ldr r3, TopOfROM
0
ldmia r0!, {r4-r7} ;开始时，r0 = ResetEntry --- source
stmia r2!, {r4-r7} ;开始时，r2 = BaseOfROM --- destination
cmp r2, r3 ;终止条件：复制了TopOfROM-BaseOfROM大小
bcc %B0
;---------------------------------------------------------------
; 下面2行，根据理解，由tinko添加
; 猜测上面的代码不应该用" ! "，以至于地址被修改。这里重新赋值
;---------------------------------------------------------------
adrl r0, ResetEntry ;don't use adr, 'cause out of range error occures
ldr r2, BaseOfROM
;旨在计算出正确的RW区起始位置
; 下面2行目的是为了计算正确的r0（必须使之指向code区中的rw域开始处）
sub r2, r2, r3 ;r2=BaseOfROM-TopOfROM=(-)代码长度
sub r0, r0, r2 ;r0=ResetEntry-(-)代码长度=ResetEntry+代码长度
InitRam
;复制代码加载位置中的RM区到|Image$$RW$$Base|
ldr r2, BaseOfBSS ;BaseOfBSS->r2 , BaseOfBSS = |Image$$RW$$Base|
ldr r3, BaseOfZero ;BaseOfZero->r3 , BaseOfZero = |Image$$ZI$$Base|
0
cmp r2, r3 ;比较BaseOfBSS和BaseOfZero
ldrcc r1, [r0], #4 ;当代码在内存中运行时，r0(初始值) = TopOfROM.
;这之后的BaseOfZero-BaseOfBSS仍属于code，需拷贝到BaseOfBSS
strcc r1, [r2], #4
bcc %B0
;用0初始化ZI区
mov r0, #0
ldr r3, EndOfBSS ;EndOfBSS = |Image$$ZI$$Limit|
1
cmp r2, r3
strcc r0, [r2], #4
bcc %B1
;要是r21 ; means Fclk:Hclk is not 1:1.
; bl MMU_SetAsyncBusMode
; |
; bl MMU_SetFastBusMode ; default value.
; ]
;bl Led_Test
;===========================================================
; 进入C语言前的最后一步了,就是把我们用说查二级向量表
; 的中断例程安装到一级向量表(异常向量表)里.
;//5.设置缺省中断处理函数
; Setup IRQ handler
ldr r0,=HandleIRQ ;This routine is needed
ldr r1,=IsrIRQ ;if there isn't 'subs pc,lr,#4' at 0x18, 0x1c
str r1,[r0]
;//initialize the IRQ 将普通中断判断程序的入口地址给HandleIRQ
;/////////////////////////////////////////////////////////
;注意，以下这段可能不需要!!!!!!!!!!!!!!!!!!
;//6.将数据段拷贝到ram中 将零初始化数据段清零 跳入C语言的main函数执行到这步结束bootloader初步引导结束
;If main() is used, the variable initialization will be done in __main().
[ {FALSE} ;by tinko -- 最外面的条件由tinko添加，实际上不再执行这段
[  NOT:USE_MAIN ;initialized {FALSE}
;Copy and paste RW data/zero initialized data
LDR r0, =|Image$$RO$$Limit| ; Get pointer to ROM data
LDR r1, =|Image$$RW$$Base| ; and RAM copy
LDR r3, =|Image$$ZI$$Base|
;Zero init base => top of initialised data
CMP r0, r1 ; Check that they are different just for debug????????
BEQ %F2
1
CMP r1, r3 ; Copy init data
LDRCC r2, [r0], #4 ;--> LDRCC r2, [r0] + ADD r0, r0, #4
STRCC r2, [r1], #4 ;--> STRCC r2, [r1] + ADD r1, r1, #4
BCC %B1
2
LDR r1, =|Image$$ZI$$Limit| ; Top of zero init segment
MOV r2, #0
3
CMP r3, r1 ; Zero init
STRCC r2, [r3], #4
BCC %B3
]
]
;!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
;*************************************** |
