/*   `Deep Thought', a softcore CPU implemented on a FPGA

    Copyright (C) 2010 Markus Hofstaetter <markus.manrow@gmx.at>
    Copyright (C) 2010 Martin Perner <e0725782@student.tuwien.ac.at>
    Copyright (C) 2010 Stefan Rebernig <stefan.rebernig@gmail.com>
    Copyright (C) 2010 Manfred Schwarz <e0725898@student.tuwien.ac.at>
    Copyright (C) 2010 Bernhard Urban <lewurm@gmail.com>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>. */

#include "../Iinstr.hpp"

class Cshift : public Iinstr {
		char m_typ;
	public:
		Cshift();
		void evalInstr();
		void execInstr();
		std::string toString();
		Iinstr* getNew();
};

/**
 * Name:      create_instruction
 * Purpose:   if compiled as shared library, this functions creates the 
              instruction object

 * Returns:   pointer to instruction object
 */
extern "C" Iinstr* create_instruction() {
    return new Cshift();
}

Iinstr* Cshift::getNew()
{
	return new Cshift();
}
/**
 * Name:      destroy_instruction
 * Purpose:   if compiled as shared library, this functions destoys the 
              instruction object

 * Parameter: IInstruction - the instruction object to delete
 */
extern "C" void destroy_instruction(Iinstr* p) {
    delete p;
}

Cshift::Cshift() : m_typ(0)
{
	opcode = B5(01010);
	name = "shift";
}

void Cshift::evalInstr()
{
	this->m_d = argbits[0];
	this->m_c = argbits[1];
	argbits >>= 2;

	dynamic_bitset<> type = argbits;
	type.resize(2);
	this->m_typ = type.to_ulong();

	switch(this->m_typ) {
		case 1:
			cerr << "INVALID shift type, using logic left shift!" << endl;
			this->m_typ = 0;
		case 0:
			this->name = "lls";
			break;
		case 2:
			this->name = "lrs";
			break;
		case 3:
			this->name = "ars";
			break;
		default:
			cerr << "What have you done? 2 bits that have more than 4 values?!" << endl;
	}

	argbits >>= 8;
	dynamic_bitset<> immb = argbits;
	immb.resize(5);
	this->m_imm = immb.to_ulong();
	argbits >>= 5;
	m_ra = this->getRegister(argbits);
	argbits >>= 4;
	m_rd = this->getRegister(argbits);
}

void Cshift::execInstr()
{
	CDatd val = this->m_cpu->getRegister(m_ra);
	switch(this->m_typ) {
		case 0:
		case 1:
//			this->name = "lls";
			for(unsigned int i = 0; i < m_imm; i++) {
				val = val << 1;
			}
			//carry
			if(m_c) {
				this->m_cpu->updateCarry(((val >> BIT_LEN) & 0x1) != 0);
			}
			break;
		case 2:
//			this->name = "lrs";
			{
				bool carry = this->m_cpu->getCarry();
				for(unsigned int i = 0; i < m_imm; i++) {
					val = val >> 1;

					//carry!
					//if user wants carry, and carry is set
					if(this->m_c && carry) {
						//set highest bit 1
						val |= (CDat)(1<<(BIT_LEN-1));
					}
					else {
						//set highest bit 0
						val &= (~(1<<(BIT_LEN-1)));
					}
				}
			}
			break;
		case 3:
//			this->name = "ars";
			//>> is a ars, but val is CDatd => we have to set the MSB manually
			{
				bool msb = (val & (1<<(BIT_LEN-1)) >> (BIT_LEN-1));
				for(unsigned int i = 0; i < m_imm; i++) {
					val = val >> 1;
					if(msb) {
						//set highest bit 1
						val |= (CDat)(1<<(BIT_LEN-1));
					}
					else {
					//set highest bit 0
					val &= (~(1<<(BIT_LEN-1)));
					}
				}
			}
			break;
		default:
			cerr << "What have you done? 2 bits that have more than 4 values?!" << endl;
	}
	this->m_cpu->setRegister(m_rd, val);
}

std::string Cshift::toString()
{
	stringstream op;
	op << this->getName();
	if(m_c) op << "C";
	if(m_d) op << "D";

	op << this->getConditionFlag();
	op << " r" << m_rd << ", r" << m_ra << ", " << m_imm;
	return op.str();
}