00001 /* 00002 * SPUC - Signal processing using C++ - A DSP library 00003 * 00004 * This program is free software; you can redistribute it and/or modify 00005 * it under the terms of the GNU General Public License as published by 00006 * the Free Software Foundation; either version 2, or (at your option) 00007 * any later version. 00008 * 00009 * This program is distributed in the hope that it will be useful, 00010 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00011 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00012 * GNU General Public License for more details. 00013 * 00014 * You should have received a copy of the GNU General Public License 00015 * along with this program; if not, write to the Free Software 00016 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00017 */ 00018 #ifndef BSCRAM 00019 #define BSCRAM 00020 namespace SPUC { 00029 00030 class bit_scrambler { 00031 public: 00032 unsigned long g; 00033 long span; 00034 00035 public: 00036 unsigned long u; 00037 bit_scrambler(long gen=0x48, long bits=7, long uinit=-1) 00038 : g(gen), span(bits), u(uinit) {;} 00039 void reset() { u=~0; } 00040 bool scramble(bool data_in) { 00041 bool res = xor_bits(u&g); 00042 u <<= 1; 00043 u += res; 00044 return(data_in ^ res); 00045 } 00047 bool xor_bits(long x) { 00048 bool c=0; 00049 for (int i =0;i<span;i++) { 00050 c ^= (x & 0x01); 00051 x >>= 1; 00052 } 00053 return(c); 00054 } 00055 }; 00056 } // namespace SPUC 00057 #endif
1.4.4