mirror of
https://github.com/make-42/xyosc
synced 2025-01-19 02:57:34 +01:00
59 lines
1.7 KiB
Go
59 lines
1.7 KiB
Go
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package math32
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const (
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uvnan = 0x7FE00000
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uvinf = 0x7F800000
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uvone = 0x3f800000
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uvneginf = 0xFF800000
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mask = 0xFF
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shift = 32 - 8 - 1
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bias = 127
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signMask = 1 << 31
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fracMask = 1<<shift - 1
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)
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// Inf returns positive infinity if sign >= 0, negative infinity if sign < 0.
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func Inf(sign int) float32 {
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var v uint32
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if sign >= 0 {
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v = uvinf
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} else {
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v = uvneginf
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}
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return Float32frombits(v)
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}
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// NaN returns an IEEE 754 ``not-a-number'' value.
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func NaN() float32 { return Float32frombits(uvnan) }
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// IsNaN reports whether f is an IEEE 754 ``not-a-number'' value.
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func IsNaN(f float32) (is bool) {
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// IEEE 754 says that only NaNs satisfy f != f.
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// To avoid the floating-point hardware, could use:
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// x := Float32bits(f)
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// return uint32(x>>shift)&mask == mask && x != uvinf && x != uvneginf
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return f != f
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}
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// IsInf reports whether f is an infinity, according to sign.
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// If sign > 0, IsInf reports whether f is positive infinity.
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// If sign < 0, IsInf reports whether f is negative infinity.
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// If sign == 0, IsInf reports whether f is either infinity.
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func IsInf(f float32, sign int) bool {
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// Test for infinity by comparing against maximum float.
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// To avoid the floating-point hardware, could use:
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// x := Float32bits(f)
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// return sign >= 0 && x == uvinf || sign <= 0 && x == uvneginf
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return sign >= 0 && f > MaxFloat32 || sign <= 0 && f < -MaxFloat32
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}
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// normalize returns a normal number y and exponent exp
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// satisfying x == y × 2**exp. It assumes x is finite and non-zero.
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func normalize(x float32) (y float32, exp int) {
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const SmallestNormal = 1.1754943508222875079687365e-38 // 2**-(127 - 1)
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if Abs(x) < SmallestNormal {
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return x * (1 << shift), -shift
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}
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return x, 0
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}
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