vlogefp

Vector Log Base 2 Estimate Floating-Point

vlogefp VRT,VRB

Estimates the base 2 logarithm of single-precision floating-point elements in a vector register.

Encoding

Binary Layout

0

0:5

VRT

6:10

VRB

11:30

11000000000000000000000000000000

31

 

Format VX-form

Opcode 0x100001CA

Extension VMX (AltiVec)

Operands

• VRT
  Target Vector Register
• VRB
  Source Vector Register

Example

vlogefp v1, v3

Registers Altered

MSR

Related

More in VMX (AltiVec)

Reference

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

Description

For vlogefp, the single-precision floating-point estimate of the base 2 logarithm of each element in VSR[VRB+32] is placed into the corresponding element in VSR[VRT+32].

Operation

if MSR.VEC=0 then
    Vector_Unavailable()
do i = 0 to 3
    src ← VSR[VRB+32].word[i]
    VSR[VRT+32].word[i] ← bfp32_LOG_BASE2_ESTIMATE(src)
end

Programming Note

This instruction is used for estimating the base 2 logarithm of single-precision floating-point numbers in vector registers. Ensure that the Vector Facility (MSR.VEC) is enabled before using this instruction; otherwise, a Vector_Unavailable exception will be raised. The operation processes four elements at a time, so ensure proper alignment and data handling to avoid unexpected results.