pstfs

Prefixed Store Floating-Point Single MLS:D-form

pstfs FRT,RA,RB

Stores a single-precision floating-point value from a register to memory.

Encoding

Binary Layout

000001

0:5

100

6:10

Rc

11

.//..

12:16

FRT

17:21

RA

22:26

RB

27:63

 

Format MLS:D-form

Opcode 0x06000000D0000000

Extension Floating-Point

Operands

• FRT
  Target Floating-Point Register
• RA
  Base General Purpose Register
• RB
  Offset General Purpose Register

Example

pstfs f1, r4, r5

Related

More in Floating-Point

Reference

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

Description

The double-precision floating-point value in register FRS is converted to single-precision and stored as a 32-bit single-precision value at the effective address (EA). The EA is formed by adding the sign-extended 34-bit immediate displacement D to the contents of general-purpose register RA (or zero if RA=0). This is the prefixed form of the stfs instruction, allowing a larger displacement field than the non-prefixed variant.

Operation

EA ← (RA|0) + D
MEM(EA, 4) ← SINGLE(FRS)

Programming Note

The pstfs instruction is useful for storing single-precision floating-point values with an extended displacement. Ensure that the EA calculation does not result in an invalid memory address to avoid exceptions. This instruction operates at user privilege level and requires proper alignment of the EA for optimal performance.