Reverse Engineering - 어쎔블리어 Intel x86 JUMP quick reference

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Reverse Engineering - Jump Assemble

Intel x86 JUMP quick reference

So I have grouped these functionally, with all instruction synonyms in the same row.

Instruction	Description	signed-ness	Flags	short  jump  opcodes	near  jump  opcodes
JO	Jump if overflow		OF = 1	70	0F 80
JNO	Jump if not overflow		OF = 0	71	0F 81
JS	Jump if sign		SF = 1	78	0F 88
JNS	Jump if not sign		SF = 0	79	0F 89
JE  JZ	Jump if equal  Jump if zero		ZF = 1	74	0F 84
JNE  JNZ	Jump if not equal  Jump if not zero		ZF = 0	75	0F 85
JB  JNAE  JC	Jump if below  Jump if not above or equal  Jump if carry	unsigned	CF = 1	72	0F 82
JNB  JAE  JNC	Jump if not below  Jump if above or equal  Jump if not carry	unsigned	CF = 0	73	0F 83
JBE  JNA	Jump if below or equal  Jump if not above	unsigned	CF = 1 or ZF = 1	76	0F 86
JA  JNBE	Jump if above  Jump if not below or equal	unsigned	CF = 0 and ZF = 0	77	0F 87
JL  JNGE	Jump if less  Jump if not greater or equal	signed	SF <> OF	7C	0F 8C
JGE  JNL	Jump if greater or equal  Jump if not less	signed	SF = OF	7D	0F 8D
JLE  JNG	Jump if less or equal  Jump if not greater	signed	ZF = 1 or SF <> OF	7E	0F 8E
JG  JNLE	Jump if greater  Jump if not less or equal	signed	ZF = 0 and SF = OF	7F	0F 8F
JP  JPE	Jump if parity  Jump if parity even		PF = 1	7A	0F 8A
JNP  JPO	Jump if not parity  Jump if parity odd		PF = 0	7B	0F 8B
JCXZ  JECXZ	Jump if %CX register is 0  Jump if %ECX register is 0		%CX = 0  %ECX = 0	E3

Processor Flags

The x86 processors have a large set of flags that represent the state of the processor, and the conditional jump instructions can key off of them in combination.

CF - carry flag

Set on high-order bit carry or borrow; cleared otherwise

PF - parity flag

Set if low-order eight bits of result contain an even number of "1" bits; cleared otherwise

ZF - zero flags

Set if result is zero; cleared otherwise

SF - sign flag

Set equal to high-order bit of result (0 if positive 1 if negative)

OF - overflow flag

Set if result is too large a positive number or too small a negative number (excluding sign bit) to fit in destination operand; cleared otherwise