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List:       linux-arm-kernel
Subject:    arm assembly code starting address and define
From:       Mark Yang <markarmlinux () yahoo ! com>
Date:       2002-07-31 16:50:37
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Hi, 
   I am writing some boot up code to boot up my own OS
kernal and my own board, can anyone tell me how do I
make my code starting from adress 0 instead of the
default address 0x8000? and also how do i add #define
to the code? sorry this sounds stupid but I did try
the normal way to do it, but it doesn't work.
Below is a piece of my code:
////////////////////////////////////////////
#define IOPDATA 8
	.code 32
	.align 0
	.globl _start
	.org 0
.text

.globl _start
_start:
	
	b	reset



	/*b	undefined_instruction
	  b	software_interrupt
	  b	prefetch_abort
	  b	data_abort
	  b	not_used
	  b	irq
	  b	fiq*/




reset:
	/* First, mask **ALL** interrupts 
	ldr	r0, INTBASE
	mov	r1, #00
	str	r1, [r0, #0x00]	/* set interrupt pending register
INTPND to pending status */ 

	/* switch CPU to correct speed
	ldr	r0, CLKBASE
	ldr	r1, CPU_SPEED
	str	r1, [r0, #0]*/

	/*init LED*/
	bl ledinit
	bl led_on
loop:
	b loop

/* initialise LED GPIO and turn LED on.
 clobbers r0 and r1
*/
ledinit:
	ldr r0,IOPBASE
		/* IOPMOD initialize, set to output*/
	mov r1, #0
	str	r1, [r0, #8]		/* IOPDATA turn LED on */
	mov	pc, lr
	
	
led_on:
	ldr r0, IOPBASE
	mov r1,#3 
	str r1,[r0, #IOPDATA] /*IOPDATA*/ 
	mov pc,lr

IOPBASE: .word 0x03FF5000
////////////////////////////////////////////////
I am using arm-elf-as and arm-elf-ld,  the code starts
from address 0x8000 and it could not recognize IOPDATA
if I use it instead of putting 8 there.

Thanks so much!
Mark

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