xvcpsgndp

VSX Vector Copy Sign Double-Precision

xvcpsgndp XT,XA,XB

Copies the sign bit from one double-precision vector element to another.

Encoding

Binary Layout

T

0:10

A

11:15

B

16:20

AX

21:28

BX

29

TX

30:31

 

Format XX3-form

Opcode 0xF0000780

Extension VSX

Operands

• XT
  Target Vector-Specific Register
• XA
  Source Vector-Specific Register
• XB
  Source Vector-Specific Register

Example

xvcpsgndp vs1, vs2, vs3

Related

More in VSX

Reference

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

Description

For xvcpsgndp, the sign bit of each doubleword element in VSR[XB] is copied to the corresponding doubleword element in VSR[XT], while the magnitude bits remain unchanged.

Operation

if MSR.VSX=0 then VSX_Unavailable()
do i = 0 to 1
    src1 ←VSR[32×AX+A].dword[i] & 0x8000_0000_0000_0000
    src2 ←VSR[32×BX+B].dword[i] & 0x7FFF_FFFF_FFFF_FFFF
    VSR[32×TX+T].dword[i] ←src1 | src2
end

Extended Mnemonics

Extended Mnemonic	Equivalent Instruction
xvmovdp

Programming Note

This instruction is useful for copying the sign of double-precision floating-point numbers while preserving their magnitude. Ensure that VSX (Vector Scalar Extensions) are enabled in the MSR register to avoid exceptions. The operation is performed on each doubleword element independently, so alignment requirements are per-element rather than per-vector.