vspltb

Vector Splat Byte

vspltb vD, vB, UIM

Splat a byte from one vector element into all elements of another vector.

Encoding

Binary Layout

1001010

0:5

VRT

6:10

UIM

11:15

VRB

16:31

 

Format VX-form

Opcode 0x1000020C

Extension VMX (AltiVec)

Operands

• vD
  Target
• vB
  Source
• UIM
  Index
• VRT
  Target Vector Register
• VRB
  Source Vector Register

Example

vspltb vd, vb, uim

Registers Altered

MSR

Related

More in VMX (AltiVec)

Reference

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

Description

Splats (replicates) a single byte element from vB across all 16 byte elements of vD. The byte element selected is determined by the 4-bit unsigned immediate UIM (where UIM=0 selects byte 0, UIM=15 selects byte 15 in big-endian order). No status flags are affected. This is a VMX/AltiVec instruction.

Operation

index ← UIM
vD ← replicate(vB[index*8:index*8+7] to all 16 byte positions)

Programming Note

The Vector Splat instructions can be used in preparation for performing arithmetic for which one source vector is to consist of elements that all have the same value (e.g., multiplying all elements of a VSR by a constant).