ARM汇编实验-工作模式

USR_STACK_LEGTH EQU 64
SVC_STACK_LEGTH EQU 0
FIQ_STACK_LEGTH EQU 16
IRQ_STACK_LEGTH EQU 64
ABT_STACK_LEGTH EQU 0
UND_STACK_LEGTH EQU 0

AREA Example5, CODE, READONLY
ENTRY
CODE32
START
MOV R0, #0 ;0x40000000
MOV R1, #1 ;0x40000004
MOV R2, #2 ;0x40000008
MOV R3, #3 ;0x4000000c
MOV R4, #4 ;0x40000010
MOV R5, #5 ;0x40000014
MOV R6, #6 ;0x40000018
MOV R7, #7 ;0x4000001c
MOV R8, #8 ;0x40000020
MOV R9, #9 ;0x40000024
MOV R10, #10 ;0x40000028
MOV R11, #11 ;0x4000002c
MOV R12, #12 ;0x40000030

BL InitStack ;0x40000034

;打开IRQ中断(将CPSR寄存器的I位清零)
MRS R0,CPSR ;0x40000038
BIC R0,R0,#0X80 ;0x4000003c
MSR CPSR_cxsf, R0 ;0x40000040

;切换到用户模式
MSR CPSR_c, #0xd0 ;0x40000044
MRS R0, CPSR ;0x40000048

;切换到管理模式
MSR CPSR_c, #0xdf ;0x4000004c
MRS R0, CPSR ;0x40000050

HALT B HALT ;0x40000054

InitStack
MOV R0, LR ;0x40000058

;设置管理模式堆栈
MSR CPSR_c, #0xd3 ;0x4000005c
LDR SP, StackSvc ;0x40000060

;设置中断模式堆栈
MSR CPSR_c, #0xd2 ;0x40000064
LDR SP, StackIrq ;0x40000068

;设置快速中断模式堆栈
MSR CPSR_c, #0xd1 ;0x4000006c
LDR SP, StackFiq ;0x40000070

;设置中止模式堆栈
MSR CPSR_c, #0xd7 ;0x40000074
LDR SP, StackAbt ;0x40000078

;设置未定义模式堆栈
MSR CPSR_c, #0xdb ;0x4000007c
LDR SP, StackUnd ;0x40000080

;设置系统模式堆栈
MSR CPSR_c, #0xdf ;0x40000084
LDR SP,StackUsr ;0x40000088

MOV PC,R0 ;0x4000008c

StackUsr DCD UsrStackSpace + (USR_STACK_LEGTH - 1)*4 ;0x40003000+FC(252)=0x400030FC(用户(系统)模式堆栈起始地址)
StackSvc DCD SvcStackSpace + (SVC_STACK_LEGTH - 1)*4 ;0x40003100+(-4) =0x400030FC(管理模式堆栈起始地址)
StackIrq DCD IrqStackSpace + (IRQ_STACK_LEGTH - 1)*4 ;0x40003100+FC(252)=0x400031FC(向量中断模式堆栈起始地址)
StackFiq DCD FiqStackSpace + (FIQ_STACK_LEGTH - 1)*4 ;0x40003200+3C(60) =0x4000323C(快速中断模式起始地址)
StackAbt DCD AbtStackSpace + (ABT_STACK_LEGTH - 1)*4 ;0x40003240+(-4) =0x4000323C(中止模式堆栈起始地址)
StackUnd DCD UndStackSpace + (UND_STACK_LEGTH - 1)*4 ;0x40003240+(-4) =0x4000323C(未定义模式堆栈起始地址)

AREA MyStacks, DATA, NOINIT, ALIGN=2
UsrStackSpace SPACE USR_STACK_LEGTH * 4 ;0x40003000 连续分配256B
SvcStackSpace SPACE SVC_STACK_LEGTH * 4 ;0x40003100 连续分配0B
IrqStackSpace SPACE IRQ_STACK_LEGTH * 4 ;0x40003100 连续分配256B
FiqStackSpace SPACE FIQ_STACK_LEGTH * 4 ;0x40003200 连续分配64B
AbtStackSpace SPACE ABT_STACK_LEGTH * 4 ;0x40003040 连续分配0B
UndStackSpace SPACE UND_STACK_LEGTH * 4 ;0x40003040 连续分配0B
END