added u16_wcstombs().

1 files changed, 173 insertions, 0 deletions

diff --git a/src/u16_wcstombs.c b/src/u16_wcstombs.c
new file mode 100644
index 0000000..9cec117
--- /dev/null
+++ b/src/u16_wcstombs.c
@@ -0,0 +1,173 @@
+/*******************************************************************/
+/*  u16ports: u16 variants of wide character string functions.     */
+/*  Copyright (C) 2017  Z. Gilboa                                  */
+/*  Released under the Standard MIT License; see COPYING.U16PORTS. */
+/*******************************************************************/
+
+#include <stdint.h>
+#include <u16ports/u16ports.h>
+
+/**
+ *  scalar	nickname	utf-16		utf-8[0]  utf-8[1]  utf-8[2]  utf-8[3]
+ *  ------	--------	--------	--------  --------  --------  --------
+ *  00000000	7x		00000000	0xxxxxxx
+ *  0xxxxxxx			0xxxxxxx
+ *
+ *  00000yyy	5y6x		00000yyy	110yyyyy  10xxxxxx
+ *  yyxxxxxx			yyxxxxxx
+ *
+ *  zzzzyyyy	4z6y6x		zzzzyyyy	1110zzzz  10yyyyyy  10xxxxxx
+ *  yyxxxxxx			yyxxxxxx
+ *
+ *  000uuuuu	5u4z6y6x	110110ww	11110uuu  10uuzzzz  10yyyyyy  10xxxxxx
+ *  zzzzyyyy			wwzzzzyy
+ *  yyxxxxxx			110111yy
+ *				yyxxxxxx        (where wwww = uuuuu - 1)
+ *
+**/
+
+size_t u16_wcstombs(char * s, const uint16_t * src, size_t n)
+{
+	size_t		ret;
+	ssize_t		len;
+	char *		dst;
+	uint16_t	wx;
+	uint16_t	wy;
+	uint16_t	wz;
+	uint16_t	ww;
+	uint16_t	wy_low;
+	uint16_t	wy_high;
+	uint16_t	u_low;
+	uint16_t	u_high;
+	uint16_t	uuuuu;
+
+	if (!s) {
+		for (ret=0; *src; src++) {
+			if (*src <= 0x7F)
+				ret += 1;
+
+			else if (*src <= 0x7FF)
+				ret += 2;
+
+			else if ((*src < 0xD800) || (*src >= 0xE000))
+				ret += 3;
+
+			else if (*src++ >= 0xDC00)
+				return -1;
+
+			else if (*src < 0xDC00)
+				return -1;
+
+			else if (*src >= 0xE000)
+				return -1;
+
+			else
+				ret += 4;
+		}
+
+		return ret;
+	}
+
+	if ((len = (ssize_t)n) < 0)
+		return -1;
+
+	for (dst=s; *src; src++) {
+		if (*src <= 0x7F) {
+			*dst++ = (char)*src;
+			len--;
+
+		} else if (*src <= 0x7FF) {
+			if ((len = len - 2) < 0)
+				return -1;
+
+			wy  = *src;
+			wy >>= 6;
+
+			wx  = *src;
+			wx <<= 10;
+			wx >>= 10;
+
+			*dst++ = (char)(0xC0 | wy);
+			*dst++ = (char)(0x80 | wx);
+
+		} else if ((*src < 0xD800) || (*src >= 0xE000)) {
+			if ((len = len - 3) < 0)
+				return -1;
+
+			wz  = *src;
+			wz >>= 12;
+
+			wy  = *src;
+			wy <<= 4;
+			wy >>= 10;
+
+			wx  = *src;
+			wx <<= 10;
+			wx >>= 10;
+
+			*dst++ = (char)(0xE0 | wz);
+			*dst++ = (char)(0x80 | wy);
+			*dst++ = (char)(0x80 | wx);
+
+		} else if (src[0] >= 0xDC00) {
+			return -1;
+
+		} else if (src[1] < 0xDC00) {
+			return -1;
+
+		} else if (src[1] >= 0xE000) {
+			return -1;
+
+		} else {
+			if ((len = len - 4) < 0)
+				return -1;
+
+			/* low two bytes */
+			wy_high   = *src;
+			wy_high <<= 14;
+			wy_high >>= 10;
+
+			wz   = *src;
+			wz <<= 10;
+			wz >>= 12;
+
+			ww   = *src;
+			ww <<= 6;
+			ww >>= 12;
+
+			/* (surrogate pair) */
+			src++;
+
+			/* high two bytes */
+			wx   = *src;
+			wx <<= 10;
+			wx >>= 10;
+
+			wy_low   = *src;
+			wy_low <<= 6;
+			wy_low >>= 12;
+
+			/* uuuuu */
+			uuuuu    = ww + 1;
+			u_low    = uuuuu;
+			u_low  >>= 2;
+
+			u_high  = uuuuu;
+			u_high <<= 14;
+			u_high >>= 10;
+
+			*dst++ = (char)(0xF0 | u_low);
+			*dst++ = (char)(0x80 | u_high | wz);
+			*dst++ = (char)(0x80 | wy_low | wy_high);
+			*dst++ = (char)(0x80 | wx);
+		}
+
+		if (len == 0)
+			return dst - s;
+	}
+
+	if (len)
+		*dst = 0;
+
+	return dst - s;
+}