Initial QSfera import

Server/vendor/github.com/segmentio/asm/base64/base64_amd64.go

@@ -0,0 +1,78 @@
+//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
+}