mirror of
https://github.com/Rain-kl/OpenFlare.git
synced 2026-09-29 22:06:38 +08:00
ryan
46 lines
1.1 KiB
Go
46 lines
1.1 KiB
Go
package cap
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import (
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"fmt"
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"strings"
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)
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// fnv1a returns the 32-bit FNV-1a hash of a string
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func fnv1a(str string) uint32 {
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var hash uint32 = 2166136261
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for i := 0; i < len(str); i++ {
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hash ^= uint32(str[i])
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hash += (hash << 1) + (hash << 4) + (hash << 7) + (hash << 8) + (hash << 24)
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}
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return hash
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}
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// fnv1aResume resumes FNV-1a hashing from a given state
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func fnv1aResume(state uint32, str string) uint32 {
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h := state
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for i := 0; i < len(str); i++ {
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h ^= uint32(str[i])
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h += (h << 1) + (h << 4) + (h << 7) + (h << 8) + (h << 24)
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}
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return h
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}
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// prng generates a hex string of specified length using a seed
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func prng(seed string, length int) string {
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return prngFromHash(fnv1a(seed), length)
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}
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// prngFromHash generates a hex string of specified length using an initial hash state
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func prngFromHash(initialHash uint32, length int) string {
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state := initialHash
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var result strings.Builder
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for result.Len() < length {
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state ^= state << 13
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state ^= state >> 17
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state ^= state << 5
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hexStr := fmt.Sprintf("%08x", state)
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result.WriteString(hexStr)
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}
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return result.String()[:length]
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}
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