sportisr.c

来自「ADI 公司的DSP ADSP21262 EZ-KIT LITE开发板的全部源代」· C语言 代码 · 共 65 行

#include "Sample Playback.h"
#include <stdio.h>


//function is called when there is room in the TXSP2 buffer 
//for another audio word.
void play_sample_ISR(int sig_int)
{
    Csample* p2samp; 
    float temp, div;
    int nSamps=1;

    

    //toggle LRflag (is LRflag == zero? if true set 1:if false set 0)
    LRflag = (LRflag==0 ? 1 : 0) ;   
    
    //Sample in FLASH is mono sample, and the same data is played back 
    //over both left and right channels.  Because the CODEC connnection
    //is using I2S data, this means that every other word is a R sample 
    //and then L sample. These two facts require a new audio sample on
    //every-other interrupt, not EVERY interrupt.
    if (LRflag == 1) {
        UpdatePlaylist(); //increment pointers and wrap if necessary
        read_flash_samples();        
        
    }

    
    //adjust_balance returns a float - first cast to (int), then
    //to make left-justified, shift left by 16 (or multiply by 2^16)
    adjust_balance();

    
    //always play first sample
    //if current sample is L sample        
    if (LRflag == 1)    { 
       temp = FirstSample->CurrentVal * Lgain; 
       }
    //if current sample is R sample   
    else{
       temp = FirstSample->CurrentVal *= Rgain;
      }
    
    
             
    p2samp = FirstSample->Next;        
    
    
    //for each next active sample, combine values
    while(p2samp){
        
        div=0.5; //1/(float)nSamps;
        //average-in this  sample
        temp = (temp*div) + (p2samp ->CurrentVal)*(div);
        
        //point to next sample and increment the number of samples       
        p2samp=p2samp->Next;
    }
          
    (*pTXSP2B)= (int)temp<<16;  
    
    
}