88 lines
2.0 KiB
Go
88 lines
2.0 KiB
Go
package metro
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import "encoding/binary"
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func Hash64(buffer []byte, seed uint64) uint64 {
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const (
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k0 = 0xD6D018F5
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k1 = 0xA2AA033B
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k2 = 0x62992FC1
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k3 = 0x30BC5B29
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)
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ptr := buffer
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hash := (seed + k2) * k0
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if len(ptr) >= 32 {
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v := [4]uint64{hash, hash, hash, hash}
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for len(ptr) >= 32 {
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v[0] += binary.LittleEndian.Uint64(ptr[:8]) * k0
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v[0] = rotate_right(v[0], 29) + v[2]
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v[1] += binary.LittleEndian.Uint64(ptr[8:16]) * k1
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v[1] = rotate_right(v[1], 29) + v[3]
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v[2] += binary.LittleEndian.Uint64(ptr[16:24]) * k2
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v[2] = rotate_right(v[2], 29) + v[0]
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v[3] += binary.LittleEndian.Uint64(ptr[24:32]) * k3
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v[3] = rotate_right(v[3], 29) + v[1]
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ptr = ptr[32:]
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}
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v[2] ^= rotate_right(((v[0]+v[3])*k0)+v[1], 37) * k1
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v[3] ^= rotate_right(((v[1]+v[2])*k1)+v[0], 37) * k0
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v[0] ^= rotate_right(((v[0]+v[2])*k0)+v[3], 37) * k1
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v[1] ^= rotate_right(((v[1]+v[3])*k1)+v[2], 37) * k0
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hash += v[0] ^ v[1]
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}
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if len(ptr) >= 16 {
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v0 := hash + (binary.LittleEndian.Uint64(ptr[:8]) * k2)
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v0 = rotate_right(v0, 29) * k3
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v1 := hash + (binary.LittleEndian.Uint64(ptr[8:16]) * k2)
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v1 = rotate_right(v1, 29) * k3
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v0 ^= rotate_right(v0*k0, 21) + v1
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v1 ^= rotate_right(v1*k3, 21) + v0
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hash += v1
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ptr = ptr[16:]
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}
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if len(ptr) >= 8 {
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hash += binary.LittleEndian.Uint64(ptr[:8]) * k3
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ptr = ptr[8:]
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hash ^= rotate_right(hash, 55) * k1
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}
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if len(ptr) >= 4 {
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hash += uint64(binary.LittleEndian.Uint32(ptr[:4])) * k3
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hash ^= rotate_right(hash, 26) * k1
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ptr = ptr[4:]
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}
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if len(ptr) >= 2 {
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hash += uint64(binary.LittleEndian.Uint16(ptr[:2])) * k3
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ptr = ptr[2:]
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hash ^= rotate_right(hash, 48) * k1
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}
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if len(ptr) >= 1 {
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hash += uint64(ptr[0]) * k3
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hash ^= rotate_right(hash, 37) * k1
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}
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hash ^= rotate_right(hash, 28)
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hash *= k0
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hash ^= rotate_right(hash, 29)
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return hash
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}
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func Hash64Str(buffer string, seed uint64) uint64 {
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return Hash64([]byte(buffer), seed)
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}
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func rotate_right(v uint64, k uint) uint64 {
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return (v >> k) | (v << (64 - k))
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}
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