make Rabin-Miller prime check available as nqp::isprime_I

also special-case 1 not to be a prime

Author: moritz

src/QAST/Operations.nqp

@@ -1282,6 +1282,7 @@ QAST::Operations.add_core_pirop_mapping('div_n', 'div', 'Nnn', :inlinable(1));
 QAST::Operations.add_core_pirop_mapping('mod_i', 'mod', 'Iii', :inlinable(1));
 QAST::Operations.add_core_pirop_mapping('mod_I', 'nqp_bigint_mod', 'PPPP', :inlinable(1));
 QAST::Operations.add_core_pirop_mapping('expmod_I', 'nqp_bigint_exp_mod', 'PPPPP', :inlinable(1));
+QAST::Operations.add_core_pirop_mapping('isprime_I', 'nqp_bigint_is_prime', 'IPi', :inlinable(1));
 QAST::Operations.add_core_pirop_mapping('mod_n', 'mod', 'Nnn', :inlinable(1));
 QAST::Operations.add_core_pirop_mapping('pow_n', 'pow', 'Nnn', :inlinable(1));
 QAST::Operations.add_core_pirop_mapping('pow_I', 'nqp_bigint_pow', 'PPPPP', :inlinable(1));

src/ops/nqp_bigint.ops

@@ -186,6 +186,19 @@ inline op nqp_bigint_exp_mod(out PMC, in PMC, in PMC, in PMC, in PMC) :base_core
     mp_exptmod(a, b, c, get_bigint(interp, $1));
 }
 
+inline op nqp_bigint_is_prime(out INT, invar PMC, in INT) {
+    /* mp_prime_is_prime returns True for 1, and I think
+     * it's worth special-casing this particular number :-)
+     */
+    mp_int *a = get_bigint(interp, $2);
+    if (mp_cmp_d(a, 1) == MP_EQ) {
+        $1 = 0;
+    }
+    else {
+        mp_prime_is_prime(a, $3, (int *) &$1);
+    }
+}
+
 
 inline op nqp_bigint_neg(out PMC, in PMC, in PMC) :base_core {
     mp_int *a = get_bigint(interp, $2);