Add GSM full rate codec to LCR's source repository

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

diff --git a/libgsmfr/src/decode.c b/libgsmfr/src/decode.c
new file mode 100644 (file)
index 0000000..d51c54a
--- /dev/null
+++ b/libgsmfr/src/decode.c
@@ -0,0 +1,63 @@
+/*
+ * 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/decode.c,v 1.1 1992/10/28 00:15:50 jutta Exp $ */
+
+#include <stdio.h>
+
+#include       "private.h"
+#include       "gsm.h"
+#include       "proto.h"
+
+/*
+ *  4.3 FIXED POINT IMPLEMENTATION OF THE RPE-LTP DECODER
+ */
+
+static void Postprocessing P2((S,s),
+       struct gsm_state        * S,
+       register word           * s)
+{
+       register int            k;
+       register word           msr = S->msr;
+       register longword       ltmp;   /* for GSM_ADD */
+       register word           tmp;
+
+       for (k = 160; k--; s++) {
+               tmp = GSM_MULT_R( msr, 28180 );
+               msr = GSM_ADD(*s, tmp);            /* Deemphasis             */
+               *s  = GSM_ADD(msr, msr) & 0xFFF8;  /* Truncation & Upscaling */
+       }
+       S->msr = msr;
+}
+
+void Gsm_Decoder P8((S,LARcr, Ncr,bcr,Mcr,xmaxcr,xMcr,s),
+       struct gsm_state        * S,
+
+       word            * LARcr,        /* [0..7]               IN      */
+
+       word            * Ncr,          /* [0..3]               IN      */
+       word            * bcr,          /* [0..3]               IN      */
+       word            * Mcr,          /* [0..3]               IN      */
+       word            * xmaxcr,       /* [0..3]               IN      */
+       word            * xMcr,         /* [0..13*4]            IN      */
+
+       word            * s)            /* [0..159]             OUT     */
+{
+       int             j, k;
+       word            erp[40], wt[160];
+       word            * drp = S->dp0 + 120;
+
+       for (j=0; j <= 3; j++, xmaxcr++, bcr++, Ncr++, Mcr++, xMcr += 13) {
+
+               Gsm_RPE_Decoding( S, *xmaxcr, *Mcr, xMcr, erp );
+               Gsm_Long_Term_Synthesis_Filtering( S, *Ncr, *bcr, erp, drp );
+
+               for (k = 0; k <= 39; k++) wt[ j * 40 + k ] =  drp[ k ];
+       }
+
+       Gsm_Short_Term_Synthesis_Filter( S, LARcr, wt, s );
+       Postprocessing(S, s);
+}