |
| 161 | STEP( 0, 5 ); STEP( 0, 6 ); STEP( 0, 7 ); STEP( 0, 8 ); |
| 162 | STEP( 0, 9 ); STEP( 0, 10); STEP( 0, 11); STEP( 0, 12); |
| 163 | L_common_0_3 = L_result; |
| 164 | |
| 165 | /* i = 0 */ |
| 166 | |
| 167 | STEP( 0, 0 ); |
| 168 | L_result <<= 1; /* implicit in L_MULT */ |
| 169 | EM = L_result; |
| 170 | |
| 171 | /* i = 1 */ |
| 172 | |
| 173 | L_result = 0; |
| 174 | STEP( 1, 0 ); |
| 175 | STEP( 1, 1 ); STEP( 1, 2 ); STEP( 1, 3 ); STEP( 1, 4 ); |
| 176 | STEP( 1, 5 ); STEP( 1, 6 ); STEP( 1, 7 ); STEP( 1, 8 ); |
| 177 | STEP( 1, 9 ); STEP( 1, 10); STEP( 1, 11); STEP( 1, 12); |
| 178 | L_result <<= 1; |
| 179 | if (L_result > EM) { |
| 180 | Mc = 1; |
| 181 | EM = L_result; |
| 182 | } |
| 183 | |
| 184 | /* i = 2 */ |
| 185 | |
| 186 | L_result = 0; |
| 187 | STEP( 2, 0 ); |
| 188 | STEP( 2, 1 ); STEP( 2, 2 ); STEP( 2, 3 ); STEP( 2, 4 ); |
| 189 | STEP( 2, 5 ); STEP( 2, 6 ); STEP( 2, 7 ); STEP( 2, 8 ); |
| 190 | STEP( 2, 9 ); STEP( 2, 10); STEP( 2, 11); STEP( 2, 12); |
| 191 | L_result <<= 1; |
| 192 | if (L_result > EM) { |
| 193 | Mc = 2; |
| 194 | EM = L_result; |
| 195 | } |
| 196 | |
| 197 | /* i = 3 */ |
| 198 | |
| 199 | L_result = L_common_0_3; |
| 200 | STEP( 3, 12 ); |
| 201 | L_result <<= 1; |
| 202 | if (L_result > EM) { |
| 203 | Mc = 3; |
| 204 | EM = L_result; |
| 205 | } |
| 206 | |
| 207 | /**/ |
| 208 | |
| 209 | /* Down-sampling by a factor 3 to get the selected xM[0..12] |
| 210 | * RPE sequence. |
| 211 | */ |
| 212 | for (i = 0; i <= 12; i ++) xM[i] = x[Mc + 3*i]; |
| 213 | *Mc_out = Mc; |
| 214 | } |
| 215 | |
| 216 | /* 4.12.15 */ |
| 217 | |
| 218 | static void APCM_quantization_xmaxc_to_exp_mant ( |
| 219 | word xmaxc, /* IN */ |
| 220 | word * expon_out, /* OUT */ |
| 221 | word * mant_out ) /* OUT */ |
| 222 | { |
| 223 | word expon, mant; |
| 224 | |
| 225 | /* Compute expononent and mantissa of the decoded version of xmaxc |
| 226 | */ |
| 227 | |
| 228 | expon = 0; |
| 229 | if (xmaxc > 15) expon = SASR_W(xmaxc, 3) - 1; |
| 230 | mant = xmaxc - (expon << 3); |
| 231 | |
| 232 | if (mant == 0) { |
| 233 | expon = -4; |
| 234 | mant = 7; |
| 235 | } |
| 236 | else { |
| 237 | while (mant <= 7) { |
| 238 | mant = mant << 1 | 1; |
| 239 | expon--; |
| 240 | } |
| 241 | mant -= 8; |
| 242 | } |
| 243 | |
| 244 | assert( expon >= -4 && expon <= 6 ); |
| 245 | assert( mant >= 0 && mant <= 7 ); |
| 246 | |
| 247 | *expon_out = expon; |
| 248 | *mant_out = mant; |
| 249 | } |
| 250 | |
| 251 | static void APCM_quantization ( |
| 252 | word * xM, /* [0..12] IN */ |
| 253 | word * xMc, /* [0..12] OUT */ |
| 254 | word * mant_out, /* OUT */ |
| 255 | word * expon_out, /* OUT */ |
| 256 | word * xmaxc_out /* OUT */ |
| 257 | ) |
| 258 | { |
| 259 | int i, itest; |
| 260 | |
| 261 | word xmax, xmaxc, temp, temp1, temp2; |
| 262 | word expon, mant; |
| 263 | |
| 264 | |
| 265 | /* Find the maximum absolute value xmax of xM[0..12]. |
| 266 | */ |
| 267 | |
| 268 | xmax = 0; |
| 269 | for (i = 0; i <= 12; i++) { |
| 270 | temp = xM[i]; |
| 271 | temp = GSM_ABS(temp); |
| 272 | if (temp > xmax) xmax = temp; |
| 273 | } |
| 274 | |
| 275 | /* Qantizing and coding of xmax to get xmaxc. |
| 276 | */ |
| 277 | |
| 278 | expon = 0; |
| 279 | temp = SASR_W( xmax, 9 ); |
| 280 | itest = 0; |
| 281 | |
| 282 | for (i = 0; i <= 5; i++) { |
| 283 | |
| 284 | itest |= (temp <= 0); |
| 285 | temp = SASR_W( temp, 1 ); |
| 286 | |
| 287 | assert(expon <= 5); |
| 288 | if (itest == 0) expon++; /* expon = add (expon, 1) */ |
| 289 | } |
| 290 | |
| 291 | assert(expon <= 6 && expon >= 0); |
| 292 | temp = expon + 5; |
| 293 | |
| 294 | assert(temp <= 11 && temp >= 0); |
| 295 | xmaxc = gsm_add( SASR_W(xmax, temp), (word) (expon << 3) ); |
| 296 | |
| 297 | /* Quantizing and coding of the xM[0..12] RPE sequence |
| 298 | * to get the xMc[0..12] |
| 299 | */ |
| 300 | |
| 301 | APCM_quantization_xmaxc_to_exp_mant( xmaxc, &expon, &mant ); |
| 302 | |
| 303 | /* This computation uses the fact that the decoded version of xmaxc |
| 304 | * can be calculated by using the expononent and the mantissa part of |
| 305 | * xmaxc (logarithmic table). |
| 306 | * So, this method avoids any division and uses only a scaling |
| 307 | * of the RPE samples by a function of the expononent. A direct |
| 308 | * multiplication by the inverse of the mantissa (NRFAC[0..7] |
| 309 | * found in table 4.5) gives the 3 bit coded version xMc[0..12] |
| 310 | * of the RPE samples. |
| 311 | */ |
| 312 | |
| 313 | |
| 314 | /* Direct computation of xMc[0..12] using table 4.5 |
| 315 | */ |
| 316 | |
| 317 | assert( expon <= 4096 && expon >= -4096); |
| 318 | assert( mant >= 0 && mant <= 7 ); |
| 319 | |
| 320 | temp1 = 6 - expon; /* normalization by the expononent */ |
| 321 | temp2 = gsm_NRFAC[ mant ]; /* inverse mantissa */ |
| 322 | |
| 323 | for (i = 0; i <= 12; i++) { |
| 324 | |
| 325 | assert(temp1 >= 0 && temp1 < 16); |
| 326 | |
| 327 | temp = xM[i] << temp1; |
| 328 | temp = GSM_MULT( temp, temp2 ); |
| 329 | temp = SASR_W(temp, 12); |
| 330 | xMc[i] = temp + 4; /* see note below */ |
| 331 | } |
| 332 | |
| 333 | /* NOTE: This equation is used to make all the xMc[i] positive. |
| 334 | */ |
| 335 | |
| 336 | *mant_out = mant; |
| 337 | *expon_out = expon; |
| 338 | *xmaxc_out = xmaxc; |
| 339 | } |
| 340 | |
| 341 | /* 4.2.16 */ |
| 342 | |
| 343 | static void APCM_inverse_quantization ( |
| 344 | register word * xMc, /* [0..12] IN */ |
| 345 | word mant, |
| 346 | word expon, |
| 347 | register word * xMp) /* [0..12] OUT */ |
| 348 | /* |
| 349 | * This part is for decoding the RPE sequence of coded xMc[0..12] |
| 350 | * samples to obtain the xMp[0..12] array. Table 4.6 is used to get |
| 351 | * the mantissa of xmaxc (FAC[0..7]). |
| 352 | */ |
| 353 | { |
| 354 | int i; |
| 355 | word temp, temp1, temp2, temp3; |
| 356 | |
| 357 | assert( mant >= 0 && mant <= 7 ); |
| 358 | |
| 359 | temp1 = gsm_FAC[ mant ]; /* see 4.2-15 for mant */ |
| 360 | temp2 = gsm_sub( 6, expon ); /* see 4.2-15 for exp */ |
| 361 | temp3 = gsm_asl( 1, gsm_sub( temp2, 1 )); |
| 362 | |
| 363 | for (i = 13; i--;) { |
| 364 | |
| 365 | assert( *xMc <= 7 && *xMc >= 0 ); /* 3 bit unsigned */ |
| 366 | |
| 367 | /* temp = gsm_sub( *xMc++ << 1, 7 ); */ |
| 368 | temp = (*xMc++ << 1) - 7; /* restore sign */ |
| 369 | assert( temp <= 7 && temp >= -7 ); /* 4 bit signed */ |
| 370 | |
| 371 | temp <<= 12; /* 16 bit signed */ |
| 372 | temp = GSM_MULT_R( temp1, temp ); |
| 373 | temp = GSM_ADD( temp, temp3 ); |
| 374 | *xMp++ = gsm_asr( temp, temp2 ); |
| 375 | } |
| 376 | } |
| 377 | |
| 378 | /* 4.2.17 */ |
| 379 | |
| 380 | static void RPE_grid_positioning ( |
| 381 | word Mc, /* grid position IN */ |
| 382 | register word * xMp, /* [0..12] IN */ |
| 383 | register word * ep /* [0..39] OUT */ |
| 384 | ) |
| 385 | /* |
| 386 | * This procedure computes the reconstructed long term residual signal |
| 387 | * ep[0..39] for the LTP analysis filter. The inputs are the Mc |
| 388 | * which is the grid position selection and the xMp[0..12] decoded |
| 389 | * RPE samples which are upsampled by a factor of 3 by inserting zero |
| 390 | * values. |
| 391 | */ |
| 392 | { |
| 393 | int i = 13; |
| 394 | |
| 395 | assert(0 <= Mc && Mc <= 3); |
| 396 | |
| 397 | switch (Mc) { |
| 398 | case 3: *ep++ = 0; |
| 399 | case 2: do { |
| 400 | *ep++ = 0; |
| 401 | case 1: *ep++ = 0; |
| 402 | case 0: *ep++ = *xMp++; |
| 403 | } while (--i); |
| 404 | } |
| 405 | while (++Mc < 4) *ep++ = 0; |
| 406 | |
| 407 | /* |
| 408 | |
| 409 | int i, k; |
| 410 | for (k = 0; k <= 39; k++) ep[k] = 0; |
| 411 | for (i = 0; i <= 12; i++) { |
| 412 | ep[ Mc + (3*i) ] = xMp[i]; |
| 413 | } |
| 414 | */ |
| 415 | } |
| 416 | |
| 417 | /* 4.2.18 */ |
| 418 | |
| 419 | /* This procedure adds the reconstructed long term residual signal |
| 420 | * ep[0..39] to the estimated signal dpp[0..39] from the long term |
| 421 | * analysis filter to compute the reconstructed short term residual |
| 422 | * signal dp[-40..-1]; also the reconstructed short term residual |
| 423 | * array dp[-120..-41] is updated. |
| 424 | */ |
| 425 | |
| 426 | #if 0 /* Has been inlined in code.c */ |
| 427 | void Gsm_Update_of_reconstructed_short_time_residual_signal ( |
| 428 | word * dpp, /* [0...39] IN */ |
| 429 | word * ep, /* [0...39] IN */ |
| 430 | word * dp) /* [-120...-1] IN/OUT */ |
| 431 | { |
| 432 | int k; |
| 433 | |
| 434 | for (k = 0; k <= 79; k++) |
| 435 | dp[ -120 + k ] = dp[ -80 + k ]; |
| 436 | |
| 437 | for (k = 0; k <= 39; k++) |
| 438 | dp[ -40 + k ] = gsm_add( ep[k], dpp[k] ); |
| 439 | } |
| 440 | #endif /* Has been inlined in code.c */ |
| 441 | |
| 442 | void Gsm_RPE_Encoding ( |
| 443 | /*-struct gsm_state * S,-*/ |
| 444 | |
| 445 | word * e, /* -5..-1][0..39][40..44 IN/OUT */ |
| 446 | word * xmaxc, /* OUT */ |
| 447 | word * Mc, /* OUT */ |
| 448 | word * xMc) /* [0..12] OUT */ |
| 449 | { |
| 450 | word x[40]; |
| 451 | word xM[13], xMp[13]; |
| 452 | word mant, expon; |
| 453 | |
| 454 | Weighting_filter(e, x); |
| 455 | RPE_grid_selection(x, xM, Mc); |
| 456 | |
| 457 | APCM_quantization( xM, xMc, &mant, &expon, xmaxc); |
| 458 | APCM_inverse_quantization( xMc, mant, expon, xMp); |
| 459 | |
| 460 | RPE_grid_positioning( *Mc, xMp, e ); |
| 461 | |
| 462 | } |
| 463 | |
| 464 | void Gsm_RPE_Decoding ( |
| 465 | /*-struct gsm_state * S,-*/ |
| 466 | |
| 467 | word xmaxcr, |
| 468 | word Mcr, |
| 469 | word * xMcr, /* [0..12], 3 bits IN */ |
| 470 | word * erp /* [0..39] OUT */ |
| 471 | ) |
| 472 | { |
| 473 | word expon, mant; |
| 474 | word xMp[ 13 ]; |
| 475 | |
| 476 | APCM_quantization_xmaxc_to_exp_mant( xmaxcr, &expon, &mant ); |
| 477 | APCM_inverse_quantization( xMcr, mant, expon, xMp ); |
| 478 | RPE_grid_positioning( Mcr, xMp, erp ); |
| 479 | |
| 480 | } |