Compaq ECQD2KCTE manual Table B-2 Ieee Floating-Point Trap Handling User Hardware1

Models: ECQD2KCTE

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Table B–2: IEEE Floating-Point Trap Handling

 

 

 

OS

User

 

Hardware1

PAL-

Completion

Signal

Alpha Instructions

Code

Handler

Handler

FBEQ FBNE FBLT FBLE FBGT

Bits Only – No Exceptions

 

 

 

FBGE

 

 

 

 

 

LDS LDT

Bits Only—No Exceptions

 

 

 

STS STT

Bits Only—No Exceptions

 

 

 

CPYS CPYSN

Bits Only—No Exceptions

 

 

 

FCMOVx

Bits Only—No Exceptions

 

 

 

 

 

 

 

 

ADDx SUBx INPUT Exceptions:

 

 

 

 

 

 

 

 

 

Denormal operand

Trap

Trap

Supply sum

[Denormal Op2]

+/-Inf operand

Trap

Trap

Supply sum

 

QNaN operand

Trap

Trap

Supply QNaN

 

SNaN operand

Trap

Trap

Supply QNaN

[Invalid Op]

+Inf + –Inf

Trap

Trap

Supply QNaN

[Invalid Op]

 

 

 

 

 

ADDx SUBx OUTPUT Exceptions:

 

 

 

 

 

 

 

 

 

Exponent overflow

Trap

Trap

Supply

[Overflow3]

 

 

 

+/–Inf

Scale by bias

 

 

 

+/–MAX

adjust

Exponent underflow and disabled

Supply +0

4

 

 

 

 

 

Exponent underflow and enabled

Supply +0

Trap

Supply

[Underflow3]

 

and trap

 

+/–MIN

Scale by bias

 

 

 

denorm

adjust

 

 

 

+/–0

 

 

Inexact and disabled

 

Inexact and enabled

Supply sum

Trap

[Inexact]

 

and trap

 

 

 

 

 

 

 

 

 

 

MULx INPUT Exceptions:

 

 

 

 

 

 

 

 

 

 

Denormal operand

Trap

Trap

Supply prod.

[Denormal Op2]

+/-Inf operand

Trap

Trap

Supply prod.

 

QNaN operand

Trap

Trap

Supply QNaN

 

SNaN operand

Trap

Trap

Supply QNaN

[Invalid Op]

0 * Inf

Trap

Trap

Supply QNaN

[Invalid Op]

 

 

 

 

 

 

B–8Alpha Architecture Handbook

Page 298
Image 298
Compaq ECQD2KCTE manual Table B-2 Ieee Floating-Point Trap Handling User Hardware1