GSM Modem and PIC16F877A

#include <stdio.h>
#include <htc.h>
#include "usart.h"
#include "lcd.h"
#include "string.h"

__CONFIG(HS & WDTDIS & UNPROTECT &  LVPDIS);

unsigned char gsmInput[60];
unsigned int i=0;
unsigned int lenOfGSMInput = 0;

bit OK;
bit Error;
bit Ring;

void showGSM_DATA(char GSM_DATA[]){ //to show the GSM OUTPUT after eliminating the chars '\r' and '\n'
    
    if (strcmp(GSM_DATA, "OK") == 0){ 
        OK = 1;
    }
    else if (strcmp(GSM_DATA, "ERROR") == 0){
            Error = 1;
    }
    else if (strcmp(GSM_DATA, "RING") == 0){
       
        Ring = 1;
        
        GSM_DATA[0] = '\x00';
        puts("AT+CLCC");
        putch(0x0D);
        
    }
    else{
        lcd_clear();
        lcd_goto(0);
        lcd_puts(GSM_DATA);
    }
  GSM_DATA[0] = '\x00';
 
} // end function showGSM_DATA

void main(int argc, char* argv[]){

	unsigned char input;
       
	INTCON=0;	// purpose of disabling the interrupts.
    
	lcd_init(); // initiate LCD
	
	init_comms();	// set up the USART - settings defined in usart.h
    			    
    puts("ATE0");
    putch(0X0D);
    
    puts("AT+CMGF=1");
    putch(0X0D);
    
    while(1){
		               
        input = getch();	// read a response from the GSM
        
        switch(input){
            
            case '\x0A': // if line feed detected in the GSM output i.e. '\n'
                        break;
            case '\x0D': // if carriage return detected i.e. '\r'
                        gsmInput[i] = '\x00';
                        
						lenOfGSMInput = strlen(gsmInput);
                        if (lenOfGSMInput > 0){
                            i = 0;
                            lenOfGSMInput = 0;
                            showGSM_DATA(gsmInput);
                        }
                        break;
            case '\x3E': // if greater-sign (in order to send SMS)
                        break;
            
        default: // if characters received
                gsmInput[i] = input;
                i++;
                break;
        }//end brace for switch
	} //end brace for while loop
}//end brace for main</htc.h></stdio.h>