1 files changed, 108 insertions, 0 deletions
diff --git a/trunk/codecs/ilbc/syntFilter.c b/trunk/codecs/ilbc/syntFilter.c
new file mode 100644
index 000000000..bb7f7a559
--- /dev/null
+++ b/trunk/codecs/ilbc/syntFilter.c
@@ -0,0 +1,108 @@
+
+/******************************************************************
+
+    iLBC Speech Coder ANSI-C Source Code
+
+    syntFilter.c 
+
+    Copyright (C) The Internet Society (2004). 
+    All Rights Reserved.
+
+******************************************************************/
+
+#include "iLBC_define.h"
+#include "syntFilter.h"
+
+/*----------------------------------------------------------------*
+ *  LP synthesis filter.
+ *---------------------------------------------------------------*/
+    
+void syntFilter(
+    float *Out,     /* (i/o) Signal to be filtered */
+    float *a,       /* (i) LP parameters */
+    int len,    /* (i) Length of signal */
+    float *mem      /* (i/o) Filter state */
+){
+    int i, j;
+    float *po, *pi, *pa, *pm;
+
+    po=Out;
+
+    /* Filter first part using memory from past */
+
+    for (i=0; i<LPC_FILTERORDER; i++) {
+        pi=&Out[i-1];
+        pa=&a[1];
+        pm=&mem[LPC_FILTERORDER-1];
+        for (j=1; j<=i; j++) {
+            *po-=(*pa++)*(*pi--);
+        }
+        for (j=i+1; j<LPC_FILTERORDER+1; j++) {
+            *po-=(*pa++)*(*pm--);
+        }
+        po++;
+    }
+
+    /* Filter last part where the state is entierly in 
+       the output vector */
+    
+    for (i=LPC_FILTERORDER; i<len; i++) {
+
+
+        pi=&Out[i-1];
+        pa=&a[1];
+        for (j=1; j<LPC_FILTERORDER+1; j++) {
+            *po-=(*pa++)*(*pi--);
+        }
+        po++;
+    }
+
+    /* Update state vector */
+
+    memcpy(mem, &Out[len-LPC_FILTERORDER], 
+        LPC_FILTERORDER*sizeof(float));
+}
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