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31 lines
906 B
Go
31 lines
906 B
Go
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// +build !appengine
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// This file encapsulates usage of unsafe.
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// xxhash_safe.go contains the safe implementations.
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package xxhash
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import (
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"reflect"
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"unsafe"
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)
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// Sum64String computes the 64-bit xxHash digest of s.
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// It may be faster than Sum64([]byte(s)) by avoiding a copy.
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//
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// TODO(caleb): Consider removing this if an optimization is ever added to make
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// it unnecessary: https://golang.org/issue/2205.
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//
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// TODO(caleb): We still have a function call; we could instead write Go/asm
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// copies of Sum64 for strings to squeeze out a bit more speed.
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func Sum64String(s string) uint64 {
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// See https://groups.google.com/d/msg/golang-nuts/dcjzJy-bSpw/tcZYBzQqAQAJ
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// for some discussion about this unsafe conversion.
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var b []byte
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bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
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bh.Data = (*reflect.StringHeader)(unsafe.Pointer(&s)).Data
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bh.Len = len(s)
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bh.Cap = len(s)
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return Sum64(b)
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}
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