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105 lines
2.3 KiB
105 lines
2.3 KiB
package fnv1a
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const (
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// FNV-1a
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offset32 = uint32(2166136261)
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prime32 = uint32(16777619)
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// Init32 is what 32 bits hash values should be initialized with.
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Init32 = offset32
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)
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// HashString32 returns the hash of s.
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func HashString32(s string) uint32 {
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return AddString32(Init32, s)
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}
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// HashBytes32 returns the hash of u.
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func HashBytes32(b []byte) uint32 {
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return AddBytes32(Init32, b)
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}
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// HashUint32 returns the hash of u.
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func HashUint32(u uint32) uint32 {
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return AddUint32(Init32, u)
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}
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// AddString32 adds the hash of s to the precomputed hash value h.
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func AddString32(h uint32, s string) uint32 {
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for len(s) >= 8 {
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h = (h ^ uint32(s[0])) * prime32
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h = (h ^ uint32(s[1])) * prime32
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h = (h ^ uint32(s[2])) * prime32
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h = (h ^ uint32(s[3])) * prime32
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h = (h ^ uint32(s[4])) * prime32
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h = (h ^ uint32(s[5])) * prime32
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h = (h ^ uint32(s[6])) * prime32
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h = (h ^ uint32(s[7])) * prime32
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s = s[8:]
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}
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if len(s) >= 4 {
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h = (h ^ uint32(s[0])) * prime32
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h = (h ^ uint32(s[1])) * prime32
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h = (h ^ uint32(s[2])) * prime32
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h = (h ^ uint32(s[3])) * prime32
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s = s[4:]
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}
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if len(s) >= 2 {
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h = (h ^ uint32(s[0])) * prime32
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h = (h ^ uint32(s[1])) * prime32
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s = s[2:]
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}
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if len(s) > 0 {
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h = (h ^ uint32(s[0])) * prime32
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}
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return h
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}
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// AddBytes32 adds the hash of b to the precomputed hash value h.
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func AddBytes32(h uint32, b []byte) uint32 {
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for len(b) >= 8 {
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h = (h ^ uint32(b[0])) * prime32
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h = (h ^ uint32(b[1])) * prime32
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h = (h ^ uint32(b[2])) * prime32
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h = (h ^ uint32(b[3])) * prime32
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h = (h ^ uint32(b[4])) * prime32
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h = (h ^ uint32(b[5])) * prime32
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h = (h ^ uint32(b[6])) * prime32
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h = (h ^ uint32(b[7])) * prime32
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b = b[8:]
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}
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if len(b) >= 4 {
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h = (h ^ uint32(b[0])) * prime32
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h = (h ^ uint32(b[1])) * prime32
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h = (h ^ uint32(b[2])) * prime32
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h = (h ^ uint32(b[3])) * prime32
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b = b[4:]
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}
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if len(b) >= 2 {
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h = (h ^ uint32(b[0])) * prime32
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h = (h ^ uint32(b[1])) * prime32
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b = b[2:]
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}
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if len(b) > 0 {
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h = (h ^ uint32(b[0])) * prime32
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}
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return h
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}
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// AddUint32 adds the hash value of the 8 bytes of u to h.
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func AddUint32(h, u uint32) uint32 {
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h = (h ^ ((u >> 24) & 0xFF)) * prime32
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h = (h ^ ((u >> 16) & 0xFF)) * prime32
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h = (h ^ ((u >> 8) & 0xFF)) * prime32
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h = (h ^ ((u >> 0) & 0xFF)) * prime32
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return h
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}
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