xsredp

Vector Scalar Reciprocal Estimate Double Precision

xsredp XT,XB

Estimates the reciprocal of a double-precision floating-point value.

Details

Computes an estimate of the reciprocal (1/XB) for a double-precision floating-point scalar value, placing the result in XT. The estimate is accurate to about 15 bits of precision. This instruction requires VSX support and may update FPSCR exception flags if the source is invalid or zero.

Pseudocode Operation

XT[0:63] ← reciprocal_estimate(XB[0:63])
FPSCR ← update_exception_flags(FPSCR, result)

Programming Note

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

xsredp vs1, vs3

Encoding

Binary Layout
18
0
T
6
B
11
90
16
 
Format XX2-form
Opcode 0xF0000168
Extension VSX
Registers Altered FPSCR.FR, FPSCR.FPRF, FPSCR.FI, FPSCR.VXSNAN, FPSCR.OX, FPSCR.UX, FPSCR.ZX

Operands

  • XT
    Target Vector-Specific Register
  • XB
    Source Vector-Specific Register
  • %xT
    Target Vector Register
  • %xS
    Source Vector Register