audio.c

visual dsp++环境下

//***********************************************************************
//      Audio interrupt routine for the TigerSHARC EZ-Kit
//      Audio Pass Through example in C
//      Audio.c
//***********************************************************************
        
//************************* Includes ************************************
#include <sysreg.h>
#include <builtins.h>
#include <defTS201.h>
#include "TSEZKitDef.h"
#include <stats.h>
#include <math.h>

//************************* Externs *************************************
extern long ReadDataLeft, ReadDataRight, WriteDataLeft, WriteDataRight;


//***********************************************************************
#define  	PI   		 3.1415926535
#define 	NUM_POINTS	 1024        //Number of sample points in the calculation

//int Window;							//control the window type
float W[NUM_POINTS];				//Windows
float Inbuf[NUM_POINTS],Outbuf[NUM_POINTS];//Inbuffer and outbuffer length
float InbufLeft[NUM_POINTS],InbufRight[NUM_POINTS];//Left channel and right channel length
float Outputbuf[NUM_POINTS];			//Outbuffer length
int Counter0;						//the Inbuffer pointer
int Sample;							//control the state of calculation,Sample=0,the function 
									//work in the sample state,and Sample=1 the function work
									//in the Acorr calculate state

int OutNum;							//the Outbuffer pointer
//--------------------------------------------------------------------------//
// Function:	Init_Windows												//
//																			//
// Description:	Initialize Process Data for Acorr							//
//--------------------------------------------------------------------------//
void Init_Window(void)
{   
	int i;
	for(i=0;i<NUM_POINTS;i++)
	{
   	  	if(Window==1)  
			  W[i]=0.54-0.46*cos(2*PI*i/(NUM_POINTS-1)); 
   	  	else  W[i]=1.0;
	}
}


//************************* Audio Interrupt *****************************
void audio_int( void )
{
	int i;
	/**************Sample the data******************/ 
	if(Sample==0)				//if Sample=0,start to sample the data
	{
		InbufLeft[Counter0]=(float)((ReadDataLeft<<8)>>8);;//从A/D得到的数据数据为低24位有效的有符号数,
		                                                   //要先左移8位保证其符号位在最高位，在右移8位保证数值大小不变。									 
		
		WriteDataLeft=(long)Outbuf[Counter0];
 		Counter0++;
 		if(Counter0>=NUM_POINTS)
 		{
 			Counter0=0;
 			Sample=1;		//sample is over,start to Acorr calculate
 		}
	}
	/************do Autocorrelation*****************/ 
	if(Sample==1)
	{
		for(i=0;i<NUM_POINTS;i++)
		{
			Inbuf[i]=((float)InbufLeft[i]*W[i]);//add the Window
							
		}
			/////////////
		autocorrf(Inbuf,NUM_POINTS,NUM_POINTS,Outbuf);//do Autocorrelation
		Sample=0;					//the Acorr calculate is over,and start to sample the data again	
	}
	
}
//********************************************************************