4.10.20 VAX Floating Multiply

Format:

MULxFa.rx,Fb.rx,Fc.wx!Floating-point Operate format

Operation:

Fc Fav * Fbv

Exceptions:

Invalid Operation

Overflow

Underflow

Instruction mnemonics:

MULF

Multiply F_floating

MULG

Multiply G_floating

Qualifiers:

Rounding:

Chopped (/C)

Trapping:

Exception Completion (/S)

 

Underflow Enable (/U)

Description:

The multiplicand operand in register Fb is multiplied by the multiplier operand in register Fa and the product is written to register Fc.

The product is rounded or chopped to the specified precision and then the corresponding range is checked for overflow/underflow. The single-precision operation on canonical single-preci- sion values produces a canonical single-precision result.

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.

See Section 4.7.7 for details of the stored result on overflow or underflow.

4–126Alpha Architecture Handbook

Page 182
Image 182
Compaq ECQD2KCTE manual VAX Floating Multiply, Mulf