Assembler:Commands:JMP

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command jmp size operand

Jumps to the given operand (address).


Transfers program control to a different point in the instruction stream without recording return information. The destination (target) operand specifies the address of the instruction being jumped to. This operand can be an immediate value, a general-purpose register, or a memory location.

This instruction can be used to execute four different types of jumps:

Near jump
A jump to an instruction within the current code segment (the segment currently pointed to by the CS register), sometimes referred to as an intrasegment jump.
Short jump
A near jump where the jump range is limited to -128 to +127 from the current EIP value.
Far jump
A jump to an instruction located in a different segment than the current code segment but at the same privilege level, sometimes referred to as an intersegment jump.
Task switch
A jump to an instruction located in a different task.

c9x.me/x86/html/file_module_x86_id_147.html


Contents

[edit] Command Parameters

Parameter Description
size OPTIONAL The preferred size of the assembled address
operand The address or symbol to jump to


[edit] Examples

jmp +1A   // Jump from end of command to +1A (hex).
jmp 00123ABC   // Jump to address.
jmp 0000123456ABCDEF   // Jump to address.
jmp eax   // Jump to value of eax.
jmp rax   // Jump to value of rax.
jmp someSymbol   // Jump to user defined symbol.
jmp someLabel   // Jump to label.
jmp short someLabel   // Jump to label with short byte code.
jmp long someLabel   // Jump to label with full address.
jmp @b   // Jump back to closest label
jmp @f   // Jump forward to closest label


Running this script in 32 bit mode:

globalAlloc(memTest, 0x200)
label(testLbl)
memTest:
                          add [eax],al // db 00 00
@@:
                          add [eax],al
jmp short @b
jmp short @f
                          add [eax],al
@@:
                          add [eax],al
                          add [eax],al
jmp short -4
jmp short +2
                          add [eax],al
testLbl:
                          add [eax],al
jmp 02EA0002
                          add [eax],al
jmp eax
                          add [eax],al
jmp memTest
                          add [eax],al
jmp testLbl
                          add [eax],al
jmp short testLbl
                          add [eax],al
jmp long testLbl
                          add [eax],al
db 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90

File:Assembler.JMP.02.png


Running this script in 64 bit mode:

globalAlloc(memTest, 0x200)
label(testLbl)
memTest:
                          add [rax],al // db 00 00
@@:
                          add [rax],al
jmp short @b
jmp short @f
                          add [rax],al
@@:
                          add [rax],al
                          add [rax],al
jmp short -4
jmp short +2
                          add [rax],al
testLbl:
                          add [rax],al
jmp 01160002
                          add [rax],al
jmp rax
                          add [rax],al
jmp memTest
                          add [rax],al
jmp testLbl
                          add [rax],al
jmp short testLbl
                          add [rax],al
jmp long testLbl
                          add [rax],al
db 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90

File:Assembler.JMP.01.png


[edit] See also

[edit] External links

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