/**********************************************************************MPEG-4 Audio VMCommon moduleThis software module was originally developed byBodo Teichmann (FhG)and edited byin the course of development of the MPEG-2 NBC/MPEG-4 Audio standardISO/IEC 13818-7, 14496-1,2 and 3. This software module is animplementation of a part of one or more MPEG-2 NBC/MPEG-4 Audio toolsas specified by the MPEG-2 NBC/MPEG-4 Audio standard. ISO/IEC givesusers of the MPEG-2 NBC/MPEG-4 Audio standards free license to thissoftware module or modifications thereof for use in hardware orsoftware products claiming conformance to the MPEG-2 NBC/ MPEG-4 Audiostandards. Those intending to use this software module in hardware orsoftware products are advised that this use may infringe existingpatents. The original developer of this software module and his/hercompany, the subsequent editors and their companies, and ISO/IEC haveno liability for use of this software module or modifications thereofin an implementation. Copyright is not released for non MPEG-2NBC/MPEG-4 Audio conforming products. The original developer retainsfull right to use the code for his/her own purpose, assign or donatethe code to a third party and to inhibit third party from using thecode for non MPEG-2 NBC/MPEG-4 Audio conforming products. Thiscopyright notice must be included in all copies or derivative works.Copyright (c) 1997.Source file: fir_filt.c$Id: fir_filt.c,v 1.1 2002/05/13 18:57:42 wmaycisco Exp $Authors:tmn       Bodo Teichmann mailto:tmn@iis.fhg.deChanges:**********************************************************************/#include <stdio.h>#include <stdlib.h>#include <string.h>#include "common_m4a.h"#include "fir_filt.h"static float fir48_4_120[] =  { -0.0000000000F, -0.0004061767F, -0.0006554074F, -0.0005603479F,    +0.0000000000F, +0.0010332072F, +0.0024067306F, +0.0038511274F,    +0.0049972718F, +0.0054446460F, +0.0048504364F, +0.0030230276F,    -0.0000000000F, -0.0039090311F, -0.0081300062F, -0.0118895363F,    -0.0143338396F, -0.0146862233F, -0.0124177060F, -0.0073988790F,    +0.0000000000F, +0.0088885044F, +0.0179316783F, +0.0255223974F,    +0.0300328067F, +0.0301098647F, +0.0249669378F, +0.0146174761F,    -0.0000000000F, -0.0170435762F, -0.0339530545F, -0.0477884869F,    -0.0556838859F, -0.0553529653F, -0.0455668957F, -0.0265189851F,    +0.0000000000F, +0.0306695549F, +0.0609699140F, +0.0857542392F,    +0.1000000000F, +0.0996415654F, +0.0823628662F, +0.0482228773F,    -0.0000000000F, -0.0568263967F, -0.1144916118F, -0.1637363938F,    -0.1948936008F, -0.1991420526F, -0.1697652726F, -0.1032409730F,    +0.0000000000F, +0.1352696593F, +0.2938416526F, +0.4636919170F,    +0.6306889405F, +0.7800976241F, +0.8982140690F, +0.9739261298F,    +1.0000000000F, +0.9739261298F, +0.8982140690F, +0.7800976241F,    +0.6306889405F, +0.4636919170F, +0.2938416526F, +0.1352696593F,    +0.0000000000F, -0.1032409730F, -0.1697652726F, -0.1991420526F,    -0.1948936008F, -0.1637363938F, -0.1144916118F, -0.0568263967F,    -0.0000000000F, +0.0482228773F, +0.0823628662F, +0.0996415654F,    +0.1000000000F, +0.0857542392F, +0.0609699140F, +0.0306695549F,    +0.0000000000F, -0.0265189851F, -0.0455668957F, -0.0553529653F,    -0.0556838859F, -0.0477884869F, -0.0339530545F, -0.0170435762F,    -0.0000000000F, +0.0146174761F, +0.0249669378F, +0.0301098647F,    +0.0300328067F, +0.0255223974F, +0.0179316783F, +0.0088885044F,    +0.0000000000F, -0.0073988790F, -0.0124177060F, -0.0146862233F,    -0.0143338396F, -0.0118895363F, -0.0081300062F, -0.0039090311F,    -0.0000000000F, +0.0030230276F, +0.0048504364F, +0.0054446460F,    +0.0049972718F, +0.0038511274F, +0.0024067306F, +0.0010332072F,    +0.0000000000F, -0.0005603479F, -0.0006554074F, -0.0004061767F,    -0.0000000000F,  };#define SCALE 0.128FIR_FILT *initFirLowPass(float stopBand,int taps){  FIR_FILT *filter;    filter = (FIR_FILT*)malloc(sizeof(FIR_FILT));  filter->filtLength=taps;  filter->memoryPtr = (float*)malloc(sizeof(float)*(taps+1));  filter->writeIdx =0 ;  filter->readIdx = taps;  if ((stopBand == 48000/4000)&& (taps == 120))    filter->filtPtr=fir48_4_120;  else     CommonExit(-1,"\nthis filter is not yet defined in fir_filt.c");    return filter;    }void firLowPass(float* inBuffer,float *outBuffer,int no, FIR_FILT *filter ){   int i,j,k;  float y;  for (j=0;j<no;j++) {     filter->memoryPtr[(filter->readIdx)] = inBuffer[j];    filter->readIdx=(filter->readIdx + 1)%(filter->filtLength + 1);        y = 0.0;     k=0;    for (i = filter->writeIdx; i <= filter->filtLength ; i++)       y += (filter->filtPtr[k++] * filter->memoryPtr[i]);    for (i = 0; i < filter->writeIdx; i++)       y += (filter->filtPtr[k++] * filter->memoryPtr[i]);    filter->writeIdx=(filter->writeIdx+1)%(filter->filtLength+1);    #if 1     outBuffer[j] = y*SCALE;#else     outBuffer[j] = y;#endif#if 0    if ((long)(y*SCALE) != (short)(y*SCALE)){       fprintf(stderr,"\nclipping!");       exit(-1);    }#endif  }}void subSampl(float * inBuff, float * outBuff,int factor,int *noOfSampl){  int i ;  if ((*noOfSampl%6)!= 0)    CommonExit(-1,"\n Error in downsampling");  else    *noOfSampl = *noOfSampl/6;  for (i=0;i< *noOfSampl;i++){    outBuff[i]=inBuff[i * factor];  }}