Drizzled Public API Documentation

bit_count.cc
1 
2 /* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
3  * vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
4  *
5  * Copyright (C) 2008 Sun Microsystems, Inc.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; version 2 of the License.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include <config.h>
22 
23 #include <plugin/utility_functions/bit_count.h>
24 
25 namespace drizzled
26 {
27 
28 namespace utility_functions
29 {
30 
31 static const char _my_bits_nbits[256] = {
32  0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
33  1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
34  1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
35  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
36  1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
37  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
38  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
39  3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
40  1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
41  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
42  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
43  3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
44  2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
45  3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
46  3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
47  4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
48 };
49 
50 /*
51  perl -e 'print map{", 0x".unpack H2,pack B8,unpack b8,chr$_}(0..255)'
52 */
53 static const unsigned char _my_bits_reverse_table[256]={
54 0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30,
55 0xB0, 0x70, 0xF0, 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98,
56 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, 0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64,
57 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, 0x0C, 0x8C, 0x4C, 0xCC,
58 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, 0x02,
59 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2,
60 0x72, 0xF2, 0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A,
61 0xDA, 0x3A, 0xBA, 0x7A, 0xFA, 0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6,
62 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, 0x0E, 0x8E, 0x4E, 0xCE, 0x2E,
63 0xAE, 0x6E, 0xEE, 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, 0x01, 0x81,
64 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71,
65 0xF1, 0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9,
66 0x39, 0xB9, 0x79, 0xF9, 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, 0x15,
67 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5, 0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD,
68 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD, 0x03, 0x83, 0x43,
69 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3,
70 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, 0x1B, 0x9B, 0x5B, 0xDB, 0x3B,
71 0xBB, 0x7B, 0xFB, 0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97,
72 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, 0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F,
73 0xEF, 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
74 };
75 
76 
77 static uint32_t my_count_bits(uint64_t v)
78 {
79 #if SIZEOF_LONG_LONG > 4
80  /* The following code is a bit faster on 16 bit machines than if we would
81  only shift v */
82  ulong v2=(unsigned long) (v >> 32);
83  return (uint32_t) (unsigned char) (_my_bits_nbits[(unsigned char) v] +
84  _my_bits_nbits[(unsigned char) (v >> 8)] +
85  _my_bits_nbits[(unsigned char) (v >> 16)] +
86  _my_bits_nbits[(unsigned char) (v >> 24)] +
87  _my_bits_nbits[(unsigned char) (v2)] +
88  _my_bits_nbits[(unsigned char) (v2 >> 8)] +
89  _my_bits_nbits[(unsigned char) (v2 >> 16)] +
90  _my_bits_nbits[(unsigned char) (v2 >> 24)]);
91 #else
92  return (uint32_t) (unsigned char) (_my_bits_nbits[(unsigned char) v] +
93  _my_bits_nbits[(unsigned char) (v >> 8)] +
94  _my_bits_nbits[(unsigned char) (v >> 16)] +
95  _my_bits_nbits[(unsigned char) (v >> 24)]);
96 #endif
97 }
98 
99 #if 0
100 static uint32_t my_count_bits_ushort(ushort v)
101 {
102  return _my_bits_nbits[v];
103 }
104 #endif
105 
107 {
108  assert(fixed == 1);
109  uint64_t value= (uint64_t) args[0]->val_int();
110 
111  if ((null_value= args[0]->null_value))
112  return 0; /* purecov: inspected */
113 
114  return (int64_t) my_count_bits(value);
115 }
116 
117 
118 } /* namespace utility_functions */
119 } /* namespace drizzled */
bool fixed
Definition: item.h:120
bool null_value
Definition: item.h:122