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b2dad0e372
2000-04-21 Benjamin Kosnik <bkoz@redhat.com> * libstdc++-v3: New directory. From-SVN: r33317
108 lines
3.3 KiB
C++
108 lines
3.3 KiB
C++
/* Low-level implementation of bitset template class from ISO C++. */
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// Copyright (C) 1997-1999 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 2, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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#include <bits/std_bitset.h>
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#include <bits/std_climits.h>
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static const size_t word_bits = sizeof (__bitset_word) * CHAR_BIT;
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void
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__bitset_base_lshift (__bitset_word *arr, size_t n, size_t nlast,
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size_t offset, size_t nbits)
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{
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arr[n - 1] = arr[n - 1 - offset] << nbits;
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for (size_t cnt = n - 1; cnt > offset; --cnt)
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{
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arr[cnt] |= arr[cnt - 1 - offset] >> (word_bits - nbits);
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arr[cnt - 1] = arr[cnt - 1 - offset] << nbits;
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}
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memset (arr, '\0', offset * sizeof (__bitset_word));
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}
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void
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__bitset_base_rshift (__bitset_word *arr, size_t n, size_t nlast,
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size_t offset, size_t nbits)
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{
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arr[0] = arr[offset] >> nbits;
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for (size_t cnt = offset + 1; cnt < n; ++cnt)
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{
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arr[cnt - 1 - offset] |= arr[cnt] << (word_bits - nbits);
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arr[cnt - offset] = arr[cnt] >> nbits;
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}
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memset (&arr[n - offset], '\0', offset * sizeof (__bitset_word));
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}
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size_t
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__bitset_base_count (__bitset_word *arr, size_t n)
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{
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size_t result = 0;
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while (n > 0)
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{
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__bitset_word word = arr[n];
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if (sizeof (__bitset_word) == 4)
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{
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word = (word & 0x55555555) + ((word >> 1) & 0x55555555);
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word = (word & 0x33333333) + ((word >> 2) & 0x33333333);
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word = (word + (word >> 4)) & 0x0f0f0f0f;
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word = word + (word >> 8);
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word = (word + (word >> 16)) & 0xff;
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}
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else
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{
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// The only other possibility is a 64 bit word.
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word = ((word & ((0x55555555UL << 16) << 16 | 0x55555555UL))
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+ ((word >> 1)
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& ((0x55555555UL << 16) << 16 | 0x55555555UL)));
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word = ((word & ((0x33333333UL << 16) << 16 | 0x33333333UL))
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+ ((word >> 1)
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& ((0x33333333UL << 16) << 16 | 0x33333333UL)));
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word = ((word + (word >> 4))
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& ((0x0f0f0f0fUL << 16) << 16 | 0x0f0f0f0fUL));
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word = (word + (word >> 8));
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word = (word + (word >> 16));
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word = (word + ((word >> 16) >> 16)) & 0xff;
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}
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result += word;
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}
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return result;
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}
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