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b58ddff026
* merged mpfr 3.0.0 and gmp 5.0.1 in buildtools trunk git-svn-id: file:///srv/svn/repos/haiku/buildtools/trunk@37378 a95241bf-73f2-0310-859d-f6bbb57e9c96
81 lines
2.0 KiB
C
81 lines
2.0 KiB
C
/* mpz_combit -- complement a specified bit.
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Copyright 2002, 2003 Free Software Foundation, Inc.
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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
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
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#include "gmp.h"
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#include "gmp-impl.h"
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void
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mpz_combit (mpz_ptr d, mp_bitcnt_t bit_index)
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{
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mp_size_t dsize = ABSIZ(d);
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mp_ptr dp = LIMBS(d);
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mp_size_t limb_index = bit_index / GMP_NUMB_BITS;
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mp_limb_t bit = ((mp_limb_t) 1 << (bit_index % GMP_NUMB_BITS));
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if (limb_index >= dsize)
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{
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MPZ_REALLOC(d, limb_index + 1);
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dp = LIMBS(d);
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MPN_ZERO(dp + dsize, limb_index + 1 - dsize);
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dsize = limb_index + 1;
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}
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if (SIZ(d) >= 0)
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{
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dp[limb_index] ^= bit;
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MPN_NORMALIZE (dp, dsize);
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SIZ(d) = dsize;
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}
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else
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{
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mp_limb_t x = -dp[limb_index];
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mp_size_t i;
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/* non-zero limb below us means ones-complement */
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for (i = limb_index-1; i >= 0; i--)
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if (dp[i] != 0)
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{
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x--; /* change twos comp to ones comp */
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break;
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}
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if (x & bit)
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{
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mp_limb_t c;
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/* Clearing the bit increases the magitude. We might need a carry. */
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MPZ_REALLOC(d, dsize + 1);
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dp = LIMBS(d);
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__GMPN_ADD_1 (c, dp+limb_index, dp+limb_index,
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dsize - limb_index, bit);
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dp[dsize] = c;
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dsize += c;
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}
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else
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/* Setting the bit decreases the magnitude */
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mpn_sub_1(dp+limb_index, dp+limb_index, dsize + limb_index, bit);
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MPN_NORMALIZE (dp, dsize);
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SIZ(d) = -dsize;
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}
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}
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