Add turned

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

1 files changed, 78 insertions, 0 deletions

diff --git a/libcharconv_turned.c b/libcharconv_turned.c
new file mode 100644
index 0000000..8436305
--- /dev/null
+++ b/libcharconv_turned.c
@@ -0,0 +1,78 @@
+/* See LICENSE file for copyright and license details. */
+#include "lib-common.h"
+
+
+static struct {
+	uint_least32_t a;
+	uint_least32_t b;
+} pairs[] = {
+	{0x0032, 0x218A},
+	{0x0033, 0x218B},
+	{0x2616, 0x26C9},
+	{0x2617, 0x26CA},
+	{0x0021, 0x00A1},
+	{0x003F, 0x00BF},
+	{0x2E35, 0x003B},
+	{0x203D, 0x2E18}
+};
+
+
+enum libcharconv_result
+libcharconv_turned(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;
+		}
+
+		if (UINT32_C(0x1F031) <= c && c <= UINT32_C(0x1F061)) {
+			c -= UINT32_C(0x1F031);
+			c = c % 7u * 7u + c / 7u;
+			c += UINT32_C(0x1F031);
+			goto conv;
+		} else if (UINT32_C(0x1F063) <= c && c <= UINT32_C(0x1F093)) {
+			c -= UINT32_C(0x1F063);
+			c = c % 7u * 7u + c / 7u;
+			c += UINT32_C(0x1F063);
+			goto conv;
+		} else {
+			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;
+}