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https://github.com/make-42/xyosc
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32 lines
723 B
Go
32 lines
723 B
Go
package math32
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// Frexp breaks f into a normalized fraction
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// and an integral power of two.
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// It returns frac and exp satisfying f == frac × 2**exp,
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// with the absolute value of frac in the interval [½, 1).
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//
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// Special cases are:
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// Frexp(±0) = ±0, 0
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// Frexp(±Inf) = ±Inf, 0
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// Frexp(NaN) = NaN, 0
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func Frexp(f float32) (frac float32, exp int) {
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return frexp(f)
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}
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func frexp(f float32) (frac float32, exp int) {
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// special cases
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switch {
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case f == 0:
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return f, 0 // correctly return -0
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case IsInf(f, 0) || IsNaN(f):
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return f, 0
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}
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f, exp = normalize(f)
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x := Float32bits(f)
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exp += int((x>>shift)&mask) - bias + 1
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x &^= mask << shift
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x |= (-1 + bias) << shift
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frac = Float32frombits(x)
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return
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}
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