AMD Am186 Series, Instruction Set

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Instruction Set 4-251
XOR Logical Exclusive OR XOR
What It Does
XOR complements particular bits of a component according to a mask.
Syntax
Description
XOR computes the exclusive OR of the two operands. If corresponding bits of the operands
are different, the resulting bit is 1. If the bits are the same, the result is 0. The answer
replaces the first operand.
Operation It Performs
Flag Settings After Instruction
Form Opcode Description
Clocks
Am186 Am188
XOR AL,
imm8
34
ib
XOR immediate byte with AL 3 3
XOR AX, imm16 35 iw XOR immediate word with AX 4 4
XOR r/m8,imm8 80 /6 ib XOR immediate byte with r/m byte 4/16 4/16
XOR r/m16,imm16 81 /6 iw XOR immediate word with r/m word 4/16 4/20
XOR r/m16,imm8 83 /6 ib XOR sign-extended immediate byte with r/m word 4/16 4/20
XOR r/m8,r8 30 /r XOR byte register with r/m byte 3/10 3/10
XOR
r/m16,r16
31
/r
XOR word register with r/m word 3/10 3/14
XOR
r8,r/m8
32
/r
XOR r/m byte with byte register 3/10 3/10
XOR r16,r/m16 33 /r XOR r/m word with word register 3/10 3/14
XOR component,mask
/* XOR component with mask */
component = component ^ mask;
/* clear overflow and carry flags */
OF = CF = 0;
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Processor Status
Flags Register
reserved
OF DF IF TF SF ZF AF PF CF
? = undefined; – = unchanged
SF=1 if result is 0 or positive
SF=0 if result is negative ZF=1 if result equal to 0
ZF=0 if result not equal to 0
PF=1 if low byte of result has even number of set bits
PF=0 otherwise
0 – – – res ? res res 0