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Intel x86 JUMP quick reference

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Getting the sense for jumps and flags has long been a troublesome area for me, especially since the Intel assembler book shows 32 of these, all with similar-sounding names. Looking more closely I found that many of the instructions were synonyms for each other, and in practice the whole gamut is not needed, and in the process found that my copy of Intel's 80386 Programmer's Reference Manual gave an incorrect description for one of the instructions.

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