学 Win32 汇编[24] - 移位: SHL、SHR、SAL、SAR、ROL、ROR、RCL、RCR、SHLD、SHRD
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2021-04-30
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
posted on 2010-04-15 11:39 万一 阅读(9351) 评论(1) 编辑 收藏©著作权归作者所有:来自51CTO博客作者JLee79的原创作品,如需转载,请注明出处,否则将追究法律责任
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