xsrdpim

VSX Scalar Round to Double-Precision Integer using round toward -Infinity

xsrdpim XT,XB

Rounds a double-precision floating-point value in VSR[XB] towards negative infinity and places the result into VSR[XT].

Details

The instruction rounds the double-precision floating-point value in VSR[XB] towards negative infinity. The result is placed into doubleword element 0 of VSR[XT], and doubleword element 1 of VSR[XT] is set to 0. FPRF is set to the class and sign of the result, while FR and FI are set to 0.

Pseudocode Operation

if MSR.VSX=0 then VSX_Unavailable()
reset_xflags()
src ← bfp_CONVERT_FROM_BFP64(VSR[VRB+32].dword[0])
rnd ← bfp_ROUND_TO_INTEGER(0b011, src)
result ← bfp64_CONVERT_FROM_BFP(rnd)
if vxsnan_flag=1 then SetFX(FPSCR.VXSNAN)
vex_flag ← FPSCR.VE & vxsnan_flag
if vex_flag=0 then
do
    VSR[32×TX+T].dword[0] ← result
    VSR[32×TX+T].dword[1] ← 0x0000_0000_0000_0000
    FPSCR.FPRF ← fprf_CLASS_BFP64(result)
end
FPSCR.FR ← 0b0
FPSCR.FI ← 0b0

Programming Note

['This instruction can be used to operate on a single-precision source operand.', 'Previous versions of the architecture allowed the contents of doubleword 1 of the result register to be undefined. However, all processors that support this instruction write 0s into doubleword 1 of the result register, as is required by this version of the architecture.']

Example

xsrdpim vs1, vs3

Encoding

Binary Layout
T
0
B
6
121
11
BX
16
TX
21
 
Format XX2-form
Opcode 0xF00001E4
Extension VSX
Registers Altered FPSCR (FPRF, FX, VXSNAN, FR, FI)

Operands

  • XT
    Target Vector-Scalar Register
  • XB
    Source Vector-Scalar Register