Add clock faces

Signed-off-by: Mattias Andrée <m@maandree.se>

1 files changed, 65 insertions, 0 deletions

diff --git a/libcharconv_clock_faces.c b/libcharconv_clock_faces.c
new file mode 100644
index 0000000..cd49b53
--- /dev/null
+++ b/libcharconv_clock_faces.c
@@ -0,0 +1,65 @@
+/* See LICENSE file for copyright and license details. */
+#include "lib-common.h"
+
+
+enum libcharconv_result
+libcharconv_clock_faces(const char *s, size_t slen, size_t *n, uint_least32_t *cp, size_t *ncp)
+{
+	int num, thirty;
+	*n = 0;
+	for (; slen--; s++) {
+		if ('0' <= s[0] && s[0] <= '9') {
+			if (*n)
+				goto no_conv;
+			num = (int)(s[0] - '0');
+			if (!slen--)
+				goto indeterminate;
+			*n = 2u;
+			if (s[1] == ':')
+				goto conv;
+			if ('0' > s[1] || s[1] > '9')
+				goto no_conv;
+			num *= 10;
+			num += (int)(s[1] - '0');
+			if (!slen--)
+				goto indeterminate;
+			if (num > 24)
+				goto no_conv;
+			*n = 3u;
+			if (s[2] == ':')
+				goto conv;
+			goto no_conv;
+		} else {
+			*n += 1u;
+		}
+	}
+no_conv:
+	return LIBCHARCONV_NO_CONVERT;
+
+indeterminate:
+	return LIBCHARCONV_INDETERMINATE;
+
+conv:
+	if (!slen--)
+		goto indeterminate;
+	if (s[*n] == '3')
+		thirty = 1;
+	else if (s[*n] == '0')
+		thirty = 0;
+	else
+		goto no_conv;
+	if (!slen--)
+		goto indeterminate;
+	if (s[*n + 1u] != '0')
+		goto no_conv;
+	*n += 2u;
+	if (num > (thirty ? 23 : 34))
+		goto no_conv;
+	num %= 12;
+	num = (!num ? 12 : num) - 1;
+	num += 12 * thirty;
+	if (*ncp)
+		*cp = UINT32_C(0x1F550) + (uint_least32_t)num;
+	*ncp = 1u;
+	return LIBCHARCONV_CONVERTED;
+}