学 Win32 汇编[24] - 移位: SHL、SHR、SAL、SAR、ROL、ROR、RCL、RCR、SHLD、SHRD
SHL、SHR、SAL、SAR: 移位指令
;SHL(Shift Left):? ? ? 逻辑左移;SHR(Shift Right):? ? ? 逻辑右移;SAL(Shift Arithmetic Left): 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, i8SHL r/m, CL; Test24_1.asm.386.model flat, stdcallinclude windows.incinclude kernel32.incinclude masm32.incinclude debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.codemain proc ;SHL、AL? mov al, 11100111b? shl al, 1? PrintHex al ;CE - 11001110b? sal al, 2? PrintHex al ;38 - 00111000b? ? mov al, 11100111b? mov cl, 2? shl al, cl? PrintHex al ;9C - 10011100b? ;SHR? mov al, 11100111b? shr al, 2? PrintHex al ;39 - 00111001b? ;SAR? mov al, 11100111b? sar al, 2? PrintHex al ;F9 - 11111001b? retmain endpend main
ROL、ROR、RCL、RCR: 循环移位指令
;ROL(Rotate Left):? ? ? ? 循环左移;ROR(Rotate Right):? ? ? 循环右移;RCL(Rotate through Carry Left): 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, i8SHL r/m, CL; Test24_2.asm.386.model flat, stdcallinclude windows.incinclude kernel32.incinclude masm32.incinclude debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.codemain proc ;ROL? mov al, 11000011b? rol al, 1? PrintHex al ;87 - 010000111b? ;ROR? mov al, 11000011b? ror al, 1? PrintHex al ;E1 - 11100001b? ;RCL? clc? mov al, 10101111b? rcl al, 1? PrintHex al ;5E - 01011110b? ? stc? mov al, 10101111b? rcl al, 1? PrintHex al ;5F - 01011111b? ? clc? mov al, 10101111b? rcl al, 2? PrintHex al ;BD - 10111101b? ;RCR? clc? mov al, 11101011b? rcr al, 2? PrintHex al ;BA - 10111010b? retmain endpend main
SHLD、SHRD: 双精度移位
;SHLD(Double-Precision Shift Left): 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, i8SHLD r16/32/m16/m32, r16/32, CL; Test25_3.asm.386.model flat, stdcallinclude windows.incinclude kernel32.incinclude masm32.incinclude debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.codemain proc ;SHLD? mov ax, 1100110011110000b? mov dx, 1111111100000000b? shld ax, dx, 2? PrintHex ax ;33C3 - 0011001111000011b? ;SHRD? mov ax, 0000111100110011b? mov dx, 0000000011111111b? shrd ax, dx, 2? PrintHex ax ;C3CC - 1100001111001100b? retmain endpend main
