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Merge pull request #462 from czurnieden/repair_div_recursive

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Repair of sign handling in mp_div_recursive
This commit is contained in:
Steffen Jaeckel 2019-11-22 11:31:20 +01:00 committed by GitHub
commit 6e779e69a8
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 42 additions and 5 deletions
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45
demo/test.c
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@ -729,7 +729,7 @@ static int test_mp_sqrt(void)
printf("\nmp_sqrt() error!");
goto LBL_ERR;
}
DO(mp_root_n(&a, 2u, &c));
DO(mp_root_n(&a, 2, &c));
if (mp_cmp_mag(&b, &c) != MP_EQ) {
printf("mp_sqrt() bad result!\n");
goto LBL_ERR;
@ -2082,16 +2082,53 @@ static int test_s_mp_div_recursive(void)
DO(s_mp_div_recursive(&a, &b, &c_q, &c_r));
DO(s_mp_div_school(&a, &b, &d_q, &d_r));
if (mp_cmp(&c_q, &d_q) != MP_EQ) {
fprintf(stderr, "1. Recursive division failed at sizes %d / %d, wrong quotient\n",
fprintf(stderr, "1a. Recursive division failed at sizes %d / %d, wrong quotient\n",
10 * size, size);
goto LBL_ERR;
}
if (mp_cmp(&c_r, &d_r) != MP_EQ) {
fprintf(stderr, "1. Recursive division failed at sizes %d / %d, wrong remainder\n",
fprintf(stderr, "1a. Recursive division failed at sizes %d / %d, wrong remainder\n",
10 * size, size);
goto LBL_ERR;
}
printf("\rsizes = %d / %d", 2 * size, size);
/* Relation 10:1 negative numerator*/
DO(mp_rand(&a, 10 * size));
DO(mp_neg(&a, &a));
DO(mp_rand(&b, size));
DO(s_mp_div_recursive(&a, &b, &c_q, &c_r));
DO(s_mp_div_school(&a, &b, &d_q, &d_r));
if (mp_cmp(&c_q, &d_q) != MP_EQ) {
fprintf(stderr, "1b. Recursive division failed at sizes %d / %d, wrong quotient\n",
10 * size, size);
goto LBL_ERR;
}
if (mp_cmp(&c_r, &d_r) != MP_EQ) {
fprintf(stderr, "1b. Recursive division failed at sizes %d / %d, wrong remainder\n",
10 * size, size);
goto LBL_ERR;
}
printf("\rsizes = %d / %d, negative numerator", 2 * size, size);
/* Relation 10:1 negative denominator*/
DO(mp_rand(&a, 10 * size));
DO(mp_rand(&b, size));
DO(mp_neg(&b, &b));
DO(s_mp_div_recursive(&a, &b, &c_q, &c_r));
DO(s_mp_div_school(&a, &b, &d_q, &d_r));
if (mp_cmp(&c_q, &d_q) != MP_EQ) {
fprintf(stderr, "1c. Recursive division failed at sizes %d / %d, wrong quotient\n",
10 * size, size);
goto LBL_ERR;
}
if (mp_cmp(&c_r, &d_r) != MP_EQ) {
fprintf(stderr, "1c. Recursive division failed at sizes %d / %d, wrong remainder\n",
10 * size, size);
goto LBL_ERR;
}
printf("\rsizes = %d / %d, negative denominator", 2 * size, size);
/* Relation 2:1 */
DO(mp_rand(&a, 2 * size));
DO(mp_rand(&b, size));
@ -2326,7 +2363,7 @@ static int unit_tests(int argc, char **argv)
T1(mp_set_double, MP_SET_DOUBLE),
#endif
T1(mp_signed_rsh, MP_SIGNED_RSH),
T2(mp_sqrt, MP_SQRT, mp_root_n),
T2(mp_sqrt, MP_SQRT, MP_ROOT_N),
T1(mp_sqrtmod_prime, MP_SQRTMOD_PRIME),
T1(mp_xor, MP_XOR),
T2(s_mp_div_recursive, S_MP_DIV_RECURSIVE, S_MP_DIV_SCHOOL),

2
s_mp_div_recursive.c
View File

@ -159,7 +159,7 @@ mp_err s_mp_div_recursive(const mp_int *a, const mp_int *b, mp_int *q, mp_int *r
if ((err = mp_add(&Q, &Q1, &Q)) != MP_OKAY) goto LBL_ERR;
/* get sign before writing to c */
Q.sign = (mp_iszero(&Q) ? MP_ZPOS : a->sign);
R.sign = (mp_iszero(&Q) ? MP_ZPOS : a->sign);
if (q != NULL) {
mp_exch(&Q, q);