cstartup_ads_ram.s

ARM AT9260的一段初始代码,主要是用来测试SDRAM

;------------------------------------------------------------------------------
;-         ATMEL Microcontroller Software Support  -  ROUSSET  -
;------------------------------------------------------------------------------
; The software is delivered "AS IS" without warranty or condition of any
; kind, either express, implied or statutory. This includes without
; limitation any warranty or condition with respect to merchantability or
; fitness for any particular purpose, or against the infringements of
; intellectual property rights of others.
;-----------------------------------------------------------------------------
;- File source          : cstartup_boot.arm
;- Object               : Generic CStartup
;- Compilation flag     : None
;-
;- 1.0 23/10/02 	FB  : Creation ARM ADS
;------------------------------------------------------------------------------

	;INCLUDE   AT91RM9200.inc

;--------------------------------
;- ARM Core Mode and Status Bits
;--------------------------------
RAM0_BASE               EQU     0x200000
RAM0_SIZE               EQU     4*1024
RAM0_END                EQU     RAM0_BASE + RAM0_SIZE

RAM1_BASE               EQU     0x300000
RAM1_SIZE               EQU     4*1024
RAM1_END                EQU     RAM0_BASE + RAM0_SIZE

 

ARM_MODE_USER           EQU     0x10
ARM_MODE_FIQ            EQU     0x11
ARM_MODE_IRQ            EQU     0x12
ARM_MODE_SVC            EQU     0x13
ARM_MODE_ABORT          EQU     0x17
ARM_MODE_UNDEF          EQU     0x1B
ARM_MODE_SYS            EQU     0x1F

I_BIT                   EQU     0x80
F_BIT                   EQU     0x40
T_BIT                   EQU     0x20

IRQ_STACK_SIZE          EQU     (2*8*4)



;------------------------------------------------------------------------------
;- Area Definition
;-----------------
;- Must be defined as function to put first in the code as it must be mapped
;- at offset 0 of the flash EBI_CSR0, ie. at address 0 before remap.
;------------------------------------------------------------------------------
                AREA        reset, CODE, READONLY


;	IMPORT __use_no_semihosting_swi
;------------------------------------------------------------------------------
;- Define the entry point
;------------------------

	EXPORT	__ENTRY
__ENTRY

;------------------------------------------------------------------------------
;- Exception vectors ( before Remap )
;------------------------------------
;- These vectors are read at address 0.
;- They absolutely requires to be in relative addresssing mode in order to
;- guarantee a valid jump. For the moment, all are just looping (what may be
;- dangerous in a final system). If an exception occurs before remap, this
;- would result in an infinite loop.
;------------------------------------------------------------------------------
                B           InitReset       	;
undefvec
                B           undefvec        	; Undefined Instruction
swivec
                B           swivec          	; Software Interrupt
pabtvec
                B           pabtvec         	; Prefetch Abort
dabtvec
                B           dabtvec         	; Data Abort
rsvdvec
                B           rsvdvec         	; reserved
irqvec
                ldr         pc, [pc,#-0xF20]    ; IRQ : read the AIC
fiqvec
                B           fiqvec          	; FIQ




;-------------------
;- The reset handler
;-------------------
InitReset
   

	IMPORT    AT91F_LowLevelInit
    ldr       r13,= RAM1_END              ;//设置堆栈在RAM1。
	ldr       r0, = AT91F_LowLevelInit    ;//初始化系统外围设备。
	mov       lr, pc
	bx        r0





;------------------------------------------------------------------------------
;- Setup the stack for each mode
;-------------------------------
                ldr     r0, = RAM1_END

;- Set up Fast Interrupt Mode and set FIQ Mode Stack
                msr     CPSR_c, #ARM_MODE_FIQ | I_BIT | F_BIT
;- Init the FIQ register
            	ldr     r8, =0xFFFFF000

;- Set up Interrupt Mode and set IRQ Mode Stack
                msr     CPSR_c, #ARM_MODE_IRQ | I_BIT | F_BIT
                mov     r13, r0                     ; Init stack IRQ
                sub     r0, r0, #IRQ_STACK_SIZE

;- Enable interrupt & Set up Supervisor Mode and set Supervisor Mode Stack
                msr     CPSR_c, #ARM_MODE_SVC | F_BIT | I_BIT
                mov     r13, r0


;------------------------------------------------------------------------------
;- Branch on C code Main function (with interworking)
;----------------------------------------------------
;- Branch must be performed by an interworking call as either an ARM or Thumb
;- main C function must be supported. This makes the code not position-
;- independant. A Branch with link would generate errors
;------------------------------------------------------------------------------
	IMPORT      main
_main
__main
	EXPORT    _main
	EXPORT    __main
	ldr       r0, =main
	mov       lr, pc
	bx        r0

;------------------------------------------------------------------------------
;- Loop for ever
;---------------
;- End of application. Normally, never occur.
;- Could jump on Software Reset ( B 0x0 ).
;------------------------------------------------------------------------------
End
	b           End



            END