You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
46 lines
1.4 KiB
46 lines
1.4 KiB
// Copyright GoFrame Author(https://goframe.org). All Rights Reserved.
|
|
//
|
|
// This Source Code Form is subject to the terms of the MIT License.
|
|
// If a copy of the MIT was not distributed with this file,
|
|
// You can obtain one at https://github.com/gogf/gf.
|
|
|
|
package ghash
|
|
|
|
// PJW implements the classic PJW hash algorithm for 32 bits.
|
|
func PJW(str []byte) uint32 {
|
|
var (
|
|
BitsInUnsignedInt uint32 = 32 // 4 * 8
|
|
ThreeQuarters = (BitsInUnsignedInt * 3) / 4
|
|
OneEighth = BitsInUnsignedInt / 8
|
|
HighBits uint32 = (0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth)
|
|
hash uint32
|
|
test uint32
|
|
)
|
|
for i := 0; i < len(str); i++ {
|
|
hash = (hash << OneEighth) + uint32(str[i])
|
|
if test = hash & HighBits; test != 0 {
|
|
hash = (hash ^ (test >> ThreeQuarters)) & (^HighBits + 1)
|
|
}
|
|
}
|
|
return hash
|
|
}
|
|
|
|
// PJW64 implements the classic PJW hash algorithm for 64 bits.
|
|
func PJW64(str []byte) uint64 {
|
|
var (
|
|
BitsInUnsignedInt uint64 = 32 // 4 * 8
|
|
ThreeQuarters = (BitsInUnsignedInt * 3) / 4
|
|
OneEighth = BitsInUnsignedInt / 8
|
|
HighBits uint64 = (0xFFFFFFFFFFFFFFFF) << (BitsInUnsignedInt - OneEighth)
|
|
hash uint64
|
|
test uint64
|
|
)
|
|
for i := 0; i < len(str); i++ {
|
|
hash = (hash << OneEighth) + uint64(str[i])
|
|
if test = hash & HighBits; test != 0 {
|
|
hash = (hash ^ (test >> ThreeQuarters)) & (^HighBits + 1)
|
|
}
|
|
}
|
|
return hash
|
|
}
|