cstartup_ads_ram.s

AT91RM9200的异步串口调试程序,波特率为1152

;- Set up Supervisor Mode and set SVC Mode Stack
	msr     cpsr_c, #ARM_MODE_SVC:OR:I_BIT:OR:F_BIT
	bic     r1, r1, #3                  ; Insure word alignement
	mov     sp, r1                      ; Init stack SYS
	
;- Set up Interrupt Mode and set IRQ Mode Stack
	msr     CPSR_c, #ARM_MODE_IRQ:OR:I_BIT:OR:F_BIT
	bic     r2, r2, #3                  ; Insure word alignement
	mov     sp, r2                      ; Init stack IRQ

;- Set up Fast Interrupt Mode and set FIQ Mode Stack
	msr     CPSR_c, #ARM_MODE_FIQ:OR:I_BIT:OR:F_BIT
	bic     r3, r3, #3                  ; Insure word alignement
	mov     sp, r3                      ; Init stack FIQ

;- Set up Abort Mode and set Abort Mode Stack
	msr     CPSR_c, #ARM_MODE_ABORT:OR:I_BIT:OR:F_BIT
	bic     r4, r4, #3                  ; Insure word alignement
	mov     sp, r4                      ; Init stack Abort

;- Set up Undefined Instruction Mode and set Undef Mode Stack
	msr     CPSR_c, #ARM_MODE_UNDEF:OR:I_BIT:OR:F_BIT
	bic     r5, r5, #3                  ; Insure word alignement
	mov     sp, r5                      ; Init stack Undef

;- Set up user Mode and set Undef Mode Stack
	msr     CPSR_c, #ARM_MODE_SYS:OR:I_BIT:OR:F_BIT
	bic     r6, r6, #3                  ; Insure word alignement
	mov     sp, r6                      ; Init stack Undef

	b       EndInitStack
	
StackData
	DCD     AT91_SVC_Stack_Begin
	DCD     AT91_IRQ_Stack_Begin
	DCD     AT91_FIQ_Stack_Begin
	DCD     AT91_ABT_Stack_Begin
	DCD     AT91_UND_Stack_Begin
	DCD     AT91_USER_Stack_Begin	
EndInitStack

;------------------------------------------------------------------------------
;-Low level Init (PMC, AIC, EBI, ....)
;------------------------------------------------------------------------------

;- Add loop to compensate Main Oscillator startup time	 
	ldr 	r0, =0x00000010
LoopOsc
	subs    r0, r0, #1              
	bhi     LoopOsc
    
    LDR R0,=AT91C_BASE_YPIOC
    LDR R1,=0xFFFF0000
    STR R1,[R0,#0x70]
    
    LDR R1,= 0x0
    STR R1,[R0,#0x74]
    
    LDR R1,= 0xFFFF0000
    STR R1,[R0,#0x4]
    
    
    LDR R1,=0x02
    LDR R0,=0xFFFFFF60
    STR R1,[R0]
    
    
    LDR R1,=0x2188c155
    LDR R0,=0xFFFFFF98
    STR R1,[R0]
    
    LDR R1,=0x2
    LDR R0,=0xFFFFFF90 
    STR R1,[R0]

    LDR R1,=0x0
   LDR R0,=0x20000000
   STR R1,[R0]
    
    
    LDR R1,=0x4
    LDR R0,=0xFFFFFF90
    STR R1,[R0]
    
    
    
    LDR R1,=0x0
    LDR R0,=0x20000000
   STR R1,[R0]
    
    
    
    
    LDR R1,=0x3
   LDR R0,=0xFFFFFF90
   STR R1,[R0] 
    
    
    LDR R1,=0x0
   LDR R0,=0x20000080
   STR R1,[R0]
   
   
    
    LDR R1,=0x2E0
   LDR R0,=0xFFFFFF94
   STR R1,[R0] 
    
    LDR R1,=0x0
   LDR R0,=0x20000000
   STR R1,[R0] 
    
    
    LDR R1,=0x00
    LDR R0,=0xFFFFFF90
    STR R1,[R0]
    
    
    LDR R1,=0x0
   LDR R0,=0x20000000
    STR R1,[R0]
	
	
	IMPORT    AT91F_LowLevelInit
	
	ldr       r0, = AT91F_LowLevelInit
	mov       lr, pc
	bx        r0

;----------------------------------------
; Read/modify/write CP15 control register 
;----------------------------------------
    MRC     p15, 0, r0, c1, c0,0 ; read cp15 control registre (cp15 r1) in r0
    ldr     r3, =0xC0000080      ; Reset bit :Little Endian end fast bus mode
    ldr     r4, =0xC0000000      ; Set bit :Asynchronous clock mode, Not Fast Bus
    BIC     r0, r0, r3             
    ORR     r0, r0, r4             
    MCR     p15, 0, r0, c1, c0,0 ; write r0 in cp15 control registre (cp15 r1)

;------------------------------------------------------------------------------
;- Initialise C variables
;------------------------
;- Following labels are automatically generated by the linker. 
;- RO: Read-only = the code
;- RW: Read Write = the data pre-initialized and zero-initialized.
;- ZI: Zero-Initialized.
;- Pre-initialization values are located after the code area in the image.
;- Zero-initialized datas are mapped after the pre-initialized.
;- Note on the Data position : 
;- If using the ARMSDT, when no -rw-base option is used for the linker, the 
;- data area is mapped after the code. You can map the data either in internal
;- SRAM ( -rw-base=0x40 or 0x34) or in external SRAM ( -rw-base=0x2000000 ).
;- Note also that to improve the code density, the pre_initialized data must 
;- be limited to a minimum.
;------------------------------------------------------------------------------

	add     r2, pc,#-(8+.-CInitData)  ; @ where to read values (relative)
	ldmia   r2, {r0, r1, r3, r4}
	
	cmp         r0, r1                  ; Check that they are different
	beq         EndRW
LoopRW	
	cmp         r1, r3                  ; Copy init data
	ldrcc       r2, [r0], #4
	strcc       r2, [r1], #4
	bcc         LoopRW
	ldr         r2,=0xff
	str         r2,[r1] 

EndRW

	mov         r2, #0
LoopZI	
	cmp         r3, r4                  ; Zero init
	strcc       r2, [r3], #4
	bcc         LoopZI
 
	b           EndInitC
                
CInitData
 	IMPORT      |Image$$RO$$Limit|      ; End of ROM code (=start of ROM data)
	IMPORT      |Image$$RW$$Base|       ; Base of RAM to initialise
	IMPORT      |Image$$ZI$$Base|       ; Base and limit of area
	IMPORT      |Image$$ZI$$Limit|      ; Top of zero init segment
	
	DCD     |Image$$RO$$Limit|      ; End of ROM code (=start of ROM data)
 	DCD     |Image$$RW$$Base|       ; Base of RAM to initialise
 	DCD     |Image$$ZI$$Base|       ; Base and limit of area
 	DCD     |Image$$ZI$$Limit|      ; Top of zero init segment
EndInitC

  
;------------------------------------------------------------------------------
;- 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