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40 lines
533 B
Go
40 lines
533 B
Go
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// +build !amd64 appengine
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package bits
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// Ctz counts trailing zeroes
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func Ctz(x uint64) uint64 {
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if x == 0 {
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return 64
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}
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var n uint64
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if (x & 0x00000000FFFFFFFF) == 0 {
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n = n + 32
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x = x >> 32
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}
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if (x & 0x000000000000FFFF) == 0 {
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n = n + 16
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x = x >> 16
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}
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if (x & 0x00000000000000FF) == 0 {
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n = n + 8
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x = x >> 8
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}
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if (x & 0x000000000000000F) == 0 {
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n = n + 4
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x = x >> 4
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}
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if (x & 0x0000000000000003) == 0 {
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n = n + 2
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x = x >> 2
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}
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if (x & 0x0000000000000001) == 0 {
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n = n + 1
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}
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return n
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}
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