--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/intercom/ilbc/LPCdecode.c	Fri Jun 25 09:57:52 2010 +0200
@@ -0,0 +1,145 @@
+
+   /******************************************************************
+
+       iLBC Speech Coder ANSI-C Source Code
+
+       LPC_decode.c
+
+       Copyright (C) The Internet Society (2004).
+       All Rights Reserved.
+
+   ******************************************************************/
+
+#include <math.h>
+#include <string.h>
+
+#include "helpfun.h"
+#include "lsf.h"
+#include "iLBC_define.h"
+#include "constants.h"
+
+   /*---------------------------------------------------------------*
+    *  interpolation of lsf coefficients for the decoder
+    *--------------------------------------------------------------*/
+
+void LSFinterpolate2a_dec(float *a,     /* (o) lpc coefficients for a sub-frame */
+  float *lsf1,                  /* (i) first lsf coefficient vector */
+  float *lsf2,                  /* (i) second lsf coefficient vector */
+  float coef,                   /* (i) interpolation weight */
+  int length                    /* (i) length of lsf vectors */
+  )
+{
+  float lsftmp[LPC_FILTERORDER];
+
+  interpolate(lsftmp, lsf1, lsf2, coef, length);
+  lsf2a(a, lsftmp);
+}
+
+   /*---------------------------------------------------------------*
+    *  obtain dequantized lsf coefficients from quantization index
+    *--------------------------------------------------------------*/
+
+void SimplelsfDEQ(float *lsfdeq,        /* (o) dequantized lsf coefficients */
+  int *index,                   /* (i) quantization index */
+  int lpc_n                     /* (i) number of LPCs */
+  )
+{
+  int i, j, pos, cb_pos;
+
+
+
+
+
+  /* decode first LSF */
+
+  pos = 0;
+  cb_pos = 0;
+  for (i = 0; i < LSF_NSPLIT; i++) {
+    for (j = 0; j < dim_lsfCbTbl[i]; j++) {
+      lsfdeq[pos + j] = lsfCbTbl[cb_pos +
+        (long) (index[i]) * dim_lsfCbTbl[i] + j];
+    }
+    pos += dim_lsfCbTbl[i];
+    cb_pos += size_lsfCbTbl[i] * dim_lsfCbTbl[i];
+  }
+
+  if (lpc_n > 1) {
+
+    /* decode last LSF */
+
+    pos = 0;
+    cb_pos = 0;
+    for (i = 0; i < LSF_NSPLIT; i++) {
+      for (j = 0; j < dim_lsfCbTbl[i]; j++) {
+        lsfdeq[LPC_FILTERORDER + pos + j] =
+          lsfCbTbl[cb_pos +
+          (long) (index[LSF_NSPLIT + i]) * dim_lsfCbTbl[i] + j];
+      }
+      pos += dim_lsfCbTbl[i];
+      cb_pos += size_lsfCbTbl[i] * dim_lsfCbTbl[i];
+    }
+  }
+}
+
+   /*----------------------------------------------------------------*
+    *  obtain synthesis and weighting filters form lsf coefficients
+    *---------------------------------------------------------------*/
+
+void DecoderInterpolateLSF(float *syntdenum,    /* (o) synthesis filter coefficients */
+  float *weightdenum,           /* (o) weighting denumerator
+                                   coefficients */
+  float *lsfdeq,                /* (i) dequantized lsf coefficients */
+  int length,                   /* (i) length of lsf coefficient vector */
+  iLBC_Dec_Inst_t * iLBCdec_inst
+  /* (i) the decoder state structure */
+  )
+{
+  int i, pos, lp_length;
+  float lp[LPC_FILTERORDER + 1], *lsfdeq2;
+
+
+
+
+
+
+  lsfdeq2 = lsfdeq + length;
+  lp_length = length + 1;
+
+  if (iLBCdec_inst->mode == 30) {
+    /* sub-frame 1: Interpolation between old and first */
+
+    LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold, lsfdeq,
+      lsf_weightTbl_30ms[0], length);
+    memcpy(syntdenum, lp, lp_length * sizeof(float));
+    bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
+
+    /* sub-frames 2 to 6: interpolation between first
+       and last LSF */
+
+    pos = lp_length;
+    for (i = 1; i < 6; i++) {
+      LSFinterpolate2a_dec(lp, lsfdeq, lsfdeq2,
+        lsf_weightTbl_30ms[i], length);
+      memcpy(syntdenum + pos, lp, lp_length * sizeof(float));
+      bwexpand(weightdenum + pos, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
+      pos += lp_length;
+    }
+  } else {
+    pos = 0;
+    for (i = 0; i < iLBCdec_inst->nsub; i++) {
+      LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold,
+        lsfdeq, lsf_weightTbl_20ms[i], length);
+      memcpy(syntdenum + pos, lp, lp_length * sizeof(float));
+      bwexpand(weightdenum + pos, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
+      pos += lp_length;
+    }
+  }
+
+  /* update memory */
+
+  if (iLBCdec_inst->mode == 30)
+    memcpy(iLBCdec_inst->lsfdeqold, lsfdeq2, length * sizeof(float));
+  else
+    memcpy(iLBCdec_inst->lsfdeqold, lsfdeq, length * sizeof(float));
+
+}