vrfin

Vector Round to Floating-Point Integer Nearest

vrfin vD, vB

Rounds 4 floats to nearest integer.

Encoding

Binary Layout

4

0:5

vD

6:10

0

11:15

vB

16:20

522

21:31

 

Format VX-form

Opcode 0x1000020A

Extension VMX (AltiVec)

Operands

• vD
  Target
• vB
  Source

Example

vrfin vd, vb

Registers Altered

MSR

Related

More in VMX (AltiVec)

Reference

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

Description

Rounds four single-precision floating-point elements in vB to the nearest integer value (using round-to-nearest-even), storing IEEE 754 results in vD. No condition flags are set. This is a Classic VMX (AltiVec) instruction.

Operation

for i in 0 to 3 do
  vD[i] ← round_nearest_even(vB[i])  (IEEE 754 single precision)
endfor

Programming Note

The vrfin instruction is commonly used for rounding floating-point numbers in vector operations. Ensure that the Vector Facility (MSR.VEC) is enabled before using this instruction; otherwise, a Vector_Unavailable exception will be raised. Be aware of potential precision loss when rounding to integers, especially with ties. This instruction operates on 32-bit floating-point elements and requires proper alignment for optimal performance.