Single chip heart rate meter source code

Place your index finger gently on the sensor, and you will see the LED indicator light flashing with your heartbeat. The arteries in the fingertips of the human body are well developed. When the arteries contract and relax periodically with the heart, the blood volume in the blood vessels will also change. The above is the schematic diagram of the acquisition part. Please go to http://www.51hei.com/bbs/dpj-22525-1.html to download the complete set of production materials . The following is the source code of the microcontroller part of the  heart rate meter.

/*
  Project: Measuring heart rate through fingertip
  Copyright @ Rajendra Bhatt
  January 18, 2011
  PIC16F628A at 4.0 MHz external clock, MCLR enabled
*/

sbit IR_Tx at RA3_bit; sbit DD0_Set at
RA2_bit; sbit DD1_Set at RA1_bit ; sbit DD2_Set at RA0_bit ; ------------- Function to Return mask for common anode 7-seg. display unsigned short  mask (unsigned short num) {  switch (num) {  case 0 : return 0xC0;  case 1 : return 0xF9 ;  case 2 : return 0xA4;  case 3 : return 0xB0;  case 4 : return 0x99;  case 5 : return 0x92;  case 6 : return 0x82;  case 7 : return 0xF8;  case 8: return 0x80;  case 9: return 0x90;  } //case end }

void delay_debounce(){
 Delay_ms(300);
}

void delay_refresh(){
 Delay_ms(5);
}

void countpulse(){
 IR_Tx = 1;
 delay_debounce();
 delay_debounce();
 TMR0=0;
 Delay_ms(15000); // Delay 1 Sec
 IR_Tx = 0;
 pulsecount = TMR0;
 pulserate = pulsecount*4;
}

void display(){
  DD0 = pulserate%10;
  DD0 = mask(DD0);
  DD1 = (pulserate/10)%10;
  DD1 = mask(DD1);
  DD2 = pulserate/100;
  DD2 =  mask (DD2);
  for ( i = 0; i<=180*j; i++) {
    DD0_Set = 0;
    DD1_Set = 1
    ; DD2_Set = 1;
    PORTB = DD0;
    delay_refresh();
    DD0_Set = 1;
    DD1_Set = 0;
    DD2_Set = 1;
    PORTB = DD1;
    delay_refresh();
    DD0_Set = 1;
    DD1_Set = 1;
    DD2_Set = 0;
    PORTB = DD2;
    delay_refresh();
    }
  DD2_Set = 1;
}

void main() {
 CMCON = 0x07; // Disable Comparators
 TRISA = 0b00110000; // RA4/T0CKI input, RA5 is I/P only
 TRISB = 0b10000000; // RB7 input, rest output
 OPTION_REG = 0b00101000; // Prescaler (1 :1), TOCS =1 for counter mode
 pulserate = 0;
 j = 1;
 display();
 do {
  if(!start){
   delay_debounce();
   countpulse();
   j= 3;
   display();
  }
 } while( 1); // Infinite loop
}