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f64.go
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f64.go
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// Copyright (C) 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package f64
import "math"
// MinOf returns the minimum value of all the arguments.
func MinOf(a float64, b ...float64) float64 {
v := a
for _, x := range b {
if x < v {
v = x
}
}
return v
}
// MaxOf returns the maximum value of all the arguments.
func MaxOf(a float64, b ...float64) float64 {
v := a
for _, x := range b {
if x > v {
v = x
}
}
return v
}
// Round rounds v to the nearest integer.
// Examples:
// Round(-0.9) = -1
// Round(-0.1) = 0
// Round(0.0) = 0
// Round(0.1) = 0
// Round(0.9) = 1
func Round(v float64) int {
if v < 0 {
return int(math.Ceil(v - 0.5))
}
return int(math.Floor(v + 0.5))
}
// FromBits takes binary representation of floating-point value
// with user-defined bit sizes and expands it to full float64.
func FromBits(val uint64, expBits, manBits uint32) float64 {
manMask := (uint64(1) << manBits) - 1
expMask := (uint64(1) << expBits) - 1
expBias := expMask / 2
const expMaskFloat64 = (1 << 11) - 1
const expBiasFloat64 = expMaskFloat64 / 2 // 1023
// Extract mantissa, exponent and sign from the packed value
man, val := val&manMask, val>>manBits
exp, sig := val&expMask, val>>expBits
// Special cases in increasing numerical order of the value
if exp == 0 {
if man == 0 {
// Zero - return zero with the same sign
return math.Float64frombits(sig << 63)
} else if expMask != expMaskFloat64 {
// Denormalized number - promote it to normalized
exp++
for man&(1<<manBits) == 0 {
man *= 2
exp--
}
man &= manMask
exp += expBiasFloat64 - expBias
}
} else if exp < expMask {
// Normalized number - just adjust the exponent's bias
exp += expBiasFloat64 - expBias
} else /* exp == expMask */ {
// NaN or Inf - set all bits in exponent; keep mantissa
exp = expMaskFloat64
}
// Compact mantissa, exponent and sign to 64-bit float value
val = (sig << 63) | (exp << 52) | (man << (52 - manBits))
return math.Float64frombits(val)
}