stfsx

Store Floating-Point Single Indexed X-form

stfsx FRS,RA,RB

Stores a single-precision floating-point value from a register to memory using an indexed address.

Encoding

Binary Layout

0

FRS

RA

RB

 

Format X-form

Opcode 0x7C00052E

Extension Floating-Point

Operands

• FRS
  Floating-Point Register Source
• RA
  General Purpose Register (Base Address)
• RB
  General Purpose Register (Index)

Example

stfsx f1, r4, r5

Registers Altered

FPSCR

Related

More in Floating-Point

Reference

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

Description

The contents of register FRS are converted to single format and stored into the word in storage addressed by EA, which is the sum of RA (or RA|0) and RB. If RA is not zero, it is used directly; otherwise, b is set to zero.

Operation

if RA = 0 then
    b ← 0
else
    b ← (RA)
EA ← b + (RB)
MEM(EA, 4) ← SINGLE((FRS))

Programming Note

The stfsx instruction stores a single-precision floating-point value from register FRS to memory. Ensure that the base address (RA or RA|0) and offset (RB) are correctly aligned for optimal performance. If RA is zero, the effective address is solely determined by RB; otherwise, it's the sum of RA and RB. This instruction operates at user privilege level.