--- /dev/null
+/*
+ * 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.
+ */
+
+#include <stdio.h>
+#include <assert.h>
+
+#include "gsm610_priv.h"
+
+/*
+ * 4.2.4 .. 4.2.7 LPC ANALYSIS SECTION
+ */
+
+/* 4.2.4 */
+
+
+static void Autocorrelation (
+ word * s, /* [0..159] IN/OUT */
+ longword * L_ACF) /* [0..8] OUT */
+/*
+ * The goal is to compute the array L_ACF[k]. The signal s[i] must
+ * be scaled in order to avoid an overflow situation.
+ */
+{
+ register int k, i;
+
+ word temp, smax, scalauto;
+
+#ifdef USE_FLOAT_MUL
+ float float_s[160];
+#endif
+
+ /* Dynamic scaling of the array s[0..159]
+ */
+
+ /* Search for the maximum.
+ */
+ smax = 0;
+ for (k = 0; k <= 159; k++) {
+ temp = GSM_ABS( s[k] );
+ if (temp > smax) smax = temp;
+ }
+
+ /* Computation of the scaling factor.
+ */
+ if (smax == 0) scalauto = 0;
+ else {
+ assert(smax > 0);
+ scalauto = 4 - gsm_norm( (longword)smax << 16 );/* sub(4,..) */
+ }
+
+ /* Scaling of the array s[0...159]
+ */
+
+ if (scalauto > 0) {
+
+# ifdef USE_FLOAT_MUL
+# define SCALE(n) \
+ case n: for (k = 0; k <= 159; k++) \
+ float_s[k] = (float) \
+ (s[k] = GSM_MULT_R(s[k], 16384 >> (n-1)));\
+ break;
+# else
+# define SCALE(n) \
+ case n: for (k = 0; k <= 159; k++) \
+ s[k] = GSM_MULT_R( s[k], 16384 >> (n-1) );\
+ break;
+# endif /* USE_FLOAT_MUL */
+
+ switch (scalauto) {
+ SCALE(1)
+ SCALE(2)
+ SCALE(3)
+ SCALE(4)
+ }
+# undef SCALE
+ }
+# ifdef USE_FLOAT_MUL
+ else for (k = 0; k <= 159; k++) float_s[k] = (float) s[k];
+# endif
+
+ /* Compute the L_ACF[..].
+ */
+ {
+# ifdef USE_FLOAT_MUL
+ register float * sp = float_s;
+ register float sl = *sp;
+
+# define STEP(k) L_ACF[k] += (longword)(sl * sp[ -(k) ]);
+# else
+ word * sp = s;
+ word sl = *sp;
+
+# define STEP(k) L_ACF[k] += ((longword)sl * sp[ -(k) ]);
+# endif
+
+# define NEXTI sl = *++sp
+
+
+ for (k = 9; k--; L_ACF[k] = 0) ;
+
+ STEP (0);
+ NEXTI;
+ STEP(0); STEP(1);
+ NEXTI;
+ STEP(0); STEP(1); STEP(2);
+ NEXTI;
+ STEP(0); STEP(1); STEP(2); STEP(3);
+ NEXTI;
+ STEP(0); STEP(1); STEP(2); STEP(3); STEP(4);
+ NEXTI;
+ STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5);
+ NEXTI;
+ STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5); STEP(6);
+ NEXTI;
+ STEP(0); STEP(1); STEP(2); STEP(3); STEP(4); STEP(5); STEP(6); STEP(7);
+
+ for (i = 8; i <= 159; i++) {
+
+ NEXTI;
+
+ STEP(0);
+ STEP(1); STEP(2); STEP(3); STEP(4);
+ STEP(5); STEP(6); STEP(7); STEP(8);
+ }
+
+ for (k = 9; k--; L_ACF[k] <<= 1) ;
+
+ }
+ /* Rescaling of the array s[0..159]
+ */
+ if (scalauto > 0) {
+ assert(scalauto <= 4);
+ for (k = 160; k--; *s++ <<= scalauto) ;
+ }
+}
+
+#if defined(USE_FLOAT_MUL) && defined(FAST)
+
+static void Fast_Autocorrelation (
+ word * s, /* [0..159] IN/OUT */
+ longword * L_ACF) /* [0..8] OUT */
+{
+ register int k, i;
+ float f_L_ACF[9];
+ float scale;
+
+ float s_f[160];
+ register float *sf = s_f;
+
+ for (i = 0; i < 160; ++i) sf[i] = s[i];
+ for (k = 0; k <= 8; k++) {
+ register float L_temp2 = 0;
+ register float *sfl = sf - k;
+ for (i = k; i < 160; ++i) L_temp2 += sf[i] * sfl[i];
+ f_L_ACF[k] = L_temp2;
+ }
+ scale = MAX_LONGWORD / f_L_ACF[0];
+
+ for (k = 0; k <= 8; k++) {
+ L_ACF[k] = f_L_ACF[k] * scale;
+ }
+}
+#endif /* defined (USE_FLOAT_MUL) && defined (FAST) */
+
+/* 4.2.5 */
+
+static void Reflection_coefficients (
+ longword * L_ACF, /* 0...8 IN */
+ register word * r /* 0...7 OUT */
+)
+{
+ register int i, m, n;
+ register word temp;
+ word ACF[9]; /* 0..8 */
+ word P[ 9]; /* 0..8 */
+ word K[ 9]; /* 2..8 */
+
+ /* Schur recursion with 16 bits arithmetic.
+ */
+
+ if (L_ACF[0] == 0) {
+ for (i = 8; i--; *r++ = 0) ;
+ return;
+ }
+
+ assert( L_ACF[0] != 0 );
+ temp = gsm_norm( L_ACF[0] );
+
+ assert(temp >= 0 && temp < 32);
+
+ /* ? overflow ? */
+ for (i = 0; i <= 8; i++) ACF[i] = SASR_L( L_ACF[i] << temp, 16 );
+
+ /* Initialize array P[..] and K[..] for the recursion.
+ */
+
+ for (i = 1; i <= 7; i++) K[ i ] = ACF[ i ];
+ for (i = 0; i <= 8; i++) P[ i ] = ACF[ i ];
+
+ /* Compute reflection coefficients
+ */
+ for (n = 1; n <= 8; n++, r++) {
+
+ temp = P[1];
+ temp = GSM_ABS(temp);
+ if (P[0] < temp) {
+ for (i = n; i <= 8; i++) *r++ = 0;
+ return;
+ }
+
+ *r = gsm_div( temp, P[0] );
+
+ assert(*r >= 0);
+ if (P[1] > 0) *r = -*r; /* r[n] = sub(0, r[n]) */
+ assert (*r != MIN_WORD);
+ if (n == 8) return;
+
+ /* Schur recursion
+ */
+ temp = GSM_MULT_R( P[1], *r );
+ P[0] = GSM_ADD( P[0], temp );
+
+ for (m = 1; m <= 8 - n; m++) {
+ temp = GSM_MULT_R( K[ m ], *r );
+ P[m] = GSM_ADD( P[ m+1 ], temp );
+
+ temp = GSM_MULT_R( P[ m+1 ], *r );
+ K[m] = GSM_ADD( K[ m ], temp );
+ }
+ }
+}
+
+/* 4.2.6 */
+
+static void Transformation_to_Log_Area_Ratios (
+ register word * r /* 0..7 IN/OUT */
+)
+/*
+ * The following scaling for r[..] and LAR[..] has been used:
+ *
+ * r[..] = integer( real_r[..]*32768. ); -1 <= real_r < 1.
+ * LAR[..] = integer( real_LAR[..] * 16384 );
+ * with -1.625 <= real_LAR <= 1.625
+ */
+{
+ register word temp;
+ register int i;
+
+
+ /* Computation of the LAR[0..7] from the r[0..7]
+ */
+ for (i = 1; i <= 8; i++, r++) {
+
+ temp = *r;
+ temp = GSM_ABS(temp);
+ assert(temp >= 0);
+
+ if (temp < 22118) {
+ temp >>= 1;
+ } else if (temp < 31130) {
+ assert( temp >= 11059 );
+ temp -= 11059;
+ } else {
+ assert( temp >= 26112 );
+ temp -= 26112;
+ temp <<= 2;
+ }
+
+ *r = *r < 0 ? -temp : temp;
+ assert( *r != MIN_WORD );
+ }
+}
+
+/* 4.2.7 */
+
+static void Quantization_and_coding (
+ register word * LAR /* [0..7] IN/OUT */
+)
+{
+ register word temp;
+
+ /* This procedure needs four tables; the following equations
+ * give the optimum scaling for the constants:
+ *
+ * A[0..7] = integer( real_A[0..7] * 1024 )
+ * B[0..7] = integer( real_B[0..7] * 512 )
+ * MAC[0..7] = maximum of the LARc[0..7]
+ * MIC[0..7] = minimum of the LARc[0..7]
+ */
+
+# undef STEP
+# define STEP( A, B, MAC, MIC ) \
+ temp = GSM_MULT( A, *LAR ); \
+ temp = GSM_ADD( temp, B ); \
+ temp = GSM_ADD( temp, 256 ); \
+ temp = SASR_W( temp, 9 ); \
+ *LAR = temp>MAC ? MAC - MIC : (temp<MIC ? 0 : temp - MIC); \
+ LAR++;
+
+ STEP( 20480, 0, 31, -32 );
+ STEP( 20480, 0, 31, -32 );
+ STEP( 20480, 2048, 15, -16 );
+ STEP( 20480, -2560, 15, -16 );
+
+ STEP( 13964, 94, 7, -8 );
+ STEP( 15360, -1792, 7, -8 );
+ STEP( 8534, -341, 3, -4 );
+ STEP( 9036, -1144, 3, -4 );
+
+# undef STEP
+}
+
+void Gsm_LPC_Analysis (
+ struct gsm_state *S,
+ word * s, /* 0..159 signals IN/OUT */
+ word * LARc) /* 0..7 LARc's OUT */
+{
+ longword L_ACF[9];
+
+#if defined(USE_FLOAT_MUL) && defined(FAST)
+ if (S->fast) Fast_Autocorrelation (s, L_ACF );
+ else
+#endif
+ Autocorrelation (s, L_ACF );
+ Reflection_coefficients (L_ACF, LARc );
+ Transformation_to_Log_Area_Ratios (LARc);
+ Quantization_and_coding (LARc);
+}
projects / Faustine.git / blobdiff