From c28859c3e10c84fd9f81ebf88336c9b693448eeb Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Sat, 6 Dec 2025 10:21:36 +0100 Subject: Add overflow and underflow prediction functions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- libj2_j2u_mul_j2u_destructive.c | 72 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 71 insertions(+), 1 deletion(-) (limited to 'libj2_j2u_mul_j2u_destructive.c') diff --git a/libj2_j2u_mul_j2u_destructive.c b/libj2_j2u_mul_j2u_destructive.c index cfa36a2..ba986da 100644 --- a/libj2_j2u_mul_j2u_destructive.c +++ b/libj2_j2u_mul_j2u_destructive.c @@ -60,7 +60,9 @@ refmul(const struct libj2_j2u *a, const struct libj2_j2u *b, struct libj2_j2u *e static void mul_(const struct libj2_j2u *a, const struct libj2_j2u *b, struct libj2_j2u *expected, int expect_overflow) { - struct libj2_j2u t, x, a_saved = *a, b_saved = *b; + struct libj2_j2u t, x, a_saved = *a, b_saved = *b, t_saved; + enum libj2_overflow ofp; + int set; *expected = *a; libj2_j2u_mul_j2u(expected, b); @@ -71,17 +73,70 @@ mul_(const struct libj2_j2u *a, const struct libj2_j2u *b, struct libj2_j2u *exp EXPECT(libj2_j2u_eq_j2u(a, &a_saved)); EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + t = *a; + libj2_j2u_mul_j2u_to_j2u(&t, b, &t); + EXPECT(libj2_j2u_eq_j2u(&t, expected)); + EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + + t = *b; + libj2_j2u_mul_j2u_to_j2u(a, &t, &t); + EXPECT(libj2_j2u_eq_j2u(&t, expected)); + EXPECT(libj2_j2u_eq_j2u(a, &a_saved)); + t = *a; EXPECT(libj2_j2u_mul_j2u_overflow(&t, b) == expect_overflow); EXPECT(libj2_j2u_eq_j2u(&t, expected)); EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + t = *a; + EXPECT(libj2_j2u_mul_j2u_overflow_p(&t, b) == expect_overflow); + EXPECT(libj2_j2u_eq_j2u(&t, a)); + EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + + ofp = libj2_j2u_mul_j2u_overflow_p_quick(&t, b); + EXPECT(ofp == LIBJ2_OVERFLOW_UNKNOWN || (int)ofp == expect_overflow); + EXPECT(libj2_j2u_eq_j2u(&t, a)); + EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + + set = 999; + t = (struct libj2_j2u){111, 222}; + t_saved = t; + EXPECT(libj2_j2u_mul_j2u_to_j2u_overflow_p(a, b, &t, &set) == expect_overflow); + EXPECT(set == 0 || set == 1); + EXPECT(libj2_j2u_eq_j2u(&t, set ? expected : &t_saved)); + EXPECT(libj2_j2u_eq_j2u(a, &a_saved)); + EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + + set = 999; + t = *a; + EXPECT(libj2_j2u_mul_j2u_to_j2u_overflow_p(&t, b, &t, &set) == expect_overflow); + EXPECT(set == 0 || set == 1); + EXPECT(libj2_j2u_eq_j2u(&t, set ? expected : &a_saved)); + EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + + set = 999; + t = *b; + EXPECT(libj2_j2u_mul_j2u_to_j2u_overflow_p(a, &t, &t, &set) == expect_overflow); + EXPECT(set == 0 || set == 1); + EXPECT(libj2_j2u_eq_j2u(&t, set ? expected : &b_saved)); + EXPECT(libj2_j2u_eq_j2u(a, &a_saved)); + t = (struct libj2_j2u){111, 222}; EXPECT(libj2_j2u_mul_j2u_to_j2u_overflow(a, b, &t) == expect_overflow); EXPECT(libj2_j2u_eq_j2u(&t, expected)); EXPECT(libj2_j2u_eq_j2u(a, &a_saved)); EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + t = *a; + EXPECT(libj2_j2u_mul_j2u_to_j2u_overflow(&t, b, &t) == expect_overflow); + EXPECT(libj2_j2u_eq_j2u(&t, expected)); + EXPECT(libj2_j2u_eq_j2u(b, &b_saved)); + + t = *b; + EXPECT(libj2_j2u_mul_j2u_to_j2u_overflow(a, &t, &t) == expect_overflow); + EXPECT(libj2_j2u_eq_j2u(&t, expected)); + EXPECT(libj2_j2u_eq_j2u(a, &a_saved)); + t = *a; x = *b; libj2_j2u_mul_j2u_destructive(&t, &x); @@ -105,6 +160,21 @@ mul_(const struct libj2_j2u *a, const struct libj2_j2u *b, struct libj2_j2u *exp EXPECT(libj2_j2u_mul_j2u_overflow(&t, &t) == expect_overflow); EXPECT(libj2_j2u_eq_j2u(&t, expected)); + t = *a; + EXPECT(libj2_j2u_mul_j2u_overflow_p(&t, &t) == expect_overflow); + EXPECT(libj2_j2u_eq_j2u(&t, a)); + + t = *a; + ofp = libj2_j2u_mul_j2u_overflow_p_quick(&t, &t); + EXPECT(ofp == LIBJ2_OVERFLOW_UNKNOWN || (int)ofp == expect_overflow); + EXPECT(libj2_j2u_eq_j2u(&t, a)); + + set = 999; + t = *a; + EXPECT(libj2_j2u_mul_j2u_to_j2u_overflow_p(&t, &t, &t, &set) == expect_overflow); + EXPECT(set == 0 || set == 1); + EXPECT(libj2_j2u_eq_j2u(&t, set ? expected : a)); + t = *a; EXPECT(libj2_j2u_mul_j2u_to_j2u_overflow(&t, &t, &t) == expect_overflow); EXPECT(libj2_j2u_eq_j2u(&t, expected)); -- cgit v1.2.3-70-g09d2