学Win32汇编24 -移位:SHL、SHR、SAL、SAR、ROL、ROR、RCL、RCR、

;SHL(ShiftLeft):逻辑左移
;SHR(ShiftRight):逻辑右移
;SAL(Shift ArithmeticLeft): 算术左移
;SAR(Shift Arithmetic Right): 算术右移

;其中的 SHL 和 SAL 相同, 但 SHR 和 SAR不同.

;SHL、SAL: 每位左移, 低位补 0, 高位进CF
;SHR: 每位右移, 低位进 CF, 高位补 0
;SAR: 每位右移, 低位进 CF, 高位不变

;它们的结果影响OF、SF、ZF、PF、CF
;它们的指令格式相同:
SHL r/m, i8
SHL r/m, CL

ROL、ROR、RCL、RCR: 循环移位指令

;ROL(RotateLeft): 循环左移
;ROR(RotateRight):循环右移
;RCL(Rotate through CarryLeft): 带进位循环左移
;RCR(Rotate through Carry Right):带进位循环右移

;ROL: 循环左移, 高位到低位并送CF
;ROR: 循环右移, 低位到高位并送CF
;RCL: 循环左移, 进位值(原CF)到低位, 高位进CF
;RCR: 循环右移, 进位值(原CF)到高位, 低位进CF

;它们的结果影响 OF、CF
;它们的指令格式相同:
SHL r/m, i8
SHL r/m, CL

; Test24_2.asm
.386
.model flat, stdcall

includewindows.inc
includekernel32.inc
includemasm32.inc
includedebug.inc
includelib kernel32.lib
includelib masm32.lib
includelib debug.lib

.code
main proc
;ROL
mov al, 11000011b
rol al,1
PrintHexal ;87 -010000111b

;ROR
mov al, 11000011b
ror al,1
PrintHexal ;E1 -11100001b

;RCL
clc
mov al,10101111b
rcl al,1
PrintHexal ;5E -01011110b

stc
mov al,10101111b
rcl al,1
PrintHexal ;5F -01011111b

clc
mov al,10101111b
rcl al,2
PrintHexal ;BD -10111101b

;RCR
clc
mov al,11101011b
rcr al,2
PrintHexal ;BA -10111010b
ret
main endp
end main
SHLD、SHRD: 双精度移位

;SHLD(Double-Precision ShiftLeft): 双精度左移
;SHRD(Double-Precision Shift Right): 双精度右移

;SHLD 和 SHRD 有三个操作数
;操作数三: 是移位数目
;操作数一:是目的操作数
;SHLD左边被移出的位由操作数二相同数目的高位填充
;SHRD右边被移出的位由操作数二相同数目的低位填充
;操作数二不变,且须是寄存器

;它们的结果影响OF、SF、ZF、PF、CF
;它们的指令格式相同:
SHLD r16/32/m16/m32, r16/32,i8
SHLD r16/32/m16/m32, r16/32,CL

; Test25_3.asm
.386
.model flat, stdcall

includewindows.inc
includekernel32.inc
includemasm32.inc
includedebug.inc
includelib kernel32.lib
includelib masm32.lib
includelib debug.lib

.code
main proc
;SHLD
mov ax, 1100110011110000b
mov dx,1111111100000000b
shld ax, dx,2
PrintHexax ;33C3-0011001111000011b

;SHRD
mov ax, 0000111100110011b
mov dx,0000000011111111b
shrd ax, dx,2
PrintHexax ;C3CC-1100001111001100b
ret
main endp
end main

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