学 Win32 汇编[28] - 跳转指令: JMP、JECXZ、JA、JB、JG、JL、JE、JZ、JS、JC、JO、JP 等
http://www.cnblogs.com/del/archive/2010/04/16/1713886.html
跳转指令分三类:
一、无条件跳转: JMP;
二、根据 CX、ECX 寄存器的值跳转: JCXZ(CX 为 0 则跳转)、JECXZ(ECX 为 0 则跳转);
三、根据 EFLAGS 寄存器的标志位跳转, 这个太多了.
根据标志位跳转的指令:
JE ;等于则跳转 JNE ;不等于则跳转 JZ ;为 0 则跳转 JNZ ;不为 0 则跳转 JS ;为负则跳转 JNS ;不为负则跳转 JC ;进位则跳转 JNC ;不进位则跳转 JO ;溢出则跳转 JNO ;不溢出则跳转 JA ;无符号大于则跳转 JNA ;无符号不大于则跳转 JAE ;无符号大于等于则跳转 JNAE ;无符号不大于等于则跳转 JG ;有符号大于则跳转 JNG ;有符号不大于则跳转 JGE ;有符号大于等于则跳转 JNGE ;有符号不大于等于则跳转 JB ;无符号小于则跳转 JNB ;无符号不小于则跳转 JBE ;无符号小于等于则跳转 JNBE ;无符号不小于等于则跳转 JL ;有符号小于则跳转 JNL ;有符号不小于则跳转 JLE ;有符号小于等于则跳转 JNLE ;有符号不小于等于则跳转 JP ;奇偶位置位则跳转 JNP ;奇偶位清除则跳转 JPE ;奇偶位相等则跳转 JPO ;奇偶位不等则跳转
跳转相关的标志位:
| 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| OF | DF | IF | TF | SF | ZF | AF | PF | CF | |||
| 溢 出 |
符 号 |
零 | 未 用 |
辅 助 |
未 用 |
奇 偶 |
未 用 |
进 位 |
JMP 测试
; Test28_1.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' jmp @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main ;测试结果应该是: ;1 ;4 ;以下都应该是这样.
JE 测试
; Test28_2.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' mov eax, 123 cmp eax, 123 je @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main
JZ 测试
; Test28_3.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' xor eax, eax jz @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main
JS 测试
; Test28_4.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' xor eax, eax dec eax js @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main
JC 测试
; Test28_5.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' mov al, 0FFh add al, 1 jc @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main
JO 测试
; Test28_6.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' mov al, -128 sub al, 1 jo @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main
JA 测试
; Test28_7.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' mov eax, 22 cmp eax, 11 ja @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main
JG 测试
; Test28_8.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' mov eax, 1 cmp eax, -1 jg @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main
JP 测试
; Test28_9.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' mov al, 00001110b inc al jp @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main
JECXZ 测试
; Test28_10.asm; .386 .model flat, stdcall include windows.inc include kernel32.inc include masm32.inc include debug.inc includelib kernel32.lib includelib masm32.lib includelib debug.lib .code main proc PrintText '1' xor ecx, ecx jecxz @F PrintText '2' PrintText '3' @@: PrintText '4' ret main endp end main