1 files changed, 79 insertions, 0 deletions
diff --git a/libj2_minus_j2u.c b/libj2_minus_j2u.c
new file mode 100644
index 0000000..c0609f9
--- /dev/null
+++ b/libj2_minus_j2u.c
@@ -0,0 +1,79 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+extern inline void libj2_minus_j2u(struct libj2_j2u *a);
+/* 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
+minus_j2u(struct libj2_j2u *a)
+{
+	struct libj2_j2u r, a_saved = *a;
+	r = (struct libj2_j2u){111, 222};
+	libj2_minus_j2u_to_j2u(a, &r);
+	EXPECT(libj2_j2u_eq_j2u(a, &a_saved));
+	libj2_minus_j2u(a);
+	EXPECT(libj2_j2u_eq_j2u(a, &r));
+}
+
+
+int
+main(void)
+{
+	unsigned i;
+	struct libj2_j2u a, b;
+	uintmax_t v;
+
+	libj2_j2u_zero(&a);
+	minus_j2u(&a);
+	EXPECT(libj2_j2u_is_zero(&a));
+
+	a = (struct libj2_j2u){.high = 0, .low = 1};
+	minus_j2u(&a);
+	EXPECT(libj2_j2u_eq_j2u(&a, &(struct libj2_j2u){.high = UINTMAX_MAX, .low = UINTMAX_MAX}));
+
+	a = (struct libj2_j2u){.high = UINTMAX_MAX, .low = UINTMAX_MAX};
+	minus_j2u(&a);
+	EXPECT(libj2_j2u_eq_j2u(&a, &(struct libj2_j2u){.high = 0, .low = 1}));
+
+	for (i = 0; i < 256; i++) {
+		a.high = 0;
+		a.low = v = random_ju();
+		minus_j2u(&a);
+		EXPECT(a.high == UINTMAX_MAX);
+		EXPECT(a.low == 0U - v);
+
+		a.high = UINTMAX_MAX;
+		a.low = v = random_ju();
+		minus_j2u(&a);
+		EXPECT(a.high == 0);
+		EXPECT(a.low == 0U - v);
+	}
+
+	for (i = 0; i < 256; i++) {
+		a.high = b.high = random_ju();
+		a.low = b.low = random_ju();
+		minus_j2u(&a);
+		libj2_j2u_add_j2u(&a, &b);
+		EXPECT(libj2_j2u_is_zero(&a));
+	}
+
+	return 0;
+}
+
+#endif