diff options
Diffstat (limited to 'protocols/Tlen/src/codec/gsm_rpe.c')
| -rw-r--r-- | protocols/Tlen/src/codec/gsm_rpe.c | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/protocols/Tlen/src/codec/gsm_rpe.c b/protocols/Tlen/src/codec/gsm_rpe.c new file mode 100644 index 0000000000..21c5419672 --- /dev/null +++ b/protocols/Tlen/src/codec/gsm_rpe.c @@ -0,0 +1,248 @@ +/*
+
+Tlen Protocol Plugin for Miranda NG
+Copyright (C) 2004-2007 Piotr Piastucki
+
+This program is based on GSM 06.10 source code developed by
+Jutta Degener and Carsten Bormann,
+Copyright 1992, 1993, 1994 by Jutta Degener and Carsten Bormann,
+Technische Universitaet Berlin
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+*/
+#include "gsm.h"
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static const int gsm_H[11] = {-134, -374, 0, 2054, 5741, 8192, 5741, 2054, 0, -374, -134 };
+static const int gsm_NRFAC[8] = { 29128, 26215, 23832, 21846, 20165, 18725, 17476, 16384 };
+static const int gsm_FAC[8] = { 18431, 20479, 22527, 24575, 26623, 28671, 30719, 32767 };
+/*
+ * The coefficients of the weighting filter are stored in the gsm_H table.
+ * The following scaling is used:
+ *
+ * gsm_H[0..10] = integer( real_H[ 0..10] * 8192 );
+ */
+static void weightingFilter (int *e, int *x)
+{
+ int L_result;
+ int k, i;
+ for (k = 0; k < 40; k++) {
+ L_result = 4096;
+ for (i = 0; i < 11; i++) {
+ int ix = i + k;
+ if (ix>4 && ix<45) L_result += e[ix - 5] * gsm_H[i];
+ }
+ L_result >>= 13;
+ x[k] = (L_result < -32768 ? -32768 : (L_result > 32767 ? 32767 : L_result));
+ }
+}
+
+/*
+ * The signal x[0..39] is used to select the RPE grid which is
+ * represented by Mc.
+ */
+static void gridSelection( int *x, int *xM, int *Mc_out)
+{
+ int m, i;
+ int L_result, L_temp;
+ int EM, Mc;
+
+ EM = 0;
+ Mc = 0;
+
+ for (m = 0; m < 4; m++) {
+ L_result = 0;
+ for (i = 0; i < 13; i++) {
+ int temp = x[m + 3*i] >> 2;
+ L_temp = temp * temp << 1;
+ L_result += L_temp;
+ }
+ if (L_result > EM) {
+ Mc = m;
+ EM = L_result;
+ }
+ }
+ /* Down-sampling by a factor 3 to get the selected xM[0..12]
+ * RPE sequence.
+ */
+ for (i = 0; i < 13; i ++) xM[i] = x[Mc + 3*i];
+ *Mc_out = Mc;
+}
+
+/*
+ * 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.
+ */
+static void gridPositioning (int Mc, int *xMp, int *ep)
+{
+ int i, k;
+ for (k = 0; k < 40; k++) ep[k] = 0;
+ for (i = 0; i < 13; i++) {
+ ep[ Mc + (3*i) ] = xMp[i];
+ }
+}
+
+static void APCMXmaxcToExpMant (int xmaxc, int *exp_out, int *mant_out )
+{
+ int exp, mant;
+ /* Compute exponent and mantissa of the decoded version of xmaxc
+ */
+ exp = 0;
+ if (xmaxc > 15) exp = (xmaxc >> 3) - 1;
+ mant = xmaxc - (exp << 3);
+
+ if (mant == 0) {
+ exp = -4;
+ mant = 7;
+ }
+ else {
+ while (mant < 8) {
+ mant = mant << 1 | 1;
+ exp--;
+ }
+ mant -= 8;
+ }
+
+ *exp_out = exp;
+ *mant_out = mant;
+}
+
+static void APCMQuantization (int *xM, int *xMc, int *mant_out, int *exp_out, int *xmaxc_out)
+{
+ int i, itest;
+ int xmax, xmaxc, temp, temp1, temp2;
+ int exp, mant;
+
+
+ /* Find the maximum absolute value xmax of xM[0..12].
+ */
+
+ xmax = 0;
+ for (i = 0; i < 13; i++) {
+ temp = abs(xM[i]);
+ if (temp > xmax) xmax = temp;
+ }
+ if (xmax > 32767) xmax = 32767;
+ /* Qantizing and coding of xmax to get xmaxc.
+ */
+
+ exp = 0;
+ temp = xmax >> 9;
+ itest = 0;
+
+ for (i = 0; i < 6; i++) {
+ if (temp != 0) exp++;
+ temp = temp >> 1;
+ }
+
+ temp = exp + 5;
+
+ xmaxc = (xmax >> temp) + (exp << 3);
+
+ /* Quantizing and coding of the xM[0..12] RPE sequence
+ * to get the xMc[0..12]
+ */
+ APCMXmaxcToExpMant( 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
+ */
+ temp = (mant|8)<<(5+exp);
+ temp1 = 6 - exp;
+ temp2 = gsm_NRFAC[ mant ];
+ for (i = 0; i < 13; i++) {
+ xMc[i] = ((xM[i] << temp1) * temp2 >> 27) + 4;
+ }
+
+ /* NOTE: This equation is used to make all the xMc[i] positive.
+ */
+
+ *mant_out = mant;
+ *exp_out = exp;
+ *xmaxc_out = xmaxc;
+}
+
+static void APCMDequantization (int *xMc, int mant, int exp, int *xMp)
+{
+ int i, temp1, temp2, temp3;
+ temp1 = gsm_FAC[ mant ];
+ temp2 = 6 - exp;
+ if (temp2 <= 0) {
+ temp3 = 1 >> (1 - temp2);
+ } else {
+ temp3 = 1 << (temp2 - 1);
+ }
+ for (i = 0; i < 13; i++) {
+ xMp[i] = ((((((xMc[i]<<1)-7)<<12)*temp1+16384)>>15)+temp3)>>temp2;
+ }
+}
+
+void encodeRPE(gsm_state *state)
+{ int x[40];
+ int xM[13], xMp[13];
+ int mant, exp;
+ int *Mc = state->Mc + state->subframe;
+ int *xMaxc = state->xMaxc + state->subframe;
+ int *xMc = state->xMc + state->subframe * 13;
+ int *e = state->e + state->subframe * 40;
+ //int i;
+ /*
+ printf("RPE in: \n");
+ for (i=0;i<40;i++) {
+ printf("%7d ", e[i]);
+ }
+ printf("\n");
+ */
+ weightingFilter(e, x);
+ /*
+ printf("RPE weighting filter: \n");
+ for (i=0;i<40;i++) {
+ printf("%7d ", x[i]);
+ }
+ printf("\n");
+ */
+ gridSelection(x, xM, Mc);
+ APCMQuantization(xM, xMc, &mant, &exp, xMaxc);
+ /* printf("RPE Mc(grid #)=%d xmaxc=%d mant=%d exp=%d \n", *Mc, *xMaxc, mant, exp); */
+ APCMDequantization(xMc, mant, exp, xMp);
+ gridPositioning(*Mc, xMp, e);
+}
+
+void decodeRPE(gsm_state *state)
+{
+ int exp, mant;
+ int xMp[ 13 ];
+ int *xMc = state->xMc + state->subframe * 13;
+ int *e = state->e + state->subframe * 40;
+
+ APCMXmaxcToExpMant(state->xMaxc[state->subframe], &exp, &mant);
+ APCMDequantization(xMc, mant, exp, xMp);
+ gridPositioning(state->Mc[state->subframe], xMp, e);
+}
|