1 files changed, 88 insertions, 0 deletions
diff --git a/modules/mahonia/shiftjis.go b/modules/mahonia/shiftjis.go
new file mode 100644
index 00000000..d0b4cbc0
--- /dev/null
+++ b/modules/mahonia/shiftjis.go
@@ -0,0 +1,88 @@
+package mahonia
+
+// Converters for the Shift-JIS encoding.
+
+import (
+	"unicode/utf8"
+)
+
+func init() {
+	RegisterCharset(&Charset{
+		Name:    "Shift_JIS",
+		Aliases: []string{"MS_Kanji", "csShiftJIS", "SJIS", "ibm-943", "windows-31j", "cp932", "windows-932"},
+		NewDecoder: func() Decoder {
+			return decodeSJIS
+		},
+		NewEncoder: func() Encoder {
+			shiftJISOnce.Do(reverseShiftJISTable)
+			return encodeSJIS
+		},
+	})
+}
+
+func decodeSJIS(p []byte) (c rune, size int, status Status) {
+	if len(p) == 0 {
+		return 0, 0, NO_ROOM
+	}
+
+	b := p[0]
+	if b < 0x80 {
+		return rune(b), 1, SUCCESS
+	}
+
+	if 0xa1 <= b && b <= 0xdf {
+		return rune(b) + (0xff61 - 0xa1), 1, SUCCESS
+	}
+
+	if b == 0x80 || b == 0xa0 {
+		return utf8.RuneError, 1, INVALID_CHAR
+	}
+
+	if len(p) < 2 {
+		return 0, 0, NO_ROOM
+	}
+
+	jis := int(b)<<8 + int(p[1])
+	c = rune(shiftJISToUnicode[jis])
+
+	if c == 0 {
+		return utf8.RuneError, 2, INVALID_CHAR
+	}
+	return c, 2, SUCCESS
+}
+
+func encodeSJIS(p []byte, c rune) (size int, status Status) {
+	if len(p) == 0 {
+		return 0, NO_ROOM
+	}
+
+	if c < 0x80 {
+		p[0] = byte(c)
+		return 1, SUCCESS
+	}
+
+	if 0xff61 <= c && c <= 0xff9f {
+		// half-width katakana
+		p[0] = byte(c - (0xff61 - 0xa1))
+		return 1, SUCCESS
+	}
+
+	if len(p) < 2 {
+		return 0, NO_ROOM
+	}
+
+	if c > 0xffff {
+		p[0] = '?'
+		return 1, INVALID_CHAR
+	}
+
+	jis := unicodeToShiftJIS[c]
+	if jis == 0 {
+		p[0] = '?'
+		return 1, INVALID_CHAR
+	}
+
+	p[0] = byte(jis >> 8)
+	p[1] = byte(jis)
+	return 2, SUCCESS
+}