Compaq ECQD2KCTE manual SQRTx Output Exceptions

Table B–2: IEEE Floating-Point Trap Handling (Continued)

			OS	User
	Hardware1	PAL-	Completion	Signal
Alpha Instructions		Code	Handler	Handler
SQRTx INPUT Exceptions
Negative nonzero operand	Trap	Trap	Supply QNan	[Invalid Op]
+/–0	Supply +/–0	–	–	–
+ Denormal operand	Trap	Trap	Supply SQRT	[Denormal Op2]
– Denormal operand	Trap	Trap	Supply QNaN	[Denormal Op/
				Invalid Op]
+ Infinity operand	Trap	Trap	Supply +Inf	–
– Infinity operand	Trap	Trap	Supply QNaN	[Invalid Op]
QNaN operand	Trap	Trap	Supply QNaN	–
SNaN operand	Trap	Trap	Supply QNaN	[Invalid Op]
SQRTx OUTPUT Exceptions
Exponent overflow	Not possible
Exponent underflow	Not possible
Inexact and disabled	–	–	–	–
Inexact and enabled	Supply SQRT	Trap	–	[Inexact]

1This column describes the minimum necessary hardware support.

2[Denormal Op] signals have priority over all other signals.

3[Overflow] and [Underflow] signals have priority over [Inexact] signals.

4An implementation could choose instead to trap to PALcode and have the PALcode supply a zero result on all underflows.

5An implementation could choose instead to trap to PALcode on extreme values and have the PALcode supply a truncated result on all overflows.

Other IEEE operations (software subroutines or sequences of instructions) are listed here for completeness:

Remainder

Round float to integer-valued float Convert binary to/from decimal

Compare, other combinations than the four above

IEEE Floating-Point Conformance B–11