xvcvsphp

Vector Convert Single-Precision to Half-Precision format XX2-form

xvcvsphp XT, XB

Converts each single-precision floating-point value in a vector register to half-precision and stores the result in another vector register.

Details

For xvcvsphp, each integer value i from 0 to 3, do the following. Let src be the single-precision floating-point value in word element i of VSR[XB]. If src is an SNaN, the result is the half-precision representation of that SNaN converted to a QNaN. Otherwise, if src is a QNaN, the result is the half-precision representation of that QNaN. Otherwise, if src is an Infinity, the result is the half-precision representation of Infinity with the same sign as src. Otherwise, if src is a Zero, the result is the half-precision representation of Zero with the same sign as src. Otherwise, the result is the half-precision representation of src rounded to half-precision using the rounding mode specified by RN. The result is zero-extended and placed into word element i of VSR[XT]. If a trap-enabled exception occurs, VSR[XT] is not modified.

Pseudocode Operation

if MSR.VSX=0 then VSX_Unavailable()
reset_flags()
do i = 0 to 3
    src ←bfp_CONVERT_FROM_BFP32(VSR[BX×32+B].word[i])
    rnd ←bfp_ROUND_TO_BFP16(FPSCR.RN,src)
    vresult.word[i].hword[0] ←0x0000
    vresult.word[i].hword[1] ← bfp16_CONVERT_FROM_BFP(rnd)
    if vxsnan_flag=1 then SetFX(FPSCR.VXSNAN)
    if ox_flag=1 then SetFX(FPSCR.OX)
    if ux_flag=1 then SetFX(FPSCR.UX)
    if xx_flag=1 then SetFX(FPSCR.XX)
ex_flag ←ex_flag | (FPSCR.VE & vxsnan_flag) | (FPSCR.OE & ox_flag) | (FPSCR.UE & ux_flag) | (FPSCR.XE & xx_flag)
end
Let XT be the value 32×TX + T.
Let XB be the value 32×BX + B.

Programming Note

This instruction converts single-precision floating-point values to half-precision format, handling special cases like NaNs and infinities. Ensure VSX is enabled; otherwise, a VSX_Unavailable exception occurs. The result is zero-extended into the destination vector register. Be cautious of rounding modes specified by FPSCR.RN and exceptions that may set flags in FPSCR.

Example

xvcvsphp vs1, vs3

Encoding

Binary Layout

475

30 31

Format XX2-form

Opcode 0xF00001B9

Extension VSX

Registers Altered FPSCR

Operands

XT
Target
XB
Source