ARM裸机程序求助，编译通过，运行不正常

在某宝上买的s3c2440的板子，网上找的电子书学习了一段LED点灯的程序，然后就遇到了一个非常奇怪的问题，片外内存的初始化用C语言写，不能正常点灯，换成汇编就能正常点灯。请大神们帮忙看看到底怎么回事
Makefile:
sdram.bin:   sdram.s     GPIO_LED.c
        arm-linux-gcc  -c  -o  sdram.o sdram.s
        arm-linux-gcc  -c  -o  GPIO_LED.o GPIO_LED.c
        arm-linux-ld   -Ttext 0x30000000 sdram.o GPIO_LED.o -o sdram_elf
        arm-linux-objcopy -O binary -S sdram_elf sdram.bin
        arm-linux-objdump -D -m arm sdram_elf > sdram.dis
clean:
        rm -f  *.dis sdram.bin sdram_elf  *.o  *~
sdram.s
.text
.global _start
_start:
        ldr  sp, =4096
        bl   disable_watchdog                    //关看门狗
        bl   sdram_setup                             //初始化片外内存
        bl   nandcopy2sdram                     //将片内内存里的东西拷贝到片外内存
        ldr  pc, =sdram                                //跳转到片外内存
sdram:       
        ldr  sp, =0x34000000
        bl   main
        
halt_loop:
        b   halt_loop
GPIO_LED.c                                               //点亮开发板上的LED灯
#define        GPFCON           (*(volatile unsigned long *)0x56000050)
#define        GPFDAT           (*(volatile unsigned long *)0x56000054)
#define        WDCON           (*(unsigned long*)0x53000000)
#define        SDRAMCON      0x48000000
#define        GPF4_out        (1<<(4*2))
#define        GPF5_out        (1<<(5*2))
#define        GPF6_out        (1<<(6*2))
void  wait(volatile unsigned long dly)
{
        for(; dly > 0; dly--);
}
int main(void)
{
        unsigned long i = 0;
        GPFCON = GPF4_out|GPF5_out|GPF6_out;                // 将LED1,2,4对应的GPF4/5/6三个引脚设为输出
        while(1){
                wait(30000);
                GPFDAT = (~(i<<4));                 // 根据i的值，点亮LED1,2,4
                if(++i == 8)
                        i = 0;
        }
        return 0;
}
void disable_watchdog()
{
        WDCON  =  0 ;      //禁用watchdog
}
void sdram_setup()
{
        unsigned long const sdramfig[] = { 
                0x22011110,
                0x00000700,
                0x00000700,
                0x00000700,
                0x00000700,
                0x00000700,
                0x00000700,
                0x00018005,
                0x00018005,
                0x008c07a3,
                0x000000b1,
                0x00000030,
                0x00000030,
        };
        int i = 0;
        volatile unsigned long *p  =  (volatile unsigned long *) SDRAMCON;
        for(;i<13;i++)
        {
  &n