| Original patch from: perfpow.c.diff |
| |
| -= BEGIN original header =- |
| Copyright 1998, 1999, 2000, 2001, 2005, 2008 Free Software Foundation, Inc. |
| |
| This file is part of the GNU MP Library. |
| |
| The GNU MP Library is free software; you can redistribute it and/or modify |
| it under the terms of the GNU Lesser General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or (at your |
| option) any later version. |
| |
| The GNU MP Library is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. |
| |
| -= END original header =- |
| |
| diff -durN gmp-4.2.4.orig/mpz/perfpow.c gmp-4.2.4/mpz/perfpow.c |
| --- gmp-4.2.4.orig/mpz/perfpow.c 2007-08-30 20:31:41.000000000 +0200 |
| +++ gmp-4.2.4/mpz/perfpow.c 2009-03-08 18:36:16.000000000 +0100 |
| @@ -1,7 +1,7 @@ |
| /* mpz_perfect_power_p(arg) -- Return non-zero if ARG is a perfect power, |
| zero otherwise. |
| |
| -Copyright 1998, 1999, 2000, 2001, 2005 Free Software Foundation, Inc. |
| +Copyright 1998, 1999, 2000, 2001, 2005, 2008 Free Software Foundation, Inc. |
| |
| This file is part of the GNU MP Library. |
| |
| @@ -59,6 +59,8 @@ |
| #define SMALLEST_OMITTED_PRIME 1009 |
| |
| |
| +#define POW2P(a) (((a) & ((a) - 1)) == 0) |
| + |
| int |
| mpz_perfect_power_p (mpz_srcptr u) |
| { |
| @@ -72,16 +74,13 @@ |
| mp_size_t usize = SIZ (u); |
| TMP_DECL; |
| |
| - if (usize == 0) |
| - return 1; /* consider 0 a perfect power */ |
| + if (mpz_cmpabs_ui (u, 1) <= 0) |
| + return 1; /* -1, 0, and +1 are perfect powers */ |
| |
| n2 = mpz_scan1 (u, 0); |
| if (n2 == 1) |
| return 0; /* 2 divides exactly once. */ |
| |
| - if (n2 != 0 && (n2 & 1) == 0 && usize < 0) |
| - return 0; /* 2 has even multiplicity with negative U */ |
| - |
| TMP_MARK; |
| |
| uns = ABS (usize) - n2 / BITS_PER_MP_LIMB; |
| @@ -89,6 +88,14 @@ |
| MPZ_TMP_INIT (u2, uns); |
| |
| mpz_tdiv_q_2exp (u2, u, n2); |
| + mpz_abs (u2, u2); |
| + |
| + if (mpz_cmp_ui (u2, 1) == 0) |
| + { |
| + TMP_FREE; |
| + /* factoring completed; consistent power */ |
| + return ! (usize < 0 && POW2P(n2)); |
| + } |
| |
| if (isprime (n2)) |
| goto n2prime; |
| @@ -97,6 +104,9 @@ |
| { |
| prime = primes[i]; |
| |
| + if (mpz_cmp_ui (u2, prime) < 0) |
| + break; |
| + |
| if (mpz_divisible_ui_p (u2, prime)) /* divisible by this prime? */ |
| { |
| rem = mpz_tdiv_q_ui (q, u2, prime * prime); |
| @@ -115,12 +125,6 @@ |
| n++; |
| } |
| |
| - if ((n & 1) == 0 && usize < 0) |
| - { |
| - TMP_FREE; |
| - return 0; /* even multiplicity with negative U, reject */ |
| - } |
| - |
| n2 = gcd (n2, n); |
| if (n2 == 1) |
| { |
| @@ -128,10 +132,11 @@ |
| return 0; /* we have multiplicity 1 of some factor */ |
| } |
| |
| - if (mpz_cmpabs_ui (u2, 1) == 0) |
| + if (mpz_cmp_ui (u2, 1) == 0) |
| { |
| TMP_FREE; |
| - return 1; /* factoring completed; consistent power */ |
| + /* factoring completed; consistent power */ |
| + return ! (usize < 0 && POW2P(n2)); |
| } |
| |
| /* As soon as n2 becomes a prime number, stop factoring. |
| @@ -169,6 +174,10 @@ |
| else |
| { |
| unsigned long int nth; |
| + |
| + if (usize < 0 && POW2P(n2)) |
| + return 0; |
| + |
| /* We found some factors above. We just need to consider values of n |
| that divides n2. */ |
| for (nth = 2; nth <= n2; nth++) |
| @@ -184,8 +193,11 @@ |
| exact = mpz_root (q, u2, nth); |
| if (exact) |
| { |
| - TMP_FREE; |
| - return 1; |
| + if (! (usize < 0 && POW2P(nth))) |
| + { |
| + TMP_FREE; |
| + return 1; |
| + } |
| } |
| if (mpz_cmp_ui (q, SMALLEST_OMITTED_PRIME) < 0) |
| { |
| @@ -199,6 +211,9 @@ |
| } |
| |
| n2prime: |
| + if (usize < 0 && POW2P(n2)) |
| + return 0; |
| + |
| exact = mpz_root (NULL, u2, n2); |
| TMP_FREE; |
| return exact; |