Add libteken (from FreeBSD) to third_party.

third_party/libteken/teken/teken_scs.h

Index: third_party/libteken/teken/teken_scs.h
diff --git a/third_party/libteken/teken/teken_scs.h b/third_party/libteken/teken/teken_scs.h
new file mode 100644
index 0000000000000000000000000000000000000000..c055894a1bdbc84e437f7401acb21d5075580b3f
--- /dev/null
+++ b/third_party/libteken/teken/teken_scs.h
@@ -0,0 +1,80 @@
+/*-
+ * Copyright (c) 2009 Ed Schouten <ed@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD: head/sys/teken/teken_scs.h 203659 2010-02-08 09:16:59Z ed $
+ */
+
+static inline teken_char_t
+teken_scs_process(teken_t *t, teken_char_t c)
+{
+
+	return (t->t_scs[t->t_curscs](t, c));
+}
+
+/* Unicode points for VT100 box drawing. */
+static const uint16_t teken_boxdrawing_unicode[31] = {
+    0x25c6, 0x2592, 0x2409, 0x240c, 0x240d, 0x240a, 0x00b0, 0x00b1,
+    0x2424, 0x240b, 0x2518, 0x2510, 0x250c, 0x2514, 0x253c, 0x23ba,
+    0x23bb, 0x2500, 0x23bc, 0x23bd, 0x251c, 0x2524, 0x2534, 0x252c,
+    0x2502, 0x2264, 0x2265, 0x03c0, 0x2260, 0x00a3, 0x00b7
+};
+
+/* ASCII points for VT100 box drawing. */
+static const uint8_t teken_boxdrawing_8bit[31] = {
+    '?', '?', 'H', 'F', 'C', 'L', '?', '?',
+    'N', 'V', '+', '+', '+', '+', '+', '-',
+    '-', '-', '-', '-', '+', '+', '+', '+',
+    '|', '?', '?', '?', '?', '?', '?',
+};
+
+static teken_char_t
+teken_scs_special_graphics(teken_t *t, teken_char_t c)
+{
+
+	/* Box drawing. */
+	if (c >= '`' && c <= '~')
+		return (t->t_stateflags & TS_8BIT ?
+		    teken_boxdrawing_8bit[c - '`'] :
+		    teken_boxdrawing_unicode[c - '`']);
+	return (c);
+}
+
+static teken_char_t
+teken_scs_uk_national(teken_t *t, teken_char_t c)
+{
+
+	/* Pound sign. */
+	if (c == '#')
+		return (t->t_stateflags & TS_8BIT ? 0x9c : 0xa3);
+	return (c);
+}
+
+static teken_char_t
+teken_scs_us_ascii(teken_t *t __unused, teken_char_t c)
+{
+
+	/* No processing. */
+	return (c);
+}