version 1.1.1.1, 2000/01/10 15:35:27 |
version 1.1.1.3, 2000/12/01 05:45:08 |
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/* mpz_fdiv_r_2exp -- Divide a integer by 2**CNT and produce a remainder. |
/* mpz_fdiv_r_2exp -- Divide a integer by 2**CNT and produce a remainder. |
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Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc. |
Copyright (C) 1991, 1993, 1994, 1995, 1998, 1999, 2000 Free Software |
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Foundation, 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 65 mpz_fdiv_r_2exp (res, in, cnt) |
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Line 66 mpz_fdiv_r_2exp (res, in, cnt) |
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else |
else |
{ |
{ |
/* The input operand is smaller than 2**CNT. We perform a no-op, |
/* The input operand is smaller than 2**CNT. We perform a no-op, |
apart from that we might need to copy IN to RES. */ |
apart from that we might need to copy IN to RES, and may need |
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to round the result. */ |
res_size = in_size; |
res_size = in_size; |
if (res->_mp_alloc < res_size) |
if (res->_mp_alloc < res_size) |
_mpz_realloc (res, res_size); |
_mpz_realloc (res, res_size); |
Line 75 mpz_fdiv_r_2exp (res, in, cnt) |
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Line 77 mpz_fdiv_r_2exp (res, in, cnt) |
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if (res != in) |
if (res != in) |
MPN_COPY (res->_mp_d, in->_mp_d, limb_cnt); |
MPN_COPY (res->_mp_d, in->_mp_d, limb_cnt); |
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in_size = in->_mp_size; |
res->_mp_size = res_size; |
res->_mp_size = res_size; |
if (in->_mp_size < 0 && res_size != 0) |
if (in_size < 0 && res_size != 0) |
{ |
{ |
/* Result should be 2^CNT - RES */ |
/* Result should be 2^CNT - RES */ |
mpz_t tmp; |
mpz_t tmp; |
MPZ_TMP_INIT (tmp, limb_cnt + 1); |
TMP_DECL (marker); |
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TMP_MARK (marker); |
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MPZ_TMP_INIT (tmp, cnt/BITS_PER_MP_LIMB + 2); |
mpz_set_ui (tmp, 1L); |
mpz_set_ui (tmp, 1L); |
mpz_mul_2exp (tmp, tmp, cnt); |
mpz_mul_2exp (tmp, tmp, cnt); |
mpz_sub (res, tmp, res); |
mpz_sub (res, tmp, res); |
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TMP_FREE (marker); |
} |
} |
} |
} |
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/* This is an alternative ending of the above function using just low-level |
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functions. Tested, but perhaps excessive? */ |
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#if 0 |
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if (in->_mp_size < 0 && res_size != 0) |
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{ |
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/* Result should be 2^CNT - RES */ |
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mp_ptr rp; |
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limb_cnt = cnt / BITS_PER_MP_LIMB; |
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if (res->_mp_alloc <= limb_cnt) |
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_mpz_realloc (res, limb_cnt + 1); |
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rp = PTR(res); |
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if (res_size > limb_cnt) |
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{ |
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mpn_nz_neg (rp, rp, res_size); |
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rp[limb_cnt] &= ~(~(mp_limb_t) 0 << cnt % BITS_PER_MP_LIMB); |
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MPN_NORMALIZE_NOT_ZERO (rp, res_size); |
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} |
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else |
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{ |
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mp_size_t i; |
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mpn_nz_neg (rp, rp, res_size); |
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for (i = res_size; i < limb_cnt; i++) |
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rp[i] = ~ (mp_limb_t) 0; |
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res_size = limb_cnt; |
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if (cnt % BITS_PER_MP_LIMB != 0) |
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{ |
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rp[res_size] = ((mp_limb_t) 1 << (cnt % BITS_PER_MP_LIMB)) - 1; |
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res_size++; |
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} |
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else |
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MPN_NORMALIZE_NOT_ZERO (rp, res_size); |
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} |
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} |
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SIZ(res) = res_size; |
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} |
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static void |
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mpn_nz_neg (rp, sp, n) |
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mp_ptr rp, sp; |
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mp_size_t n; |
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{ |
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mp_size_t i; |
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mp_limb_t x; |
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x = sp[0]; |
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rp[0] = -x; |
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for (i = 1; x == 0; i++) |
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{ |
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x = sp[i]; |
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rp[i] = -x; |
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} |
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for (; i < n; i++) |
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{ |
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rp[i] = ~sp[i]; |
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} |
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} |
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#endif |