25 lines
709 B
Go
25 lines
709 B
Go
package gen
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import "math/rand"
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// Generate a random uint64 with an even distribution of bits.Len64()
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func RandBiasedUint64() uint64 {
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// The shift-right by up to 64 (shifting it to 0) makes up for randomness
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// lost by setting the high bit.
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return (rand.Uint64() | 0x8000000000000000) >> rand.Intn(65)
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}
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// Generate a random int64 with an even distribution of the tuple
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// {sign, bits.Len64(math.Abs())}
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func RandBiasedInt64() int64 {
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shift := rand.Intn(127)
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// [0,62]: positive
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// [63,63]: zero
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// [64,126]: negative
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if shift < 64 {
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return int64((rand.Uint64() | 0x8000000000000000) >> (shift + 1))
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} else {
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return int64((rand.Uint64() | 0x8000000000000000) >> (shift - 63)) * -1
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}
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}
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