mirror of
https://github.com/MariaDB/server.git
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359 lines
9.1 KiB
C++
359 lines
9.1 KiB
C++
/* Copyright (c) 2003, 2013, Oracle and/or its affiliates
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Copyright (c) 2009, 2013, Monty Program Ab.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program 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
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
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/*
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Implementation of a bitmap type.
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The idea with this is to be able to handle any constant number of bits but
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also be able to use 32 or 64 bits bitmaps very efficiently
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*/
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#ifndef SQL_BITMAP_INCLUDED
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#define SQL_BITMAP_INCLUDED
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#include <my_sys.h>
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#include <my_bitmap.h>
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#include <my_bit.h>
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template <uint width> class Bitmap
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{
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uint32 buffer[(width + 31) / 32];
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public:
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Bitmap()
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{
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clear_all();
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}
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explicit Bitmap(uint prefix)
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{
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set_prefix(prefix);
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}
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void init(uint prefix)
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{
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set_prefix(prefix);
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}
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uint length() const
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{
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return width;
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}
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void set_bit(uint n)
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{
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DBUG_ASSERT(n < width);
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((uchar*)buffer)[n / 8] |= (1 << (n & 7));
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}
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void clear_bit(uint n)
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{
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DBUG_ASSERT(n < width);
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((uchar*)buffer)[n / 8] &= ~(1 << (n & 7));
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}
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void set_prefix(uint prefix_size)
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{
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set_if_smaller(prefix_size, width);
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uint prefix_bytes, prefix_bits, d;
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uchar* m = (uchar*)buffer;
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if ((prefix_bytes = prefix_size / 8))
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memset(m, 0xff, prefix_bytes);
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m += prefix_bytes;
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if ((prefix_bits = prefix_size & 7))
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{
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*(m++) = (1 << prefix_bits) - 1;
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// As the prefix bits are set, lets count this byte too as a prefix byte.
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prefix_bytes++;
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}
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if ((d = (width + 7) / 8 - prefix_bytes))
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memset(m, 0, d);
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}
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void set_all()
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{
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set_prefix(width);
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}
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void clear_all()
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{
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memset(buffer, 0x00, sizeof(buffer));
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}
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void intersect(Bitmap & map2)
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{
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for (uint i = 0; i < array_elements(buffer); i++)
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buffer[i] &= map2.buffer[i];
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}
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private:
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/*
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Intersect with a bitmap represented as as longlong.
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In addition, pad the rest of the bitmap with 0 or 1 bits
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depending on pad_with_ones parameter.
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*/
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void intersect_and_pad(ulonglong map2buff, bool pad_with_ones)
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{
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compile_time_assert(sizeof(ulonglong) == 8);
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uint32 tmp[2];
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int8store(tmp, map2buff);
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buffer[0] &= tmp[0];
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if (array_elements(buffer) > 1)
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buffer[1] &= tmp[1];
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if (array_elements(buffer) <= 2)
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return;
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if (pad_with_ones)
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{
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memset((char*)buffer + 8, 0xff , sizeof(buffer) - 8);
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if (width != sizeof(buffer) * 8)
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{
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((uchar*)buffer)[sizeof(buffer)-1] = last_byte_mask(width);
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}
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}
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else
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memset((char*)buffer + 8, 0 , sizeof(buffer) - 8);
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}
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public:
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void intersect(ulonglong map2buff)
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{
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intersect_and_pad(map2buff, 0);
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}
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/* Use highest bit for all bits above sizeof(ulonglong)*8. */
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void intersect_extended(ulonglong map2buff)
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{
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intersect_and_pad(map2buff, (map2buff & (1ULL << 63)));
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}
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void subtract(Bitmap & map2)
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{
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for (size_t i = 0; i < array_elements(buffer); i++)
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buffer[i] &= ~(map2.buffer[i]);
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}
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void merge(Bitmap & map2)
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{
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for (size_t i = 0; i < array_elements(buffer); i++)
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buffer[i] |= map2.buffer[i];
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}
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bool is_set(uint n) const
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{
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DBUG_ASSERT(n < width);
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return ((uchar*)buffer)[n / 8] & (1 << (n & 7));
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}
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bool is_prefix(uint prefix_size) const
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{
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uint prefix_mask = last_byte_mask(prefix_size);
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uchar* m = (uchar*)buffer;
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uchar* end_prefix = m + (prefix_size - 1) / 8;
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uchar* end;
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DBUG_ASSERT(prefix_size <= width);
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/* Empty prefix is always true */
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if (!prefix_size)
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return true;
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while (m < end_prefix)
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if (*m++ != 0xff)
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return false;
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end = ((uchar*)buffer) + (width + 7) / 8 - 1;
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if (m == end)
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return ((*m & last_byte_mask(width)) == prefix_mask);
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if (*m != prefix_mask)
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return false;
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while (++m < end)
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if (*m != 0)
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return false;
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return ((*m & last_byte_mask(width)) == 0);
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}
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bool is_clear_all() const
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{
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for (size_t i= 0; i < array_elements(buffer); i++)
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if (buffer[i])
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return false;
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return true;
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}
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bool is_set_all() const
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{
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if (width == sizeof(buffer) * 8)
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{
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for (size_t i = 0; i < array_elements(buffer); i++)
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if (buffer[i] != 0xFFFFFFFFU)
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return false;
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return true;
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}
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else
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return is_prefix(width);
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}
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bool is_subset(const Bitmap & map2) const
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{
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for (size_t i= 0; i < array_elements(buffer); i++)
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if (buffer[i] & ~(map2.buffer[i]))
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return false;
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return true;
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}
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bool is_overlapping(const Bitmap & map2) const
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{
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for (size_t i = 0; i < array_elements(buffer); i++)
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if (buffer[i] & map2.buffer[i])
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return true;
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return false;
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}
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bool operator==(const Bitmap & map2) const
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{
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return memcmp(buffer, map2.buffer, sizeof(buffer)) == 0;
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}
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bool operator!=(const Bitmap & map2) const
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{
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return !(*this == map2);
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}
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char *print(char *buf) const
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{
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char *s=buf;
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const uchar *e=(uchar *)buffer, *b=e+sizeof(buffer)-1;
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while (!*b && b>e)
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b--;
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if ((*s=_dig_vec_upper[*b >> 4]) != '0')
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s++;
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*s++=_dig_vec_upper[*b & 15];
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while (--b>=e)
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{
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*s++=_dig_vec_upper[*b >> 4];
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*s++=_dig_vec_upper[*b & 15];
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}
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*s=0;
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return buf;
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}
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ulonglong to_ulonglong() const
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{
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DBUG_ASSERT(sizeof(buffer) >= 4);
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uchar *b=(uchar *)buffer;
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if (sizeof(buffer) >= 8)
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return uint8korr(b);
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return (ulonglong) uint4korr(b);
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}
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uint bits_set()
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{
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uint res = 0;
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for (size_t i = 0; i < array_elements(buffer); i++)
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res += my_count_bits_uint32(buffer[i]);
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return res;
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}
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class Iterator
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{
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Bitmap ↦
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uint no;
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public:
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Iterator(Bitmap<width> &map2): map(map2), no(0) {}
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int operator++(int) {
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if (no == width) return BITMAP_END;
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while (!map.is_set(no))
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{
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if ((++no) == width) return BITMAP_END;
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}
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return no++;
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}
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enum { BITMAP_END = width };
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};
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};
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/* An iterator to quickly walk over bits in ulonglong bitmap. */
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class Table_map_iterator
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{
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ulonglong bmp;
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uint no;
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public:
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Table_map_iterator(ulonglong t) : bmp(t), no(0) {}
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uint next_bit()
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{
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static const uchar last_bit[16]= {32, 0, 1, 0,
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2, 0, 1, 0,
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3, 0, 1, 0,
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2, 0, 1, 0};
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uint bit;
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while ((bit= last_bit[bmp & 0xF]) == 32)
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{
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no += 4;
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bmp= bmp >> 4;
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if (!bmp)
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return BITMAP_END;
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}
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bmp &= ~(1ULL << bit);
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return no + bit;
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}
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uint operator++(int) { return next_bit(); }
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enum { BITMAP_END= 64 };
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};
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template <> class Bitmap<64>
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{
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ulonglong map;
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public:
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Bitmap<64>() { }
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explicit Bitmap<64>(uint prefix_to_set) { set_prefix(prefix_to_set); }
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void init(uint prefix_to_set) { set_prefix(prefix_to_set); }
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uint length() const { return 64; }
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void set_bit(uint n) { map|= ((ulonglong)1) << n; }
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void clear_bit(uint n) { map&= ~(((ulonglong)1) << n); }
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void set_prefix(uint n)
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{
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if (n >= length())
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set_all();
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else
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map= (((ulonglong)1) << n)-1;
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}
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void set_all() { map=~(ulonglong)0; }
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void clear_all() { map=(ulonglong)0; }
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void intersect(Bitmap<64>& map2) { map&= map2.map; }
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void intersect(ulonglong map2) { map&= map2; }
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void intersect_extended(ulonglong map2) { map&= map2; }
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void subtract(Bitmap<64>& map2) { map&= ~map2.map; }
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void merge(Bitmap<64>& map2) { map|= map2.map; }
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bool is_set(uint n) const { return MY_TEST(map & (((ulonglong) 1) << n)); }
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bool is_prefix(uint n) const { return map == (((ulonglong)1) << n)-1; }
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bool is_clear_all() const { return map == (ulonglong)0; }
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bool is_set_all() const { return map == ~(ulonglong)0; }
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bool is_subset(const Bitmap<64>& map2) const { return !(map & ~map2.map); }
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bool is_overlapping(const Bitmap<64>& map2) const { return (map & map2.map)!= 0; }
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bool operator==(const Bitmap<64>& map2) const { return map == map2.map; }
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char *print(char *buf) const {
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longlong2str(longlong(map), buf, 16);
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return buf;
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}
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ulonglong to_ulonglong() const { return map; }
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class Iterator : public Table_map_iterator
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{
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public:
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Iterator(Bitmap<64> &map2) : Table_map_iterator(map2.map) {}
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};
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uint bits_set()
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{
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//TODO: use my_count_bits()
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uint res= 0, i= 0;
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for (; i < 64 ; i++)
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{
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if (map & ((ulonglong)1<<i))
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res++;
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}
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return res;
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}
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};
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#if MAX_INDEXES <= 64
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typedef Bitmap<64> key_map; /* Used for finding keys */
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#elif MAX_INDEXES > 128
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#error "MAX_INDEXES values greater than 128 is not supported."
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#else
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typedef Bitmap<((MAX_INDEXES+7)/8*8)> key_map; /* Used for finding keys */
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#endif
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#endif /* SQL_BITMAP_INCLUDED */
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