关于S3C2440定时器中断

各位哥些，我在学习S3C2440定时器中断的时候碰到了一个问题，希望大家不吝赐教一下。。。下面是我写的c程序：
#define _ISR_STARTADDRESS 0x33ffff00
#define U32 unsigned int
#define pISR_TIMER4 (*(unsigned *)(_ISR_STARTADDRESS+0x58))
#define SRCPND  (*(volatile unsigned *)0x4a000000)
#define INTMASK (*(volatile unsigned *)0x4a000008)
#define INTPND  (*(volatile unsigned *)0x4a000010)
#define GPBCON  (*(volatile unsigned *)0x56000010)
#define GPBDAT  (*(volatile unsigned *)0x56000014)
#define GPBUP   (*(volatile unsigned *)0x56000018)
#define MPLLCON (*(volatile unsigned *)0x4c000004)
#define CLKDIVN (*(volatile unsigned *)0x4c000014)
#define TCFG0 (*(volatile unsigned *)0x51000000)
#define TCFG1 (*(volatile unsigned *)0x51000004)
#define TCON  (*(volatile unsigned *)0x51000008)
#define TCNTB4 (*(volatile unsigned *)0x5100003c)
#define TCNTO4 (*(volatile unsigned *)0x51000040)
void __irq Timer4_ISR(void);
void Main(void)
{
   
   GPBCON =(1<<0)|(1<<10)|(1<<12)|(1<<14)|(1<<16);
   GPBDAT = 0x1e0;
   GPBUP  = 0x7ff;
   MPLLCON=0x7f021;
   CLKDIVN=0x05;
   
   SRCPND = SRCPND|(0x1<<14);
   INTPND = INTPND|(0x1<<14);
   INTMASK =~(1<<14);
   
   TCFG0  = 0xf900;
   TCFG1  = 0x2000;
   TCNTB4 = 25000;
   TCON   = 0x700000;
        
   pISR_TIMER4=(U32)Timer4_ISR;
   while(1);
}
void __irq Timer4_ISR(void)
{
  static int count;
  count=0;
  count++;
  SRCPND = SRCPND|(1<<14);
  INTPND = INTPND|(1<<14);
  if(count%4==0)
     GPBDAT=~0x1e0;
  else if(count%4==1)
     GPBDAT=0x1e0;
}
启动代码如下：

IMPORT Main
AREA Init,CODE,READONLY
ENTRY
ldr r0,=0x53000000;看门狗定时器控制寄存器
ldr r1,=0x0
str r1,[r0]

ldr r0,=0x4a000008;中断屏蔽寄存器
ldr r1,=0xffffffff;屏蔽所有中断
str r1,[r0]

ldr r0,=0x4a00001c;子中断屏蔽寄存器
ldr r1,=0x7ff     ;屏蔽所有子中断
str r1,[r0]

ldr r0,=0x4c000000;锁相环锁定时间计数器
ldr r1,=0xffffff  
str r1,[r0]
b Main
END
编译通过后用Hjtag调试的时候，光标一直指到中断服务程序，根本就进不到主程序中，希望大家帮我看一下，跪求。。。万分感谢。。。