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