1 files changed, 52 insertions, 0 deletions
diff --git a/libcharconv_box_drawing.c b/libcharconv_box_drawing.c
new file mode 100644
index 0000000..0cba3bb
--- /dev/null
+++ b/libcharconv_box_drawing.c
@@ -0,0 +1,52 @@
+/* See LICENSE file for copyright and license details. */
+#include "lib-common.h"
+
+
+enum libcharconv_result
+libcharconv_box_drawing(const char *s, size_t slen, size_t *n, uint_least32_t *cp, size_t *ncp)
+{
+	uint_least32_t a, c;
+	size_t i;
+	*n = 0;
+	for (; slen--; s++, ++*n) {
+		PLAIN_CASE_SELECT("/\\X", 0x2571);
+		if ('1' <= *s && *s <= '4') {
+			c = (uint_least32_t)1 << (*s - '1');
+			for (i = 1u;; i++) {
+				if (slen < i)
+					goto indeterminate;
+				if ('1' <= s[i] && s[i] <= '4') {
+					a = (uint_least32_t)1 << (s[i] - '1');
+					if (a & c)
+						goto next;
+					c |= a;
+				} else if (s[i] == 'O') {
+					c = (uint_least32_t)" \x00\x01\x07\x02\x04\x09\x0D\x03\x08\x05\x0C\x06\x0B\x0A\x0E"[c];
+					c |= UINT32_C(0x1FBA0);
+					if (*n)
+						goto no_conv;
+					*n += i + 1u;
+					goto conv_prechecked;
+				}
+			}
+		}
+	next:;
+	}
+no_conv:
+	return LIBCHARCONV_NO_CONVERT;
+
+indeterminate:
+	if (*n)
+		goto no_conv;
+	return LIBCHARCONV_INDETERMINATE;
+
+conv:
+	if (*n)
+		goto no_conv;
+	*n += 1u;
+conv_prechecked:
+	if (*ncp)
+		*cp = c;
+	*ncp = 1u;
+	return LIBCHARCONV_CONVERTED;
+}