xscvqpuqz

VSX Scalar Convert with round to zero Quad-Precision to Unsigned Quadword

xscvqpuqz VRT,VRB

Converts a quad-precision floating-point value to an unsigned quadword integer, rounding towards zero.

Details

The instruction converts the quad-precision floating-point value in VSR[VRB+32] to an unsigned quadword integer and places the result into VSR[VRT+32]. The conversion rounds towards zero. If the source is a NaN or Infinity, an Invalid Operation exception occurs.

Pseudocode Operation

if MSR.VSX=0 then
    VSypX_Unavailable()
else if src.class.QNaN=1 | src.class.SNaN=1 then do
    vxsnan_flag ←src.class.SNaN
    vxcvi_flag ←1
    result ←0x0000_0000_0000_0000_0000_0000_0000_0000
end
else if src.class.Infinity=1 then do
    vxcvi_flag ←1
    if src.sign=0 then
        result ←0xFFFF_FFFF_FFFF_FFFF_FFFF_FFFF_FFFF_FFFF
    else
        result ←0x0000_0000_0000_0000_0000_0000_0000_0000
end
else if src.class.Zero=1 then
    result ←0x0000_0000_0000_0000_0000_0000_0000_0000
else do
    rnd ←bfp_ROUND_TO_INTEGER(0b001,src)
    if bfp_COMPARE_GT(rnd, +2128-1) then do
        result ←0xFFFF_FFFF_FFFF_FFFF_FFFF_FFFF_FFFF_FFFF
        vxcvi_flag ←1
    end
    else if bfp_COMPARE_LT(rnd, 0) then do
        result ←0x0000_0000_0000_0000_0000_0000_0000_0000
        vxcvi_flag ←1
    end
    else do
        result ←si128_CONVERT_FROM_BFP(rnd)
        if xx_flag=1 then SetFX(FPSCR.XX)
    end
end
if vxsnan_flag=1 then SetFX(FPSCR.VXSNAN)
if vxcvi_flag=1  then SetFX(FPSCR.VXCVI)
vx_flag ←vxsnan_flag | vxcvi_flag
ex_flag ←FPSCR.VE & vx_flag
if ex_flag=0 then do
    VSR[VRT+32] ←result
    FPSCR.FPRF ←0bUUUUU
end
FPSCR.FR ←(vx_flag=0) & inc_flag
FPSCR.FI ←(vx_flag=0) & xx_flag

Programming Note

This instruction is used to convert a quad-precision floating-point number to an unsigned quadword integer, rounding towards zero. Be cautious with NaNs and infinities, as they will trigger exceptions. Ensure VSX is enabled in the MSR register before using this instruction.

Example

xscvqpuqz v1, v3

Encoding

Binary Layout

FRT

FRB

836

Format X-form

Opcode 0xFC000688

Extension VSX

Registers Altered FPSCR.FR, FPSCR.FI, FPSCR.FPRF, FPSCR.FX

Operands

VRT
Target Vector-Scalar Register
VRB
Source Vector-Scalar Register
VT
Target Vector-Scalar Register
VS32
Target Vector Register
VS31
Source Vector Register