95 lines
2.2 KiB
Go
95 lines
2.2 KiB
Go
// Copyright 2016 Tom Thorogood. All rights reserved.
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// Use of this source code is governed by a
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// Modified BSD License license that can be found in
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// the LICENSE file.
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// +build amd64,!gccgo,!appengine
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package hex
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import "golang.org/x/sys/cpu"
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// RawEncode encodes src into EncodedLen(len(src))
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// bytes of dst. As a convenience, it returns the number
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// of bytes written to dst, but this value is always EncodedLen(len(src)).
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// RawEncode implements hexadecimal encoding for a given alphabet.
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func RawEncode(dst, src, alpha []byte) int {
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if len(alpha) != 16 {
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panic("invalid alphabet")
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}
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if len(dst) < len(src)*2 {
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panic("dst buffer is too small")
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}
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if len(src) == 0 {
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return 0
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}
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switch {
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case cpu.X86.HasAVX:
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encodeAVX(&dst[0], &src[0], uint64(len(src)), &alpha[0])
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case cpu.X86.HasSSE41:
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encodeSSE(&dst[0], &src[0], uint64(len(src)), &alpha[0])
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default:
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encodeGeneric(dst, src, alpha)
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}
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return len(src) * 2
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}
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// Decode decodes src into DecodedLen(len(src)) bytes, returning the actual
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// number of bytes written to dst.
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//
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// If Decode encounters invalid input, it returns an error describing the failure.
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func Decode(dst, src []byte) (int, error) {
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if len(src)%2 != 0 {
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return 0, errLength
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}
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if len(dst) < len(src)/2 {
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panic("dst buffer is too small")
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}
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if len(src) == 0 {
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return 0, nil
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}
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var (
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n uint64
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ok bool
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)
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switch {
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case cpu.X86.HasAVX:
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n, ok = decodeAVX(&dst[0], &src[0], uint64(len(src)))
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case cpu.X86.HasSSE41:
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n, ok = decodeSSE(&dst[0], &src[0], uint64(len(src)))
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default:
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n, ok = decodeGeneric(dst, src)
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}
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if !ok {
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return 0, InvalidByteError(src[n])
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}
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return len(src) / 2, nil
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}
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//go:generate go run asm_gen.go
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// This function is implemented in hex_encode_amd64.s
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//go:noescape
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func encodeAVX(dst *byte, src *byte, len uint64, alpha *byte)
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// This function is implemented in hex_encode_amd64.s
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//go:noescape
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func encodeSSE(dst *byte, src *byte, len uint64, alpha *byte)
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// This function is implemented in hex_decode_amd64.s
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//go:noescape
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func decodeAVX(dst *byte, src *byte, len uint64) (n uint64, ok bool)
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// This function is implemented in hex_decode_amd64.s
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//go:noescape
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func decodeSSE(dst *byte, src *byte, len uint64) (n uint64, ok bool)
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