1 files changed, 152 insertions, 0 deletions
diff --git a/trunk/codecs/ilbc/LPCdecode.c b/trunk/codecs/ilbc/LPCdecode.c
new file mode 100644
index 000000000..f4bc9896d
--- /dev/null
+++ b/trunk/codecs/ilbc/LPCdecode.c
@@ -0,0 +1,152 @@
+
+/******************************************************************
+
+    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 "LPCdecode.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));
+
+}
+
+