s3c2440 -- Marquee C+ assembly code

/*led_asm_c.c*/
#define rGPFCON (*(volatile unsigned *)0x56000050) //Port F control
#define rGPFDAT (*(volatile unsigned *)0x56000054) //Port F data
#define rGPFUP (*(volatile unsigned *)0x56000058) //Pull-up control F
 //GPFCON 8 port
extern int delay(int time); /*Declare assembly function*/

int main()
{
 /*Set GPFCON*/
 rGPFCON &= 0x00ff; //GPF4 - 7 is set to 0
 rGPFCON |= 0x55ff; //GPF4 - 7 is set to output

 /*Set GPFUP*/
 rGPFUP |= 0xff00;

 while(1)
 {
    /*Turn on GPF4*/
    rGPFDAT |= 0xf0; //GPF4 - 7 is set to 1
    rGPFDAT &= 0xe0; //GPF4 is set to 0
    delay(0x1ffffff); //Call the delay program written by the assembly program

     /*Turn on GPF5*/
    rGPFDAT |= 0xf0; //GPF4 - 7 is set to 1
    rGPFDAT &= 0xd0; //GPF5 is set to 0
    delay(0x1ffffff); //Call the delay program written by the assembler

     /*Turn on GPF6*/
    rGPFDAT |= 0xf0; //GPF4 - 7 is set to 1
    rGPFDAT &= 0xb0; //GPF6 is set to 0
    delay(0x1ffffff); //Call the delay program written by the assembler

     /*Turn on GPF7*/
    rGPFDAT |= 0xf0; //Set GPF4 - 7 to 1
    rGPFDAT &= 0x70; //Set GPF7 to 0
    delay(0x1ffffff); //Call the delay program written by the assembly program
 }
}

;delay.s

 EXPORT delay
 AREA delay1,CODE,READONLY; This pseudo instruction defines a code segment delay1. Note the name
; the following delay subroutine

 ENTRY
delay
 ; pass a parameter, put the parameter into r0
 sub r0 ,r0 ,#1
 cmp r0 ,#0x0
 bne delay ; result is not 0 and continue delay
 mov pc ,lr ; return

 END; //end