ref: 41190aa441c0dad219431069f2707af302ecd392
dir: /libgsm/long_term.c/
/* * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische * Universitaet Berlin. See the accompanying file "COPYRIGHT" for * details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE. */ /* $Header: /cvsroot/sox/sox/libgsm/long_term.c,v 1.2 2007/11/04 16:32:36 robs Exp $ */ #include <stdio.h> #include <assert.h> #include "private.h" #include "gsm.h" /* * 4.2.11 .. 4.2.12 LONG TERM PREDICTOR (LTP) SECTION */ /* * This module computes the LTP gain (bc) and the LTP lag (Nc) * for the long term analysis filter. This is done by calculating a * maximum of the cross-correlation function between the current * sub-segment short term residual signal d[0..39] (output of * the short term analysis filter; for simplification the index * of this array begins at 0 and ends at 39 for each sub-segment of the * RPE-LTP analysis) and the previous reconstructed short term * residual signal dp[ -120 .. -1 ]. A dynamic scaling must be * performed to avoid overflow. */ /* The next procedure exists in six versions. First two integer * version (if USE_FLOAT_MUL is not defined); then four floating * point versions, twice with proper scaling (USE_FLOAT_MUL defined), * once without (USE_FLOAT_MUL and FAST defined, and fast run-time * option used). Every pair has first a Cut version (see the -C * option to toast or the LTP_CUT option to gsm_option()), then the * uncut one. (For a detailed explanation of why this is altogether * a bad idea, see Henry Spencer and Geoff Collyer, ``#ifdef Considered * Harmful''.) */ #ifndef USE_FLOAT_MUL #ifdef LTP_CUT static void Cut_Calculation_of_the_LTP_parameters ( struct gsm_state * st, register word * d, /* [0..39] IN */ register word * dp, /* [-120..-1] IN */ word * bc_out, /* OUT */ word * Nc_out /* OUT */ ) { register int k, lambda; word Nc, bc; word wt[40]; longword L_result; longword L_max, L_power; word R, S, dmax, scal, best_k; word ltp_cut; register word temp, wt_k; /* Search of the optimum scaling of d[0..39]. */ dmax = 0; for (k = 0; k <= 39; k++) { temp = d[k]; temp = GSM_ABS( temp ); if (temp > dmax) { dmax = temp; best_k = k; } } temp = 0; if (dmax == 0) scal = 0; else { assert(dmax > 0); temp = gsm_norm( (longword)dmax << 16 ); } if (temp > 6) scal = 0; else scal = 6 - temp; assert(scal >= 0); /* Search for the maximum cross-correlation and coding of the LTP lag */ L_max = 0; Nc = 40; /* index for the maximum cross-correlation */ wt_k = SASR(d[best_k], scal); for (lambda = 40; lambda <= 120; lambda++) { L_result = (longword)wt_k * dp[best_k - lambda]; if (L_result > L_max) { Nc = lambda; L_max = L_result; } } *Nc_out = Nc; L_max <<= 1; /* Rescaling of L_max */ assert(scal <= 100 && scal >= -100); L_max = L_max >> (6 - scal); /* sub(6, scal) */ assert( Nc <= 120 && Nc >= 40); /* Compute the power of the reconstructed short term residual * signal dp[..] */ L_power = 0; for (k = 0; k <= 39; k++) { register longword L_temp; L_temp = SASR( dp[k - Nc], 3 ); L_power += L_temp * L_temp; } L_power <<= 1; /* from L_MULT */ /* Normalization of L_max and L_power */ if (L_max <= 0) { *bc_out = 0; return; } if (L_max >= L_power) { *bc_out = 3; return; } temp = gsm_norm( L_power ); R = SASR( L_max << temp, 16 ); S = SASR( L_power << temp, 16 ); /* Coding of the LTP gain */ /* Table 4.3a must be used to obtain the level DLB[i] for the * quantization of the LTP gain b to get the coded version bc. */ for (bc = 0; bc <= 2; bc++) if (R <= gsm_mult(S, gsm_DLB[bc])) break; *bc_out = bc; } #endif /* LTP_CUT */ static void Calculation_of_the_LTP_parameters ( register word * d, /* [0..39] IN */ register word * dp, /* [-120..-1] IN */ word * bc_out, /* OUT */ word * Nc_out /* OUT */ ) { register int k, lambda; word Nc, bc; word wt[40]; longword L_max, L_power; word R, S, dmax, scal; register word temp; /* Search of the optimum scaling of d[0..39]. */ dmax = 0; for (k = 0; k <= 39; k++) { temp = d[k]; temp = GSM_ABS( temp ); if (temp > dmax) dmax = temp; } temp = 0; if (dmax == 0) scal = 0; else { assert(dmax > 0); temp = gsm_norm( (longword)dmax << 16 ); } if (temp > 6) scal = 0; else scal = 6 - temp; assert(scal >= 0); /* Initialization of a working array wt */ for (k = 0; k <= 39; k++) wt[k] = SASR( d[k], scal ); /* Search for the maximum cross-correlation and coding of the LTP lag */ L_max = 0; Nc = 40; /* index for the maximum cross-correlation */ for (lambda = 40; lambda <= 120; lambda++) { # undef STEP # define STEP(k) (longword)wt[k] * dp[k - lambda] register longword L_result; L_result = STEP(0) ; L_result += STEP(1) ; L_result += STEP(2) ; L_result += STEP(3) ; L_result += STEP(4) ; L_result += STEP(5) ; L_result += STEP(6) ; L_result += STEP(7) ; L_result += STEP(8) ; L_result += STEP(9) ; L_result += STEP(10) ; L_result += STEP(11) ; L_result += STEP(12) ; L_result += STEP(13) ; L_result += STEP(14) ; L_result += STEP(15) ; L_result += STEP(16) ; L_result += STEP(17) ; L_result += STEP(18) ; L_result += STEP(19) ; L_result += STEP(20) ; L_result += STEP(21) ; L_result += STEP(22) ; L_result += STEP(23) ; L_result += STEP(24) ; L_result += STEP(25) ; L_result += STEP(26) ; L_result += STEP(27) ; L_result += STEP(28) ; L_result += STEP(29) ; L_result += STEP(30) ; L_result += STEP(31) ; L_result += STEP(32) ; L_result += STEP(33) ; L_result += STEP(34) ; L_result += STEP(35) ; L_result += STEP(36) ; L_result += STEP(37) ; L_result += STEP(38) ; L_result += STEP(39) ; if (L_result > L_max) { Nc = lambda; L_max = L_result; } } *Nc_out = Nc; L_max <<= 1; /* Rescaling of L_max */ assert(scal <= 100 && scal >= -100); L_max = L_max >> (6 - scal); /* sub(6, scal) */ assert( Nc <= 120 && Nc >= 40); /* Compute the power of the reconstructed short term residual * signal dp[..] */ L_power = 0; for (k = 0; k <= 39; k++) { register longword L_temp; L_temp = SASR( dp[k - Nc], 3 ); L_power += L_temp * L_temp; } L_power <<= 1; /* from L_MULT */ /* Normalization of L_max and L_power */ if (L_max <= 0) { *bc_out = 0; return; } if (L_max >= L_power) { *bc_out = 3; return; } temp = gsm_norm( L_power ); R = SASR( L_max << temp, 16 ); S = SASR( L_power << temp, 16 ); /* Coding of the LTP gain */ /* Table 4.3a must be used to obtain the level DLB[i] for the * quantization of the LTP gain b to get the coded version bc. */ for (bc = 0; bc <= 2; bc++) if (R <= gsm_mult(S, gsm_DLB[bc])) break; *bc_out = bc; } #else /* USE_FLOAT_MUL */ #ifdef LTP_CUT static void Cut_Calculation_of_the_LTP_parameters ( struct gsm_state * st, /* IN */ register word * d, /* [0..39] IN */ register word * dp, /* [-120..-1] IN */ word * bc_out, /* OUT */ word * Nc_out /* OUT */ ) { register int k, lambda; word Nc, bc; word ltp_cut; float wt_float[40]; float dp_float_base[120], * dp_float = dp_float_base + 120; longword L_max, L_power; word R, S, dmax, scal; register word temp; /* Search of the optimum scaling of d[0..39]. */ dmax = 0; for (k = 0; k <= 39; k++) { temp = d[k]; temp = GSM_ABS( temp ); if (temp > dmax) dmax = temp; } temp = 0; if (dmax == 0) scal = 0; else { assert(dmax > 0); temp = gsm_norm( (longword)dmax << 16 ); } if (temp > 6) scal = 0; else scal = 6 - temp; assert(scal >= 0); ltp_cut = (longword)SASR(dmax, scal) * st->ltp_cut / 100; /* Initialization of a working array wt */ for (k = 0; k < 40; k++) { register word w = SASR( d[k], scal ); if (w < 0 ? w > -ltp_cut : w < ltp_cut) { wt_float[k] = 0.0; } else { wt_float[k] = w; } } for (k = -120; k < 0; k++) dp_float[k] = dp[k]; /* Search for the maximum cross-correlation and coding of the LTP lag */ L_max = 0; Nc = 40; /* index for the maximum cross-correlation */ for (lambda = 40; lambda <= 120; lambda += 9) { /* Calculate L_result for l = lambda .. lambda + 9. */ register float *lp = dp_float - lambda; register float W; register float a = lp[-8], b = lp[-7], c = lp[-6], d = lp[-5], e = lp[-4], f = lp[-3], g = lp[-2], h = lp[-1]; register float E; register float S0 = 0, S1 = 0, S2 = 0, S3 = 0, S4 = 0, S5 = 0, S6 = 0, S7 = 0, S8 = 0; # undef STEP # define STEP(K, a, b, c, d, e, f, g, h) \ if ((W = wt_float[K]) != 0.0) { \ E = W * a; S8 += E; \ E = W * b; S7 += E; \ E = W * c; S6 += E; \ E = W * d; S5 += E; \ E = W * e; S4 += E; \ E = W * f; S3 += E; \ E = W * g; S2 += E; \ E = W * h; S1 += E; \ a = lp[K]; \ E = W * a; S0 += E; } else (a = lp[K]) # define STEP_A(K) STEP(K, a, b, c, d, e, f, g, h) # define STEP_B(K) STEP(K, b, c, d, e, f, g, h, a) # define STEP_C(K) STEP(K, c, d, e, f, g, h, a, b) # define STEP_D(K) STEP(K, d, e, f, g, h, a, b, c) # define STEP_E(K) STEP(K, e, f, g, h, a, b, c, d) # define STEP_F(K) STEP(K, f, g, h, a, b, c, d, e) # define STEP_G(K) STEP(K, g, h, a, b, c, d, e, f) # define STEP_H(K) STEP(K, h, a, b, c, d, e, f, g) STEP_A( 0); STEP_B( 1); STEP_C( 2); STEP_D( 3); STEP_E( 4); STEP_F( 5); STEP_G( 6); STEP_H( 7); STEP_A( 8); STEP_B( 9); STEP_C(10); STEP_D(11); STEP_E(12); STEP_F(13); STEP_G(14); STEP_H(15); STEP_A(16); STEP_B(17); STEP_C(18); STEP_D(19); STEP_E(20); STEP_F(21); STEP_G(22); STEP_H(23); STEP_A(24); STEP_B(25); STEP_C(26); STEP_D(27); STEP_E(28); STEP_F(29); STEP_G(30); STEP_H(31); STEP_A(32); STEP_B(33); STEP_C(34); STEP_D(35); STEP_E(36); STEP_F(37); STEP_G(38); STEP_H(39); if (S0 > L_max) { L_max = S0; Nc = lambda; } if (S1 > L_max) { L_max = S1; Nc = lambda + 1; } if (S2 > L_max) { L_max = S2; Nc = lambda + 2; } if (S3 > L_max) { L_max = S3; Nc = lambda + 3; } if (S4 > L_max) { L_max = S4; Nc = lambda + 4; } if (S5 > L_max) { L_max = S5; Nc = lambda + 5; } if (S6 > L_max) { L_max = S6; Nc = lambda + 6; } if (S7 > L_max) { L_max = S7; Nc = lambda + 7; } if (S8 > L_max) { L_max = S8; Nc = lambda + 8; } } *Nc_out = Nc; L_max <<= 1; /* Rescaling of L_max */ assert(scal <= 100 && scal >= -100); L_max = L_max >> (6 - scal); /* sub(6, scal) */ assert( Nc <= 120 && Nc >= 40); /* Compute the power of the reconstructed short term residual * signal dp[..] */ L_power = 0; for (k = 0; k <= 39; k++) { register longword L_temp; L_temp = SASR( dp[k - Nc], 3 ); L_power += L_temp * L_temp; } L_power <<= 1; /* from L_MULT */ /* Normalization of L_max and L_power */ if (L_max <= 0) { *bc_out = 0; return; } if (L_max >= L_power) { *bc_out = 3; return; } temp = gsm_norm( L_power ); R = SASR( L_max << temp, 16 ); S = SASR( L_power << temp, 16 ); /* Coding of the LTP gain */ /* Table 4.3a must be used to obtain the level DLB[i] for the * quantization of the LTP gain b to get the coded version bc. */ for (bc = 0; bc <= 2; bc++) if (R <= gsm_mult(S, gsm_DLB[bc])) break; *bc_out = bc; } #endif /* LTP_CUT */ static void Calculation_of_the_LTP_parameters ( register word * d, /* [0..39] IN */ register word * dp, /* [-120..-1] IN */ word * bc_out, /* OUT */ word * Nc_out /* OUT */ ) { register int k, lambda; word Nc, bc; float wt_float[40]; float dp_float_base[120], * dp_float = dp_float_base + 120; longword L_max, L_power; word R, S, dmax, scal; register word temp; /* Search of the optimum scaling of d[0..39]. */ dmax = 0; for (k = 0; k <= 39; k++) { temp = d[k]; temp = GSM_ABS( temp ); if (temp > dmax) dmax = temp; } temp = 0; if (dmax == 0) scal = 0; else { assert(dmax > 0); temp = gsm_norm( (longword)dmax << 16 ); } if (temp > 6) scal = 0; else scal = 6 - temp; assert(scal >= 0); /* Initialization of a working array wt */ for (k = 0; k < 40; k++) wt_float[k] = SASR( d[k], scal ); for (k = -120; k < 0; k++) dp_float[k] = dp[k]; /* Search for the maximum cross-correlation and coding of the LTP lag */ L_max = 0; Nc = 40; /* index for the maximum cross-correlation */ for (lambda = 40; lambda <= 120; lambda += 9) { /* Calculate L_result for l = lambda .. lambda + 9. */ register float *lp = dp_float - lambda; register float W; register float a = lp[-8], b = lp[-7], c = lp[-6], d = lp[-5], e = lp[-4], f = lp[-3], g = lp[-2], h = lp[-1]; register float E; register float S0 = 0, S1 = 0, S2 = 0, S3 = 0, S4 = 0, S5 = 0, S6 = 0, S7 = 0, S8 = 0; # undef STEP # define STEP(K, a, b, c, d, e, f, g, h) \ W = wt_float[K]; \ E = W * a; S8 += E; \ E = W * b; S7 += E; \ E = W * c; S6 += E; \ E = W * d; S5 += E; \ E = W * e; S4 += E; \ E = W * f; S3 += E; \ E = W * g; S2 += E; \ E = W * h; S1 += E; \ a = lp[K]; \ E = W * a; S0 += E # define STEP_A(K) STEP(K, a, b, c, d, e, f, g, h) # define STEP_B(K) STEP(K, b, c, d, e, f, g, h, a) # define STEP_C(K) STEP(K, c, d, e, f, g, h, a, b) # define STEP_D(K) STEP(K, d, e, f, g, h, a, b, c) # define STEP_E(K) STEP(K, e, f, g, h, a, b, c, d) # define STEP_F(K) STEP(K, f, g, h, a, b, c, d, e) # define STEP_G(K) STEP(K, g, h, a, b, c, d, e, f) # define STEP_H(K) STEP(K, h, a, b, c, d, e, f, g) STEP_A( 0); STEP_B( 1); STEP_C( 2); STEP_D( 3); STEP_E( 4); STEP_F( 5); STEP_G( 6); STEP_H( 7); STEP_A( 8); STEP_B( 9); STEP_C(10); STEP_D(11); STEP_E(12); STEP_F(13); STEP_G(14); STEP_H(15); STEP_A(16); STEP_B(17); STEP_C(18); STEP_D(19); STEP_E(20); STEP_F(21); STEP_G(22); STEP_H(23); STEP_A(24); STEP_B(25); STEP_C(26); STEP_D(27); STEP_E(28); STEP_F(29); STEP_G(30); STEP_H(31); STEP_A(32); STEP_B(33); STEP_C(34); STEP_D(35); STEP_E(36); STEP_F(37); STEP_G(38); STEP_H(39); if (S0 > L_max) { L_max = S0; Nc = lambda; } if (S1 > L_max) { L_max = S1; Nc = lambda + 1; } if (S2 > L_max) { L_max = S2; Nc = lambda + 2; } if (S3 > L_max) { L_max = S3; Nc = lambda + 3; } if (S4 > L_max) { L_max = S4; Nc = lambda + 4; } if (S5 > L_max) { L_max = S5; Nc = lambda + 5; } if (S6 > L_max) { L_max = S6; Nc = lambda + 6; } if (S7 > L_max) { L_max = S7; Nc = lambda + 7; } if (S8 > L_max) { L_max = S8; Nc = lambda + 8; } } *Nc_out = Nc; L_max <<= 1; /* Rescaling of L_max */ assert(scal <= 100 && scal >= -100); L_max = L_max >> (6 - scal); /* sub(6, scal) */ assert( Nc <= 120 && Nc >= 40); /* Compute the power of the reconstructed short term residual * signal dp[..] */ L_power = 0; for (k = 0; k <= 39; k++) { register longword L_temp; L_temp = SASR( dp[k - Nc], 3 ); L_power += L_temp * L_temp; } L_power <<= 1; /* from L_MULT */ /* Normalization of L_max and L_power */ if (L_max <= 0) { *bc_out = 0; return; } if (L_max >= L_power) { *bc_out = 3; return; } temp = gsm_norm( L_power ); R = SASR( L_max << temp, 16 ); S = SASR( L_power << temp, 16 ); /* Coding of the LTP gain */ /* Table 4.3a must be used to obtain the level DLB[i] for the * quantization of the LTP gain b to get the coded version bc. */ for (bc = 0; bc <= 2; bc++) if (R <= gsm_mult(S, gsm_DLB[bc])) break; *bc_out = bc; } #ifdef FAST #ifdef LTP_CUT static void Cut_Fast_Calculation_of_the_LTP_parameters ( struct gsm_state * st, /* IN */ register word * d, /* [0..39] IN */ register word * dp, /* [-120..-1] IN */ word * bc_out, /* OUT */ word * Nc_out /* OUT */ ) { register int k, lambda; register float wt_float; word Nc, bc; word wt_max, best_k, ltp_cut; float dp_float_base[120], * dp_float = dp_float_base + 120; register float L_result, L_max, L_power; wt_max = 0; for (k = 0; k < 40; ++k) { if ( d[k] > wt_max) wt_max = d[best_k = k]; else if (-d[k] > wt_max) wt_max = -d[best_k = k]; } assert(wt_max >= 0); wt_float = (float)wt_max; for (k = -120; k < 0; ++k) dp_float[k] = (float)dp[k]; /* Search for the maximum cross-correlation and coding of the LTP lag */ L_max = 0; Nc = 40; /* index for the maximum cross-correlation */ for (lambda = 40; lambda <= 120; lambda++) { L_result = wt_float * dp_float[best_k - lambda]; if (L_result > L_max) { Nc = lambda; L_max = L_result; } } *Nc_out = Nc; if (L_max <= 0.) { *bc_out = 0; return; } /* Compute the power of the reconstructed short term residual * signal dp[..] */ dp_float -= Nc; L_power = 0; for (k = 0; k < 40; ++k) { register float f = dp_float[k]; L_power += f * f; } if (L_max >= L_power) { *bc_out = 3; return; } /* Coding of the LTP gain * Table 4.3a must be used to obtain the level DLB[i] for the * quantization of the LTP gain b to get the coded version bc. */ lambda = L_max / L_power * 32768.; for (bc = 0; bc <= 2; ++bc) if (lambda <= gsm_DLB[bc]) break; *bc_out = bc; } #endif /* LTP_CUT */ static void Fast_Calculation_of_the_LTP_parameters ( register word * d, /* [0..39] IN */ register word * dp, /* [-120..-1] IN */ word * bc_out, /* OUT */ word * Nc_out /* OUT */ ) { register int k, lambda; word Nc, bc; float wt_float[40]; float dp_float_base[120], * dp_float = dp_float_base + 120; register float L_max, L_power; for (k = 0; k < 40; ++k) wt_float[k] = (float)d[k]; for (k = -120; k < 0; ++k) dp_float[k] = (float)dp[k]; /* Search for the maximum cross-correlation and coding of the LTP lag */ L_max = 0; Nc = 40; /* index for the maximum cross-correlation */ for (lambda = 40; lambda <= 120; lambda += 9) { /* Calculate L_result for l = lambda .. lambda + 9. */ register float *lp = dp_float - lambda; register float W; register float a = lp[-8], b = lp[-7], c = lp[-6], d = lp[-5], e = lp[-4], f = lp[-3], g = lp[-2], h = lp[-1]; register float E; register float S0 = 0, S1 = 0, S2 = 0, S3 = 0, S4 = 0, S5 = 0, S6 = 0, S7 = 0, S8 = 0; # undef STEP # define STEP(K, a, b, c, d, e, f, g, h) \ W = wt_float[K]; \ E = W * a; S8 += E; \ E = W * b; S7 += E; \ E = W * c; S6 += E; \ E = W * d; S5 += E; \ E = W * e; S4 += E; \ E = W * f; S3 += E; \ E = W * g; S2 += E; \ E = W * h; S1 += E; \ a = lp[K]; \ E = W * a; S0 += E # define STEP_A(K) STEP(K, a, b, c, d, e, f, g, h) # define STEP_B(K) STEP(K, b, c, d, e, f, g, h, a) # define STEP_C(K) STEP(K, c, d, e, f, g, h, a, b) # define STEP_D(K) STEP(K, d, e, f, g, h, a, b, c) # define STEP_E(K) STEP(K, e, f, g, h, a, b, c, d) # define STEP_F(K) STEP(K, f, g, h, a, b, c, d, e) # define STEP_G(K) STEP(K, g, h, a, b, c, d, e, f) # define STEP_H(K) STEP(K, h, a, b, c, d, e, f, g) STEP_A( 0); STEP_B( 1); STEP_C( 2); STEP_D( 3); STEP_E( 4); STEP_F( 5); STEP_G( 6); STEP_H( 7); STEP_A( 8); STEP_B( 9); STEP_C(10); STEP_D(11); STEP_E(12); STEP_F(13); STEP_G(14); STEP_H(15); STEP_A(16); STEP_B(17); STEP_C(18); STEP_D(19); STEP_E(20); STEP_F(21); STEP_G(22); STEP_H(23); STEP_A(24); STEP_B(25); STEP_C(26); STEP_D(27); STEP_E(28); STEP_F(29); STEP_G(30); STEP_H(31); STEP_A(32); STEP_B(33); STEP_C(34); STEP_D(35); STEP_E(36); STEP_F(37); STEP_G(38); STEP_H(39); if (S0 > L_max) { L_max = S0; Nc = lambda; } if (S1 > L_max) { L_max = S1; Nc = lambda + 1; } if (S2 > L_max) { L_max = S2; Nc = lambda + 2; } if (S3 > L_max) { L_max = S3; Nc = lambda + 3; } if (S4 > L_max) { L_max = S4; Nc = lambda + 4; } if (S5 > L_max) { L_max = S5; Nc = lambda + 5; } if (S6 > L_max) { L_max = S6; Nc = lambda + 6; } if (S7 > L_max) { L_max = S7; Nc = lambda + 7; } if (S8 > L_max) { L_max = S8; Nc = lambda + 8; } } *Nc_out = Nc; if (L_max <= 0.) { *bc_out = 0; return; } /* Compute the power of the reconstructed short term residual * signal dp[..] */ dp_float -= Nc; L_power = 0; for (k = 0; k < 40; ++k) { register float f = dp_float[k]; L_power += f * f; } if (L_max >= L_power) { *bc_out = 3; return; } /* Coding of the LTP gain * Table 4.3a must be used to obtain the level DLB[i] for the * quantization of the LTP gain b to get the coded version bc. */ lambda = L_max / L_power * 32768.; for (bc = 0; bc <= 2; ++bc) if (lambda <= gsm_DLB[bc]) break; *bc_out = bc; } #endif /* FAST */ #endif /* USE_FLOAT_MUL */ /* 4.2.12 */ static void Long_term_analysis_filtering ( word bc, /* IN */ word Nc, /* IN */ register word * dp, /* previous d [-120..-1] IN */ register word * d, /* d [0..39] IN */ register word * dpp, /* estimate [0..39] OUT */ register word * e /* long term res. signal [0..39] OUT */ ) /* * In this part, we have to decode the bc parameter to compute * the samples of the estimate dpp[0..39]. The decoding of bc needs the * use of table 4.3b. The long term residual signal e[0..39] * is then calculated to be fed to the RPE encoding section. */ { register int k; register longword ltmp; # undef STEP # define STEP(BP) \ for (k = 0; k <= 39; k++) { \ dpp[k] = GSM_MULT_R( BP, dp[k - Nc]); \ e[k] = GSM_SUB( d[k], dpp[k] ); \ } switch (bc) { case 0: STEP( 3277 ); break; case 1: STEP( 11469 ); break; case 2: STEP( 21299 ); break; case 3: STEP( 32767 ); break; } } void Gsm_Long_Term_Predictor ( /* 4x for 160 samples */ struct gsm_state * S, word * d, /* [0..39] residual signal IN */ word * dp, /* [-120..-1] d' IN */ word * e, /* [0..39] OUT */ word * dpp, /* [0..39] OUT */ word * Nc, /* correlation lag OUT */ word * bc /* gain factor OUT */ ) { (void)S; /* Denotes intentionally unused */ assert( d ); assert( dp ); assert( e ); assert( dpp); assert( Nc ); assert( bc ); #if defined(FAST) && defined(USE_FLOAT_MUL) if (S->fast) #if defined (LTP_CUT) if (S->ltp_cut) Cut_Fast_Calculation_of_the_LTP_parameters(S, d, dp, bc, Nc); else #endif /* LTP_CUT */ Fast_Calculation_of_the_LTP_parameters(d, dp, bc, Nc ); else #endif /* FAST & USE_FLOAT_MUL */ #ifdef LTP_CUT if (S->ltp_cut) Cut_Calculation_of_the_LTP_parameters(S, d, dp, bc, Nc); else #endif Calculation_of_the_LTP_parameters(d, dp, bc, Nc); Long_term_analysis_filtering( *bc, *Nc, dp, d, dpp, e ); } /* 4.3.2 */ void Gsm_Long_Term_Synthesis_Filtering ( struct gsm_state * S, word Ncr, word bcr, register word * erp, /* [0..39] IN */ register word * drp /* [-120..-1] IN, [-120..40] OUT */ ) /* * This procedure uses the bcr and Ncr parameter to realize the * long term synthesis filtering. The decoding of bcr needs * table 4.3b. */ { register longword ltmp; /* for ADD */ register int k; word brp, drpp, Nr; /* Check the limits of Nr. */ Nr = Ncr < 40 || Ncr > 120 ? S->nrp : Ncr; S->nrp = Nr; assert(Nr >= 40 && Nr <= 120); /* Decoding of the LTP gain bcr */ brp = gsm_QLB[ bcr ]; /* Computation of the reconstructed short term residual * signal drp[0..39] */ assert(brp != MIN_WORD); for (k = 0; k <= 39; k++) { drpp = GSM_MULT_R( brp, drp[ k - Nr ] ); drp[k] = GSM_ADD( erp[k], drpp ); } /* * Update of the reconstructed short term residual signal * drp[ -1..-120 ] */ for (k = 0; k <= 119; k++) drp[ -120 + k ] = drp[ -80 + k ]; }