79 lines
2.0 KiB
Go
79 lines
2.0 KiB
Go
//go:build amd64 && !purego
|
|
// +build amd64,!purego
|
|
|
|
package base64
|
|
|
|
import (
|
|
"encoding/base64"
|
|
|
|
"github.com/segmentio/asm/cpu"
|
|
"github.com/segmentio/asm/cpu/x86"
|
|
)
|
|
|
|
const (
|
|
encLutSize = 32
|
|
decLutSize = 48
|
|
minEncodeLen = 28
|
|
minDecodeLen = 45
|
|
)
|
|
|
|
func newEncoding(encoder string) *Encoding {
|
|
e := &Encoding{base: base64.NewEncoding(encoder)}
|
|
if cpu.X86.Has(x86.AVX2) {
|
|
e.enableEncodeAVX2(encoder)
|
|
e.enableDecodeAVX2(encoder)
|
|
}
|
|
return e
|
|
}
|
|
|
|
func (e *Encoding) enableEncodeAVX2(encoder string) {
|
|
// Translate values 0..63 to the Base64 alphabet. There are five sets:
|
|
//
|
|
// From To Add Index Example
|
|
// [0..25] [65..90] +65 0 ABCDEFGHIJKLMNOPQRSTUVWXYZ
|
|
// [26..51] [97..122] +71 1 abcdefghijklmnopqrstuvwxyz
|
|
// [52..61] [48..57] -4 [2..11] 0123456789
|
|
// [62] [43] -19 12 +
|
|
// [63] [47] -16 13 /
|
|
tab := [encLutSize]int8{int8(encoder[0]), int8(encoder[letterRange]) - letterRange}
|
|
for i, ch := range encoder[2*letterRange:] {
|
|
tab[2+i] = int8(ch) - 2*letterRange - int8(i)
|
|
}
|
|
|
|
e.enc = encodeAVX2
|
|
e.enclut = tab
|
|
}
|
|
|
|
func (e *Encoding) enableDecodeAVX2(encoder string) {
|
|
c62, c63 := int8(encoder[62]), int8(encoder[63])
|
|
url := c63 == '_'
|
|
if url {
|
|
c63 = '/'
|
|
}
|
|
|
|
// Translate values from the Base64 alphabet using five sets. Values outside
|
|
// of these ranges are considered invalid:
|
|
//
|
|
// From To Add Index Example
|
|
// [47] [63] +16 1 /
|
|
// [43] [62] +19 2 +
|
|
// [48..57] [52..61] +4 3 0123456789
|
|
// [65..90] [0..25] -65 4,5 ABCDEFGHIJKLMNOPQRSTUVWXYZ
|
|
// [97..122] [26..51] -71 6,7 abcdefghijklmnopqrstuvwxyz
|
|
tab := [decLutSize]int8{
|
|
0, 63 - c63, 62 - c62, 4, -65, -65, -71, -71,
|
|
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
|
0x15, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
|
|
0x11, 0x11, 0x13, 0x1B, 0x1B, 0x1B, 0x1B, 0x1B,
|
|
}
|
|
tab[(c62&15)+16] = 0x1A
|
|
tab[(c63&15)+16] = 0x1A
|
|
|
|
if url {
|
|
e.dec = decodeAVX2URI
|
|
} else {
|
|
e.dec = decodeAVX2
|
|
}
|
|
e.declut = tab
|
|
}
|