qca

bit_ops.cpp

00001 /*
00002 Copyright (C) 1999-2007 The Botan Project. All rights reserved.
00003 
00004 Redistribution and use in source and binary forms, for any use, with or without
00005 modification, is permitted provided that the following conditions are met:
00006 
00007 1. Redistributions of source code must retain the above copyright notice, this
00008 list of conditions, and the following disclaimer.
00009 
00010 2. Redistributions in binary form must reproduce the above copyright notice,
00011 this list of conditions, and the following disclaimer in the documentation
00012 and/or other materials provided with the distribution.
00013 
00014 THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) "AS IS" AND ANY EXPRESS OR IMPLIED
00015 WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00016 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.
00017 
00018 IN NO EVENT SHALL THE AUTHOR(S) OR CONTRIBUTOR(S) BE LIABLE FOR ANY DIRECT,
00019 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00020 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
00021 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00022 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
00023 OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
00024 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00025 */
00026 // LICENSEHEADER_END
00027 namespace QCA { // WRAPNS_LINE
00028 /*************************************************
00029 * Bit/Word Operations Source File                *
00030 * (C) 1999-2007 The Botan Project                *
00031 *************************************************/
00032 
00033 } // WRAPNS_LINE
00034 #include <botan/bit_ops.h>
00035 namespace QCA { // WRAPNS_LINE
00036 
00037 namespace Botan {
00038 
00039 /*************************************************
00040 * XOR arrays together                            *
00041 *************************************************/
00042 void xor_buf(byte data[], const byte mask[], u32bit length)
00043    {
00044    while(length >= 8)
00045       {
00046       data[0] ^= mask[0]; data[1] ^= mask[1];
00047       data[2] ^= mask[2]; data[3] ^= mask[3];
00048       data[4] ^= mask[4]; data[5] ^= mask[5];
00049       data[6] ^= mask[6]; data[7] ^= mask[7];
00050       data += 8; mask += 8; length -= 8;
00051       }
00052    for(u32bit j = 0; j != length; ++j)
00053       data[j] ^= mask[j];
00054    }
00055 
00056 void xor_buf(byte out[], const byte in[], const byte mask[], u32bit length)
00057    {
00058    while(length >= 8)
00059       {
00060       out[0] = in[0] ^ mask[0]; out[1] = in[1] ^ mask[1];
00061       out[2] = in[2] ^ mask[2]; out[3] = in[3] ^ mask[3];
00062       out[4] = in[4] ^ mask[4]; out[5] = in[5] ^ mask[5];
00063       out[6] = in[6] ^ mask[6]; out[7] = in[7] ^ mask[7];
00064       in += 8; out += 8; mask += 8; length -= 8;
00065       }
00066    for(u32bit j = 0; j != length; ++j)
00067       out[j] = in[j] ^ mask[j];
00068    }
00069 
00070 /*************************************************
00071 * Return true iff arg is 2**n for some n > 0     *
00072 *************************************************/
00073 bool power_of_2(u64bit arg)
00074    {
00075    if(arg == 0 || arg == 1)
00076       return false;
00077    if((arg & (arg-1)) == 0)
00078       return true;
00079    return false;
00080    }
00081 
00082 /*************************************************
00083 * Return the index of the highest set bit        *
00084 *************************************************/
00085 u32bit high_bit(u64bit n)
00086    {
00087    for(u32bit count = 64; count > 0; --count)
00088       if((n >> (count - 1)) & 0x01)
00089          return count;
00090    return 0;
00091    }
00092 
00093 /*************************************************
00094 * Return the index of the lowest set bit         *
00095 *************************************************/
00096 u32bit low_bit(u64bit n)
00097    {
00098    for(u32bit count = 0; count != 64; ++count)
00099       if((n >> count) & 0x01)
00100          return (count + 1);
00101    return 0;
00102    }
00103 
00104 /*************************************************
00105 * Return the number of significant bytes in n    *
00106 *************************************************/
00107 u32bit significant_bytes(u64bit n)
00108    {
00109    for(u32bit j = 0; j != 8; ++j)
00110       if(get_byte(j, n))
00111          return 8-j;
00112    return 0;
00113    }
00114 
00115 /*************************************************
00116 * Return the Hamming weight of n                 *
00117 *************************************************/
00118 u32bit hamming_weight(u64bit n)
00119    {
00120    u32bit weight = 0;
00121    for(u32bit j = 0; j != 64; ++j)
00122       if((n >> j) & 0x01)
00123          ++weight;
00124    return weight;
00125    }
00126 
00127 }
00128 } // WRAPNS_LINE
qca

bit_ops.cpp

qca

KDE Support
