Add flipped

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

4 files changed, 72 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index ab81ea1..55369ae 100644
--- a/Makefile
+++ b/Makefile
@@ -60,7 +60,8 @@ BIN =\
 	convert-to-yijing-trigrams\
 	convert-to-yijing-tetragrams\
 	convert-to-yijing-hexagrams\
-	convert-to-vulgar-fractions
+	convert-to-vulgar-fractions\
+	convert-to-flipped
 
 LIBOBJ =\
 	libcharconv_decode_utf8_.o\
@@ -109,7 +110,8 @@ LIBOBJ =\
 	libcharconv_yijing_trigrams.o\
 	libcharconv_yijing_tetragrams.o\
 	libcharconv_yijing_hexagrams.o\
-	libcharconv_vulgar_fractions.o
+	libcharconv_vulgar_fractions.o\
+	libcharconv_flipped.o
 
 LOBJ = $(LIBOBJ:.o=.lo)
 
diff --git a/convert-to-flipped.c b/convert-to-flipped.c
new file mode 100644
index 0000000..f3e42f9
--- /dev/null
+++ b/convert-to-flipped.c
@@ -0,0 +1,4 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+SIMPLE(libcharconv_flipped)
diff --git a/libcharconv.h b/libcharconv.h
index 402c839..4aa9d27 100644
--- a/libcharconv.h
+++ b/libcharconv.h
@@ -328,6 +328,11 @@ LIBCHARCONV_FUNC_(libcharconv_yijing_hexagrams);
  */
 LIBCHARCONV_FUNC_(libcharconv_vulgar_fractions);
 
+/**
+ * Flip characters vertically
+ */
+LIBCHARCONV_FUNC_(libcharconv_flipped);
+
 
 #undef LIBCHARCONV_FUNC_
 #endif
diff --git a/libcharconv_flipped.c b/libcharconv_flipped.c
new file mode 100644
index 0000000..43893fc
--- /dev/null
+++ b/libcharconv_flipped.c
@@ -0,0 +1,59 @@
+/* See LICENSE file for copyright and license details. */
+#include "lib-common.h"
+
+
+static struct {
+	uint_least32_t a;
+	uint_least32_t b;
+} pairs[] = {
+	{0x00A1, 0x0021}
+};
+
+
+enum libcharconv_result
+libcharconv_flipped(const char *s, size_t slen, size_t *n, uint_least32_t *cp, size_t *ncp)
+{
+	uint_least32_t c;
+	size_t i, clen;
+	*n = 0;
+	while (slen) {
+		clen = libcharconv_decode_utf8_(s, slen, &c);
+		if (clen > slen) {
+			if (*n)
+				goto no_conv;
+			return LIBCHARCONV_INDETERMINATE;
+		}
+		if (!clen) {
+			*n += 1u;
+			slen -= 1u;
+			s = &s[1];
+			continue;
+		}
+
+		for (i = 0u; i < sizeof(pairs) / sizeof(*pairs); i++) {
+			if (c == pairs[i].a) {
+				c = pairs[i].b;
+				goto conv;
+			}
+			if (c == pairs[i].b) {
+				c = pairs[i].a;
+				goto conv;
+			}
+		}
+
+		*n += clen;
+		s = &s[clen];
+		slen -= clen;
+	}
+no_conv:
+	return LIBCHARCONV_NO_CONVERT;
+
+conv:
+	if (*n)
+		goto no_conv;
+	if (*ncp)
+		*cp = c;
+	*n += clen;
+	*ncp = 1u;
+	return LIBCHARCONV_CONVERTED;
+}