1 files changed, 43 insertions, 0 deletions
diff --git a/util.c b/util.c
new file mode 100644
index 0000000..b9f37de
--- /dev/null
+++ b/util.c
@@ -0,0 +1,43 @@
+#define _XOPEN_SOURCE 600
+
+#include "util.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <wctype.h>
+
+int
+strnwidth(const char *s, int n)
+{
+	mbstate_t shift_state;
+	wchar_t wc;
+	size_t wc_len;
+	size_t width = 0;
+
+	memset(&shift_state, '\0', sizeof shift_state);
+
+	for (size_t i = 0; i < n; i += wc_len) {
+		wc_len = mbrtowc(&wc, s + i, MB_CUR_MAX, &shift_state);
+		if (!wc_len) {
+			break;
+		} else if (wc_len >= (size_t)-2) {
+			width += MIN(n - 1, strlen(s + i));
+			break;
+		} else {
+			width += iswcntrl(wc) ? 2 : MAX(0, wcwidth(wc));
+		}
+	}
+
+done:
+	return width;
+}
+
+void
+assert(int cond, const char *file, int line, const char *condstr)
+{
+	if (cond) return;
+
+	fprintf(stderr, "Assertion failed %s:%i (%s)", file, line, condstr);
+	exit(1);
+}