/* | |

* Copyright (c) 2015 ARM Limited | |

* All rights reserved | |

* | |

* The license below extends only to copyright in the software and shall | |

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* to a hardware implementation of the functionality of the software | |

* licensed hereunder. You may use the software subject to the license | |

* terms below provided that you ensure that this notice is replicated | |

* unmodified and in its entirety in all distributions of the software, | |

* modified or unmodified, in source code or in binary form. | |

* | |

* Redistribution and use in source and binary forms, with or without | |

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* met: redistributions of source code must retain the above copyright | |

* notice, this list of conditions and the following disclaimer; | |

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* notice, this list of conditions and the following disclaimer in the | |

* documentation and/or other materials provided with the distribution; | |

* neither the name of the copyright holders nor the names of its | |

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* this software without specific prior written permission. | |

* | |

* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |

* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |

* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |

* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |

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*/ | |

#ifndef __SIM_LINEAR_SOLVER_HH__ | |

#define __SIM_LINEAR_SOLVER_HH__ | |

#include <cassert> | |

#include <sstream> | |

#include <string> | |

#include <vector> | |

namespace gem5 | |

{ | |

/** | |

* This class describes a linear equation with constant coefficients. | |

* The equation has a certain (variable) number of unkowns and it can hold | |

* N+1 coefficients. | |

*/ | |

class LinearEquation | |

{ | |

public: | |

LinearEquation(unsigned unknowns) { | |

eq = std::vector <double> (unknowns + 1, 0); | |

} | |

// Add two equations | |

LinearEquation operator+ (const LinearEquation& rhs) { | |

assert(this->eq.size() == rhs.eq.size()); | |

LinearEquation res(this->eq.size() - 1); | |

for (unsigned i = 0; i < res.eq.size(); i++) | |

res.eq[i] = this->eq[i] + rhs.eq[i]; | |

return res; | |

} | |

// Multiply the equation by a constant | |

LinearEquation & operator*= (const double cnt) { | |

for (auto & c: eq) | |

c *= cnt; | |

return *this; | |

} | |

// Access a certain equation coefficient | |

double & operator[] (unsigned unkw) { | |

assert(unkw < eq.size()); | |

return eq[unkw]; | |

} | |

// Get a string representation | |

std::string toStr() const { | |

std::ostringstream oss; | |

for (unsigned i = 0; i < eq.size(); i++) { | |

if (i) | |

oss << " + "; | |

oss << eq[i]; | |

if (i != eq.size() - 1) | |

oss << "*x" << i; | |

} | |

oss << " = 0"; | |

return oss.str(); | |

} | |

// Index for the constant term | |

unsigned cnt() const { return eq.size() - 1; } | |

private: | |

/** Coefficients */ | |

std::vector <double> eq; | |

}; | |

class LinearSystem | |

{ | |

public: | |

LinearSystem(unsigned unknowns) { | |

for (unsigned i = 0; i < unknowns; i++) | |

matrix.push_back(LinearEquation(unknowns)); | |

} | |

LinearEquation & operator[] (unsigned eq) { | |

assert(eq < matrix.size()); | |

return matrix[eq]; | |

} | |

std::string toStr() const { | |

std::string r; | |

for (auto & eq: matrix) | |

r += eq.toStr() + "\n"; | |

return r; | |

} | |

std::vector <double> solve() const; | |

private: | |

std::vector < LinearEquation > matrix; | |

}; | |

} // namespace gem5 | |

#endif |