INSTRUCTION SET DESCRIPTIONS

Table C-4. Instruction Set (Continued)

Name

Description

Operation

Flags

Affected

 

 

 

 

 

 

 

WAIT

Wait:

None

AF –

 

WAIT

 

CF –

 

 

DF –

 

Causes the CPU to enter the wait state

 

 

 

IF –

 

while its test line is not active.

 

 

 

OF –

 

Instruction Operands:

 

 

 

PF –

 

none

 

SF –

 

 

 

TF –

 

 

 

ZF –

 

 

 

 

XCHG

Exchange:

(temp) (dest)

AF –

 

XCHG dest, src

(dest) (src)

CF –

 

(src) (temp)

DF –

 

Switches the contents of the source

 

 

IF –

 

and destination operands (bytes or

 

 

 

OF –

 

words). When used in conjunction with

 

 

 

PF –

 

the LOCK prefix, XCHG can test and

 

 

 

SF –

 

set a semaphore that controls access

 

 

 

TF –

 

to a resource shared by multiple

 

 

 

ZF –

 

processors.

 

 

 

 

 

Instruction Operands:

 

 

 

XCHG accum, reg

 

 

 

XCHG mem, reg

 

 

 

XCHG reg, reg

 

 

 

 

 

 

NOTE: The three symbols used in the Flags Affected column are defined as follows:

the contents of the flag remain unchanged after the instruction is executed ¸? the contents of the flag is undefined after the instruction is executed

the flag is updated after the instruction is executed

C-46

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Intel 80C186XL, 80C188XL user manual Wait, Exchange, Xchg dest, src