103 lines
2.1 KiB
Go
103 lines
2.1 KiB
Go
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package farm
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func hash32Len5to12(s []byte, seed uint32) uint32 {
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slen := len(s)
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a := uint32(len(s))
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b := uint32(len(s) * 5)
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c := uint32(9)
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d := b + seed
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a += fetch32(s, 0)
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b += fetch32(s, slen-4)
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c += fetch32(s, ((slen >> 1) & 4))
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return fmix(seed ^ mur(c, mur(b, mur(a, d))))
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}
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// Hash32 hashes a byte slice and returns a uint32 hash value
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func Hash32(s []byte) uint32 {
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slen := len(s)
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if slen <= 24 {
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if slen <= 12 {
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if slen <= 4 {
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return hash32Len0to4(s, 0)
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}
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return hash32Len5to12(s, 0)
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}
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return hash32Len13to24Seed(s, 0)
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}
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// len > 24
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h := uint32(slen)
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g := c1 * uint32(slen)
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f := g
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a0 := rotate32(fetch32(s, slen-4)*c1, 17) * c2
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a1 := rotate32(fetch32(s, slen-8)*c1, 17) * c2
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a2 := rotate32(fetch32(s, slen-16)*c1, 17) * c2
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a3 := rotate32(fetch32(s, slen-12)*c1, 17) * c2
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a4 := rotate32(fetch32(s, slen-20)*c1, 17) * c2
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h ^= a0
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h = rotate32(h, 19)
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h = h*5 + 0xe6546b64
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h ^= a2
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h = rotate32(h, 19)
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h = h*5 + 0xe6546b64
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g ^= a1
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g = rotate32(g, 19)
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g = g*5 + 0xe6546b64
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g ^= a3
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g = rotate32(g, 19)
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g = g*5 + 0xe6546b64
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f += a4
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f = rotate32(f, 19) + 113
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iters := (slen - 1) / 20
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for {
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a := fetch32(s, 0)
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b := fetch32(s, 4)
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c := fetch32(s, 8)
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d := fetch32(s, 12)
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e := fetch32(s, 16)
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h += a
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g += b
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f += c
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h = mur(d, h) + e
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g = mur(c, g) + a
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f = mur(b+e*c1, f) + d
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f += g
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g += f
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s = s[20:]
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iters--
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if iters == 0 {
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break
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}
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}
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g = rotate32(g, 11) * c1
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g = rotate32(g, 17) * c1
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f = rotate32(f, 11) * c1
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f = rotate32(f, 17) * c1
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h = rotate32(h+g, 19)
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h = h*5 + 0xe6546b64
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h = rotate32(h, 17) * c1
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h = rotate32(h+f, 19)
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h = h*5 + 0xe6546b64
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h = rotate32(h, 17) * c1
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return h
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}
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// Hash32WithSeed hashes a byte slice and a uint32 seed and returns a uint32 hash value
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func Hash32WithSeed(s []byte, seed uint32) uint32 {
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slen := len(s)
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if slen <= 24 {
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if slen >= 13 {
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return hash32Len13to24Seed(s, seed*c1)
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}
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if slen >= 5 {
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return hash32Len5to12(s, seed)
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}
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return hash32Len0to4(s, seed)
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}
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h := hash32Len13to24Seed(s[:24], seed^uint32(slen))
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return mur(Hash32(s[24:])+seed, h)
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}
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