/*
 * A barrel shifter for FloPoCo
 *
 * Author : Florent de Dinechin, Bogdan Pasca
 *
 * This file is part of the FloPoCo project developed by the Arenaire
 * team at Ecole Normale Superieure de Lyon
 *
 * This program 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 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 General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  
*/

#include <iostream>
#include <sstream>
#include <vector>
#include <gmp.h>
#include <mpfr.h>
#include <stdio.h>
#include <gmpxx.h>
#include "utils.hpp"
#include "Operator.hpp"

#include "Shifters.hpp"

using namespace std;

// TODO there is a small inefficiency here, as most bits of s don't need to be copied all the way down

namespace flopoco{


	Shifter::Shifter(Target* target, int wIn, int maxShift, ShiftDirection direction, map<string, double> inputDelays) :
		Operator(target), wIn_(wIn), maxShift_(maxShift), direction_(direction) {
	
		setOperatorName();

		// -------- Parameter set up -----------------
		wOut_         = wIn_ + maxShift_;
		wShiftIn_     = intlog2(maxShift_);
		maxInputDelay_ = getMaxInputDelays(inputDelays); 

		addInput ("X", wIn_);
		addInput ("S", wShiftIn_);  
		addOutput("R", wOut_);

		vhdl << tab << declare("level0",wIn_  ) << "<= X;" <<endl;
		vhdl << tab << declare("ps", wShiftIn_) << "<= S;" <<endl;
	
		// local variables
		double period = (1.0)/target->frequency();
		double stageDelay = 0.0;
		int    lastRegLevel = -1;
		int    unregisteredLevels = 0;
		int    dep = 0;
		
		for (int currentLevel=0; currentLevel<wShiftIn_; currentLevel++){
			//compute current level delay
			//TODO REMEMBER WHY THIS DOES WORK
			unregisteredLevels = currentLevel - lastRegLevel;
			if ( intpow2(unregisteredLevels-1) > wIn_+currentLevel+1 ) 
				dep = wIn + currentLevel + unregisteredLevels;
			else
				dep = intpow2(unregisteredLevels-1);
		
			if (verbose)
				cerr<<"> Shifters\t depth = "<<dep<<" at i="<<currentLevel<<endl;	

			stageDelay = intlog(mpz_class(target->lutInputs()), mpz_class(dep)) * target->lutDelay() + (intlog(mpz_class(target->lutInputs()),mpz_class(dep))-1) * target->localWireDelay();
			if (lastRegLevel == -1)
				stageDelay+= maxInputDelay_;
		
			if (stageDelay>period){
				lastRegLevel = currentLevel;
				nextCycle(); ////////////////////////////////////////////////
			}
			ostringstream currentLevelName, nextLevelName;
			currentLevelName << "level"<<currentLevel;
			nextLevelName << "level"<<currentLevel+1;
			if (direction==Right){
				vhdl << tab << declare(nextLevelName.str(),wIn+intpow2(currentLevel+1)-1 ) 
					  <<"<=  ("<<intpow2(currentLevel)-1 <<" downto 0 => '0') & "<<use(currentLevelName.str())<<" when "<<use("ps");
				if (wShiftIn_ > 1) 
					vhdl << "(" << currentLevel << ")";
				vhdl << " = '1' else "
					  << tab << use(currentLevelName.str()) <<" & ("<<intpow2(currentLevel)-1<<" downto 0 => '0');"<<endl;
			}else{
				vhdl << tab << declare(nextLevelName.str(),wIn+intpow2(currentLevel+1)-1 )
					  << "<= " << use(currentLevelName.str()) << " & ("<<intpow2(currentLevel)-1 <<" downto 0 => '0') when "<<use("ps");
				if (wShiftIn_>1) 
					vhdl << "(" << currentLevel<< ")";
				vhdl << "= '1' else "
					  << tab <<" ("<<intpow2(currentLevel)-1<<" downto 0 => '0') & "<< use(currentLevelName.str()) <<";"<<endl;
			}
			
		}
		//update the output slack
		outDelayMap["R"] = period - stageDelay;
	
		ostringstream lastLevelName;
		lastLevelName << "level"<<wShiftIn_;
		if (direction==Right)
			vhdl << tab << "R <= "<<use(lastLevelName.str())<<"("<< wIn + intpow2(wShiftIn_)-1-1 << " downto " << wIn_ + intpow2(wShiftIn_)-1 - wOut_ <<");"<<endl;
		else
			vhdl << tab << "R <= "<<use(lastLevelName.str())<<"("<< wOut_-1 << " downto 0);"<<endl;


	}

	Shifter::~Shifter() {
	}

	void Shifter::setOperatorName(){
		ostringstream name;
		if(direction_==Left) name <<"LeftShifter_";
		else                 name <<"RightShifter_";
		name<<wIn_<<"_by_max_"<<maxShift_;
		uniqueName_=name.str();
	}

	void Shifter::outputVHDL(std::ostream& o, std::string name) {
		ostringstream signame;
		licence(o,"Florent de Dinechin, Bogdan Pasca (2007,2008,2009)");
		Operator::stdLibs(o);
		outputVHDLEntity(o);
		newArchitecture(o,name);
		o << buildVHDLSignalDeclarations();
		beginArchitecture(o);
		o << buildVHDLRegisters();
		o << vhdl.str();
		endArchitecture(o);
	}

	void Shifter::emulate(TestCase* tc)
	{
		mpz_class sx = tc->getInputValue("X");
		mpz_class ss = tc->getInputValue("S");
		mpz_class sr ;

		mpz_class shiftedInput = sx;
		int i;
	
		if (direction_==Left){
			mpz_class shiftAmount = ss;
			for (i=0;i<shiftAmount;i++)
				shiftedInput=shiftedInput*2;
		
			for (i= wIn_+intpow2(wShiftIn_)-1-1; i>=wOut_;i--)
				if ( mpzpow2(i) <= shiftedInput )
					shiftedInput-=mpzpow2(i);
		}else{
			mpz_class shiftAmount = maxShift_-ss;

			if (shiftAmount > 0){
				for (i=0;i<shiftAmount;i++)
					shiftedInput=shiftedInput*2;
			}else{
				for (i=0;i>shiftAmount;i--)
					shiftedInput=shiftedInput/2;
			}
		}

		sr=shiftedInput;
		tc->addExpectedOutput("R", sr);
	}



}