stfd

Store Floating-Point Double D-form

stfd FRS,D(RA)

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

Encoding

Binary Layout

0

0:5

FRS

6:10

RA

11:15

D

16:31

 

Format D-form

Opcode 0xD8000000

Extension Floating-Point

Operands

• FRS
  Floating-point Source Register
• D
  16-bit signed displacement
• RA
  Base General Purpose Register

Example

stfd f1, 0(r4)

Registers Altered

FPSCR

Related

More in Floating-Point

Reference

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

Description

The contents of the specified floating-point register (FRS) are stored into the double-word in storage addressed by the effective address (EA). The EA is calculated as the sum of the contents of register RA or 0 if RA=0, and the sign-extended value D.

Operation

if RA = 0 then
    b ← 0
else
    b ← (RA)
EA ← b + EXTS64(D)
MEM(EA, 8) ← (FRS)

Programming Note

The stfd instruction stores a double-precision floating-point value from a specified register into memory. Ensure the destination address is properly aligned to avoid alignment faults. The effective address is calculated by adding the base address in RA (or zero if RA is 0) and the sign-extended displacement D. This instruction operates at user privilege level.