subfc.

Subtract from Complement with Carry-Out

subfc. RT,RA,RB

Subtracts the contents of one register from the complement of another and updates the carry-out flag.

Encoding

Binary Layout

01000

0:5

LI

6:29

AA

30

LK

31

 

Format XO-form

Opcode 0x7C000010

Extension Base

Operands

• RT
  Target General Purpose Register
• RA
  Source General Purpose Register
• RB
  Source General Purpose Register

Example

subfc. r3, r4, r5

Registers Altered

CR0, XER

Related

More in Base

Reference

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

Description

For subfc., the complement of the contents of register RB is subtracted from the contents of register RA, and the result is placed into register RT. The carry-out flag is updated based on the operation.

Operation

if 'subfc.' then
    RT <- (RA) - (~RB)
    XER.CA <- carry-out

Programming Note

Use subfc. to subtract the bitwise complement of one register from another, updating the carry-out flag in XER.CA. Ensure registers are properly aligned and consider the effect on CR0 for conditional branching.