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0001 /*
0002 Copyright (C) 1999-2007 The Botan Project. All rights reserved.
0003 
0004 Redistribution and use in source and binary forms, for any use, with or without
0005 modification, is permitted provided that the following conditions are met:
0006 
0007 1. Redistributions of source code must retain the above copyright notice, this
0008 list of conditions, and the following disclaimer.
0009 
0010 2. Redistributions in binary form must reproduce the above copyright notice,
0011 this list of conditions, and the following disclaimer in the documentation
0012 and/or other materials provided with the distribution.
0013 
0014 THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) "AS IS" AND ANY EXPRESS OR IMPLIED
0015 WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
0016 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.
0017 
0018 IN NO EVENT SHALL THE AUTHOR(S) OR CONTRIBUTOR(S) BE LIABLE FOR ANY DIRECT,
0019 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
0020 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
0021 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
0022 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
0023 OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
0024 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
0025 */
0026 // LICENSEHEADER_END
0027 namespace QCA { // WRAPNS_LINE
0028 /*************************************************
0029  * Bit/Word Operations Source File                *
0030  * (C) 1999-2007 The Botan Project                *
0031  *************************************************/
0032 
0033 } // WRAPNS_LINE
0034 #include <botan/bit_ops.h>
0035 namespace QCA { // WRAPNS_LINE
0036 
0037 namespace Botan {
0038 
0039 /*************************************************
0040  * XOR arrays together                            *
0041  *************************************************/
0042 void xor_buf(byte data[], const byte mask[], u32bit length)
0043 {
0044     while (length >= 8) {
0045         data[0] ^= mask[0];
0046         data[1] ^= mask[1];
0047         data[2] ^= mask[2];
0048         data[3] ^= mask[3];
0049         data[4] ^= mask[4];
0050         data[5] ^= mask[5];
0051         data[6] ^= mask[6];
0052         data[7] ^= mask[7];
0053         data += 8;
0054         mask += 8;
0055         length -= 8;
0056     }
0057     for (u32bit j = 0; j != length; ++j)
0058         data[j] ^= mask[j];
0059 }
0060 
0061 void xor_buf(byte out[], const byte in[], const byte mask[], u32bit length)
0062 {
0063     while (length >= 8) {
0064         out[0] = in[0] ^ mask[0];
0065         out[1] = in[1] ^ mask[1];
0066         out[2] = in[2] ^ mask[2];
0067         out[3] = in[3] ^ mask[3];
0068         out[4] = in[4] ^ mask[4];
0069         out[5] = in[5] ^ mask[5];
0070         out[6] = in[6] ^ mask[6];
0071         out[7] = in[7] ^ mask[7];
0072         in += 8;
0073         out += 8;
0074         mask += 8;
0075         length -= 8;
0076     }
0077     for (u32bit j = 0; j != length; ++j)
0078         out[j] = in[j] ^ mask[j];
0079 }
0080 
0081 /*************************************************
0082  * Return true iff arg is 2**n for some n > 0     *
0083  *************************************************/
0084 bool power_of_2(u64bit arg)
0085 {
0086     if (arg == 0 || arg == 1)
0087         return false;
0088     if ((arg & (arg - 1)) == 0)
0089         return true;
0090     return false;
0091 }
0092 
0093 /*************************************************
0094  * Return the index of the highest set bit        *
0095  *************************************************/
0096 u32bit high_bit(u64bit n)
0097 {
0098     for (u32bit count = 64; count > 0; --count)
0099         if ((n >> (count - 1)) & 0x01)
0100             return count;
0101     return 0;
0102 }
0103 
0104 /*************************************************
0105  * Return the index of the lowest set bit         *
0106  *************************************************/
0107 u32bit low_bit(u64bit n)
0108 {
0109     for (u32bit count = 0; count != 64; ++count)
0110         if ((n >> count) & 0x01)
0111             return (count + 1);
0112     return 0;
0113 }
0114 
0115 /*************************************************
0116  * Return the number of significant bytes in n    *
0117  *************************************************/
0118 u32bit significant_bytes(u64bit n)
0119 {
0120     for (u32bit j = 0; j != 8; ++j)
0121         if (get_byte(j, n))
0122             return 8 - j;
0123     return 0;
0124 }
0125 
0126 /*************************************************
0127  * Return the Hamming weight of n                 *
0128  *************************************************/
0129 u32bit hamming_weight(u64bit n)
0130 {
0131     u32bit weight = 0;
0132     for (u32bit j = 0; j != 64; ++j)
0133         if ((n >> j) & 0x01)
0134             ++weight;
0135     return weight;
0136 }
0137 
0138 }
0139 } // WRAPNS_LINE