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Diffstat (limited to 'lib/decoding/openbts/BitVector.h')
-rw-r--r-- | lib/decoding/openbts/BitVector.h | 432 |
1 files changed, 432 insertions, 0 deletions
diff --git a/lib/decoding/openbts/BitVector.h b/lib/decoding/openbts/BitVector.h new file mode 100644 index 0000000..c8782eb --- /dev/null +++ b/lib/decoding/openbts/BitVector.h @@ -0,0 +1,432 @@ +/* + * Copyright 2008, 2009, 2014 Free Software Foundation, Inc. + * Copyright 2014 Range Networks, Inc. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU Affero General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program 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 Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + * This use of this software may be subject to additional restrictions. + * See the LEGAL file in the main directory for details. + */ + +#ifndef BITVECTORS_H +#define BITVECTORS_H + +#include "Vector.h" +#include <stdint.h> +#include <stdio.h> + + +class BitVector; +class SoftVector; + + + + +/** Shift-register (LFSR) generator. */ +class Generator { + + private: + + uint64_t mCoeff; ///< polynomial coefficients. LSB is zero exponent. + uint64_t mState; ///< shift register state. LSB is most recent. + uint64_t mMask; ///< mask for reading state + unsigned mLen; ///< number of bits used in shift register + unsigned mLen_1; ///< mLen - 1 + + public: + + Generator(uint64_t wCoeff, unsigned wLen) + :mCoeff(wCoeff),mState(0), + mMask((1ULL<<wLen)-1), + mLen(wLen),mLen_1(wLen-1) + { assert(wLen<64); } + + void clear() { mState=0; } + + /**@name Accessors */ + //@{ + uint64_t state() const { return mState & mMask; } + unsigned size() const { return mLen; } + //@} + + /** + Calculate one bit of a syndrome. + This is in the .h for inlining. + */ + void syndromeShift(unsigned inBit) + { + const unsigned fb = (mState>>(mLen_1)) & 0x01; + mState = (mState<<1) ^ (inBit & 0x01); + if (fb) mState ^= mCoeff; + } + + /** + Update the generator state by one cycle. + This is in the .h for inlining. + */ + void encoderShift(unsigned inBit) + { + const unsigned fb = ((mState>>(mLen_1)) ^ inBit) & 0x01; + mState <<= 1; + if (fb) mState ^= mCoeff; + } + + +}; + + + + +/** Parity (CRC-type) generator and checker based on a Generator. */ +class Parity : public Generator { + + protected: + + unsigned mCodewordSize; + + public: + + Parity(uint64_t wCoefficients, unsigned wParitySize, unsigned wCodewordSize) + :Generator(wCoefficients, wParitySize), + mCodewordSize(wCodewordSize) + { } + + /** Compute the parity word and write it into the target segment. */ + void writeParityWord(const BitVector& data, BitVector& parityWordTarget, bool invert=true); + + /** Compute the syndrome of a received sequence. */ + uint64_t syndrome(const BitVector& receivedCodeword); +}; + + +// (pat) Nov 2013. I rationalized the behavior of BitVector and added assertions to core dump code +// that relied on the bad aspects of the original behavior. See comments at VectorBase. +class BitVector : public VectorBase<char> +{ + public: + /**@name Constructors. */ + //@{ + + /**@name Casts of Vector constructors. */ + BitVector(VectorDataType wData, char* wStart, char* wEnd) : VectorBase<char>(wData, wStart, wEnd) {} + + // The one and only copy-constructor. + BitVector(const BitVector&other) : VectorBase<char>() { + VECTORDEBUG("BitVector(%p)",(void*)&other); + if (other.getData()) { + this->clone(other); + } else { + this->makeAlias(other); + } + } + + // (pat) Removed default value for len and added 'explicit'. Please do not remove 'explicit'; + // it prevents auto-conversion of int to BitVector in constructors. + // Previous code was often ambiguous, especially for L3Frame and descendent constructors, leading to latent bugs. + explicit BitVector(size_t len) { this->vInit(len); } + BitVector() { this->vInit(0); } + + /** Build a BitVector by concatenation. */ + BitVector(const BitVector& other1, const BitVector& other2) : VectorBase<char>() + { + assert(this->getData() == 0); + this->vConcat(other1,other2); + } + + /** Construct from a string of "0" and "1". */ + // (pat) Characters that are not '0' or '1' map to '0'. + BitVector(const char* valString); + //@} + + /**@name Casts and overrides of Vector operators. */ + //@{ + // (pat) Please DO NOT add a const anywhere in this method. Use cloneSegment instead. + BitVector segment(size_t start, size_t span) + { + char* wStart = this->begin() + start; + char* wEnd = wStart + span; + assert(wEnd<=this->end()); +#if BITVECTOR_REFCNTS + return BitVector(mData,wStart,wEnd); +#else + return BitVector(NULL,wStart,wEnd); +#endif + } + + // (pat) Historically the BitVector segment method had const and non-const versions with different behavior. + // I changed the name of the const version to cloneSegment and replaced all uses throughout OpenBTS. + const BitVector cloneSegment(size_t start, size_t span) const + { + BitVector seg = const_cast<BitVector*>(this)->segment(start,span); + // (pat) We are depending on the Return Value Optimization not to invoke the copy-constructor on the result, + // which would result in its immediate destruction while we are still using it. + BitVector result; + result.clone(seg); + return result; + } + + BitVector alias() const { + return const_cast<BitVector*>(this)->segment(0,size()); + } + + BitVector head(size_t span) { return segment(0,span); } + BitVector tail(size_t start) { return segment(start,size()-start); } + + // (pat) Please do NOT put the const version of head and tail back in, because historically they were messed up. + // Use cloneSegment instead. + //const BitVector head(size_t span) const { return segment(0,span); } + //const BitVector tail(size_t start) const { return segment(start,size()-start); } + //@} + + + void zero() { fill(0); } + + /**@name FEC operations. */ + //@{ + /** Calculate the syndrome of the vector with the given Generator. */ + uint64_t syndrome(Generator& gen) const; + /** Calculate the parity word for the vector with the given Generator. */ + uint64_t parity(Generator& gen) const; + //@} + + + /** Invert 0<->1. */ + void invert(); + + /**@name Byte-wise operations. */ + //@{ + /** Reverse an 8-bit vector. */ + void reverse8(); + /** Reverse groups of 8 within the vector (byte reversal). */ + void LSB8MSB(); + //@} + + /**@name Serialization and deserialization. */ + //@{ + uint64_t peekField(size_t readIndex, unsigned length) const; + uint64_t peekFieldReversed(size_t readIndex, unsigned length) const; + uint64_t readField(size_t& readIndex, unsigned length) const; + uint64_t readFieldReversed(size_t& readIndex, unsigned length) const; + void fillField(size_t writeIndex, uint64_t value, unsigned length); + void fillFieldReversed(size_t writeIndex, uint64_t value, unsigned length); + void writeField(size_t& writeIndex, uint64_t value, unsigned length); + void writeFieldReversed(size_t& writeIndex, uint64_t value, unsigned length); + void write0(size_t& writeIndex) { writeField(writeIndex,0,1); } + void write1(size_t& writeIndex) { writeField(writeIndex,1,1); } + + //@} + + /** Sum of bits. */ + unsigned sum() const; + + /** Reorder bits, dest[i] = this[map[i]]. */ + void map(const unsigned *map, size_t mapSize, BitVector& dest) const; + + /** Reorder bits, dest[map[i]] = this[i]. */ + void unmap(const unsigned *map, size_t mapSize, BitVector& dest) const; + + /** Pack into a char array. */ + void pack(unsigned char*) const; + + /* Roman: This is here for debugging */ + void pack2(unsigned char*) const; + + // Same as pack but return a string. + std::string packToString() const; + + /** Unpack from a char array. */ + void unpack(const unsigned char*); + + /** Make a hexdump string. */ + void hex(std::ostream&) const; + std::string hexstr() const; + + /** Unpack from a hexdump string. + * @returns true on success, false on error. */ + bool unhex(const char*); + + // For this method, 'other' should have been run through the copy-constructor already + // (unless it was newly created, ie foo.dup(L2Frame(...)), in which case we are screwed anyway) + // so the call to makeAlias is redundant. + // This only works if other is already an alias. + void dup(BitVector other) { assert(!this->getData()); makeAlias(other); assert(this->mStart == other.mStart); } + void dup(BitVector &other) { makeAlias(other); assert(this->mStart == other.mStart); } + +#if 0 + void operator=(const BitVector& other) { + printf("BitVector::operator=\n"); + assert(0); + //this->dup(other); + } +#endif + + bool operator==(const BitVector &other) const; + + /** Copy to dst, not including those indexed in puncture. */ + void copyPunctured(BitVector &dst, const unsigned *puncture, const size_t plth); + + /** Index a single bit. */ + // (pat) Cant have too many ways to do this, I guess. + bool bit(size_t index) const + { + // We put this code in .h for fast inlining. + const char *dp = this->begin()+index; + assert(dp<this->end()); + return (*dp) & 0x01; + } + + char& operator[](size_t index) + { + assert(this->mStart+index<this->mEnd); + return this->mStart[index]; + } + + const char& operator[](size_t index) const + { + assert(this->mStart+index<this->mEnd); + return this->mStart[index]; + } + + /** Set a bit */ + void settfb(size_t index, int value) + { + char *dp = this->mStart+index; + assert(dp<this->mEnd); + *dp = value; + } + + typedef char* iterator; + typedef const char* const_iterator; +}; + +// (pat) BitVector2 was an intermediate step in fixing BitVector but is no longer needed. +#define BitVector2 BitVector + + +std::ostream& operator<<(std::ostream&, const BitVector&); + + + + + + +/** + The SoftVector class is used to represent a soft-decision signal. + Values 0..1 represent probabilities that a bit is "true". + */ +class SoftVector: public Vector<float> { + + public: + + /** Build a SoftVector of a given length. */ + SoftVector(size_t wSize=0):Vector<float>(wSize) {} + + /** Construct a SoftVector from a C string of "0", "1", and "X". */ + SoftVector(const char* valString); + + /** Construct a SoftVector from a BitVector. */ + SoftVector(const BitVector& source); + + /** + Wrap a SoftVector around a block of floats. + The block will be delete[]ed upon desctuction. + */ + SoftVector(float *wData, unsigned length) + :Vector<float>(wData,length) + {} + + SoftVector(float* wData, float* wStart, float* wEnd) + :Vector<float>(wData,wStart,wEnd) + { } + + /** + Casting from a Vector<float>. + Note that this is NOT pass-by-reference. + */ + SoftVector(Vector<float> source) + :Vector<float>(source) + {} + + + /**@name Casts and overrides of Vector operators. */ + //@{ + SoftVector segment(size_t start, size_t span) + { + float* wStart = mStart + start; + float* wEnd = wStart + span; + assert(wEnd<=mEnd); + return SoftVector(NULL,wStart,wEnd); + } + + SoftVector alias() + { return segment(0,size()); } + + const SoftVector segment(size_t start, size_t span) const + { return (SoftVector)(Vector<float>::segment(start,span)); } + + SoftVector head(size_t span) { return segment(0,span); } + const SoftVector head(size_t span) const { return segment(0,span); } + SoftVector tail(size_t start) { return segment(start,size()-start); } + const SoftVector tail(size_t start) const { return segment(start,size()-start); } + //@} + + // (pat) How good is the SoftVector in the sense of the bits being solid? + // Result of 1 is perfect and 0 means all the bits were 0.5 + // If plow is non-NULL, also return the lowest energy bit. + float getEnergy(float *low=0) const; + float getSNR() const; + + /** Fill with "unknown" values. */ + void unknown() { fill(0.5F); } + + /** Return a hard bit value from a given index by slicing. */ + bool bit(size_t index) const + { + const float *dp = mStart+index; + assert(dp<mEnd); + return (*dp)>0.5F; + } + + /** Slice the whole signal into bits. */ + BitVector sliced() const; + + /** Copy to dst, adding in 0.5 for those indexed in puncture. */ + void copyUnPunctured(SoftVector &dst, const unsigned *puncture, const size_t plth); + + /** Return a soft bit. */ + float softbit(size_t index) const + { + const float *dp = mStart+index; + assert(dp<mEnd); + return *dp; + } + + /** Set a soft bit */ + void settfb(size_t index, float value) + { + float *dp = mStart+index; + assert(dp<mEnd); + *dp = value; + } +}; + + + +std::ostream& operator<<(std::ostream&, const SoftVector&); + + + + +#endif +// vim: ts=4 sw=4 |