fre.

Reciprocal Estimate

fre. FRT,FRB

Estimates the reciprocal of a floating-point number.

Encoding

Binary Layout

63

0:5

FRT

6:10

0

11:15

0

16:20

FRB

21:25

24

26:30

/

31

 

Format A-form

Opcode 0xFC000030

Extension Floating-Point

Operands

• FRT
  Target
• FRB
  Source

Example

fre. r3, r4

Related

More in Floating-Point

Reference

View in PowerISA v3.1C Specification ↗ OPF Power ISA v3.1C

Description

The fre. instruction estimates the reciprocal of the contents of register RA and places the result into register RT.

Operation

if 'fre.' then
    RT <- estimate_reciprocal(RA)

Programming Note

The fre. instruction provides a fast, approximate reciprocal value, useful for performance-critical applications like graphics or scientific computing where precision can be traded for speed. Ensure that the input register RA contains a non-zero value to avoid undefined behavior; otherwise, consider adding checks to handle zero inputs gracefully.