1 files changed, 64 insertions, 0 deletions
diff --git a/libj2_ju_sub_ju_to_j2u.c b/libj2_ju_sub_ju_to_j2u.c
new file mode 100644
index 0000000..b61e96a
--- /dev/null
+++ b/libj2_ju_sub_ju_to_j2u.c
@@ -0,0 +1,64 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+extern inline void libj2_ju_sub_ju_to_j2u(uintmax_t a, uintmax_t b, struct libj2_j2u *res);
+/* TODO Add man page */
+
+
+#else
+
+static uintmax_t
+random_ju(void)
+{
+	size_t n = LIBJ2_JU_BIT;
+	uintmax_t r = 0;
+	while (n--)
+		if (rand() < rand())
+			r |= (uintmax_t)1 << n;
+	return r;
+}
+
+
+static void
+check(uintmax_t a, uintmax_t b)
+{
+	struct libj2_j2u r, expected;
+	int expected_overflow;
+
+	libj2_ju_to_j2u(a, &expected);
+	expected_overflow = libj2_j2u_sub_ju_overflow(&expected, b);
+
+	r = (struct libj2_j2u){111, 222};
+	libj2_ju_sub_ju_to_j2u(a, b, &r);
+	EXPECT(libj2_j2u_eq_j2u(&r, &expected));
+
+	r = (struct libj2_j2u){111, 222};
+	EXPECT(libj2_ju_sub_ju_to_j2u_overflow(a, b, &r) == expected_overflow);
+	EXPECT(libj2_j2u_eq_j2u(&r, &expected));
+}
+
+
+int
+main(void)
+{
+	unsigned i;
+
+	srand((unsigned)time(NULL));
+
+	check(0, 0);
+	check(0, UINTMAX_MAX);
+	check(UINTMAX_MAX, 0);
+	check(UINTMAX_MAX, UINTMAX_MAX);
+	for (i = 0; i < 256; i++) {
+		check(0, random_ju());
+		check(UINTMAX_MAX, random_ju());
+		check(random_ju(), 0);
+		check(random_ju(), random_ju());
+		check(random_ju(), UINTMAX_MAX);
+	}
+
+	return 0;
+}
+
+#endif