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-
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/* if a < 0 return MP_VAL */
if (mp_isneg(a) == MP_YES) {
return MP_VAL;
}
/* if n <= 0 return MP_VAL */
if (mp_cmp_d(n, 0) != MP_GT) {
if (mp_cmp_d(n, 0uL) != MP_GT) {
return MP_VAL;
}
/* step 1. handle case of a == 0 */
if (mp_iszero(a) == MP_YES) {
/* special case of a == 0 and n == 1 */
if (mp_cmp_d(n, 1) == MP_EQ) {
if (mp_cmp_d(n, 1uL) == MP_EQ) {
*c = 1;
} else {
*c = 0;
}
return MP_OKAY;
}
/* step 2. if a == 1, return 1 */
if (mp_cmp_d(a, 1) == MP_EQ) {
if (mp_cmp_d(a, 1uL) == MP_EQ) {
*c = 1;
return MP_OKAY;
}
/* default */
s = 0;
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/* divide out larger power of two */
k = mp_cnt_lsb(&a1);
if ((res = mp_div_2d(&a1, k, &a1, NULL)) != MP_OKAY) {
goto LBL_P1;
}
/* step 4. if e is even set s=1 */
if ((k & 1) == 0) {
if (((unsigned)k & 1u) == 0u) {
s = 1;
} else {
/* else set s=1 if p = 1/7 (mod 8) or s=-1 if p = 3/5 (mod 8) */
residue = n->dp[0] & 7;
residue = n->dp[0] & 7u;
if ((residue == 1) || (residue == 7)) {
if ((residue == 1u) || (residue == 7u)) {
s = 1;
} else if ((residue == 3) || (residue == 5)) {
} else if ((residue == 3u) || (residue == 5u)) {
s = -1;
}
}
/* step 5. if p == 3 (mod 4) *and* a1 == 3 (mod 4) then s = -s */
if (((n->dp[0] & 3) == 3) && ((a1.dp[0] & 3) == 3)) {
if (((n->dp[0] & 3u) == 3u) && ((a1.dp[0] & 3u) == 3u)) {
s = -s;
}
/* if a1 == 1 we're done */
if (mp_cmp_d(&a1, 1) == MP_EQ) {
if (mp_cmp_d(&a1, 1uL) == MP_EQ) {
*c = s;
} else {
/* n1 = n mod a1 */
if ((res = mp_mod(n, &a1, &p1)) != MP_OKAY) {
goto LBL_P1;
}
if ((res = mp_jacobi(&p1, &a1, &r)) != MP_OKAY) {
|