i2c interfacing

hello sir/mam,
i want to use i2c interface for my project in which i m using the LPC2468 microcontroller.
i m using keil software.i got one code for i2c that is as follows but in this i have some quaries can u please help me.
code:
#include "LPC213x.h"
void initialize(void);
__irq void I2C_ISR(void);
/* Master Transmitter states */
void ISR_8(void);
void ISR_18(void);
void ISR_28(void);
/*************************** MAIN ************************/
int main()
{ /* Initialize system */
initialize();
/* Send start bit */
I2C0CONSET=0x60;
/* Do forever */
while(1)
{ IOCLR0=0x40;
IOSET0=0x40;
} }
/*************** System Initialization ***************/
void initialize()
{ /* Remap interrupt vectors to SRAM */
MEMMAP=0x2;
/* Initialize GPIO ports to be used as indicators */
IODIR0=0xF0;
IOSET0=0xF0;
/* Initialize Pin Connect Block */
PINSEL0=0x50;
/* Initialize I2C */
I2C0CONCLR=0x6c; /* clearing all flags */
I2C0CONSET=0x40; /* enabling I2C */
I2C0SCLH=0xC; /* 100 KHz */
I2C0SCLL=0xD;
/* Initialize VIC for I2C use */
VICIntSelect=0x0; /* selecting IRQ */
VICIntEnable= 0x200; /* enabling I2C */
VICVectCntl0= 0x29; /* highest priority and enabled */
VICVectAddr0=(unsigned long) I2C_ISR;
/* ISR address written to the respective address register*/

}
/********************** I2C ISR **************************/ __irq void I2C_ISR()
{ int temp=0;
temp=I2C0STAT;
switch(temp)
{ case 8:
ISR_8();
break;
case 24:
ISR_18();
break;
case 40:
ISR_28();
break;
default :
break;
} VICVectAddr=0xFF;
} /* I2C states*/
/* Start condition transmitted */
void ISR_8()
{ /* Port Indicator */
IOCLR0=0x10;
/* Slave address + write */
I2C0DAT=0x74;
/* Clear SI and Start flag */
I2C0CONCLR=0x28;
/* Port Indicator */
IOSET0=0x10;
}

/* Acknowledgement received from slave for slave address */
void ISR_18()
{ /* Port Indicator */
IOCLR0=0x20;
/* Data to be transmitted */
I2C0DAT=0x55;
/* clear SI */
I2C0CONCLR=0x8;
/* Port Indicator */
IOSET0=0x20;
} /* Acknowledgement received from slave for byte transmitted from master. Stop
condition is transmitted in this state signaling the end of transmission */
void ISR_28()
{ /* Port Indicator */
IOCLR0=0x80;
/* Transmit stop condition */
I2C0CONSET=0x10;
/* clear SI */
I2C0CONCLR=0x8;
/* Port Indicator */
IOSET0=0x80;
} /********************************************************/
in this code i m not getting what is I2C_ISR..in this code initialization is perfect but after that it is going to the infinite loop..in the startup code it is going in the infinite loop....and i m also not getting what is the meaning of LDR PC, [PC, #-0x0120]..after that while loop it is coming on this lable which is in the startup file and then not comming out....can u please help me..thank u.