xxbrh

VSX Vector Byte-Reverse Halfword

xxbrh XT,XB

Reverses the bytes of each halfword in a vector register.

Encoding

Binary Layout

475

30 31

Format XX2-form

Opcode 0xF007076C

Extension VSX

Operands

XT
Target Vector Register
XB
Source Vector Register

Example

xxbrh vs1, vs3

Registers Altered

MSR

Reference

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

Description

Reverses the byte order within each 16-bit (halfword) element in XB and stores the result in XT. This is a VSX instruction commonly used for endianness conversion on 16-bit data granules. No condition registers or status fields are affected.

Operation

for i in 0 to 7 do
  hw ← XB[i*16:(i+1)*16-1]
  XT[i*16:(i+1)*16-1] ← REVERSE_BYTES(hw, 2)
end for

Programming Note

The xxbrh instruction is useful for reversing the byte order of each halfword in a vector, which can be necessary for data format conversion or compatibility. Ensure that the VSX (Vector Scalar Extensions) are enabled by checking and setting the appropriate bit in the MSR register. This instruction operates on 128-bit vectors and requires proper alignment of the source and target registers. Be cautious of endianness issues when using this instruction, as it directly manipulates byte order.