initial bits of ilbc codec mod.

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@452 d0543943-73ff-0310-b7d9-9358b9ac24b2

libs/codec/ilbc/src/hpInput.c

@@ -0,0 +1,59 @@
+   
+   /******************************************************************
+   
+       iLBC Speech Coder ANSI-C Source Code
+   
+       hpInput.c 
+   
+       Copyright (C) The Internet Society (2004). 
+       All Rights Reserved.
+   
+   ******************************************************************/
+   
+   #include "constants.h"
+   
+   /*----------------------------------------------------------------*
+    *  Input high-pass filter                          
+    *---------------------------------------------------------------*/
+   
+   void hpInput( 
+       float *In,  /* (i) vector to filter */
+       int len,    /* (i) length of vector to filter */
+       float *Out, /* (o) the resulting filtered vector */
+       float *mem  /* (i/o) the filter state */
+   ){
+       int i;
+       float *pi, *po;
+   
+       /* all-zero section*/
+   
+       pi = &In[0];
+       po = &Out[0];
+       for (i=0; i<len; i++) {
+           *po = hpi_zero_coefsTbl[0] * (*pi);
+           *po += hpi_zero_coefsTbl[1] * mem[0];
+           *po += hpi_zero_coefsTbl[2] * mem[1];
+   
+           mem[1] = mem[0];
+           mem[0] = *pi;
+           po++;
+   
+   
+           pi++;
+   
+       }
+   
+       /* all-pole section*/
+   
+       po = &Out[0];
+       for (i=0; i<len; i++) {
+           *po -= hpi_pole_coefsTbl[1] * mem[2];
+           *po -= hpi_pole_coefsTbl[2] * mem[3];
+   
+           mem[3] = mem[2];
+           mem[2] = *po;
+           po++;
+       }
+   }
+   
+