From 8b1e9c4dd1fd12e3b85750a5c0044b54ced216c7 Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Thu, 12 Feb 2026 13:45:48 +0100 Subject: Add subtraction and addition with carry/borrow and add abs_diff MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- libj2_j2u_abs_diff_j2u_to_j2u.c | 118 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 libj2_j2u_abs_diff_j2u_to_j2u.c (limited to 'libj2_j2u_abs_diff_j2u_to_j2u.c') diff --git a/libj2_j2u_abs_diff_j2u_to_j2u.c b/libj2_j2u_abs_diff_j2u_to_j2u.c new file mode 100644 index 0000000..6199e27 --- /dev/null +++ b/libj2_j2u_abs_diff_j2u_to_j2u.c @@ -0,0 +1,118 @@ +/* See LICENSE file for copyright and license details. */ +#include "common.h" +#ifndef TEST + +extern inline void libj2_j2u_abs_diff_j2u_to_j2u(const struct libj2_j2u *a, const struct libj2_j2u *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 +check_(const struct libj2_j2u *a, const struct libj2_j2u *b, const struct libj2_j2u *expected) +{ + struct libj2_j2u r, a_saved = *a, b_saved = *b; + + r = (struct libj2_j2u){111, 222}; + libj2_j2u_abs_diff_j2u_to_j2u(a, b, &r); + EXPECT(libj2_j2u_eq_j2u(a, &a_saved)); + EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + EXPECT(libj2_j2u_eq_j2u(&r, expected)); + + r = *a; + libj2_j2u_abs_diff_j2u_to_j2u(&r, b, &r); + EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + EXPECT(libj2_j2u_eq_j2u(&r, expected)); + + r = *b; + libj2_j2u_abs_diff_j2u_to_j2u(a, &r, &r); + EXPECT(libj2_j2u_eq_j2u(a, &a_saved)); + EXPECT(libj2_j2u_eq_j2u(&r, expected)); + + r = *a; + libj2_j2u_abs_diff_j2u(&r, b); + EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + EXPECT(libj2_j2u_eq_j2u(&r, expected)); + + r = (struct libj2_j2u){111, 222}; + libj2_j2u_abs_diff_j2u_to_j2u(a, a, &r); + EXPECT(libj2_j2u_eq_j2u(a, &a_saved)); + EXPECT(libj2_j2u_is_zero(&r)); + + r = *a; + libj2_j2u_abs_diff_j2u_to_j2u(&r, &r, &r); + EXPECT(libj2_j2u_is_zero(&r)); + + r = *a; + libj2_j2u_abs_diff_j2u(&r, &r); + EXPECT(libj2_j2u_is_zero(&r)); +} + + +static void +check(const struct libj2_j2u *a, const struct libj2_j2u *b) +{ + struct libj2_j2u expected; + + if (libj2_j2u_ge_j2u(a, b)) + libj2_j2u_sub_j2u_to_j2u(a, b, &expected); + else + libj2_j2u_sub_j2u_to_j2u(b, a, &expected); + + check_(a, b, &expected); + check_(b, a, &expected); +} + + +int +main(void) +{ + struct libj2_j2u 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 -- cgit v1.2.3-70-g09d2