/* 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); }