vasilito
ff4ff35918
Red Bear OS is a full fork. All sources must be available from git clone with zero network access. Removed gitignore rules that excluded fetched source trees under recipes/*/source/, local/recipes/kde/*/source/, local/recipes/qt/*/source/, and vendor source trees. Build artifacts (target/, build/, source.tar, *.o, *.so) remain excluded. 127291 files added — kernel, relibc, base, bootloader, pkgar, all KDE/Qt frameworks, mesa, wayland, DRM drivers, and every other recipe source.
124 lines
3.6 KiB
C
124 lines
3.6 KiB
C
/* mpz_scan1 -- search for a 1 bit.
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Copyright 2000-2002, 2004, 2012, 2015 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 either:
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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or
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* the GNU General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any
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later version.
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or both in parallel, as here.
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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 General Public License
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for more details.
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You should have received copies of the GNU General Public License and the
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GNU Lesser General Public License along with the GNU MP Library. If not,
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see https://www.gnu.org/licenses/. */
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#include "gmp-impl.h"
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#include "longlong.h"
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/* mpn_scan0 can't be used for the inverted u<0 search since there might not
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be a 0 bit before the end of the data. mpn_scan1 could be used under u>0
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(except when in the high limb), but usually the search won't go very far
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so it seems reasonable to inline that code. */
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mp_bitcnt_t
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mpz_scan1 (mpz_srcptr u, mp_bitcnt_t starting_bit) __GMP_NOTHROW
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{
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mp_srcptr u_ptr = PTR(u);
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mp_size_t size = SIZ(u);
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mp_size_t abs_size = ABS(size);
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mp_srcptr u_end = u_ptr + abs_size - 1;
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mp_size_t starting_limb = starting_bit / GMP_NUMB_BITS;
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mp_srcptr p = u_ptr + starting_limb;
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mp_limb_t limb;
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int cnt;
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/* Past the end there's no 1 bits for u>=0, or an immediate 1 bit for u<0.
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Notice this test picks up any u==0 too. */
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if (starting_limb >= abs_size)
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return (size >= 0 ? ~(mp_bitcnt_t) 0 : starting_bit);
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/* This is an important case, where sign is not relevant! */
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if (starting_bit == 0)
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goto short_cut;
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limb = *p;
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if (size >= 0)
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{
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/* Mask to 0 all bits before starting_bit, thus ignoring them. */
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limb &= (MP_LIMB_T_MAX << (starting_bit % GMP_NUMB_BITS));
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if (limb == 0)
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{
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/* If it's the high limb which is zero after masking, then there's
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no 1 bits after starting_bit. */
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if (p == u_end)
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return ~(mp_bitcnt_t) 0;
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/* Otherwise search further for a non-zero limb. The high limb is
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non-zero, if nothing else. */
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search_nonzero:
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do
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{
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ASSERT (p != u_end);
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p++;
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short_cut:
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limb = *p;
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}
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while (limb == 0);
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}
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}
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else
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{
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/* If there's a non-zero limb before ours then we're in the ones
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complement region. */
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if (starting_limb == 0 || mpn_zero_p (u_ptr, starting_limb)) {
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if (limb == 0)
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/* Seeking for the first non-zero bit, it is the same for u and -u. */
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goto search_nonzero;
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/* Adjust so ~limb implied by searching for 0 bit becomes -limb. */
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limb--;
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}
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/* Now seeking a 0 bit. */
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/* Mask to 1 all bits before starting_bit, thus ignoring them. */
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limb |= (CNST_LIMB(1) << (starting_bit % GMP_NUMB_BITS)) - 1;
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/* Search for a limb which is not all ones. If the end is reached
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then the zero immediately past the end is the result. */
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while (limb == GMP_NUMB_MAX)
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{
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if (p == u_end)
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return (mp_bitcnt_t) abs_size * GMP_NUMB_BITS;
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p++;
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limb = *p;
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}
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/* Now seeking low 1 bit. */
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limb = ~limb;
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}
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ASSERT (limb != 0);
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count_trailing_zeros (cnt, limb);
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return (mp_bitcnt_t) (p - u_ptr) * GMP_NUMB_BITS + cnt;
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}
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