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@arnehormann
Last active Aug 26, 2015
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benchmarks for possible implementations for github.com/golang/go/issues/6721
package main
import (
"math"
"testing"
)
const bits32 = 24
const step32 float32 = 1 / (1 << bits32)
const mask32 uint32 = (1 << bits32) - 1
func Float32(i uint32) float32 {
return float32(i&mask32) * step32
}
const bits64 = 53
const step64 float64 = 1 / (1 << bits64)
const mask64 uint64 = (1 << bits64) - 1
func Float64(i uint64) float64 {
return float64(i&mask64) * step64
}
func Float64b(i uint64) float64 {
return (float64(i >> 10)) * (1.0 / 9007199254740992.0)
}
const range_1_2Exp64 = 0x3ff0000000000000
const mantissaMask64 = 0x000fffffffffffff
func Float64c(i uint64) float64 {
return math.Float64frombits(range_1_2Exp64|(mantissaMask64&i)) - 1.0
}
func BenchmarkF64a(b *testing.B) {
for i := 0; i < b.N; i++ {
Float64(uint64(i))
}
}
func BenchmarkF64b(b *testing.B) {
for i := 0; i < b.N; i++ {
Float64b(uint64(i))
}
}
func BenchmarkF64c(b *testing.B) {
for i := 0; i < b.N; i++ {
Float64c(uint64(i))
}
}
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