init_ice.s

最近在國外網站抓到的作業系統 以Arm為基礎去開發的

;init the mem map no the integrate board


	include hardware_gfd.h


	AREA INIT, CODE, READONLY                                                     
	       ENTRY                           ; Mark first instruction to execute 
		
	;init sp_svc
	ldr		sp, =SP_SVC 
	
	
	;chmod to irq and init sp_irq                                       
	mov		RTA, #0xD2                                                  
	msr		cpsr_cf, RTA                                                
	ldr		sp, =SP_IRQ                                                 
                                                                    
                                                                    
	;chomod to fiq and init sp_fiq                                      
	mov		RTA, #0XD1                                                  
	msr		cpsr_cf, RTA                                                
	ldr		sp, =SP_FIQ                                                 
                                                                    
	;chomod to abt and init sp_ABT                                      
	mov		RTA, #0XD7                                                  
	msr		cpsr_cf, RTA                                                
	ldr		sp, =SP_ABT                                                 
                                                                    
	;chomod to undf and init sp_UNDF                                    
	mov		RTA, #0XDB                                                  
	msr		cpsr_cf, RTA                                                
	ldr		sp, =SP_UND 	                                            
                                                                    
	;CHMOD TO SYS AND INTI SP_SYS                                       
	mov 	RTA, #0xDF		;@all interrupts disabled,                  
	msr		cpsr_cxsf, RTA   ; @SYSTEM mode, @32-bit code mode          
	ldr		sp, =SP_SYS   ;INIT SYS_SP                                  
                                                                    
	;chmod to svc modle                                                 
	mov		RTA, #0XD3                                                  
	msr		cpsr_c, RTA   
	
	
;***************************************************************
;    	enable CPSR IRQ bit
;***************************************************************
  	mrs		RTA, cpsr
	bic		RTA, RTA, #0x80  		;set bit7 to zero
	msr		cpsr_c, RTA     

	
	IMPORT	__main
	
	B	__main
	
	END