Compaq ECQD2KCTE Laptop User Manual


 
4–112 Alpha Architecture Handbook
4.10.7 VAX Floating Compare
Format:
Operation:
IF Fav SIGNED_RELATION Fbv THEN
Fc 4000 0000 0000 0000
16
ELSE
Fc 0000 0000 0000 0000
16
Exceptions:
Instruction mnemonics:
Qualifiers:
Description:
The two operands in Fa and Fb are compared. If the relationship specified by the qualifier is
true, a non-zero floating value (0.5) is written to register Fc; otherwise, a true zero is written to
Fc.
Comparisons are exact and never overflow or underflow. Three mutually exclusive relations
are possible: less than, equal, and greater than.
An invalid operation trap is signaled if either operand has exp=0 and is not a true zero (that is,
VAX reserved operands and dirty zeros trap). The contents of Fc are UNPREDICTABLE if
this occurs.
Notes:
Compare Less Than A,B is the same as Compare Greater Than B,A; Compare Less
Than or Equal A,B is the same as Compare Greater Than or Equal B,A. Therefore, only
the less-than operations are included.
CMPGyy Fa.rg,Fb.rg,Fc.wq
!Floating-point Operate format
Invalid Operation
CMPGEQ Compare G_floating Equal
CMPGLE Compare G_floating Less Than or Equal
CMPGLT Compare G_floating Less Than
Trapping: Exception Completion (/S)