Mercurial > pygar

     1 #include <stdio.h>

     2 #include <assert.h>

     3 #include <string.h>

     4 #include "SndfileWavUtil.h"

     5 

     6 const  int Taps = 9;

     7 static int newest;

     8 static short int x[Taps] = {0,0,0,0,0,0,0,0,0};

     9 static short int fir(short int);

    10 const  int short_sz = sizeof(short);

    11 

    12 // lifted from the bluespec code

    13 static double h[Taps] =  {-0.0124,

    14 			  0.0,

    15 			  -0.0133,

    16 			  0.0,

    17 			  0.8181,

    18 			  0.0,

    19 			  -0.0133,

    20 			  0.0,

    21 			  -0.0124};

    22 

    23 

    24 int

    25 main (int argc, char * argv [])

    26 {

    27   const char* inputWavFileName;

    28   const char* outputWavFileName;

    29 

    30   FILE *inputPcmFile;

    31   FILE *outputPcmFile;

    32 

    33   short int sample;

    34 

    35   inputWavFileName = argv[1];

    36   outputWavFileName = argv[2];

    37 

    38   // Convert input wav to pcm

    39   generate_pcm(inputWavFileName, "input.pcm");

    40 

    41   inputPcmFile = fopen("input.pcm", "r");

    42   outputPcmFile = fopen("output.pcm", "w");

    43 

    44   assert(inputPcmFile);

    45   assert(outputPcmFile);

    46 

    47   newest = 0;

    48   memset(x, 0, sizeof(x));

    49 

    50   while(fread(&sample, short_sz, 1, inputPcmFile)) {

    51     sample = fir(sample);

    52     assert(fwrite(&sample,short_sz,1,outputPcmFile));

    53   } 

    54 

    55   fclose(inputPcmFile);

    56   fclose(outputPcmFile);

    57 

    58   generate_wav("output.pcm", inputWavFileName, outputWavFileName);

    59 }

    60 

    61 short int

    62 fir(short int sample)

    63 {

    64 

    65   x[newest] = sample; 

    66   double y = 0;

    67 

    68   for (int k = 0; k < Taps; k++) { 

    69 

    70     short int bits = x[(newest+k)%Taps];

    71     double x = (double)bits;

    72     y += h[k] * x; 

    73 

    74   }

    75 

    76   newest = (newest == 0) ? (Taps-1) : (newest-1);

    77 

    78   short int rv = ((short int)y)&0x0000FFFF;

    79   return rv;

    80 }

    81