Add GSM full rate codec to LCR's source repository

[lcr.git] / libgsmfr / src / code.c

diff --git a/libgsmfr/src/code.c b/libgsmfr/src/code.c
new file mode 100644 (file)
index 0000000..65dd0a3
--- /dev/null
+++ b/libgsmfr/src/code.c
@@ -0,0 +1,97 @@
+/*
+ * 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/code.c,v 1.3 1996/07/02 09:59:05 jutta Exp $ */
+
+#include       "config.h"
+
+
+#ifdef HAS_STDLIB_H
+#include       <stdlib.h>
+#else
+#      include "proto.h"
+       extern char     * memcpy P((char *, char *, int));
+#endif
+
+#include       "private.h"
+#include       "gsm.h"
+#include       "proto.h"
+
+/* 
+ *  4.2 FIXED POINT IMPLEMENTATION OF THE RPE-LTP CODER 
+ */
+
+void Gsm_Coder P8((S,s,LARc,Nc,bc,Mc,xmaxc,xMc),
+
+       struct gsm_state        * S,
+
+       word    * s,    /* [0..159] samples                     IN      */
+
+/*
+ * The RPE-LTD coder works on a frame by frame basis.  The length of
+ * the frame is equal to 160 samples.  Some computations are done
+ * once per frame to produce at the output of the coder the
+ * LARc[1..8] parameters which are the coded LAR coefficients and 
+ * also to realize the inverse filtering operation for the entire
+ * frame (160 samples of signal d[0..159]).  These parts produce at
+ * the output of the coder:
+ */
+
+       word    * LARc, /* [0..7] LAR coefficients              OUT     */
+
+/*
+ * Procedure 4.2.11 to 4.2.18 are to be executed four times per
+ * frame.  That means once for each sub-segment RPE-LTP analysis of
+ * 40 samples.  These parts produce at the output of the coder:
+ */
+
+       word    * Nc,   /* [0..3] LTP lag                       OUT     */
+       word    * bc,   /* [0..3] coded LTP gain                OUT     */
+       word    * Mc,   /* [0..3] RPE grid selection            OUT     */
+       word    * xmaxc,/* [0..3] Coded maximum amplitude       OUT     */
+       word    * xMc   /* [13*4] normalized RPE samples        OUT     */
+)
+{
+       int     k;
+       word    * dp  = S->dp0 + 120;   /* [ -120...-1 ] */
+       word    * dpp = dp;             /* [ 0...39 ]    */
+
+       word    so[160];
+
+       Gsm_Preprocess                  (S, s, so);
+       Gsm_LPC_Analysis                (S, so, LARc);
+       Gsm_Short_Term_Analysis_Filter  (S, LARc, so);
+
+       for (k = 0; k <= 3; k++, xMc += 13) {
+
+               Gsm_Long_Term_Predictor ( S,
+                                        so+k*40, /* d      [0..39] IN  */
+                                        dp,      /* dp  [-120..-1] IN  */
+                                       S->e + 5, /* e      [0..39] OUT */
+                                       dpp,      /* dpp    [0..39] OUT */
+                                        Nc++,
+                                        bc++);
+
+               Gsm_RPE_Encoding        ( S,
+                                       S->e + 5,/* e     ][0..39][ IN/OUT */
+                                         xmaxc++, Mc++, xMc );
+               /*
+                * Gsm_Update_of_reconstructed_short_time_residual_signal
+                *                      ( dpp, S->e + 5, dp );
+                */
+
+               { register int i;
+                 register longword ltmp;
+                 for (i = 0; i <= 39; i++)
+                       dp[ i ] = GSM_ADD( S->e[5 + i], dpp[i] );
+               }
+               dp  += 40;
+               dpp += 40;
+
+       }
+       (void)memcpy( (char *)S->dp0, (char *)(S->dp0 + 160),
+               120 * sizeof(*S->dp0) );
+}