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Diffstat (limited to 'contrib/libgmp/mpz/pow_ui.c')
-rw-r--r-- | contrib/libgmp/mpz/pow_ui.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/contrib/libgmp/mpz/pow_ui.c b/contrib/libgmp/mpz/pow_ui.c new file mode 100644 index 0000000..d8cf7a6 --- /dev/null +++ b/contrib/libgmp/mpz/pow_ui.c @@ -0,0 +1,129 @@ +/* mpz_pow_ui(res, base, exp) -- Set RES to BASE**EXP. + +Copyright (C) 1991, 1993, 1994, 1996 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 Library General Public License as published by +the Free Software Foundation; either version 2 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 Library General Public +License for more details. + +You should have received a copy of the GNU Library General Public License +along with the GNU MP Library; see the file COPYING.LIB. If not, write to +the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, +MA 02111-1307, USA. */ + +#ifdef BERKELEY_MP +#include "mp.h" +#endif +#include "gmp.h" +#include "gmp-impl.h" +#include "longlong.h" + +#ifndef BERKELEY_MP +void +#if __STDC__ +mpz_pow_ui (mpz_ptr r, mpz_srcptr b, unsigned long int e) +#else +mpz_pow_ui (r, b, e) + mpz_ptr r; + mpz_srcptr b; + unsigned long int e; +#endif +#else /* BERKELEY_MP */ +void +#if __STDC__ +rpow (const MINT *b, signed short int e, MINT *r) +#else +rpow (b, e, r) + const MINT *b; + signed short int e; + MINT *r; +#endif +#endif /* BERKELEY_MP */ +{ + mp_ptr rp, bp, tp, xp; + mp_size_t rsize, bsize; + int cnt, i; + mp_limb_t blimb; + TMP_DECL (marker); + + bsize = ABS (b->_mp_size); + + /* Single out cases that give result == 0 or 1. These tests are here + to simplify the general code below, not to optimize. */ + if (e == 0) + { + r->_mp_d[0] = 1; + r->_mp_size = 1; + return; + } + if (bsize == 0 +#ifdef BERKELEY_MP + || e < 0 +#endif + ) + { + r->_mp_size = 0; + return; + } + + bp = b->_mp_d; + + blimb = bp[bsize - 1]; + if (bsize == 1 && blimb < 0x100) + { + /* Estimate space requirements accurately. Using the code from the + `else' path would over-estimate space requirements wildly. */ + float lb = __mp_bases[blimb].chars_per_bit_exactly; + rsize = 2 + ((mp_size_t) (e / lb) / BITS_PER_MP_LIMB); + } + else + { + /* Over-estimate space requirements somewhat. */ + count_leading_zeros (cnt, blimb); + rsize = bsize * e - cnt * e / BITS_PER_MP_LIMB + 1; + } + + TMP_MARK (marker); + + /* The two areas are used to alternatingly hold the input and recieve the + product for mpn_mul. (This scheme is used to fulfill the requirements + of mpn_mul; that the product space may not be the same as any of the + input operands.) */ + rp = (mp_ptr) TMP_ALLOC (rsize * BYTES_PER_MP_LIMB); + tp = (mp_ptr) TMP_ALLOC (rsize * BYTES_PER_MP_LIMB); + + MPN_COPY (rp, bp, bsize); + rsize = bsize; + count_leading_zeros (cnt, e); + + for (i = BITS_PER_MP_LIMB - cnt - 2; i >= 0; i--) + { + mpn_mul_n (tp, rp, rp, rsize); + rsize = 2 * rsize; + rsize -= tp[rsize - 1] == 0; + xp = tp; tp = rp; rp = xp; + + if ((e & ((mp_limb_t) 1 << i)) != 0) + { + rsize = rsize + bsize - (mpn_mul (tp, rp, rsize, bp, bsize) == 0); + xp = tp; tp = rp; rp = xp; + } + } + + /* Now then we know the exact space requirements, reallocate if + necessary. */ + if (r->_mp_alloc < rsize) + _mpz_realloc (r, rsize); + + MPN_COPY (r->_mp_d, rp, rsize); + r->_mp_size = (e & 1) == 0 || b->_mp_size >= 0 ? rsize : -rsize; + TMP_FREE (marker); +} |