ref: 221db683821e9767847dff63503f7835037444c7
dir: /src/libgsm/rpe.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/src/libgsm/Attic/rpe.c,v 1.5 2007/01/29 03:09:33 cbagwell Exp $ */ #include <stdio.h> #include <assert.h> #include "private.h" #include "gsm.h" /* 4.2.13 .. 4.2.17 RPE ENCODING SECTION */ /* 4.2.13 */ static void Weighting_filter ( register word * e, /* signal [-5..0.39.44] IN */ word * x /* signal [0..39] OUT */ ) /* * The coefficients of the weighting filter are stored in a table * (see table 4.4). The following scaling is used: * * H[0..10] = integer( real_H[ 0..10] * 8192 ); */ { /* word wt[ 50 ]; */ register longword L_result; register int k /* , i */ ; /* Initialization of a temporary working array wt[0...49] */ /* for (k = 0; k <= 4; k++) wt[k] = 0; * for (k = 5; k <= 44; k++) wt[k] = *e++; * for (k = 45; k <= 49; k++) wt[k] = 0; * * (e[-5..-1] and e[40..44] are allocated by the caller, * are initially zero and are not written anywhere.) */ e -= 5; /* Compute the signal x[0..39] */ for (k = 0; k <= 39; k++) { L_result = 8192 >> 1; /* for (i = 0; i <= 10; i++) { * L_temp = GSM_L_MULT( wt[k+i], gsm_H[i] ); * L_result = GSM_L_ADD( L_result, L_temp ); * } */ #undef STEP #define STEP( i, H ) (e[ k + i ] * (longword)H) /* Every one of these multiplications is done twice -- * but I don't see an elegant way to optimize this. * Do you? */ #ifdef STUPID_COMPILER L_result += STEP( 0, -134 ) ; L_result += STEP( 1, -374 ) ; /* + STEP( 2, 0 ) */ L_result += STEP( 3, 2054 ) ; L_result += STEP( 4, 5741 ) ; L_result += STEP( 5, 8192 ) ; L_result += STEP( 6, 5741 ) ; L_result += STEP( 7, 2054 ) ; /* + STEP( 8, 0 ) */ L_result += STEP( 9, -374 ) ; L_result += STEP( 10, -134 ) ; #else L_result += STEP( 0, -134 ) + STEP( 1, -374 ) /* + STEP( 2, 0 ) */ + STEP( 3, 2054 ) + STEP( 4, 5741 ) + STEP( 5, 8192 ) + STEP( 6, 5741 ) + STEP( 7, 2054 ) /* + STEP( 8, 0 ) */ + STEP( 9, -374 ) + STEP(10, -134 ) ; #endif /* L_result = GSM_L_ADD( L_result, L_result ); (* scaling(x2) *) * L_result = GSM_L_ADD( L_result, L_result ); (* scaling(x4) *) * * x[k] = SASR( L_result, 16 ); */ /* 2 adds vs. >>16 => 14, minus one shift to compensate for * those we lost when replacing L_MULT by '*'. */ L_result = SASR( L_result, 13 ); x[k] = ( L_result < MIN_WORD ? MIN_WORD : (L_result > MAX_WORD ? MAX_WORD : L_result )); } } /* 4.2.14 */ static void RPE_grid_selection ( word * x, /* [0..39] IN */ word * xM, /* [0..12] OUT */ word * Mc_out /* OUT */ ) /* * The signal x[0..39] is used to select the RPE grid which is * represented by Mc. */ { /* register word temp1; */ register int /* m, */ i; register longword L_result, L_temp; longword EM; /* xxx should be L_EM? */ word Mc; longword L_common_0_3; EM = 0; Mc = 0; /* for (m = 0; m <= 3; m++) { * L_result = 0; * * * for (i = 0; i <= 12; i++) { * * temp1 = SASR( x[m + 3*i], 2 ); * * assert(temp1 != MIN_WORD); * * L_temp = GSM_L_MULT( temp1, temp1 ); * L_result = GSM_L_ADD( L_temp, L_result ); * } * * if (L_result > EM) { * Mc = m; * EM = L_result; * } * } */ #undef STEP #define STEP( m, i ) L_temp = SASR( x[m + 3 * i], 2 ); \ L_result += L_temp * L_temp; /* common part of 0 and 3 */ L_result = 0; STEP( 0, 1 ); STEP( 0, 2 ); STEP( 0, 3 ); STEP( 0, 4 ); STEP( 0, 5 ); STEP( 0, 6 ); STEP( 0, 7 ); STEP( 0, 8 ); STEP( 0, 9 ); STEP( 0, 10); STEP( 0, 11); STEP( 0, 12); L_common_0_3 = L_result; /* i = 0 */ STEP( 0, 0 ); L_result <<= 1; /* implicit in L_MULT */ EM = L_result; /* i = 1 */ L_result = 0; STEP( 1, 0 ); STEP( 1, 1 ); STEP( 1, 2 ); STEP( 1, 3 ); STEP( 1, 4 ); STEP( 1, 5 ); STEP( 1, 6 ); STEP( 1, 7 ); STEP( 1, 8 ); STEP( 1, 9 ); STEP( 1, 10); STEP( 1, 11); STEP( 1, 12); L_result <<= 1; if (L_result > EM) { Mc = 1; EM = L_result; } /* i = 2 */ L_result = 0; STEP( 2, 0 ); STEP( 2, 1 ); STEP( 2, 2 ); STEP( 2, 3 ); STEP( 2, 4 ); STEP( 2, 5 ); STEP( 2, 6 ); STEP( 2, 7 ); STEP( 2, 8 ); STEP( 2, 9 ); STEP( 2, 10); STEP( 2, 11); STEP( 2, 12); L_result <<= 1; if (L_result > EM) { Mc = 2; EM = L_result; } /* i = 3 */ L_result = L_common_0_3; STEP( 3, 12 ); L_result <<= 1; if (L_result > EM) { Mc = 3; EM = L_result; } /**/ /* Down-sampling by a factor 3 to get the selected xM[0..12] * RPE sequence. */ for (i = 0; i <= 12; i ++) xM[i] = x[Mc + 3*i]; *Mc_out = Mc; } /* 4.12.15 */ static void APCM_quantization_xmaxc_to_exp_mant ( word xmaxc, /* IN */ word * exp_out, /* OUT */ word * mant_out ) /* OUT */ { word exp, mant; /* Compute exponent and mantissa of the decoded version of xmaxc */ exp = 0; if (xmaxc > 15) exp = SASR(xmaxc, 3) - 1; mant = xmaxc - (exp << 3); if (mant == 0) { exp = -4; mant = 7; } else { while (mant <= 7) { mant = mant << 1 | 1; exp--; } mant -= 8; } assert( exp >= -4 && exp <= 6 ); assert( mant >= 0 && mant <= 7 ); *exp_out = exp; *mant_out = mant; } static void APCM_quantization ( word * xM, /* [0..12] IN */ word * xMc, /* [0..12] OUT */ word * mant_out, /* OUT */ word * exp_out, /* OUT */ word * xmaxc_out /* OUT */ ) { int i, itest; word xmax, xmaxc, temp, temp1, temp2; word exp, mant; /* Find the maximum absolute value xmax of xM[0..12]. */ xmax = 0; for (i = 0; i <= 12; i++) { temp = xM[i]; temp = GSM_ABS(temp); if (temp > xmax) xmax = temp; } /* Qantizing and coding of xmax to get xmaxc. */ exp = 0; temp = SASR( xmax, 9 ); itest = 0; for (i = 0; i <= 5; i++) { itest |= (temp <= 0); temp = SASR( temp, 1 ); assert(exp <= 5); if (itest == 0) exp++; /* exp = add (exp, 1) */ } assert(exp <= 6 && exp >= 0); temp = exp + 5; assert(temp <= 11 && temp >= 0); xmaxc = gsm_add( SASR(xmax, temp), exp << 3 ); /* Quantizing and coding of the xM[0..12] RPE sequence * to get the xMc[0..12] */ APCM_quantization_xmaxc_to_exp_mant( xmaxc, &exp, &mant ); /* This computation uses the fact that the decoded version of xmaxc * can be calculated by using the exponent and the mantissa part of * xmaxc (logarithmic table). * So, this method avoids any division and uses only a scaling * of the RPE samples by a function of the exponent. A direct * multiplication by the inverse of the mantissa (NRFAC[0..7] * found in table 4.5) gives the 3 bit coded version xMc[0..12] * of the RPE samples. */ /* Direct computation of xMc[0..12] using table 4.5 */ assert( exp <= 4096 && exp >= -4096); assert( mant >= 0 && mant <= 7 ); temp1 = 6 - exp; /* normalization by the exponent */ temp2 = gsm_NRFAC[ mant ]; /* inverse mantissa */ for (i = 0; i <= 12; i++) { assert(temp1 >= 0 && temp1 < 16); temp = xM[i] << temp1; temp = GSM_MULT( temp, temp2 ); temp = SASR(temp, 12); xMc[i] = temp + 4; /* see note below */ } /* NOTE: This equation is used to make all the xMc[i] positive. */ *mant_out = mant; *exp_out = exp; *xmaxc_out = xmaxc; } /* 4.2.16 */ static void APCM_inverse_quantization ( register word * xMc, /* [0..12] IN */ word mant, word exp, register word * xMp) /* [0..12] OUT */ /* * This part is for decoding the RPE sequence of coded xMc[0..12] * samples to obtain the xMp[0..12] array. Table 4.6 is used to get * the mantissa of xmaxc (FAC[0..7]). */ { int i; word temp, temp1, temp2, temp3; longword ltmp; assert( mant >= 0 && mant <= 7 ); temp1 = gsm_FAC[ mant ]; /* see 4.2-15 for mant */ temp2 = gsm_sub( 6, exp ); /* see 4.2-15 for exp */ temp3 = gsm_asl( 1, gsm_sub( temp2, 1 )); for (i = 13; i--;) { assert( *xMc <= 7 && *xMc >= 0 ); /* 3 bit unsigned */ /* temp = gsm_sub( *xMc++ << 1, 7 ); */ temp = (*xMc++ << 1) - 7; /* restore sign */ assert( temp <= 7 && temp >= -7 ); /* 4 bit signed */ temp <<= 12; /* 16 bit signed */ temp = GSM_MULT_R( temp1, temp ); temp = GSM_ADD( temp, temp3 ); *xMp++ = gsm_asr( temp, temp2 ); } } /* 4.2.17 */ static void RPE_grid_positioning ( word Mc, /* grid position IN */ register word * xMp, /* [0..12] IN */ register word * ep /* [0..39] OUT */ ) /* * This procedure computes the reconstructed long term residual signal * ep[0..39] for the LTP analysis filter. The inputs are the Mc * which is the grid position selection and the xMp[0..12] decoded * RPE samples which are upsampled by a factor of 3 by inserting zero * values. */ { int i = 13; assert(0 <= Mc && Mc <= 3); switch (Mc) { case 3: *ep++ = 0; case 2: do { *ep++ = 0; case 1: *ep++ = 0; case 0: *ep++ = *xMp++; } while (--i); } while (++Mc < 4) *ep++ = 0; /* int i, k; for (k = 0; k <= 39; k++) ep[k] = 0; for (i = 0; i <= 12; i++) { ep[ Mc + (3*i) ] = xMp[i]; } */ } /* 4.2.18 */ /* This procedure adds the reconstructed long term residual signal * ep[0..39] to the estimated signal dpp[0..39] from the long term * analysis filter to compute the reconstructed short term residual * signal dp[-40..-1]; also the reconstructed short term residual * array dp[-120..-41] is updated. */ #if 0 /* Has been inlined in code.c */ void Gsm_Update_of_reconstructed_short_time_residual_signal P3((dpp, ep, dp), word * dpp, /* [0...39] IN */ word * ep, /* [0...39] IN */ word * dp) /* [-120...-1] IN/OUT */ { int k; for (k = 0; k <= 79; k++) dp[ -120 + k ] = dp[ -80 + k ]; for (k = 0; k <= 39; k++) dp[ -40 + k ] = gsm_add( ep[k], dpp[k] ); } #endif /* Has been inlined in code.c */ void Gsm_RPE_Encoding ( struct gsm_state * S, word * e, /* -5..-1][0..39][40..44 IN/OUT */ word * xmaxc, /* OUT */ word * Mc, /* OUT */ word * xMc) /* [0..12] OUT */ { word x[40]; word xM[13], xMp[13]; word mant, exp; Weighting_filter(e, x); RPE_grid_selection(x, xM, Mc); APCM_quantization( xM, xMc, &mant, &exp, xmaxc); APCM_inverse_quantization( xMc, mant, exp, xMp); RPE_grid_positioning( *Mc, xMp, e ); } void Gsm_RPE_Decoding ( struct gsm_state * S, word xmaxcr, word Mcr, word * xMcr, /* [0..12], 3 bits IN */ word * erp /* [0..39] OUT */ ) { word exp, mant; word xMp[ 13 ]; APCM_quantization_xmaxc_to_exp_mant( xmaxcr, &exp, &mant ); APCM_inverse_quantization( xMcr, mant, exp, xMp ); RPE_grid_positioning( Mcr, xMp, erp ); }