diff --git a/.gitignore b/.gitignore index d1a0b332..d560f19d 100644 --- a/.gitignore +++ b/.gitignore @@ -15,6 +15,7 @@ CommonLibs/SocketsTest CommonLibs/TimevalTest CommonLibs/URLEncodeTest CommonLibs/VectorTest +CommonLibs/PRBSTest # automake/autoconf *.in diff --git a/CommonLibs/Makefile.am b/CommonLibs/Makefile.am index f0f10619..18ec2f77 100644 --- a/CommonLibs/Makefile.am +++ b/CommonLibs/Makefile.am @@ -42,6 +42,7 @@ libcommon_la_SOURCES = \ noinst_PROGRAMS = \ BitVectorTest \ + PRBSTest \ InterthreadTest \ SocketsTest \ TimevalTest \ @@ -53,6 +54,7 @@ noinst_PROGRAMS = \ noinst_HEADERS = \ BitVector.h \ + PRBS.h \ Interthread.h \ LinkedLists.h \ Sockets.h \ @@ -66,6 +68,8 @@ noinst_HEADERS = \ BitVectorTest_SOURCES = BitVectorTest.cpp BitVectorTest_LDADD = libcommon.la $(SQLITE3_LIBS) +PRBSTest_SOURCES = PRBSTest.cpp + InterthreadTest_SOURCES = InterthreadTest.cpp InterthreadTest_LDADD = libcommon.la InterthreadTest_LDFLAGS = -lpthread diff --git a/CommonLibs/PRBS.h b/CommonLibs/PRBS.h new file mode 100644 index 00000000..0b7bbc3a --- /dev/null +++ b/CommonLibs/PRBS.h @@ -0,0 +1,110 @@ +/* + * Copyright (C) 2017 Alexander Chemeris + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef PRBS_H +#define PRBS_H + +#include +#include + +/** Pseudo-random binary sequence (PRBS) generator (a Galois LFSR implementation). */ +class PRBS { +public: + + PRBS(unsigned wLen, uint64_t wCoeff, uint64_t wState = 0x01) + : mCoeff(wCoeff), mStartState(wState), mState(wState), mLen(wLen) + { assert(wLen<=64); } + + /**@name Accessors */ + //@{ + uint64_t coeff() const { return mCoeff; } + uint64_t state() const { return mState; } + void state(uint64_t state) { mState = state & mask(); } + unsigned size() const { return mLen; } + //@} + + /** + Calculate one bit of a PRBS + */ + unsigned generateBit() + { + const unsigned result = mState & 0x01; + processBit(result); + return result; + } + + /** + Update the generator state by one bit. + If you want to synchronize your PRBS to a known state, call this function + size() times passing your PRBS to it bit by bit. + */ + void processBit(unsigned inBit) + { + mState >>= 1; + if (inBit) mState ^= mCoeff; + } + + /** Return true when PRBS is wrapping through initial state */ + bool isFinished() const { return mStartState == mState; } + +protected: + + uint64_t mCoeff; ///< polynomial coefficients. LSB is zero exponent. + uint64_t mStartState; ///< initial shift register state. + uint64_t mState; ///< shift register state. + unsigned mLen; ///< number of bits used in shift register + + /** Return mask for the state register */ + uint64_t mask() const { return (mLen==64)?0xFFFFFFFFFFFFFFFFUL:((1< + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include "PRBS.h" +#include +#include +#include + +void testPrbs(PRBS &prbs, uint64_t expectedPeriod) +{ + uint64_t period = 0; + do { + std::cout << prbs.generateBit(); + period++; + } while (!prbs.isFinished()); + std::cout << std::endl; + std::cout << "Period: " << period << std::endl; + assert(period == expectedPeriod); +} + +int main(int argc, char *argv[]) +{ + PRBS9 prbs9(0x01); + testPrbs(prbs9, (1<<9)-1); + PRBS15 prbs15(0x01); + testPrbs(prbs15, (1<<15)-1); +}