?? long_term.c
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/*
* 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: /tmp_amd/presto/export/kbs/jutta/src/gsm/RCS/long_term.c,v 1.6 1996/07/02 12:33:19 jutta Exp $ */
#include <stdio.h>
#include <assert.h>
#include "private.h"
#include "gsm.h"
#include "proto.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 P5((st, d,dp,bc_out,Nc_out),
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 P4((d,dp,bc_out,Nc_out),
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 P5((st, d,dp,bc_out,Nc_out),
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 P4((d,dp,bc_out,Nc_out),
register word * d, /* [0..39] IN */
register word * dp, /* [-120..-1] IN */
word * bc_out, /* OUT */
word * Nc_out /* OUT */
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