多寄存器和堆栈寻址的用法:多寄存器寻址:LDMIA,LDMIB,STMIA,STMIB,LDMDA,LDMDB,STMDA,STMDB;
堆栈寻址:LDMFA,LDMFD,STMFA,STMFD,LDMEA,LDMED,STMEA,STMED;
弄清堆栈寻址的SP的变化:LDMFA,LDMFD,STMFA,STMFD,LDMEA,LDMED,STMEA,STMED;
IA: 每次传送后地址加4;IB: 每次传送前地址加4;
DA: 每次传送后地址减4;
DB: 每次传送前地址减4;
FD: 满递减堆栈;
ED: 空递减堆栈;
FA: 满递增堆栈;
EA: 空递增堆栈。
1、多寄存器寻址:
LDMIA R0!,{R1-R4}
;R1
;R2
;R3
;R4
例如:
所有的示例指令执行前:
mem32[0x1000C] = 0x04
mem32[0x10008] = 0x03
mem32[0x10004] = 0x02
mem32[0x10000] = 0x01
r0 = 0x00010010
r1 = 0x00000000
r3 = 0x00000000
r4 = 0x00000000
1) ldmia r0!, {r1-r3} 2) ldmib r0!, {r1-r3}
执行后: 执行后:
r0 = 0x0010001C r0 = 0x0010001C
r1 = 0x01 r1 = 0x02
r2 = 0x02 r2 = 0x03
r3 = 0x03 r3 = 0x04
STMFD入栈指令,相当于STMDB
STMFD SP!,{R2-R4} ;[SP-4]
;[SP-8]
;[SP-12]
LDMFD出栈指令,相当于LDMIA
LDMFD SP!,{R6-R8} ;R6
;R7
;R8