1 files changed, 107 insertions, 0 deletions
diff --git a/trunk/codecs/ilbc/gainquant.c b/trunk/codecs/ilbc/gainquant.c
new file mode 100644
index 000000000..33dc19474
--- /dev/null
+++ b/trunk/codecs/ilbc/gainquant.c
@@ -0,0 +1,107 @@
+
+/******************************************************************
+
+    iLBC Speech Coder ANSI-C Source Code
+
+    gainquant.c 
+
+    Copyright (C) The Internet Society (2004). 
+    All Rights Reserved.
+
+
+
+******************************************************************/
+
+#include <string.h>
+#include <math.h>
+#include "constants.h"
+#include "gainquant.h"
+#include "filter.h"
+
+/*----------------------------------------------------------------*
+ *  quantizer for the gain in the gain-shape coding of residual
+ *---------------------------------------------------------------*/
+
+float gainquant(/* (o) quantized gain value */
+    float in,       /* (i) gain value */
+    float maxIn,/* (i) maximum of gain value */
+    int cblen,      /* (i) number of quantization indices */
+    int *index      /* (o) quantization index */
+){
+    int i, tindex;
+    float minmeasure,measure, *cb, scale;
+
+    /* ensure a lower bound on the scaling factor */
+
+    scale=maxIn;
+    
+    if (scale<0.1) {
+        scale=(float)0.1;
+    }
+
+    /* select the quantization table */
+    
+    if (cblen == 8) {
+        cb = gain_sq3Tbl;
+    } else if (cblen == 16) {
+        cb = gain_sq4Tbl;
+    } else  {
+        cb = gain_sq5Tbl;
+    }
+
+    /* select the best index in the quantization table */
+    
+    minmeasure=10000000.0;
+    tindex=0;
+    for (i=0; i<cblen; i++) {
+        measure=(in-scale*cb[i])*(in-scale*cb[i]);
+        
+        if (measure<minmeasure) {
+            tindex=i;
+            minmeasure=measure;
+        }
+    }
+    *index=tindex;
+       
+    /* return the quantized value */
+    
+
+
+    return scale*cb[tindex];
+}
+
+/*----------------------------------------------------------------*
+ *  decoder for quantized gains in the gain-shape coding of 
+ *  residual                          
+ *---------------------------------------------------------------*/
+
+float gaindequant(  /* (o) quantized gain value */
+    int index,      /* (i) quantization index */
+    float maxIn,/* (i) maximum of unquantized gain */
+    int cblen       /* (i) number of quantization indices */
+){
+    float scale;
+
+    /* obtain correct scale factor */
+
+    scale=(float)fabs(maxIn);
+    
+    if (scale<0.1) {
+        scale=(float)0.1;
+    }
+
+    /* select the quantization table and return the decoded value */
+
+    if (cblen==8) {
+        return scale*gain_sq3Tbl[index];
+    } else if (cblen==16) {
+        return scale*gain_sq4Tbl[index];
+    }
+    else if (cblen==32) {
+        return scale*gain_sq5Tbl[index];
+    }
+
+    return 0.0;
+}
+
+