rldicr

Rotate Left Doubleword Immediate Clear Right

rldicr RA, RS, SH, ME

Rotates 64-bit RS left by SH, then clears the low-order bits (ME+1 to 63).

Encoding

Binary Layout

30

0:5

RS

6:10

RA

11:15

SH

16:20

ME

21:26

01

27:30

Rc

31

 

Format MD-form

Opcode 0x78000004

Extension Base

Operands

• RA
  Target
• RS
  Source
• SH
  Shift Amount
• ME
  Mask End

Example

rldicr r3, r4, 2, 60

// Align address to 8 bytes.

Registers Altered

CR0

Related

More in Base

Reference

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

Description

Rotates the 64-bit contents of RS left by SH positions, then clears bits (ME+1) through 63, effectively creating a mask from bit 0 through ME. The condition register CR0 is updated if Rc=1.

Operation

n ← SH
mask ← MASK(0, ME)
rotated ← ROTL64(RS, n)
RA ← rotated & mask
if Rc = 1 then CR0 ← (RA < 0, RA > 0, RA = 0, SO)

Programming Note

When Rc=1 (dot form), CR0 is updated with the signed comparison of the result against zero (LT, GT, EQ) and the current SO bit from XER.