4ec1e58aa6
We have an optimization for this specific pattern, but it's really just a hack. With the addition of unsafe.Add in Go 1.17 we can directly specify the intent instead and eventually remove this special case. The code is also easier to read.
31 строка
878 Б
Go
31 строка
878 Б
Go
//go:build !runtime_memhash_tsip && !runtime_memhash_leveldb
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package runtime
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import "unsafe"
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// Get FNV-1a hash of the given memory buffer.
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//
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// https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function#FNV-1a_hash
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func hash32(ptr unsafe.Pointer, n, seed uintptr) uint32 {
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var result uint32 = 2166136261 // FNV offset basis
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result *= uint32(seed)
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for i := uintptr(0); i < n; i++ {
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c := *(*uint8)(unsafe.Add(ptr, i))
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result ^= uint32(c) // XOR with byte
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result *= 16777619 // FNV prime
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}
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return result
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}
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// Also a FNV-1a hash.
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func hash64(ptr unsafe.Pointer, n, seed uintptr) uint64 {
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var result uint64 = 14695981039346656037 // FNV offset basis
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result *= uint64(seed)
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for i := uintptr(0); i < n; i++ {
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c := *(*uint8)(unsafe.Add(ptr, i))
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result ^= uint64(c) // XOR with byte
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result *= 1099511628211 // FNV prime
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}
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return result
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}
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