scc

commit 5941ba58a5a6a8590c799e02977f4999a30d23e7
parent dcbbe9b3e64a07b1979363c71637d3e72a65a19e
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Sun,  6 Nov 2022 19:16:38 +0100

libc/wchar: Add wcrtomb()

Diffstat:
M
src/libc/objs/common-objs.mk
 | 
1
+
M
src/libc/wchar/Makefile
 | 
1
+
A
src/libc/wchar/wcrtomb.c
 | 
31
+++++++++++++++++++++++++++++++

3 files changed, 33 insertions(+), 0 deletions(-)
diff --git a/src/libc/objs/common-objs.mk b/src/libc/objs/common-objs.mk
@@ -118,4 +118,5 @@ COMMON_OBJS =\
 	time/tz.$O\
 	wchar/mbrlen.$O\
 	wchar/mbrtowc.$O\
+	wchar/wcrtomb.$O\
 	wchar/wcwidth.$O\
diff --git a/src/libc/wchar/Makefile b/src/libc/wchar/Makefile
@@ -6,6 +6,7 @@ include ../rules.mk
 OBJS =\
 	mbrlen.$O\
 	mbrtowc.$O\
+	wcrtomb.$O\
 	wcwidth.$O\
 
 all: $(OBJS)
diff --git a/src/libc/wchar/wcrtomb.c b/src/libc/wchar/wcrtomb.c
@@ -0,0 +1,31 @@
+#include <wchar.h>
+
+#undef wcrtomb
+
+size_t
+wcrtomb(char *restrict s, wchar_t wc, mbstate_t *restrict ps)
+{
+	int i, n;
+	unsigned long c = wc;
+	static unsigned long limits[] = {
+		0x80, 0x800, 0x10000, 0x200000, 0x4000000
+	};
+
+	if (!s)
+		return 1;
+
+	for (n = 0; n < 5 && c >= limits[n]; ++n)
+		;
+
+	*s = 0;
+	for (i = 0; i < n; i++) {
+		*s >>= 1;
+		*s |= 0x80;
+
+		s[n-i] = 0x80 | (c & 0x3f);
+		c >>= 6;
+	}
+	*s |= c;
+
+	return n+1;
+}