problem regarding Interfacing TIVA C SERIES launch pad with GSM modem

Hai

      currently i am working on TM4C123GH6PM micro controller,and here i have interfaced my micro controller to the GSM modem.And when i transmitting the command AT from my controller then it has to generate an interrupt in that interrupt handler i want to store only the "RESPONSE" of interrupt handler,but here i got the problem is the same data is also stored in side the buffer in the interrupt handler i.e what i send(same AT).......please help me about this issue.....thank u

here just i modified uart echo example....

 
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include "inc/tm4c123gh6pm.h"
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/pin_map.h"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include "utils/uartstdio.h"
#include "driverlib/uart.h"
 
unsigned char ok[]="OK\r\n";
unsigned char m[20];
int count=0;
int count1=0;
unsigned int i,j;
 
 
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, uint32_t ui32Line)
{
}
#endif
 
//*****************************************************************************
 
// The UART interrupt handler.
/************************************************************/
void
UART1IntHandler(void)
{
 
    uint32_t ui32Status;
    ++count1;
 
 
 
    //
    // Get the interrrupt status.
    //
    ui32Status = ROM_UARTIntStatus(UART1_BASE, true);
 
    //
    // Clear the asserted interrupts.
 
            ROM_UARTIntClear(UART1_BASE, ui32Status);
            
 
    // Loop while there are characters in the receive FIFO.
    //
 
 
    while(ROM_UARTCharsAvail(UART1_BASE))
    {
      m[count]=ROM_UARTCharGetNonBlocking(UART1_BASE);
    
     count++;
     if(count==20);
     count=0;
                
   }
 
     ROM_IntDisable(INT_UART1);
 }
/********************************************************/
int
main(void)
{
    //
    // Enable lazy stacking for interrupt handlers.  This allows floating-point
    // //instructions to be used within interrupt handlers, but at the expense of
    // extra stack usage.
    //
    ROM_FPUEnable();
    ROM_FPULazyStackingEnable();
 
    //
    // Set the clocking to run directly from the crystal.
    //
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
                       SYSCTL_XTAL_16MHZ);
 
   
     
 
    //
    // Enable the peripherals used by this example.
    //
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART1);
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
 
    //
    // Enable processor interrupts.
    //
    ROM_IntMasterEnable();
 
    //
    // Set GPIO B0 and B1 as UART pins.
    //
    GPIOPinConfigure(GPIO_PB0_U1RX);
    GPIOPinConfigure(GPIO_PB1_U1TX);
 
 
    ROM_GPIOPinTypeUART(GPIO_PORTB_BASE, GPIO_PIN_0 | GPIO_PIN_1);
 
    //
    // Configure the UART for 115,200, 8-N-1 operation.
    //
    ROM_UARTConfigSetExpClk(UART1_BASE, ROM_SysCtlClockGet(), 115200,
                            (UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |
                             UART_CONFIG_PAR_NONE));
 
    //
    // Enable the UART interrupt.
 
    ROM_UARTIntEnable(UART1_BASE, UART_INT_RX | UART_INT_RT);
 
    ROM_UARTFIFOEnable(UART1_BASE);
 
    UARTFIFOLevelSet(UART1_BASE, UART_FIFO_TX1_8, UART_FIFO_RX1_8);
 
    UARTEnable (UART1_BASE);
 
    while(1)
    {
                   do
                     {
 
                        tx("AT\r\n");
 
                        SysCtlDelay(SysCtlClockGet());
                        SysCtlDelay(SysCtlClockGet());
                        SysCtlDelay(SysCtlClockGet());
                        
                 }while((strcmp(ok,m))!=0);
 
                    
 
 
                       do
                          {
 
                                tx("AT+CREG=1\r\n");
 
                                SysCtlDelay(SysCtlClockGet());
                                SysCtlDelay(SysCtlClockGet());
                                SysCtlDelay(SysCtlClockGet());
 
                      }while((strcmp(ok,m))!=0);
 
 
                      do
                      {
 
                                tx("AT+CREG=?\r\n");
 
                                SysCtlDelay(SysCtlClockGet());
                                SysCtlDelay(SysCtlClockGet());
                                SysCtlDelay(SysCtlClockGet());
 
                     }while((strcmp(ok,m))!=0);
 
         
  }
 
}
void tx(unsigned char *p)
{
    while(*p!='\0')
    {
        ROM_UARTCharPutNonBlocking(UART1_BASE, *p);
            p++;
    }

  ROM_IntEnable(INT_UART1);
    
}