Add transposed

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

1 files changed, 48 insertions, 0 deletions

diff --git a/libcharconv_transposed.c b/libcharconv_transposed.c
new file mode 100644
index 0000000..af2a835
--- /dev/null
+++ b/libcharconv_transposed.c
@@ -0,0 +1,48 @@
+/* See LICENSE file for copyright and license details. */
+#include "lib-common.h"
+
+
+enum libcharconv_result
+libcharconv_transposed(const char *s, size_t slen, size_t *n, uint_least32_t *cp, size_t *ncp)
+{
+	uint_least32_t c;
+	size_t 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(0x1F030) <= c && c <= UINT32_C(0x1F061)) {
+			c += 0x32u;
+			goto conv;
+		} else if (UINT32_C(0x1F062) <= c && c <= UINT32_C(0x1F093)) {
+			c -= 0x32u;
+			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;
+}