cosine.c

1.分别利用计算法和查表法产生1000Hz的余弦波信号

/* Program for generates a sequence cosine signal        */ 
/*   used CY-5410usb in dsp tms320vc5410            */ 
/*   and send this signal to ad50(at CY-5410usb)        */ 
/*   If you use oscillograph you can see this signal      */ 
/* Designed by dalong2008                     */ 
/* 2004.12.25                                       */ 
/* All rights reserved. Property of dalong2008      */ 
/* "@(#) DSP/BIOS 4.51.0 06-10-02 (dalong2008)"  */ 
 
 
ioport unsigned port0bfff; 
 
#define IOSR port0bfff 
#define _COSX 0.999390827 
 
#pragma DATA_SECTION(_cosx,"data_buf1") 
	float _cosx[200]; 
#pragma DATA_SECTION(dacdata,"data_buf2") 
	int dacdata[180]; 
 
void delay(void); 
void main(void) 
{ 
	unsigned int i=0; 
	_cosx[0]=1.000; 
	dacdata[0]=4095; 
	_cosx[1]=_COSX; 
	dacdata[1]=_COSX*2047+2048; 
  	i=1; 
  	while(1) 
   {  
     	if(i++>179) 
        	break;
     	_cosx[i]=2*_COSX*_cosx[i-1]-_cosx[i-2]; 
     	dacdata[i]=_cosx[i]*2047+2048;
  } 
  i=0; 
  while(1) 
   {  
     	if(i>179) 
       	i=0; 
     	IOSR=dacdata[i++];  
   } 
 } 

/*delay*/
void delay(void) 
 { 
  long int j; 
  for(j=0; j<200; j++) 
  asm("_nop"); 
 }