Add signed arithmetics

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

1 files changed, 201 insertions, 0 deletions

diff --git a/libj2_j2i_sub_ji.c b/libj2_j2i_sub_ji.c
new file mode 100644
index 0000000..b65d6ae
--- /dev/null
+++ b/libj2_j2i_sub_ji.c
@@ -0,0 +1,201 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+extern inline void libj2_j2i_sub_ji(struct libj2_j2i *a, intmax_t b);
+/* 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
+validate(uintmax_t a_high, uintmax_t a_low, uintmax_t b_high, uintmax_t b_low, uintmax_t r_high, uintmax_t r_low, int r_overflow)
+{
+	int a_neg, b_neg, overflow;
+	struct libj2_j2u a, b;
+	struct libj2_j2i t, r;
+
+	t = (struct libj2_j2i){.high = a_high, .low = a_low};
+	if ((a_neg = libj2_j2i_is_negative(&t)))
+		libj2_minus_j2i_to_j2u(&t, &a);
+	else
+		libj2_j2i_to_j2u(&t, &a);
+
+	t = (struct libj2_j2i){.high = b_high, .low = b_low};
+	if ((b_neg = libj2_j2i_is_negative(&t)))
+		libj2_minus_j2i_to_j2u(&t, &b);
+	else
+		libj2_j2i_to_j2u(&t, &b);
+
+	if (a_neg && b_neg) {
+		overflow = 0;
+		libj2_minus_j2u(&a);
+		libj2_j2u_add_j2u_to_j2u_overflow(&a, &b, (void *)&r);
+	} else if (a_neg) {
+		overflow = -libj2_j2u_add_j2u_to_j2u_overflow(&a, &b, (void *)&r);
+		libj2_minus_j2i(&r);
+		if (!libj2_j2i_is_negative(&r))
+			overflow = -1;
+	} else if (b_neg) {
+		overflow = +libj2_j2u_add_j2u_to_j2u_overflow(&a, &b, (void *)&r);
+		if (!libj2_j2i_is_positive(&r))
+			overflow = +1;
+	} else {
+		overflow = 0;
+		libj2_minus_j2u(&b);
+		libj2_j2u_add_j2u_to_j2u(&a, &b, (void *)&r);
+	}
+
+	EXPECT(r.high == r_high);
+	EXPECT(r.low == r_low);
+	EXPECT(overflow == r_overflow);
+}
+
+
+static void
+check(uintmax_t a_high, uintmax_t a_low, uintmax_t ub)
+{
+	intmax_t b = ub >> (LIBJ2_JU_BIT - 1U) ? -(intmax_t)~ub - 1 : (intmax_t)ub;
+	struct libj2_j2i a, a_saved, r, expected;
+	int expected_overflow;
+
+#if INTMAX_MIN + 1 != -INTMAX_MAX
+	if (ub == (UINTMAX >> 1) + 1U)
+		return;
+#endif
+
+	a.high = a_high;
+	a.low = a_low;
+	a_saved = a;
+	expected = (struct libj2_j2i){111, 222};
+	expected_overflow = libj2_j2i_sub_ji_to_j2i_overflow((const struct libj2_j2i *)&a, b, &expected);
+	EXPECT(libj2_j2i_eq_j2i(&a, &a_saved));
+	EXPECT(libj2_j2i_ne_j2i(&expected, &(struct libj2_j2i){111, 222}));
+
+	validate(a.high, a.low, b < 0 ? UINTMAX_MAX : 0U, ub, expected.high, expected.low, expected_overflow);
+
+	r = (struct libj2_j2i){111, 222};
+	libj2_j2i_sub_ji_to_j2i((const struct libj2_j2i *)&a, b, &r);
+	EXPECT(libj2_j2i_eq_j2i(&a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+
+	r = a;
+	libj2_j2i_sub_ji_to_j2i((const struct libj2_j2i *)&r, b, &r);
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+
+	a_saved = a;
+	EXPECT(libj2_j2i_sub_ji_overflow_p((const struct libj2_j2i *)&a, b) == expected_overflow);
+	EXPECT(libj2_j2i_eq_j2i(&a, &a_saved));
+
+	r = a;
+	EXPECT(libj2_j2i_sub_ji_overflow(&r, b) == expected_overflow);
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+
+	r = a;
+	libj2_j2i_sub_ji(&r, b);
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+
+	libj2_minus_j2i(&expected);
+
+	a = a_saved;
+	r = (struct libj2_j2i){111, 222};
+	expected_overflow = libj2_ji_sub_j2i_to_j2i_overflow(b, (const struct libj2_j2i *)&a, &r);
+	EXPECT(libj2_j2i_eq_j2i(&a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+
+	validate(b < 0 ? UINTMAX_MAX : 0U, ub, a.high, a.low, expected.high, expected.low, expected_overflow);
+
+	EXPECT(libj2_ji_sub_j2i_overflow_p(b, (const struct libj2_j2i *)&a) == expected_overflow);
+	EXPECT(libj2_j2i_eq_j2i(&a, &a_saved));
+
+	r = (struct libj2_j2i){111, 222};
+	libj2_ji_sub_j2i_to_j2i(b, (const struct libj2_j2i *)&a, &r);
+	EXPECT(libj2_j2i_eq_j2i(&a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+
+	r = a;
+	libj2_ji_sub_j2i_to_j2i(b, (const struct libj2_j2i *)&r, &r);
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+
+	r = a;
+	EXPECT(libj2_ji_sub_j2i_to_j2i_overflow(b, (const struct libj2_j2i *)&r, &r) == expected_overflow);
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+
+	r = a;
+	EXPECT(libj2_j2i_rsub_ji_overflow(&r, b) == expected_overflow);
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+
+	EXPECT(libj2_j2i_rsub_ji_overflow_p((const struct libj2_j2i *)&a, b) == expected_overflow);
+	EXPECT(libj2_j2i_eq_j2i(&a, &a_saved));
+
+	r = a;
+	libj2_j2i_rsub_ji(&r, b);
+	EXPECT(libj2_j2i_eq_j2i(&r, &expected));
+}
+
+
+int
+main(void)
+{
+	uintmax_t a, b, c, max, min, umax, vs[12];
+	unsigned i, ii, iii, k, j;
+
+	srand((unsigned)time(NULL));
+
+	umax = UINTMAX_MAX;
+	max = umax >> 1;
+	min = ~max;
+
+	vs[0] = 0U;
+	vs[1] = 1U;
+	vs[2] = 2U;
+	vs[3] = umax - 0U;
+	vs[4] = umax - 1U;
+	vs[5] = umax - 2U;
+	vs[6] = max - 0U;
+	vs[7] = max - 1U;
+	vs[8] = max - 2U;
+	vs[9] = min + 0U;
+	vs[10] = min + 1U;
+	vs[11] = min + 2U;
+
+	for (j = 0; j < 128U; j++) {
+		for (k = 0; k < 8U; k++) {
+			a = random_ju() >> 1;
+			b = random_ju() >> 1;
+			c = random_ju() >> 1;
+			if (k & 1U) a = ~a;
+			if (k & 2U) b = ~b;
+			if (k & 4U) c = ~c;
+			check(a, b, c);
+			for (i = 0; k < 4U && i < 12U; i++) {
+				check(a, b, vs[i]);
+				check(a, vs[i], b);
+				check(vs[i], a, b);
+				for (ii = 0; k < 2U && ii < 12U; ii++) {
+					check(vs[i], vs[ii], a);
+					check(vs[i], a, vs[ii]);
+					check(a, vs[i], vs[ii]);
+					for (iii = 0; !j && k < 1U && iii < 12U; iii++)
+						check(vs[i], vs[ii], vs[iii]);
+				}
+			}
+		}
+	}
+
+	return 0;
+}
+
+#endif