interfacing IR remote using NEC protocol - mikroc for PIC

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sbit LCD_RS at Rd1_bit;
sbit LCD_EN at Rd2_bit;
sbit LCD_D4 at Rd4_bit;
sbit LCD_D5 at Rd5_bit;
sbit LCD_D6 at Rd6_bit;
sbit LCD_D7 at Rd7_bit;
sbit LCD_RS_Direction at TRISd1_bit;
sbit LCD_EN_Direction at TRISd2_bit;
sbit LCD_D4_Direction at TRISd4_bit;
sbit LCD_D5_Direction at TRISd5_bit;
sbit LCD_D6_Direction at TRISd6_bit;
sbit LCD_D7_Direction at TRISd7_bit;
// End LCD module connections
 
bit nec_ok;
char text[5];
unsigned short nec_state, command, inv_command, i;
unsigned int address, timer_value;
unsigned long nec_code;
 
void Interrupt() {
  if (RBIF_bit && RBIE_bit){         // PORTB change ISR
    RBIF_bit = 0;
    if(nec_state != 0){
      timer_value = (TMR1H << 8) + TMR1L;           // Store Timer1 value
      TMR1H = 0;                                    // Reset Timer1
      TMR1L = 0;
    }
    switch(nec_state){
     case 0 :                                       // Start receiving IR data (we're at the beginning of 9ms pulse)
       TMR1H = 0;                                   // Reset Timer1
       TMR1L = 0;
       TMR1ON_bit = 1;                              // Enable Timer1
       nec_state = 1;                               // Next state: end of 9ms pulse (start of 4.5ms space)
       i = 0;
       break;
     case 1 :                                       // End of 9ms pulse
       if((timer_value > 9500) || (timer_value < 8500)){         // Invalid interval ==> stop decoding and reset
         nec_state = 0;                             // Reset decoding process
         TMR1ON_bit = 0;                            // Disable Timer1
       }
       else
         nec_state = 2;                             // Next state: end of 4.5ms space (start of 562µs pulse)
       break;
     case 2 :                                       // End of 4.5ms space
       if((timer_value > 5000) || (timer_value < 4000)){
         nec_state = 0;                             // Reset decoding process
         TMR1ON_bit = 0;                            // Disable Timer1
       }
       else
         nec_state = 3;                             // Next state: end of 562µs pulse (start of 562µs or 1687µs space)
       return;
     case 3 :                                       // End of 562µs pulse
       if((timer_value > 700) || (timer_value < 400)){           // Invalid interval ==> stop decoding and reset
         TMR1ON_bit = 0;                            // Disable Timer1
         nec_state = 0;                             // Reset decoding process
       }
       else
         nec_state = 4;                             // Next state: end of 562µs or 1687µs space
       return;
     case 4 :                                       // End of 562µs or 1687µs space
       if((timer_value > 1800) || (timer_value < 400)){           // Time interval invalid ==> stop decoding
         TMR1ON_bit = 0;                            // Disable Timer1
         nec_state = 0;                             // Reset decoding process
         return;
       }
       if( timer_value > 1000)                           // If space width > 1ms (short space)
         nec_code = 1 << (31 - i);       // Write 1 to bit (31 - i)
       else                                              // If space width < 1ms (long space)
         nec_code = 0 << (31 - i);    // Write 0 to bit (31 - i)
       i++;
       if(i > 31){                                  // If all bits are received
         nec_ok = 1;                                // Decoding process OK
         RBIE_bit = 0;                              // Disable PORTB change interrupt
         return;
       }
       nec_state = 3;                               // Next state: end of 562µs pulse (start of 562µs or 1687µs space)
    }
  }
  if (TMR1IF_bit){                 // Timer1 ISR
    TMR1IF_bit = 0;                // Clear Timer1 overflow flag bit
    nec_state = 0;                 // Reset decoding process
    TMR1ON_bit = 0;                // Disable Timer1
  }
}
 
void main() {
 OSCCON = 0X70;
  trisd = 0x00;
  trisb0_bit = 1;
  ansel = 0x00;
  nec_ok = 0;
  nec_state = 0;
  ANSELH = 0;                      // Configure all PORTB pins as digital
  Lcd_Init();                      // Initialize LCD module
  Lcd_Cmd(_LCD_CURSOR_OFF);        // cursor off
  Lcd_Cmd(_LCD_CLEAR);             // clear LCD
  TMR1IF_bit = 0;                  // Clear Timer1 overflow interrupt flag bit
  TMR1IE_bit = 1;                  // Enable Timer1 overflow interrupt
  T1CON = 0x10;                    // Set Timer1 clock source to internal with 1:2 prescaler (Timer1 clock = 1MHz)
  INTCON = 0x90;
  INTF_bit = 0;
  INTE_bit = 1;
  IOCB0_bit = 1;
  OPTION_REG = 0XC0;
  Lcd_out(1,5,"welcome");
  Lcd_out(2,2, "dear");
  delay_ms(1000);
  Lcd_cmd(_lcd_clear);
  Lcd_Out(1, 1, "Address:0x0000");
  Lcd_Out(2, 1, "Com:0x00 In:0x00");
  delay_ms(1000);
  while(1) {
    while(nec_ok)                // Wait until NEC code receiver
    nec_ok = 0;                    // Reset decoding process
    nec_state = 0;
    TMR1ON_bit = 0;                // Disable Timer1
    address = nec_code >> 16;
    command = nec_code >> 8;
    inv_command = ~command ;
    IntToHex(address, text);       // Save address in string text with hex format
    Lcd_Out(1, 11, text);          // Display address
    ByteToHex(command, text);      // Save command in string text with hex format
    Lcd_Out(2, 7, text);           // Display command
    ByteToHex(inv_command, text);  // Save inverted command in string text with hex format
    Lcd_Out(2, 15, text);          // Display inverted command
    RBIE_bit = 1;                  // Enable PORTB change interrupt
  }
}