version 1.1.1.1, 2000/01/10 15:35:27 |
version 1.1.1.2, 2000/09/09 14:13:00 |
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/* mpz_ui_pow_ui(res, base, exp) -- Set RES to BASE**EXP. |
/* mpz_ui_pow_ui(res, base, exp) -- Set RES to BASE**EXP. |
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Copyright (C) 1991, 1993, 1994, 1996 Free Software Foundation, Inc. |
Copyright (C) 1991, 1993, 1994, 1996, 1997, 2000 Free Software Foundation, |
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Inc. |
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This file is part of the GNU MP Library. |
This file is part of the GNU MP Library. |
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The GNU MP Library is free software; you can redistribute it and/or modify |
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 |
it under the terms of the GNU Lesser General Public License as published by |
the Free Software Foundation; either version 2 of the License, or (at your |
the Free Software Foundation; either version 2.1 of the License, or (at your |
option) any later version. |
option) any later version. |
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The GNU MP Library is distributed in the hope that it will be useful, but |
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 |
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public |
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
License for more details. |
License for more details. |
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You should have received a copy of the GNU Library General Public License |
You should have received a copy of the GNU Lesser General Public License |
along with the GNU MP Library; see the file COPYING.LIB. If not, write to |
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, |
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
MA 02111-1307, USA. */ |
MA 02111-1307, USA. */ |
Line 23 MA 02111-1307, USA. */ |
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Line 24 MA 02111-1307, USA. */ |
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#include "gmp-impl.h" |
#include "gmp-impl.h" |
#include "longlong.h" |
#include "longlong.h" |
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static void mpz_pow2 _PROTO ((mpz_ptr r, mp_limb_t blimb, unsigned long int e, mp_limb_t rl)); |
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void |
void |
#if __STDC__ |
#if __STDC__ |
mpz_ui_pow_ui (mpz_ptr r, unsigned long int b, unsigned long int e) |
mpz_ui_pow_ui (mpz_ptr r, unsigned long int b, unsigned long int e) |
Line 33 mpz_ui_pow_ui (r, b, e) |
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Line 37 mpz_ui_pow_ui (r, b, e) |
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unsigned long int e; |
unsigned long int e; |
#endif |
#endif |
{ |
{ |
mp_ptr rp, tp, xp; |
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mp_size_t rsize; |
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int cnt, i; |
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mp_limb_t blimb = b; |
mp_limb_t blimb = b; |
TMP_DECL (marker); |
mp_limb_t rl; |
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/* Single out cases that give result == 0 or 1. These tests are here |
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to simplify the general code below, not to optimize. */ |
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if (e == 0) |
if (e == 0) |
{ |
{ |
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/* For x^0 we return 1, even if x is 0. */ |
r->_mp_d[0] = 1; |
r->_mp_d[0] = 1; |
r->_mp_size = 1; |
r->_mp_size = 1; |
return; |
return; |
} |
} |
if (blimb == 0) |
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/* Compute b^e as (b^n)^(e div n) * b^(e mod n), where n is chosen such that |
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the latter factor is the largest number small enough to fit in a limb. */ |
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rl = 1; |
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while (e != 0 && blimb < ((mp_limb_t) 1 << BITS_PER_MP_LIMB/2)) |
{ |
{ |
r->_mp_size = 0; |
if ((e & 1) != 0) |
return; |
rl = rl * blimb; |
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blimb = blimb * blimb; |
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e = e >> 1; |
} |
} |
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if (blimb < 0x100) |
/* rl is now b^(e mod n). (I.e., the latter factor above.) */ |
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if (e == 0) |
{ |
{ |
/* Estimate space requirements accurately. Using the code from the |
r->_mp_d[0] = rl; |
`else' path would over-estimate space requirements wildly. */ |
r->_mp_size = rl != 0; |
float lb = __mp_bases[blimb].chars_per_bit_exactly; |
return; |
rsize = 2 + ((mp_size_t) (e / lb) / BITS_PER_MP_LIMB); |
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} |
} |
else |
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{ |
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/* Over-estimate space requirements somewhat. */ |
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count_leading_zeros (cnt, blimb); |
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rsize = e - cnt * e / BITS_PER_MP_LIMB + 1; |
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} |
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mpz_pow2 (r, blimb, e, rl); |
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} |
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/* Multi-precision part of expontialization code. */ |
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static void |
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#if __STDC__ |
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mpz_pow2 (mpz_ptr r, mp_limb_t blimb, unsigned long int e, mp_limb_t rl) |
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#else |
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mpz_pow2 (r, blimb, e, rl) |
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mpz_ptr r; |
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mp_limb_t blimb; |
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unsigned long int e; |
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mp_limb_t rl; |
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#endif |
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{ |
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mp_ptr rp, tp; |
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mp_size_t ralloc, rsize; |
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int cnt, i; |
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TMP_DECL (marker); |
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TMP_MARK (marker); |
TMP_MARK (marker); |
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/* The two areas are used to alternatingly hold the input and recieve the |
/* Over-estimate temporary space requirements somewhat. */ |
product for mpn_mul. (This scheme is used to fulfill the requirements |
count_leading_zeros (cnt, blimb); |
of mpn_mul; that the product space may not be the same as any of the |
ralloc = e - cnt * e / BITS_PER_MP_LIMB + 1; |
input operands.) */ |
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rp = (mp_ptr) TMP_ALLOC (rsize * BYTES_PER_MP_LIMB); |
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tp = (mp_ptr) TMP_ALLOC (rsize * BYTES_PER_MP_LIMB); |
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/* The two areas are used to alternatingly hold the input and receive the |
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product for mpn_mul. (Needed since mpn_mul_n requires that the product |
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is distinct from either input operand.) */ |
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rp = (mp_ptr) TMP_ALLOC (ralloc * BYTES_PER_MP_LIMB); |
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tp = (mp_ptr) TMP_ALLOC (ralloc * BYTES_PER_MP_LIMB); |
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rp[0] = blimb; |
rp[0] = blimb; |
rsize = 1; |
rsize = 1; |
count_leading_zeros (cnt, e); |
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count_leading_zeros (cnt, e); |
for (i = BITS_PER_MP_LIMB - cnt - 2; i >= 0; i--) |
for (i = BITS_PER_MP_LIMB - cnt - 2; i >= 0; i--) |
{ |
{ |
mpn_mul_n (tp, rp, rp, rsize); |
mpn_mul_n (tp, rp, rp, rsize); |
rsize = 2 * rsize; |
rsize = 2 * rsize; |
rsize -= tp[rsize - 1] == 0; |
rsize -= tp[rsize - 1] == 0; |
xp = tp; tp = rp; rp = xp; |
MP_PTR_SWAP (rp, tp); |
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if ((e & ((mp_limb_t) 1 << i)) != 0) |
if ((e & ((mp_limb_t) 1 << i)) != 0) |
{ |
{ |
mp_limb_t cy; |
mp_limb_t cy; |
cy = mpn_mul_1 (tp, rp, rsize, blimb); |
cy = mpn_mul_1 (rp, rp, rsize, blimb); |
if (cy != 0) |
rp[rsize] = cy; |
{ |
rsize += cy != 0; |
tp[rsize] = cy; |
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rsize++; |
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} |
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xp = tp; tp = rp; rp = xp; |
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} |
} |
} |
} |
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/* Now then we know the exact space requirements, reallocate if |
/* We will need rsize or rsize+1 limbs for the result. */ |
necessary. */ |
if (r->_mp_alloc <= rsize) |
if (r->_mp_alloc < rsize) |
_mpz_realloc (r, rsize + 1); |
_mpz_realloc (r, rsize); |
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MPN_COPY (r->_mp_d, rp, rsize); |
/* Multiply the two factors (in rp,rsize and rl) and put the final result |
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in place. */ |
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{ |
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mp_limb_t cy; |
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cy = mpn_mul_1 (r->_mp_d, rp, rsize, rl); |
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(r->_mp_d)[rsize] = cy; |
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rsize += cy != 0; |
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} |
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r->_mp_size = rsize; |
r->_mp_size = rsize; |
TMP_FREE (marker); |
TMP_FREE (marker); |
} |
} |