mirror of
https://gitee.com/johng/gf
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46 lines
1.4 KiB
Go
46 lines
1.4 KiB
Go
// Copyright GoFrame Author(https://goframe.org). All Rights Reserved.
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//
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// This Source Code Form is subject to the terms of the MIT License.
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// If a copy of the MIT was not distributed with this file,
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// You can obtain one at https://github.com/gogf/gf.
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package ghash
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// PJW implements the classic PJW hash algorithm for 32 bits.
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func PJW(str []byte) uint32 {
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var (
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BitsInUnsignedInt uint32 = 4 * 8
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ThreeQuarters uint32 = (BitsInUnsignedInt * 3) / 4
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OneEighth uint32 = BitsInUnsignedInt / 8
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HighBits uint32 = (0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth)
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hash uint32 = 0
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test uint32 = 0
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)
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for i := 0; i < len(str); i++ {
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hash = (hash << OneEighth) + uint32(str[i])
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if test = hash & HighBits; test != 0 {
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hash = (hash ^ (test >> ThreeQuarters)) & (^HighBits + 1)
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}
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}
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return hash
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}
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// PJW64 implements the classic PJW hash algorithm for 64 bits.
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func PJW64(str []byte) uint64 {
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var (
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BitsInUnsignedInt uint64 = 4 * 8
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ThreeQuarters uint64 = (BitsInUnsignedInt * 3) / 4
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OneEighth uint64 = BitsInUnsignedInt / 8
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HighBits uint64 = (0xFFFFFFFFFFFFFFFF) << (BitsInUnsignedInt - OneEighth)
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hash uint64 = 0
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test uint64 = 0
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)
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for i := 0; i < len(str); i++ {
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hash = (hash << OneEighth) + uint64(str[i])
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if test = hash & HighBits; test != 0 {
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hash = (hash ^ (test >> ThreeQuarters)) & (^HighBits + 1)
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}
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}
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return hash
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}
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