Drizzled Public API Documentation

mf_radix.cc
1 /* Copyright (C) 2000 MySQL AB
2 
3  This program is free software; you can redistribute it and/or modify
4  it under the terms of the GNU General Public License as published by
5  the Free Software Foundation; version 2 of the License.
6 
7  This program is distributed in the hope that it will be useful,
8  but WITHOUT ANY WARRANTY; without even the implied warranty of
9  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10  GNU General Public License for more details.
11 
12  You should have received a copy of the GNU General Public License
13  along with this program; if not, write to the Free Software
14  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
15 
16 /*
17  Radixsort for pointers to fixed length strings.
18  A very quick sort for not to long (< 20 char) strings.
19  Neads a extra buffers of number_of_elements pointers but is
20  2-3 times faster than quicksort
21 */
22 
23 #include <config.h>
24 
25 #include <drizzled/internal/my_sys.h>
26 #include <drizzled/internal/m_string.h>
27 
28 namespace drizzled
29 {
30 namespace internal
31 {
32 
33  /* Radixsort */
34 
35 void radixsort_for_str_ptr(unsigned char **base, uint32_t number_of_elements, size_t size_of_element, unsigned char **buffer)
36 {
37  unsigned char **end,**ptr,**buffer_ptr;
38  uint32_t *count_ptr,*count_end,count[256];
39  int pass;
40 
41  end=base+number_of_elements; count_end=count+256;
42  for (pass=(int) size_of_element-1 ; pass >= 0 ; pass--)
43  {
44  memset(count, 0, sizeof(uint32_t)*256);
45  for (ptr= base ; ptr < end ; ptr++)
46  count[ptr[0][pass]]++;
47  if (count[0] == number_of_elements)
48  goto next;
49  for (count_ptr=count+1 ; count_ptr < count_end ; count_ptr++)
50  {
51  if (*count_ptr == number_of_elements)
52  goto next;
53  (*count_ptr)+= *(count_ptr-1);
54  }
55  for (ptr= end ; ptr-- != base ;)
56  buffer[--count[ptr[0][pass]]]= *ptr;
57  for (ptr=base, buffer_ptr=buffer ; ptr < end ;)
58  (*ptr++) = *buffer_ptr++;
59  next:;
60  }
61 }
62 
63 } /* namespace internal */
64 } /* namespace drizzled */
TODO: Rename this file - func.h is stupid.