C++ FSK解调代码

#define RISINGEDGE  0
#define DROPEDGE    1

#define ABS(x) (((x) > 0) ? (x) : (-x))
#define MARK_FREQ   980
#define SPACE_FREQ  1180

#define MARGIN   ((SPACE_FREQ-MARK_FREQ)/2)
#define STARTBIT   1

#define BAUDRATE   300

static void
FSK_decode (SNDFILE * infile, FILE * outfile, int channels, int samplerate)
{
   float buf [channels * BLOCK_SIZE] ;
   int k, readcount ;
   char bits;

   float value;
   float last_val = 0.0;
   int edge = -1;
   int last_edge = -1;
   const float dt = 1.00/samplerate;
   const int bpts = (int)(1.00/BAUDRATE/dt);

   int index = 0;      
   int edge_index = 0;
   int last_edge_index = 0;
   int bit_start_idx = 0;