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请教版主:TQ2440开发板的裸机程序TQ2440_Test 在2440init.s 中相比通用的启动程序加了下面的:
;===========================================================
ldr r0, =BWSCON
ldr r0, [r0]
ands r0, r0, #6 ;OM[1:0] != 0, NOR FLash boot
bne copy_proc_beg ;do not read nand flash
adr r0, ResetEntry ;OM[1:0] == 0, NAND FLash boot
cmp r0, #0 ;if use Multi-ice,
bne copy_proc_beg ;do not read nand flash for boot
;nop
;===========================================================
nand_boot_beg
[ {TRUE}
bl RdNF2SDRAM
]
ldr pc, =copy_proc_beg
;===========================================================
copy_proc_beg
adr r0, ResetEntry
ldr r2, BaseOfROM
cmp r0, r2
ldreq r0, TopOfROM
beq InitRam
ldr r3, TopOfROM
0
ldmia r0!, {r4-r7}
stmia r2!, {r4-r7}
cmp r2, r3
bcc %B0
sub r2, r2, r3
sub r0, r0, r2
InitRam
ldr r2, BaseOfBSS
ldr r3, BaseOfZero
0
cmp r2, r3
ldrcc r1, [r0], #4
strcc r1, [r2], #4
bcc %B0
mov r0, #0
ldr r3, EndOfBSS
1
cmp r2, r3
strcc r0, [r2], #4
bcc %B1
ldr pc, =%F2 ;goto compiler address
2
; [ CLKDIV_VAL>1 ; means Fclk:Hclk is not 1:1.
; bl MMU_SetAsyncBusMode
; |
; bl MMU_SetFastBusMode ; default value.
; ]
;----------------------------------------------------------------------------------------
版主问下,它的具体作用是什么?能不能详细讲解一下。。。。。 |
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