/*****************************************************************************

  The following code is derived, directly or indirectly, from the SystemC
  source code Copyright (c) 1996-2004 by all Contributors.
  All Rights reserved.

  The contents of this file are subject to the restrictions and limitations
  set forth in the SystemC Open Source License Version 2.4 (the "License");
  You may not use this file except in compliance with such restrictions and
  limitations. You may obtain instructions on how to receive a copy of the
  License at http://www.systemc.org/. Software distributed by Contributors
  under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF
  ANY KIND, either express or implied. See the License for the specific
  language governing rights and limitations under the License.

 *****************************************************************************/

/*****************************************************************************
 
  exec.cpp -- Integer Execution Unit.
 
  Original Author: Martin Wang, Synopsys, Inc.
 
 *****************************************************************************/
 
/*****************************************************************************
 
  MODIFICATION LOG - modifiers, enter your name, affiliation, date and
  changes you are making here.
 
      Name, Affiliation, Date:
  Description of Modification:
 
 *****************************************************************************/


#include "systemc.h"
#include "exec.h"
#include "directive.h"


void exec::entry(){

  int			        opcode_tmp = 0;
  int				add1_tmp = 0;
  signed int		        dina_tmp = 0;
  signed int		        dinb_tmp = 0;
  signed int		        dout_tmp = 0;
  unsigned int		        dest_tmp = 0;

  //
  // main loop
  //
  // 

  // initialization of output

  wait(3);
  while(1) {
   	if (in_valid.read() == true) {
		 dina_tmp = dina.read();
		 dinb_tmp = dinb.read();
		 opcode_tmp = opcode.read();
		 dest_tmp = dest.read();

    		// output MUX
    		switch (opcode_tmp) {
        		case 0:         // Stall 
                	dout_tmp = dout_tmp;
                	wait();
                	break;
		case 1: 	// add with carry
    			dout_tmp = dina_tmp + dinb_tmp + add1_tmp;
			wait();
			break;
		case 2: 	// sub with carry
    			dout_tmp = dina_tmp - dinb_tmp - add1_tmp;
			wait();
			break;
        	case 3:         // add without carry
               	 	dout_tmp = dina_tmp + dinb_tmp;
                	wait();
                	break;
        	case 4:         // sub without carry
               	 	dout_tmp = dina_tmp - dinb_tmp;
                	wait();
                	break;
        	case 5:         // multiply assume 2 clock cycle multiplication
                	dout_tmp = dina_tmp * dinb_tmp;
                	//wait();	so that BC have something to do
                	wait();
                	break;
        	case 6:         // divide assume 2 clock cycle multiplication
			if (dinb_tmp == 0) {
				printf("Division Exception - Divide by zero \n");
			} else {
                		dout_tmp = dina_tmp / dinb_tmp;
			}
                	// wait();	so that BC have something to do
                	wait();
                	break;
        	case 7:         // bitwise NAND
                	dout_tmp = ~(dina_tmp & dinb_tmp);
                	wait();
                	break;
        	case 8:         // bitwise AND 
                	dout_tmp = dina_tmp & dinb_tmp;
                	wait();
			break;
        	case 9:         // bitwise OR
                	dout_tmp = dina_tmp | dinb_tmp;
                	wait();
			break;
        	case 10:         // bitwise XOR
               	 	dout_tmp = dina_tmp ^ dinb_tmp;
                	wait();
			break;
        	case 11:         // bitwise complement
                	dout_tmp = ~ dina_tmp;
                	wait();
			break;
        	case 12:         // left shift
                	dout_tmp = dina_tmp << dinb_tmp;
                	wait();
			break;
        	case 13:         // right shift
                	dout_tmp = dina_tmp >> dinb_tmp;
                	wait();
			break;
		case 14: 	// modulo
    			dout_tmp = dina_tmp % dinb_tmp;
			wait();
			break;
		default:
			printf("ALU:      Bad Opcode %d.\n",opcode_tmp);
			break;
    		}
    

    		dout.write(dout_tmp);
    		out_valid.write(true);
		destout.write(dest_tmp);

		if (dout_tmp == 0) {
			Z.write(true);
		} else {
			Z.write(false);
		}
		if (dout_tmp > 2^32) {
			V.write(true);
		}else {
			V.write(false);
		}
		printf("\t\t\t\t\t\t\t-------------------------------\n");
    		cout << "\t\t\t\t\t\t\tALU :" << " op= " << opcode_tmp 
			<< " A= " << dina_tmp << " B= " << dinb_tmp << endl;
    		cout << "\t\t\t\t\t\t\tALU :" << " R= " << dout_tmp << "-> R" << dest_tmp;
             	cout << " at CSIM " << sc_time_stamp() << endl;
		printf("\t\t\t\t\t\t\t-------------------------------\n");
    		wait();
    		out_valid.write(false);
    		wait();

	} else {
		wait();
	}
	
  }

}

