Add subtraction and addition with carry/borrow and add abs_diff1.2

Signed-off-by: Mattias Andrée <m@maandree.se>

1 files changed, 113 insertions, 0 deletions

diff --git a/libj2_j2i_abs_diff_j2i_to_j2u.c b/libj2_j2i_abs_diff_j2i_to_j2u.c
new file mode 100644
index 0000000..bfa0851
--- /dev/null
+++ b/libj2_j2i_abs_diff_j2i_to_j2u.c
@@ -0,0 +1,113 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+extern inline void libj2_j2i_abs_diff_j2i_to_j2u(const struct libj2_j2i *a, const struct libj2_j2i *b, struct libj2_j2u *res);
+
+
+#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
+calc_expected(const struct libj2_j2i *large, const struct libj2_j2i *small, struct libj2_j2u *expected)
+{
+	struct libj2_j2u l, s;
+	struct libj2_j2i e;
+
+	if (!libj2_j2i_is_negative(small)) {
+		libj2_j2i_sub_j2i_to_j2i(large, small, &e);
+		libj2_j2i_to_j2u(&e, expected);
+	} else if (!libj2_j2i_is_positive(large)) {
+		libj2_abs_j2i_to_j2u(large, &s);
+		libj2_abs_j2i_to_j2u(small, &l);
+		libj2_j2u_sub_j2u_to_j2u(&l, &s, expected);
+	} else {
+		libj2_j2i_to_j2u(large, expected);
+		libj2_abs_j2i_to_j2u(small, &s);
+		libj2_j2u_add_j2u(expected, &s);
+	}
+}
+
+
+static void
+check(const struct libj2_j2i *a, const struct libj2_j2i *b)
+{
+	struct libj2_j2u r, expected;
+	struct libj2_j2i a_saved = *a, b_saved = *b;
+
+	if (libj2_j2i_ge_j2i(a, b))
+		calc_expected(a, b, &expected);
+	else
+		calc_expected(b, a, &expected);
+
+	r = (struct libj2_j2u){111, 222};
+	libj2_j2i_abs_diff_j2i_to_j2u(a, b, &r);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2u_eq_j2u(&r, &expected));
+
+	r = (struct libj2_j2u){111, 222};
+	libj2_j2i_abs_diff_j2i_to_j2u(b, a, &r);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2u_eq_j2u(&r, &expected));
+
+	r = (struct libj2_j2u){111, 222};
+	libj2_j2i_abs_diff_j2i_to_j2u(a, a, &r);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2u_is_zero(&r));
+}
+
+
+int
+main(void)
+{
+	struct libj2_j2i a, b;
+	uintmax_t u, v;
+	unsigned i;
+
+	srand((unsigned)time(NULL));
+
+	for (i = 0; i < 256U; i++) {
+		a.high = random_ju();
+		a.low = u = random_ju();
+		b.high = random_ju();
+		b.low = v = random_ju();
+		check(&a, &b);
+		b.low = 0;
+		check(&a, &b);
+		a.low = 0;
+		check(&a, &b);
+
+		b.high = 0;
+		a.low = u;
+		b.low = v;
+		check(&a, &b);
+		b.low = 0;
+		check(&a, &b);
+		a.low = 0;
+		check(&a, &b);
+
+		a.high = 0;
+		a.low = u;
+		b.low = v;
+		check(&a, &b);
+		b.low = 0;
+		check(&a, &b);
+	}
+
+	return 0;
+}
+
+#endif