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-rw-r--r--mysql/mysys/my_bitmap.c672
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diff --git a/mysql/mysys/my_bitmap.c b/mysql/mysys/my_bitmap.c
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+/*
+ Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */
+
+/*
+ Handling of uchar arrays as large bitmaps.
+
+ API limitations (or, rather asserted safety assumptions,
+ to encourage correct programming)
+
+ * the internal size is a set of 32 bit words
+ * the number of bits specified in creation can be any number > 0
+ a bitmap with zero bits can be created and initialized, but not used.
+ * there are THREAD safe versions of most calls called bitmap_lock_*
+
+ TODO:
+ Make assembler THREAD safe versions of these using test-and-set instructions
+
+ Original version created by Sergei Golubchik 2001 - 2004.
+ New version written and test program added and some changes to the interface
+ was made by Mikael Ronström 2005, with assistance of Tomas Ulin and Mats
+ Kindahl.
+*/
+
+#include "mysys_priv.h"
+#include "my_sys.h"
+#include <my_bitmap.h>
+#include <m_string.h>
+#include <my_bit.h>
+
+void create_last_word_mask(MY_BITMAP *map)
+{
+ /* Get the number of used bits (1..8) in the last byte */
+ unsigned int const used= 1U + ((map->n_bits-1U) & 0x7U);
+
+ /*
+ Create a mask with the upper 'unused' bits set and the lower 'used'
+ bits clear. The bits within each byte is stored in big-endian order.
+ */
+ unsigned char const mask= (~((1 << used) - 1)) & 255;
+
+ /*
+ The first bytes are to be set to zero since they represent real bits
+ in the bitvector. The last bytes are set to 0xFF since they represent
+ bytes not used by the bitvector. Finally the last byte contains bits
+ as set by the mask above.
+ */
+ unsigned char *ptr= (unsigned char*)&map->last_word_mask;
+
+ /* Avoid out-of-bounds read/write if we have zero bits. */
+ map->last_word_ptr= map->n_bits == 0 ? map->bitmap :
+ map->bitmap + no_words_in_map(map) - 1;
+
+ switch (no_bytes_in_map(map) & 3) {
+ case 1:
+ map->last_word_mask= ~0U;
+ ptr[0]= mask;
+ return;
+ case 2:
+ map->last_word_mask= ~0U;
+ ptr[0]= 0;
+ ptr[1]= mask;
+ return;
+ case 3:
+ map->last_word_mask= 0U;
+ ptr[2]= mask;
+ ptr[3]= 0xFFU;
+ return;
+ case 0:
+ map->last_word_mask= 0U;
+ ptr[3]= mask;
+ return;
+ }
+}
+
+
+static inline void bitmap_lock(MY_BITMAP *map MY_ATTRIBUTE((unused)))
+{
+ if (map->mutex)
+ mysql_mutex_lock(map->mutex);
+}
+
+
+static inline void bitmap_unlock(MY_BITMAP *map MY_ATTRIBUTE((unused)))
+{
+ if (map->mutex)
+ mysql_mutex_unlock(map->mutex);
+}
+
+
+static inline uint get_first_set(uint32 value, uint word_pos)
+{
+ uchar *byte_ptr= (uchar*)&value;
+ uchar byte_value;
+ uint byte_pos, bit_pos;
+
+ for (byte_pos=0; byte_pos < 4; byte_pos++, byte_ptr++)
+ {
+ byte_value= *byte_ptr;
+ if (byte_value)
+ {
+ for (bit_pos=0; ; bit_pos++)
+ if (byte_value & (1 << bit_pos))
+ return (word_pos*32) + (byte_pos*8) + bit_pos;
+ }
+ }
+ return MY_BIT_NONE;
+}
+
+
+static inline uint get_first_not_set(uint32 value, uint word_pos)
+{
+ uchar *byte_ptr= (uchar*)&value;
+ uchar byte_value;
+ uint byte_pos, bit_pos;
+
+ for (byte_pos=0; byte_pos < 4; byte_pos++, byte_ptr++)
+ {
+ byte_value= *byte_ptr;
+ if (byte_value != 0xFF)
+ {
+ for (bit_pos=0; ; bit_pos++)
+ if (!(byte_value & (1 << bit_pos)))
+ return (word_pos*32) + (byte_pos*8) + bit_pos;
+ }
+ }
+ return MY_BIT_NONE;
+}
+
+
+my_bool bitmap_init(MY_BITMAP *map, my_bitmap_map *buf, uint n_bits,
+ my_bool thread_safe MY_ATTRIBUTE((unused)))
+{
+ DBUG_ENTER("bitmap_init");
+ if (!buf)
+ {
+ uint size_in_bytes= bitmap_buffer_size(n_bits);
+ uint extra= 0;
+
+ if (thread_safe)
+ {
+ size_in_bytes= ALIGN_SIZE(size_in_bytes);
+ extra= sizeof(mysql_mutex_t);
+ }
+ map->mutex= 0;
+
+ if (!(buf= (my_bitmap_map*) my_malloc(key_memory_MY_BITMAP_bitmap,
+ size_in_bytes+extra, MYF(MY_WME))))
+ DBUG_RETURN(1);
+
+ if (thread_safe)
+ {
+ map->mutex= (mysql_mutex_t *) ((char*) buf + size_in_bytes);
+ mysql_mutex_init(key_BITMAP_mutex, map->mutex, MY_MUTEX_INIT_FAST);
+ }
+
+ }
+
+ else
+ {
+ DBUG_ASSERT(thread_safe == 0);
+ map->mutex= NULL;
+ }
+
+
+ map->bitmap= buf;
+ map->n_bits= n_bits;
+ create_last_word_mask(map);
+ bitmap_clear_all(map);
+ DBUG_RETURN(0);
+}
+
+
+void bitmap_free(MY_BITMAP *map)
+{
+ DBUG_ENTER("bitmap_free");
+ if (map->bitmap)
+ {
+ if (map->mutex)
+ mysql_mutex_destroy(map->mutex);
+
+ my_free(map->bitmap);
+ map->bitmap=0;
+ }
+ DBUG_VOID_RETURN;
+}
+
+
+/*
+ test if bit already set and set it if it was not (thread unsafe method)
+
+ SYNOPSIS
+ bitmap_fast_test_and_set()
+ MAP bit map struct
+ BIT bit number
+
+ RETURN
+ 0 bit was not set
+ !=0 bit was set
+*/
+
+my_bool bitmap_fast_test_and_set(MY_BITMAP *map, uint bitmap_bit)
+{
+ uchar *value= ((uchar*) map->bitmap) + (bitmap_bit / 8);
+ uchar bit= 1 << ((bitmap_bit) & 7);
+ uchar res= (*value) & bit;
+ *value|= bit;
+ return res;
+}
+
+
+/*
+ test if bit already set and set it if it was not (thread safe method)
+
+ SYNOPSIS
+ bitmap_fast_test_and_set()
+ map bit map struct
+ bitmap_bit bit number
+
+ RETURN
+ 0 bit was not set
+ !=0 bit was set
+*/
+
+my_bool bitmap_test_and_set(MY_BITMAP *map, uint bitmap_bit)
+{
+ my_bool res;
+ DBUG_ASSERT(map->bitmap && bitmap_bit < map->n_bits);
+ bitmap_lock(map);
+ res= bitmap_fast_test_and_set(map, bitmap_bit);
+ bitmap_unlock(map);
+ return res;
+}
+
+/*
+ test if bit already set and clear it if it was set(thread unsafe method)
+
+ SYNOPSIS
+ bitmap_fast_test_and_set()
+ MAP bit map struct
+ BIT bit number
+
+ RETURN
+ 0 bit was not set
+ !=0 bit was set
+*/
+
+my_bool bitmap_fast_test_and_clear(MY_BITMAP *map, uint bitmap_bit)
+{
+ uchar *byte= (uchar*) map->bitmap + (bitmap_bit / 8);
+ uchar bit= 1 << ((bitmap_bit) & 7);
+ uchar res= (*byte) & bit;
+ *byte&= ~bit;
+ return res;
+}
+
+
+my_bool bitmap_test_and_clear(MY_BITMAP *map, uint bitmap_bit)
+{
+ my_bool res;
+ DBUG_ASSERT(map->bitmap && bitmap_bit < map->n_bits);
+ bitmap_lock(map);
+ res= bitmap_fast_test_and_clear(map, bitmap_bit);
+ bitmap_unlock(map);
+ return res;
+}
+
+
+uint bitmap_set_next(MY_BITMAP *map)
+{
+ uint bit_found;
+ DBUG_ASSERT(map->bitmap);
+ if ((bit_found= bitmap_get_first(map)) != MY_BIT_NONE)
+ bitmap_set_bit(map, bit_found);
+ return bit_found;
+}
+
+
+/**
+ Set the specified number of bits in the bitmap buffer.
+
+ @param map [IN] Bitmap
+ @param prefix_size [IN] Number of bits to be set
+
+ @return void
+*/
+void bitmap_set_prefix(MY_BITMAP *map, uint prefix_size)
+{
+ uint prefix_bytes, prefix_bits, d;
+ uchar *m= (uchar *)map->bitmap;
+
+ DBUG_ASSERT(map->bitmap &&
+ (prefix_size <= map->n_bits || prefix_size == (uint) ~0));
+ set_if_smaller(prefix_size, map->n_bits);
+ if ((prefix_bytes= prefix_size / 8))
+ memset(m, 0xff, prefix_bytes);
+ m+= prefix_bytes;
+ if ((prefix_bits= prefix_size & 7))
+ {
+ *(m++)= (1 << prefix_bits)-1;
+ // As the prefix bits are set, lets count this byte too as a prefix byte.
+ prefix_bytes ++;
+ }
+ if ((d= no_bytes_in_map(map)-prefix_bytes))
+ memset(m, 0, d);
+}
+
+
+my_bool bitmap_is_prefix(const MY_BITMAP *map, uint prefix_size)
+{
+ uint prefix_bits= prefix_size % 32;
+ my_bitmap_map *word_ptr= map->bitmap, last_word;
+ my_bitmap_map *end_prefix= word_ptr + prefix_size / 32;
+ DBUG_ASSERT(word_ptr && prefix_size <= map->n_bits);
+
+ /* 1: Words that should be filled with 1 */
+ for (; word_ptr < end_prefix; word_ptr++)
+ if (*word_ptr != 0xFFFFFFFF)
+ return FALSE;
+
+ DBUG_ASSERT(map->n_bits > 0);
+ last_word= *map->last_word_ptr & ~map->last_word_mask;
+
+ /* 2: Word which contains the end of the prefix (if any) */
+ if (prefix_bits)
+ {
+ if (word_ptr == map->last_word_ptr)
+ return uint4korr((uchar*)&last_word) == (uint32)((1 << prefix_bits) - 1);
+ else if (uint4korr((uchar*)word_ptr) != (uint32)((1 << prefix_bits) - 1))
+ return FALSE;
+ word_ptr++;
+ }
+
+ /* 3: Words that should be filled with 0 */
+ for (; word_ptr < map->last_word_ptr; word_ptr++)
+ if (*word_ptr != 0)
+ return FALSE;
+
+ /*
+ We can end up here in two situations:
+ 1) We went through the whole bitmap in step 1. This will happen if the
+ whole bitmap is filled with 1 and prefix_size is a multiple of 32
+ (i.e. the prefix does not end in the middle of a word).
+ In this case word_ptr will be larger than map->last_word_ptr.
+ 2) We have gone through steps 1-3 and just need to check that also
+ the last word is 0.
+ */
+ return word_ptr > map->last_word_ptr || last_word == 0;
+}
+
+
+my_bool bitmap_is_set_all(const MY_BITMAP *map)
+{
+ my_bitmap_map *data_ptr= map->bitmap;
+ my_bitmap_map *end= map->last_word_ptr;
+
+ DBUG_ASSERT(map->n_bits > 0);
+ for (; data_ptr < end; data_ptr++)
+ if (*data_ptr != 0xFFFFFFFF)
+ return FALSE;
+ if ((*map->last_word_ptr | map->last_word_mask) != 0xFFFFFFFF)
+ return FALSE;
+ return TRUE;
+}
+
+
+my_bool bitmap_is_clear_all(const MY_BITMAP *map)
+{
+ my_bitmap_map *data_ptr= map->bitmap;
+ my_bitmap_map *end= map->last_word_ptr;
+
+ DBUG_ASSERT(map->n_bits > 0);
+ for (; data_ptr < end; data_ptr++)
+ if (*data_ptr)
+ return FALSE;
+ if (*map->last_word_ptr & ~map->last_word_mask)
+ return FALSE;
+ return TRUE;
+}
+
+/* Return TRUE if map1 is a subset of map2 */
+
+my_bool bitmap_is_subset(const MY_BITMAP *map1, const MY_BITMAP *map2)
+{
+ my_bitmap_map *m1= map1->bitmap, *m2= map2->bitmap, *end;
+
+ DBUG_ASSERT(map1->bitmap && map2->bitmap &&
+ map1->n_bits==map2->n_bits);
+
+ end= map1->last_word_ptr;
+ for (; m1 < end; m1++, m2++)
+ if (*m1 & ~(*m2))
+ return FALSE;
+
+ DBUG_ASSERT(map1->n_bits > 0);
+ DBUG_ASSERT(map2->n_bits > 0);
+
+ if ((*map1->last_word_ptr & ~map1->last_word_mask) &
+ ~(*map2->last_word_ptr & ~map2->last_word_mask))
+ return FALSE;
+ return TRUE;
+}
+
+/* True if bitmaps has any common bits */
+
+my_bool bitmap_is_overlapping(const MY_BITMAP *map1, const MY_BITMAP *map2)
+{
+ my_bitmap_map *m1= map1->bitmap, *m2= map2->bitmap, *end;
+
+ DBUG_ASSERT(map1->bitmap && map2->bitmap &&
+ map1->n_bits==map2->n_bits);
+
+ DBUG_ASSERT(map1->n_bits > 0);
+ DBUG_ASSERT(map2->n_bits > 0);
+
+ end= map1->last_word_ptr;
+ for (; m1 < end; m1++, m2++)
+ if (*m1 & *m2)
+ return TRUE;
+
+ if ((*map1->last_word_ptr & ~map1->last_word_mask) &
+ (*map2->last_word_ptr & ~map2->last_word_mask))
+ return TRUE;
+ return FALSE;
+}
+
+
+void bitmap_intersect(MY_BITMAP *map, const MY_BITMAP *map2)
+{
+ my_bitmap_map *to= map->bitmap, *from= map2->bitmap, *end;
+ uint len= no_words_in_map(map), len2 = no_words_in_map(map2);
+
+ DBUG_ASSERT(map->bitmap && map2->bitmap);
+
+ end= to + MY_MIN(len, len2);
+ for (; to < end; to++, from++)
+ *to &= *from;
+
+ if (len >= len2)
+ map->bitmap[len2 - 1] &= ~map2->last_word_mask;
+
+ if (len2 < len)
+ {
+ end+=len-len2;
+ for (; to < end; to++)
+ *to= 0;
+ }
+}
+
+
+/*
+ Set/clear all bits above a bit.
+
+ SYNOPSIS
+ bitmap_set_above()
+ map RETURN The bitmap to change.
+ from_byte The bitmap buffer byte offset to start with.
+ use_bit The bit value (1/0) to use for all upper bits.
+
+ NOTE
+ You can only set/clear full bytes.
+ The function is meant for the situation that you copy a smaller bitmap
+ to a bigger bitmap. Bitmap lengths are always multiple of eigth (the
+ size of a byte). Using 'from_byte' saves multiplication and division
+ by eight during parameter passing.
+
+ RETURN
+ void
+*/
+
+void bitmap_set_above(MY_BITMAP *map, uint from_byte, uint use_bit)
+{
+ uchar use_byte= use_bit ? 0xff : 0;
+ uchar *to= (uchar *)map->bitmap + from_byte;
+ uchar *end= (uchar *)map->bitmap + (map->n_bits+7)/8;
+
+ for (; to < end; to++)
+ *to= use_byte;
+}
+
+
+void bitmap_subtract(MY_BITMAP *map, const MY_BITMAP *map2)
+{
+ my_bitmap_map *to= map->bitmap, *from= map2->bitmap, *end;
+ DBUG_ASSERT(map->bitmap && map2->bitmap &&
+ map->n_bits==map2->n_bits);
+ DBUG_ASSERT(map->n_bits > 0);
+ end= map->last_word_ptr;
+
+ for (; to <= end; to++, from++)
+ *to &= ~(*from);
+}
+
+
+void bitmap_union(MY_BITMAP *map, const MY_BITMAP *map2)
+{
+ my_bitmap_map *to= map->bitmap, *from= map2->bitmap, *end;
+ DBUG_ASSERT(map->bitmap && map2->bitmap &&
+ map->n_bits==map2->n_bits);
+ DBUG_ASSERT(map->n_bits > 0);
+ end= map->last_word_ptr;
+
+ for (; to <= end; to++, from++)
+ *to |= *from;
+}
+
+
+void bitmap_xor(MY_BITMAP *map, const MY_BITMAP *map2)
+{
+ my_bitmap_map *to= map->bitmap, *from= map2->bitmap, *end;
+ DBUG_ASSERT(map->bitmap && map2->bitmap &&
+ map->n_bits==map2->n_bits);
+ DBUG_ASSERT(map->n_bits > 0);
+ end= map->last_word_ptr;
+
+ for (; to <= end; to++, from++)
+ *to ^= *from;
+}
+
+
+void bitmap_invert(MY_BITMAP *map)
+{
+ my_bitmap_map *to= map->bitmap, *end;
+ DBUG_ASSERT(map->bitmap);
+ DBUG_ASSERT(map->n_bits > 0);
+ end= map->last_word_ptr;
+
+ for (; to <= end; to++)
+ *to ^= 0xFFFFFFFF;
+}
+
+
+uint bitmap_bits_set(const MY_BITMAP *map)
+{
+ my_bitmap_map *data_ptr= map->bitmap;
+ my_bitmap_map *end= map->last_word_ptr;
+ uint res= 0;
+ DBUG_ASSERT(map->bitmap);
+ DBUG_ASSERT(map->n_bits > 0);
+
+ for (; data_ptr < end; data_ptr++)
+ res+= my_count_bits_uint32(*data_ptr);
+
+ /*Reset last bits to zero*/
+ res+= my_count_bits_uint32(*map->last_word_ptr & ~map->last_word_mask);
+ return res;
+}
+
+
+void bitmap_copy(MY_BITMAP *map, const MY_BITMAP *map2)
+{
+ my_bitmap_map *to= map->bitmap, *from= map2->bitmap, *end;
+ DBUG_ASSERT(map->bitmap && map2->bitmap &&
+ map->n_bits==map2->n_bits);
+ DBUG_ASSERT(map->n_bits > 0);
+ end= map->last_word_ptr;
+
+ for (; to <= end; to++, from++)
+ *to = *from;
+}
+
+
+uint bitmap_get_first_set(const MY_BITMAP *map)
+{
+ uint word_pos;
+ my_bitmap_map *data_ptr, *end= map->last_word_ptr;
+
+ DBUG_ASSERT(map->bitmap);
+ DBUG_ASSERT(map->n_bits > 0);
+ data_ptr= map->bitmap;
+
+ for (word_pos=0; data_ptr < end; data_ptr++, word_pos++)
+ if (*data_ptr)
+ return get_first_set(*data_ptr, word_pos);
+
+ return get_first_set(*map->last_word_ptr & ~map->last_word_mask, word_pos);
+}
+
+
+/**
+ Get the next set bit.
+
+ @param map Bitmap
+ @param bitmap_bit Bit to start search from
+
+ @return Index to first bit set after bitmap_bit
+*/
+
+uint bitmap_get_next_set(const MY_BITMAP *map, uint bitmap_bit)
+{
+ uint word_pos, byte_to_mask, i;
+ my_bitmap_map first_word;
+ unsigned char *ptr= (unsigned char*) &first_word;
+ my_bitmap_map *data_ptr, *end= map->last_word_ptr;
+
+ DBUG_ASSERT(map->bitmap);
+ DBUG_ASSERT(map->n_bits > 0);
+
+ /* Look for the next bit */
+ bitmap_bit++;
+ if (bitmap_bit >= map->n_bits)
+ return MY_BIT_NONE;
+ word_pos= bitmap_bit / 32;
+ data_ptr= map->bitmap + word_pos;
+ first_word= *data_ptr;
+
+ /* Mask out previous bits */
+ byte_to_mask= (bitmap_bit % 32) / 8;
+ for (i= 0; i < byte_to_mask; i++)
+ ptr[i]= 0;
+ ptr[byte_to_mask]&= 0xFFU << (bitmap_bit & 7);
+
+ if (data_ptr == end)
+ return get_first_set(first_word & ~map->last_word_mask, word_pos);
+
+ if (first_word)
+ return get_first_set(first_word, word_pos);
+
+ for (data_ptr++, word_pos++; data_ptr < end; data_ptr++, word_pos++)
+ if (*data_ptr)
+ return get_first_set(*data_ptr, word_pos);
+
+ return get_first_set(*end & ~map->last_word_mask, word_pos);
+}
+
+
+uint bitmap_get_first(const MY_BITMAP *map)
+{
+ uint word_pos;
+ my_bitmap_map *data_ptr, *end= map->last_word_ptr;
+
+ DBUG_ASSERT(map->bitmap);
+ DBUG_ASSERT(map->n_bits > 0);
+ data_ptr= map->bitmap;
+
+ for (word_pos=0; data_ptr < end; data_ptr++, word_pos++)
+ if (*data_ptr != 0xFFFFFFFF)
+ return get_first_not_set(*data_ptr, word_pos);
+
+ return get_first_not_set(*map->last_word_ptr | map->last_word_mask, word_pos);
+}
+
+
+uint bitmap_lock_set_next(MY_BITMAP *map)
+{
+ uint bit_found;
+ bitmap_lock(map);
+ bit_found= bitmap_set_next(map);
+ bitmap_unlock(map);
+ return bit_found;
+}
+
+
+void bitmap_lock_clear_bit(MY_BITMAP *map, uint bitmap_bit)
+{
+ bitmap_lock(map);
+ DBUG_ASSERT(map->bitmap && bitmap_bit < map->n_bits);
+ bitmap_clear_bit(map, bitmap_bit);
+ bitmap_unlock(map);
+}
generated by cgit v1.1 at 2024-04-20 13:07:31 +0000