xsredp

Vector Scalar Reciprocal Estimate Double Precision

xsredp XT,XB

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

Encoding

Binary Layout

18

0:5

T

6:10

B

11:15

90

16:31

 

Format XX2-form

Opcode 0xF0000168

Extension VSX

Operands

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

Example

xsredp vs1, vs3

Registers Altered

FPSCR.FR, FPSCR.FPRF, FPSCR.FI, FPSCR.VXSNAN, FPSCR.OX, FPSCR.UX, FPSCR.ZX

Related

More in VSX

Reference

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

Description

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.

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.