entry.s

ARM开发的源码

#********************************************************************************************
# NAME:		entry.s																		    *
# Author: 	Embest																		    *
# Desc:	    debugging with arm and thumb instruction										*
# History:																					*
#																	    					*
#********************************************************************************************

/*------------------------------------------------------------------------------------------*/
/*	 								constant define						 				    */
/*------------------------------------------------------------------------------------------*/	
	.equ	count, 20
	
/*------------------------------------------------------------------------------------------*/
/*	 						    	extern function  					 				    */
/*------------------------------------------------------------------------------------------*/	
	.extern thumb_function	
	
/*------------------------------------------------------------------------------------------*/
/*	 								global symbol define						 				    */
/*------------------------------------------------------------------------------------------*/	                                                    
	.global _start                           
                                                               
/*------------------------------------------------------------------------------------------*/
/*	 								code								 				    */
/*------------------------------------------------------------------------------------------*/
	.text                         	
_start:
# Setup interrupt / exception vectors          
	b       Reset_Handler
Undefined_Handler:
	b       Undefined_Handler
SWI_Handler:
	b       SWI_Handler
Prefetch_handler:
	b       Prefetch_handler
Abort_Handler:
	b       Abort_Handler
	nop	                                    /* Reserved vector */                                                                                                                                                                                                                                                   	    
IRQ_Handler:
	b       IRQ_Handler
FIQ_Handler:
	b       FIQ_Handler	    
Reset_Handler:
	ldr		sp, =0x0C002000                 /* set up user_mode stack pointer (r13) */
	mov		r0, #count                      /* the number of loop*/
	mov		r1, #0
	mov		r2, #0
	mov		r3, #0
	mov		r4, #0
	mov		r5, #0
	mov		r6, #0
loop0:
	add		r1, r1, #1
	add		r2, r2, #1
	add		r3, r3, #1
	add		r4, r4, #1
	add		r5, r5, #1
	add		r6, r6, #1

	subs	r0, r0, #1
	bne		loop0
		
	adr     r0, Thumb_Entry+1                /*jump to thumb program  */
	bx      r0

# ****************************************************
# *	  thumb program entry			                 * 	
# ****************************************************

.thumb
Thumb_Entry:
	mov		r0, #count

	mov		r1, #0
	mov		r2, #0
	mov		r3, #0
	mov		r4, #0
	mov		r5, #0
	mov		r6, #0
	mov		r7, #0
loop1:
	add		r1, #1
	add		r2, #1
	add		r3, #1
	add		r4, #1
	add		r5, #1
	add		r6, #1
	add		r7, #1

	sub		r0, #1
	bne		loop1
		
	bl 		thumb_function              
	b		Thumb_Entry
    .end