Drizzled Public API Documentation

bit_count.cc
00001 
00002 /* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
00003  *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
00004  *
00005  *  Copyright (C) 2008 Sun Microsystems, Inc.
00006  *
00007  *  This program is free software; you can redistribute it and/or modify
00008  *  it under the terms of the GNU General Public License as published by
00009  *  the Free Software Foundation; version 2 of the License.
00010  *
00011  *  This program is distributed in the hope that it will be useful,
00012  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014  *  GNU General Public License for more details.
00015  *
00016  *  You should have received a copy of the GNU General Public License
00017  *  along with this program; if not, write to the Free Software
00018  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
00019  */
00020 
00021 #include <config.h>
00022 
00023 #include <plugin/utility_functions/bit_count.h>
00024 
00025 namespace drizzled
00026 {
00027 
00028 namespace utility_functions
00029 {
00030 
00031 static const char _my_bits_nbits[256] = {
00032   0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
00033   1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
00034   1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
00035   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
00036   1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
00037   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
00038   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
00039   3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
00040   1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
00041   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
00042   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
00043   3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
00044   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
00045   3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
00046   3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
00047   4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
00048 };
00049 
00050 /*
00051   perl -e 'print map{", 0x".unpack H2,pack B8,unpack b8,chr$_}(0..255)'
00052 */
00053 static const unsigned char _my_bits_reverse_table[256]={
00054 0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30,
00055 0xB0, 0x70, 0xF0, 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98,
00056 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, 0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64,
00057 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, 0x0C, 0x8C, 0x4C, 0xCC,
00058 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, 0x02,
00059 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2,
00060 0x72, 0xF2, 0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A,
00061 0xDA, 0x3A, 0xBA, 0x7A, 0xFA, 0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6,
00062 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, 0x0E, 0x8E, 0x4E, 0xCE, 0x2E,
00063 0xAE, 0x6E, 0xEE, 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, 0x01, 0x81,
00064 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71,
00065 0xF1, 0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9,
00066 0x39, 0xB9, 0x79, 0xF9, 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, 0x15,
00067 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5, 0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD,
00068 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD, 0x03, 0x83, 0x43,
00069 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3,
00070 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, 0x1B, 0x9B, 0x5B, 0xDB, 0x3B,
00071 0xBB, 0x7B, 0xFB, 0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97,
00072 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, 0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F,
00073 0xEF, 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
00074 };
00075 
00076 
00077 static uint32_t my_count_bits(uint64_t v)
00078 {
00079 #if SIZEOF_LONG_LONG > 4
00080   /* The following code is a bit faster on 16 bit machines than if we would
00081      only shift v */
00082   ulong v2=(unsigned long) (v >> 32);
00083   return (uint32_t) (unsigned char) (_my_bits_nbits[(unsigned char)  v] +
00084                                      _my_bits_nbits[(unsigned char) (v >> 8)] +
00085                                      _my_bits_nbits[(unsigned char) (v >> 16)] +
00086                                      _my_bits_nbits[(unsigned char) (v >> 24)] +
00087                                      _my_bits_nbits[(unsigned char) (v2)] +
00088                                      _my_bits_nbits[(unsigned char) (v2 >> 8)] +
00089                                      _my_bits_nbits[(unsigned char) (v2 >> 16)] +
00090                                      _my_bits_nbits[(unsigned char) (v2 >> 24)]);
00091 #else
00092   return (uint32_t) (unsigned char) (_my_bits_nbits[(unsigned char)  v] +
00093                                      _my_bits_nbits[(unsigned char) (v >> 8)] +
00094                                      _my_bits_nbits[(unsigned char) (v >> 16)] +
00095                                      _my_bits_nbits[(unsigned char) (v >> 24)]);
00096 #endif
00097 }
00098 
00099 #if 0
00100 static uint32_t my_count_bits_ushort(ushort v)
00101 {
00102   return _my_bits_nbits[v];
00103 }
00104 #endif
00105 
00106 int64_t BitCount::val_int() 
00107 { 
00108   assert(fixed == 1);
00109   uint64_t value= (uint64_t) args[0]->val_int();
00110 
00111   if ((null_value= args[0]->null_value))
00112     return 0; /* purecov: inspected */
00113 
00114   return (int64_t) my_count_bits(value);
00115 }
00116 
00117 
00118 } /* namespace utility_functions */
00119 } /* namespace drizzled */