mirror of https://github.com/tidwall/tile38.git
60 lines
1.5 KiB
Go
60 lines
1.5 KiB
Go
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/*
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go-float16 - IEEE 754 binary16 half precision format
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Written in 2013 by h2so5 <mail@h2so5.net>
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To the extent possible under law, the author(s) have dedicated all copyright and
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related and neighboring rights to this software to the public domain worldwide.
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This software is distributed without any warranty.
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You should have received a copy of the CC0 Public Domain Dedication along with this software.
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If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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// Package half is an IEEE 754 binary16 half precision format.
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package half
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import "math"
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// A Float16 represents a 16-bit floating point number.
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type Float16 uint16
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// NewFloat16 allocates and returns a new Float16 set to f.
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func NewFloat16(f float32) Float16 {
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i := math.Float32bits(f)
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sign := uint16((i >> 31) & 0x1)
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exp := (i >> 23) & 0xff
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exp16 := int16(exp) - 127 + 15
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frac := uint16(i>>13) & 0x3ff
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if exp == 0 {
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exp16 = 0
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} else if exp == 0xff {
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exp16 = 0x1f
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} else {
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if exp16 > 0x1e {
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exp16 = 0x1f
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frac = 0
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} else if exp16 < 0x01 {
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exp16 = 0
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frac = 0
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}
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}
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f16 := (sign << 15) | uint16(exp16<<10) | frac
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return Float16(f16)
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}
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// Float32 returns the float32 representation of f.
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func (f Float16) Float32() float32 {
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sign := uint32((f >> 15) & 0x1)
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exp := (f >> 10) & 0x1f
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exp32 := uint32(exp) + 127 - 15
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if exp == 0 {
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exp32 = 0
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} else if exp == 0x1f {
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exp32 = 0xff
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}
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frac := uint32(f & 0x3ff)
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i := (sign << 31) | (exp32 << 23) | (frac << 13)
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return math.Float32frombits(i)
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}
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