--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/intercom/gsm/code.c	Fri Jun 25 09:57:52 2010 +0200
@@ -0,0 +1,90 @@
+/*
+ * 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: /home/kbs/jutta/src/gsm/gsm-1.0/src/RCS/code.c,v 1.1 1992/10/28 00:15:50 jutta Exp $ */
+
+#include	"config.h"
+
+
+#ifdef	HAS_STDLIB_H
+#include	<stdlib.h>
+#include        <string.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 ]    */
+
+  static word e[50] = { 0 };
+
+  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  */
+      e + 5,                    /* e      [0..39] OUT */
+      dpp,                      /* dpp    [0..39] OUT */
+      Nc++, bc++);
+
+    Gsm_RPE_Encoding(S, e + 5,  /* e      ][0..39][ IN/OUT */
+      xmaxc++, Mc++, xMc);
+    /*
+     * Gsm_Update_of_reconstructed_short_time_residual_signal
+     *                      ( dpp, e + 5, dp );
+     */
+
+    {
+      register int i;
+      register longword ltmp;
+      for (i = 0; i <= 39; i++)
+        dp[i] = GSM_ADD(e[5 + i], dpp[i]);
+    }
+    dp += 40;
+    dpp += 40;
+
+  }
+  (void) memcpy((char *) S->dp0, (char *) (S->dp0 + 160),
+    120 * sizeof(*S->dp0));
+}