1 files changed, 95 insertions, 0 deletions
diff --git a/libj2_ju_add_ju_to_j2u.c b/libj2_ju_add_ju_to_j2u.c
new file mode 100644
index 0000000..7622b84
--- /dev/null
+++ b/libj2_ju_add_ju_to_j2u.c
@@ -0,0 +1,95 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+extern inline void libj2_ju_add_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
+self_check(uintmax_t a, uintmax_t b, uintmax_t r_high, uintmax_t r_low)
+{
+	uintmax_t carry = 0;
+	unsigned i;
+
+	for (i = 0; i < LIBJ2_JU_BIT; i++) {
+		carry += (a >> i) & 1U;
+		carry += (b >> i) & 1U;
+		EXPECT((carry & 1U) == ((r_low >> i) & 1U));
+		carry >>= 1;
+	}
+
+	EXPECT(r_high == carry);
+}
+
+
+static void
+check(uintmax_t a, uintmax_t b)
+{
+	struct libj2_j2u r;
+	uintmax_t expected_high = (uintmax_t)(a > UINTMAX_MAX - b);
+	uintmax_t expected_low = a + b;
+
+	self_check(a, b, expected_high, expected_low);
+
+	r = (struct libj2_j2u){111, 222};
+	libj2_ju_add_ju_to_j2u(a, b, &r);
+	EXPECT(r.high == expected_high);
+	EXPECT(r.low == expected_low);
+}
+
+
+static void
+check_manual(uintmax_t a, uintmax_t b, uintmax_t expected_high, uintmax_t expected_low)
+{
+	struct libj2_j2u r;
+
+	r = (struct libj2_j2u){111, 222};
+	libj2_ju_add_ju_to_j2u(a, b, &r);
+	EXPECT(r.high == expected_high);
+	EXPECT(r.low == expected_low);
+	check(a, b);
+}
+
+
+int
+main(void)
+{
+	unsigned i;
+
+	srand((unsigned)time(NULL));
+
+	check_manual(0, 0, 0, 0);
+	check_manual(0, UINTMAX_MAX, 0, UINTMAX_MAX);
+	check_manual(UINTMAX_MAX, 0, 0, UINTMAX_MAX);
+	check_manual(UINTMAX_MAX, 1, 1, 0);
+	check_manual(1, UINTMAX_MAX, 1, 0);
+	check_manual(UINTMAX_MAX, UINTMAX_MAX, 1, UINTMAX_MAX - 1U);
+
+	for (i = 0; i < 256; i++) {
+		check(0, random_ju());
+		check(random_ju(), 0);
+		check(random_ju(), 1);
+		check(random_ju(), random_ju());
+		check(random_ju(), UINTMAX_MAX);
+		check(UINTMAX_MAX, random_ju());
+	}
+
+	return 0;
+}
+
+#endif