Doubt regarding code

I have one Doubt how void uart(void)__irq this function call in this program..........????

#include "lpc21xx.h"
// #include "lpc210x.h"
#include "stdio.h"
#define baudrate_uart1 0x0f //@115200;SYS_CLK/16*2*COUNT=0x0f
#define sender_no "+919328178092"
#define sms "Advance Technology rising company in future"
#define CR 0x0D
#define LF 0x0A
/****************************Prototypes****************************/

void delay(void);
void getch (char ch);
char *gps_strchr(char *src, char ch);
int gps_strncmp( char *s1, char *s2, unsigned char length);
int gps_strcpy1(unsigned char *s1,char *s2);
const char *uart1Puts(const char *string);
int uart1Putch(int ch);
void uart1_interrupt(void);
void uart1_initialize(void);
void check_response(char *sentence);
void lcd (int length) ;
void instwrt(void);
void datawrt(void);
void lcd_init(void);
char at_get_running;
char at_get_buff[160],*at_get_idx;

char response_ok=0;
char lcd_buffer[20],temp123[200];
static char array1[160];

int main()
{

VPBDIV=2; IODIR0=IODIR0|0x0f00fffc;

uart1_initialize(); uart1_interrupt(); lcd_init();

uart1Puts("AT" ) ; uart1Putch(CR); delay();

while(response_ok!=1) //check response for previous cmd { response_ok=0; //uart1Puts("AT+CMGF=1" ) ; // uart1Putch(CR); // delay();

//uart1Puts("AT+CMGS=" ) ; //uart1Putch('"'); //uart1Puts(sender_no) ; //uart1Putch('"'); //uart1Putch(CR); //uart1Puts(sms); // uart1Putch(26); // delay(); } while(1) {

} }

/*****************************************************************************
* FUNCTION : UART1 interrupt
* PURPOSE : for data capturig at baudrate 115.2kbps
* INPUTS : receive interrupt
* RETURNS : none
*****************************************************************************/

void uart(void)__irq
{ char status,temp; if((U0LSR & 0x01)==0x01) { status=U0RBR; getch(status);

} VICVectAddr=0; temp=U0IIR;

}
/*****************************************************************************
* FUNCTION : get_ch
* PURPOSE : gets the ch from GPRS and findout gprs responses and route table information
* INPUTS : passing ch receive from uart1 receive interrupt
* RETURNS : none
*****************************************************************************/ void getch (char ch) {

static char ch_count1=0;

if( ch_count1<150) { array1[ch_count1]=ch; ch_count1++; } else ch_count1=0;

if((ch ==LF)&&(!at_get_running)) //start of response { at_get_running = 1; //sentence being recieved flag true at_get_idx = at_get_buff; }

if(at_get_running) { if((ch== LF)&&(at_get_idx == (at_get_buff+1))) //start of response received { at_get_idx = at_get_buff; } else if((ch == CR)&&(at_get_idx > (at_get_buff+1))) //end of response { at_get_running = 0; *at_get_idx = 0; check_response( at_get_buff); } else { if(ch!=LF) *at_get_idx++ = ch; //update buffer with response on uart } }

}

/*****************************************************************************
* FUNCTION : int check_response(void)
* PURPOSE : check AT response type from response strored in buffer and
* return appropriate value according to type
* INPUTS : sentence: address of buffer
* RETURNS :1 on success 0 on error/busy

*****************************************************************************/ void check_response(char *sentence)
{

if(gps_strncmp(sentence, "RING", 4) == 0) { response_ok=1; // lcd_buffer[]={}; gps_strcpy1(lcd_buffer,"CALL FOR U"); lcd(10); uart1Puts("ATA" ) ; uart1Putch(CR); delay();

} else if(gps_strncmp(sentence, "NO CARRIER", 10) == 0) { response_ok=0; gps_strcpy1(lcd_buffer,"MISS CALL"); lcd(9); }

else if(gps_strncmp(sentence, "+CMTI:", 6) == 0) //+CMTI: "SM",16 ==cmti is receive response, sm: sim memory, 16 location number { // maximum 30 sms stored gps_strcpy1(lcd_buffer,"NEW MSG RECEIVED"); lcd(16);

//lcd(16);

} else if(gps_strncmp(sentence, "RING", 4) == 0) response_ok=1;

else if(gps_strncmp(sentence, "OK", 2) == 0) response_ok=1; }
/*****************************************************************************
* FUNCTION : gps_strchr
* PURPOSE : Searches for the character and returns the location
* * INPUTS : char *src - source string
* char ch - character to be searched

* RETURNS : address location of character in string

*****************************************************************************/