short jmp（ 转）

frensky2

BACK:Let's work through one more example in detail: If we have an offset byte of AAh, that would be 10101010 in Binary. So, it's 1's complement would be: 01010101 or 55h. Therefore, we'd have a 2's complement of: -56h (-86). But how do we translate that into a real backwards jump? Well, assuming that the address of our SHORT JMP code is 0696h, we must first add 2 to get to the address of the instruction immediately following our JMP; 0698h being that location. And finally add our negative 2's complement value of -56h to arrive at the next instruction address of: 0642h. (In MS-DEBUG, if you Enter the bytes EB AA at 696 [-e 696 eb aa], a disassembly of that address [-u 696 698] will show up as: JMP 0642 on the screen.)
JMP_Address + 2 + (2's Complement of Second Byte value) = Next_Instruction_Address                                                
FORWARD:JMP_Address      +        2 + Second_Byte_value = Next_Instruction_Address


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