From a72264006b738c8aa3d49d7835a86bcce130d20d Mon Sep 17 00:00:00 2001
From: Mattias Andrée <m@maandree.se>
Date: Sat, 27 Dec 2025 11:29:31 +0100
Subject: Add signed arithmetics
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Mattias Andrée <m@maandree.se>
---
 libj2_j2i_divmod_j2i_to_j2i.c | 459 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 459 insertions(+)
 create mode 100644 libj2_j2i_divmod_j2i_to_j2i.c

(limited to 'libj2_j2i_divmod_j2i_to_j2i.c')

diff --git a/libj2_j2i_divmod_j2i_to_j2i.c b/libj2_j2i_divmod_j2i_to_j2i.c
new file mode 100644
index 0000000..147fe0c
--- /dev/null
+++ b/libj2_j2i_divmod_j2i_to_j2i.c
@@ -0,0 +1,459 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+extern inline void libj2_j2i_divmod_j2i_to_j2i(struct libj2_j2i *a, const struct libj2_j2i *b, struct libj2_j2i *res_q);
+/* 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_result(const struct libj2_j2i *a, const struct libj2_j2i *b,
+                const struct libj2_j2i *q, const struct libj2_j2i *r)
+{
+	struct libj2_j2i v;
+	libj2_j2i_mul_j2i_to_j2i(q, b, &v);
+	libj2_j2i_add_j2i(&v, r);
+	EXPECT(libj2_j2i_eq_j2i(&v, a));
+
+	if (!a->high && !b->high) {
+		EXPECT(!q->high);
+		EXPECT(!r->high);
+		EXPECT(q->low == a->low / b->low);
+		EXPECT(r->low == a->low % b->low);
+	}
+}
+
+
+static void
+check_manual(const struct libj2_j2i *a, const struct libj2_j2i *b,
+             const struct libj2_j2i *expected_q, const struct libj2_j2i *expected_r)
+{
+	struct libj2_j2i a_saved = *a, b_saved = *b, q, r, eq, er;
+	intmax_t b_low_ji;
+	int underflow;
+
+	EXPECT(!libj2_j2i_is_zero(b));
+
+	r = (struct libj2_j2i){111, 222};
+	q = (struct libj2_j2i){333, 444};
+	libj2_j2i_divmod_j2i_to_j2i_j2i(a, b, &q, &r);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	if (expected_q) {
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	} else {
+		eq = q;
+		expected_q = &eq;
+	}
+	if (expected_r) {
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+	} else {
+		er = r;
+		expected_r = &er;
+	}
+	underflow = !libj2_j2i_is_zero(expected_r);
+
+	validate_result(a, b, expected_q, expected_r);
+
+	r = (struct libj2_j2i){111, 222};
+	q = *a;
+	libj2_j2i_divmod_j2i_to_j2i_j2i(&q, b, &q, &r);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *a;
+	q = (struct libj2_j2i){333, 444};
+	libj2_j2i_divmod_j2i_to_j2i_j2i(&r, b, &q, &r);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = (struct libj2_j2i){111, 222};
+	q = *b;
+	libj2_j2i_divmod_j2i_to_j2i_j2i(a, &q, &q, &r);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *b;
+	q = (struct libj2_j2i){333, 444};
+	libj2_j2i_divmod_j2i_to_j2i_j2i(a, &r, &q, &r);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *b;
+	q = *a;
+	libj2_j2i_divmod_j2i_to_j2i_j2i(&q, &r, &q, &r);
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *a;
+	q = *b;
+	libj2_j2i_divmod_j2i_to_j2i_j2i(&r, &q, &q, &r);
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	q = (struct libj2_j2i){333, 444};
+	libj2_j2i_div_j2i_to_j2i(a, b, &q);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	q = *a;
+	libj2_j2i_div_j2i_to_j2i(&q, b, &q);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	q = *b;
+	libj2_j2i_div_j2i_to_j2i(a, &q, &q);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	q = (struct libj2_j2i){333, 444};
+	EXPECT(libj2_j2i_div_j2i_to_j2i_underflow(a, b, &q) == underflow);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	q = *a;
+	EXPECT(libj2_j2i_div_j2i_to_j2i_underflow(&q, b, &q) == underflow);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	q = *b;
+	EXPECT(libj2_j2i_div_j2i_to_j2i_underflow(a, &q, &q) == underflow);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	r = (struct libj2_j2i){111, 222};
+	libj2_j2i_mod_j2i_to_j2i(a, b, &r);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *a;
+	libj2_j2i_mod_j2i_to_j2i(&r, b, &r);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *b;
+	libj2_j2i_mod_j2i_to_j2i(a, &r, &r);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *a;
+	q = (struct libj2_j2i){333, 444};
+	libj2_j2i_divmod_j2i_to_j2i(&r, b, &q);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *a;
+	q = *b;
+	libj2_j2i_divmod_j2i_to_j2i(&r, &q, &q);
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	q = *a;
+	libj2_j2i_div_j2i(&q, b);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	q = *a;
+	EXPECT(libj2_j2i_div_j2i_underflow(&q, b) == underflow);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	r = *a;
+	libj2_j2i_mod_j2i(&r, b);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *b;
+	q = (struct libj2_j2i){333, 444};
+	libj2_j2i_rdivmod_j2i_to_j2i(&r, a, &q);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *b;
+	q = *a;
+	libj2_j2i_rdivmod_j2i_to_j2i(&r, &q, &q);
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	q = *b;
+	libj2_j2i_rdiv_j2i(&q, a);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	q = *b;
+	EXPECT(libj2_j2i_rdiv_j2i_underflow(&q, a) == underflow);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+	r = *b;
+	libj2_j2i_rmod_j2i(&r, a);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	r = *a;
+	EXPECT(libj2_j2i_divmod_j2i(&r, b) == (intmax_t)expected_q->low);
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+	EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+	EXPECT(libj2_j2i_div_j2i_return(a, b) == (intmax_t)expected_q->low);
+	EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	EXPECT(libj2_j2i_eq_j2i(b, &b_saved));
+
+	if (!b->high && b->low <= (intmax_t)INTMAX_MAX) {
+		b_low_ji = (intmax_t)b->low;
+
+		r = (struct libj2_j2i){111, 222};
+		q = (struct libj2_j2i){333, 444};
+		libj2_j2i_divmod_ji_to_j2i_j2i(a, b_low_ji, &q, &r);
+		EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = (struct libj2_j2i){111, 222};
+		q = *a;
+		libj2_j2i_divmod_ji_to_j2i_j2i(&q, b_low_ji, &q, &r);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = *a;
+		q = (struct libj2_j2i){333, 444};
+		libj2_j2i_divmod_ji_to_j2i_j2i(&r, b_low_ji, &q, &r);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		q = (struct libj2_j2i){333, 444};
+		libj2_j2i_div_ji_to_j2i(a, b_low_ji, &q);
+		EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		q = *a;
+		libj2_j2i_div_ji_to_j2i(&q, b_low_ji, &q);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		q = (struct libj2_j2i){333, 444};
+		EXPECT(libj2_j2i_div_ji_to_j2i_underflow(a, b_low_ji, &q) == underflow);
+		EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		q = *a;
+		EXPECT(libj2_j2i_div_ji_to_j2i_underflow(&q, b_low_ji, &q) == underflow);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		r = (struct libj2_j2i){111, 222};
+		libj2_j2i_mod_ji_to_j2i(a, b_low_ji, &r);
+		EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = *a;
+		libj2_j2i_mod_ji_to_j2i(&r, b_low_ji, &r);
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = *a;
+		q = (struct libj2_j2i){333, 444};
+		libj2_j2i_divmod_ji_to_j2i(&r, b_low_ji, &q);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		q = *a;
+		libj2_j2i_div_ji(&q, b_low_ji);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		q = *a;
+		EXPECT(libj2_j2i_div_ji_underflow(&q, b_low_ji) == underflow);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		r = *a;
+		libj2_j2i_mod_ji(&r, b_low_ji);
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = *b;
+		EXPECT(libj2_j2i_rdivmod_j2i(&r, a) == (intmax_t)expected_q->low);
+		EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = *a;
+		EXPECT(libj2_j2i_divmod_ji(&r, b_low_ji) == (intmax_t)expected_q->low);
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		EXPECT(libj2_j2i_div_ji_return(a, b_low_ji) == (intmax_t)expected_q->low);
+		EXPECT(libj2_j2i_eq_j2i(a, &a_saved));
+	}
+
+	if (a == b) {
+		r = (struct libj2_j2i){111, 222};
+		q = *a;
+		libj2_j2i_divmod_j2i_to_j2i_j2i(&q, &q, &q, &r);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = *a;
+		q = (struct libj2_j2i){333, 444};
+		libj2_j2i_divmod_j2i_to_j2i_j2i(&r, &r, &q, &r);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		q = *a;
+		libj2_j2i_div_j2i_to_j2i(&q, &q, &q);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		q = *a;
+		EXPECT(libj2_j2i_div_j2i_to_j2i_underflow(&q, &q, &q) == underflow);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		r = *a;
+		libj2_j2i_mod_j2i_to_j2i(&r, &r, &r);
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = *a;
+		q = (struct libj2_j2i){333, 444};
+		libj2_j2i_divmod_j2i_to_j2i(&r, &r, &q);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		q = *a;
+		libj2_j2i_div_j2i(&q, &q);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		q = *a;
+		EXPECT(libj2_j2i_div_j2i_underflow(&q, &q) == underflow);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		r = *a;
+		libj2_j2i_mod_j2i(&r, &r);
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = *a;
+		q = (struct libj2_j2i){333, 444};
+		libj2_j2i_rdivmod_j2i_to_j2i(&r, &r, &q);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		q = *a;
+		libj2_j2i_rdiv_j2i(&q, &q);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		q = *a;
+		EXPECT(libj2_j2i_rdiv_j2i_underflow(&q, &q) == underflow);
+		EXPECT(libj2_j2i_eq_j2i(&q, expected_q));
+
+		r = *a;
+		libj2_j2i_rmod_j2i(&r, &r);
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+
+		r = *a;
+		EXPECT(libj2_j2i_divmod_j2i(&r, &r) == (intmax_t)expected_q->low);
+		EXPECT(libj2_j2i_eq_j2i(&r, expected_r));
+	}
+}
+
+
+static void
+check(const struct libj2_j2i *a, const struct libj2_j2i *b)
+{
+	struct libj2_j2i u, v;
+	if (!a) {
+		u.high = random_ju();
+		u.low = random_ju();
+		a = &u;
+	}
+	if (!b) {
+		do {
+			v.high = random_ju();
+			v.low = random_ju();
+		} while (!v.high && !v.low);
+		b = &u;
+	}
+	check_manual(a, b, NULL, NULL);
+}
+
+
+int
+main(void)
+{
+	struct libj2_j2i a = {0, 0}, b = {0, 0}, q = {0, 0}, r = {0, 0};
+	struct libj2_j2i zero = {0, 0}, one = {0, 0}, two = {0, 0}, minus_one;
+	unsigned i;
+
+	srand((unsigned)time(NULL));
+
+	one.low = 1;
+	two.low = 2;
+	libj2_ji_to_j2i(-1, &minus_one);
+
+	check_manual(&one, &one, &one, &zero);
+	check_manual(&two, &one, &two, &zero);
+	check_manual(&one, &two, &zero, &one);
+	check_manual(&zero, &one, &zero, &zero);
+
+	a.low = 35;
+	b.low = 4;
+	q.low = 8;
+	r.low = 3;
+	check_manual(&a, &b, &q, &r);
+
+	a.low = UINTMAX_C(0x14385c048097d350);
+	b.low = UINTMAX_C(0x1212734e33d9df1e);
+	r.low = a.low % b.low;
+	check(&a, &b);
+	check_manual(&a, &b, &one, &r);
+
+	for (i = 0; i < 2048; i++) {
+		a.high = b.high = 0;
+		a.low = random_ju();
+		b.low = random_ju();
+		check(NULL, NULL);
+		check(NULL, &a);
+		check(&a, NULL);
+		check(&a, &b);
+		a.high = b.low;
+		check(&a, &a);
+		if (!libj2_j2i_is_zero(&a))
+			check_manual(&zero, &a, &zero, &zero);
+		check_manual(&a, &one, &a, &zero);
+		b.high = a.high >> 1;
+		b.low = a.low >> 1;
+		b.low |= (a.high & 1U) << (LIBJ2_JU_BIT - 1U);
+		if (a.high & ((uintmax_t)INTMAX_MAX + 1U)) {
+			b.high |= (uintmax_t)INTMAX_MAX + 1U;
+			if (a.low & 1U) {
+				b.low += 1U;
+				if (b.low == 0U)
+					b.high += 1U;
+				check_manual(&a, &two, &b, &minus_one);
+			} else {
+				check_manual(&a, &two, &b, &zero);
+			}
+		} else {
+			check_manual(&a, &two, &b, (a.low & 1U) ? &one : &zero);
+		}
+	}
+
+	/* TODO test sign-issues in a better way, especially ji divisor */
+
+	return 0;
+}
+
+#endif
-- 
cgit v1.2.3-70-g09d2