xvsqrtdp

VSX Vector Square Root Double-Precision

xvsqrtdp XT, XB

Computes the square root of each double-precision floating-point element in a vector.

Encoding

Binary Layout

0:5

6:10

11:15

16:20

203

21:31

Format XX2-form

Opcode 0xF000032C

Extension VSX

Operands

XT
Target
XB
Source

Example

xvsqrtdp vs1, vs3

Registers Altered

FPSCR FX XX VXSNAN VXSQRT

Reference

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

Description

For xvsqrtdp, the unbounded-precision square root of each double-precision floating-point operand in doubleword elements of VSR[XB] is computed and rounded to double-precision format. The result is placed into corresponding elements of VSR[XT].

Operation

if MSR.VSX=0 then VSX_Unavailable()
ex_flag ←0b0
do i = 0 to 1
    reset_xflags()
    src ←bfp_CONVERT_FROM_BFP64(VSR[32×BX+B].dword[i])
    v   ←bfp_SQUARE_ROOT(src)
    rnd ←bfp_ROUND_TO_BFP64(0b0,FPSCR.RN,v)
    vresult.dword[i] ←bfp64_CONVERT_FROM_BFP(rnd)
    if vxsnan_flag=1 then SetFX(FPSCR.VXSNAN)
    if vxsqrt_flag=1 then SetFX(FPSCR.VXSQRT)
    if xx_flag=1 then SetFX(FPSCR.XX)
    ex_flag ←ex_flag | (FPSCR.VE & vxsnan_flag) | (FPSCR.VE & vxsqrt_flag) | (FPSCR.XE & xx_flag)
end
if ex_flag=0 then VSR[32×TX+T] ←vresult

Programming Note

The xvsqrtdp instruction computes the square root of each double-precision floating-point operand in a vector. Ensure that VSX is enabled by checking MSR.VSX. Handle exceptions by examining FPSCR flags such as VXSNAN, VXSQRT, and XX. The instruction operates on aligned data and requires supervisor privilege level.