rldcr.

Rotate Left Doubleword then Clear Right (Record)

rldcr. RT,RS,RB,ME

Rotates the contents of register RS left by a variable number of bits specified by (RB)58:63, and clears the rightmost bits.

Encoding

Binary Layout

0

0:5

RS

6:10

RA

11:15

RB

16:20

ME

21:26

9

27:30

Rc

31

 

Format MDS-form

Opcode 0x78000012

Extension Base

Operands

• RT
  Target General Purpose Register
• RS
  Source General Purpose Register
• RB
  Source General Purpose Register
• ME
  Mask End bit position

Example

rldcr r3, r3, r5, 31

Registers Altered

CR0 (if Rc=1)

Related

More in Base

Reference

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

Description

The contents of register RS are rotated 64 bits to the left by the number of bits specified by (RB)58:63. A mask is generated having 1-bits from bit 0 through bit ME and 0-bits elsewhere. The rotated data are ANDed with the generated mask, and the result is placed into register RA.

Operation

if 'rldcr' then
    n ← (RB)58:63
    r ← ROTL64((RS), n)
    ME ← me5 || me0:4
    m ← MASK(0, ME)
    RA ← r & m
if 'rldcr.' then
    CR0 <- updated based on result

Extended Mnemonics

Extended Mnemonic	Equivalent Instruction

Programming Note

rldcr can be used to extract an n-bit field that starts at variable bit position b in register RS, left-justified RA), by setting RB58:63=b and ME=n-1. It can also be used to rotate the contents of a register left (right) by variable n bits, by setting RB58:63=n (64-n) and ME=63.