Intel 80287, 80286 manual Jump Table for Examine Routine, Xam

Models: 80287 80286

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NUMERIC PROGRAMMING EXAMPLES

ADQ

BDQ

FLD

A

LOAD A ONTO

TOP

OF

287

STACK

FCOMP

B

COMPARE A:B,

POP

A

 

 

FSTSW

AX

STORE RESULT

TO

CPU

AX

REGISTER

,

;CPU AX REGISTER CONTAINS CONDITION CODES (RESULTS OF

;COMPARE>

;LOAD CONDITION CODES INTO CPU FLAGS

SAHF

;

;USE CONDITIONAL JUMPS TO DETERMINE ORDERING OF A TO

;B

,

J P

LLU NOR DERE D

TE ST

C2

(P F>

 

JB

LLESS

 

TE ST

CO

( CF)

 

J E

LEQUAL

;

TE ST

C3

(Z F)

·0

LG REA TE R:

CO

(C F>

·o,

C3

( ZF)

 

CO ( CF) ·o,

C3

(ZF )

·1

 

CO ( CF) ·1,

C3

(ZF )

·0

LLUNORDERED:

C2

(PF)

• 1

 

 

 

Figure 4-1. Conditional Branching for Compares

JUMP TABLE FOR EXAMINE ROUTINE

FXAM_TBL DW POS_UNNORM, POS_NAN, NEG_UNNORM, NEG_NAN, POS NORM. POS_INFINITY, NEG_NORM, NEG_INFINITY, POS_ZERO, EMPTY, NE~_Z£RO,

EM PTY, PO S_D ENOR M, EM PTY, NEG_D ENOR M, EM PTY

;EXAMINE ST AND STORE RESULT (CONDITION CODES)

F XAM

FSTSW AX

Figure 4-2.Conditional Branching for FXAM

4-2

Page 458
Image 458
Intel 80287, 80286 manual Jump Table for Examine Routine, Xam