学 Win32 汇编[29] - 串指令: MOVS*、CMPS*、SCAS*、LODS*、REP、REPE、REPNE 等


这里的 "串" 并不单指字符串, 包括所有连续的数据(如数组); 串指令只用于内存操作.

移动串指令: MOVSB、MOVSW、MOVSD ;从 ESI -> EDI; 执行后, ESI 与 EDI 的地址移动相应的单位比较串指令: CMPSB、CMPSW、CMPSD ;比较 ESI、EDI; 执行后, ESI 与 EDI 的地址移动相应的单位扫描串指令: SCASB、SCASW、SCASD ;依据 AL/AX/EAX 中的数据扫描 EDI 指向的数据, 执行后 EDI 自动变化储存串指令: STOSB、STOSW、STOSD ;将 AL/AX/EAX 中的数据储存到 EDI 给出的地址, 执行后 EDI 自动变化载入串指令: LODSB、LODSW、LODSD ;将 ESI 指向的数据载入到 AL/AX/EAX, 执行后 ESI 自动变化其中的 B、W、D 分别指 Byte、Word、DWord, 表示每次操作的数据的大小单位.上述指令可以有重复前缀:REP             ECX > 0 时REPE (或 REPZ)  ECX > 0 且 ZF=1 时REPNE(或 REPNZ) ECX > 0 且 ZF=0 时;重复前缀可以自动按单位(1、2、4)递减 ECX

MOVSB: 移动字符串
; Test29_1.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    szSource db 'Delphi 2010', 0     len      equ $ - szSource - 1    szDest   db len dup(?), 0.codemain proc    lea esi, szSource    lea edi, szDest    mov ecx, len    cld ;复位标志寄存器的方向标志, 以让串地址由低到高    rep movsb    PrintString szDest ;Delphi 2010    retmain endpend main

上面的例子, 假如不使用重复前缀...
; Test29_2.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    szSource db 'Delphi 2010', 0     len      equ $ - szSource - 1    szDest   db len dup(?), 0.codemain proc    lea esi, szSource    lea edi, szDest    mov ecx, len    cld@@: movsb    dec ecx    jnz @B    PrintString szDest    retmain endpend main

MOVSD 例:
; Test29_3.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    ddSource dd 11h,22h,33h    ddDest   dd lengthof ddSource dup(?).codemain proc    lea esi, ddSource    lea edi, ddDest    mov ecx, lengthof ddSource    cld    rep movsd    DumpMem offset ddDest, sizeof ddDest ;11 00 00 00 - 22 00 00 00 - 33 00 00 00    retmain endpend main

MOVSW 例:
; Test29_4.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    ddSource dw 11h,22h,33h    ddDest   dw lengthof ddSource dup(?).codemain proc    lea esi, ddSource    lea edi, ddDest    mov ecx, lengthof ddSource    cld    rep movsw    DumpMem offset ddDest, sizeof ddDest ;11 00 22 00 - 33 00 00 00    retmain endpend main

CMPSD 例:
; Test29_5.asm.386p.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    ddVal1 dd 1234h    ddVal2 dd 5678h.codemain proc    lea esi, ddVal1    lea edi, ddVal2    cmpsd    je L1    PrintText '两数不等'    jmp L2L1: PrintText '两数相等'L2: retmain endpend main

CMPSW 例:
; Test29_6.asm.386p.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    dwArr1 dw 1,2,3,4,5    dwArr2 dw 1,3,5,7,9.codemain proc    lea esi, dwArr1    lea edi, dwArr2    mov ecx, lengthof dwArr1    cld    repe cmpsw    je L1    PrintText '两数组不等'    jmp L2L1: PrintText '两数组相等'L2: retmain endpend main

对比数组时, 假如数组长度不一致...
; Test29_7.asm.386p.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    dwArr1 dw 1,2,3,4,5    dwArr2 dw 1,2,3,4,5,6.codemain proc    lea esi, dwArr1    lea edi, dwArr2    mov ecx, lengthof dwArr1    cmp ecx, lengthof dwArr2    jne L1    cld    repe cmpsw    jne L1    PrintText '两数组相等'    jmp L2L1: PrintText '两数组不等'L2: retmain endpend main

如果对比的是 0 结束的字符串, 长度不一致也不用考虑
; Test29_8.asm.386p.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    szText1 db 'Delphi 2010', 0    szText2 db 'Delphi 2011', 0.codemain proc    lea esi, szText1    lea edi, szText2    mov ecx, lengthof szText1    cld    repe cmpsb    je L1    PrintText '字符串不同'    jmp L2L1: PrintText '字符串相同'L2: retmain endpend main

SCASB 例:
; Test29_9.asm.386p.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    szText db 'ABCDEFGH', 0.codemain proc    lea edi, szText    mov al, 'F'    mov ecx, lengthof szText - 1    cld    repne scasb    je L1    PrintText '没找到'    jmp L2L1: sub ecx, lengthof szText - 1    neg ecx    PrintDec ecx ;如果找得到, 这里显示是第几个字符; 本例结果是 6L2: retmain endpend main

STOSB 例:
; Test29_10.asm.386p.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    len = 31    szText db len dup(0), 0.codemain proc    lea edi, szText    mov al, 'x'    mov ecx, len    cld    rep stosb    PrintString szText ;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx    retmain endpend main

LODSW 例: 数组求和
; Test29_11.asm.386p.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    dwArr dw 1,2,3,4,5,6,7,8,9,10.codemain proc    lea esi, dwArr    mov ecx, lengthof dwArr    xor edx, edx    xor eax, eax@@: lodsw    add edx, eax    loop @B    PrintDec edx ;55    retmain endpend main

posted on 2010-04-17 22:55 万一 阅读(6141) 评论(0) 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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