|
A. Yavuz Oruç |
Department of Electrical and Computer Engineering |
University of Maryland,College Park, Maryland 20742 |
Please click here to return to main navigation page. Last modified by A. Yavuz Oruç on Tuesday, February 19, 2008 2:14 AM |
/*****************************************************************************/
/* VESP COMPUTER-2.0 *
/* Author: A. Yavuz Oruc *
/* Copyright © 2000,2004, 2008. *
/* Sabatech Corporation (www.sabatech.com) *
/* All rights reserved. *
/*Copying and compiling this program for personal use is permitted. However, *
/*no part of this program may be reproduced or distributed in any form or *
/*by any means, or stored in a database or retrieval system, without the *
/*prior written permission of the Author and AlgoritiX Corporation. *
/*Neither Algoritix nor the Author makes any direct or implied claims *
/*that this program will work accurately and/or generate correct results, *
/*In addition, they provide no warranties direct or implied that using *
/*this program on any computer will be safe in so far as guarding against *
/*destroying and/or deleting any information, data, code, program or file *
/*that may be stored in the memory of user's computer. *
/*****************************************************************************/
/* Please communicate all your questions and comments to */
/* A. Yavuz Oruc at yavuz@sabatech.com */
/*--------------------Changes and additions in this version-------------------*/
/* */
/* -Instruction opcodes 8 through 15 are new in this version of VESP. */
/* vesp.MEMORY[2] is assigned to IX which is used with MXF and MXT */
/* instructions. */
/* -vesp programs which are entered at the console can be saved in a file. */
/* Warning!!!! This program overwrites any data in the filename which is */
/* specified at the console in response to the prompt for saving a vesp */
/* program. Save at your own risk!!!!! */
/******************************************************************************/
/* This computer program simulates the fetch,decode
/* and execute cycles of a hypothetical 16-bit computer,
/* called VESP (_V_Ery _Simple _Processor)
/* Revised to reduce the address field to 12 bits. 2/13/03
/* VESP has the following registers on which it executes 8 instructions:
/* A: 16 bits (Implicit) It refers to location 0 in VESP's memory
/* B: 16 bits (Implicit) It refers to location 1 in VESP's memory
/* IX: 16 bits (Implicit) It refers to location 2 in VESP's memory
/* IR: 16 bits
/* MAR: 12 bits
/* PC: 12 bits
/* Its instruction repertoire consists of the following instructions:
/* ADD: Add Opcode: 0000 ----- A = A+B HexCode: 0
/* CMP: Compl Opcode: 0001 ----- A = ~A HexCode: 1
/* LDA: Load Opcode: 0010 ----- M[IR[4:15] ] = M[MAR+1] HexCode: 2
/* MOV: Move Opcode: 0011 ----- M[IR[4:15] ] = M[M[MAR+1][3:15]] HexCode: 3
/* JMP Jump Opcode: 0100 ----- PC = IR[4:15] HexCode: 4
/* JEZ: Jump if A=0 Opcode: 0101 ----- If (A = 0) PC = IR[4:15] HexCode: 5
/* JPS: Jump if A=+ Opcode: 0110 ----- If (A > 0) PC = IR[4:15] HexCode: 6
/* HLT: Halt Opcode: 0111 ----- reset = 1 HexCode: 7
/* INC: Increment Opcode: 1000 ----- A = A + 1
/* DEC: Decrement Opcode: 1001 ----- A = A - 1
/* AND: And Opcode: 1010 ----- A = A & B
/* IOR: Or Opcode: 1011 ----- A = A | B
/* SHL: Shift left Opcode: 1100 ----- A << 1
/* SHR: Shift right Opcode: 1101 ----- A >> 1
/* MXF Move from w/IX Opcode: 1110 ----- M[IR[3:15]] = M[IX]; IX = IX + 1;HexCode: E
/* MXT Move to w/IX Opcode: 1111 ----- M[IX] = M[IR[3:15]]; IX = IX + 1;HexCode: F
/* Programs are entered and displayed in hex code. */
#include <iostream>
#include <iomanip>
#include <stdio.h>
#include <limits.h>
void initialize(void); int readprogram(void);
void displayprogram(int progend);
void displayregisters(void); void displaymemory(void);
void maincycle(int trace); void fetch(int trace);
void decode(void); void execute(void);
//AYO: Define the registers of the architecture.
typedef struct
{unsigned short MAR,PC,IR,MDR;
unsigned long clock;
short MEMORY[8192],S,C,F,Z,reset,add,cmp,lda,mov,jmp,jez,jps,hlt,inc,dec,lnd,ior,shl,shr,mxf,mxt;
} architecture; architecture vesp;
using namespace std;
int j=1;
int main(void)
{int action,action2,progend;
initialize();//AYO: Initialize all the registers.
cout << "\nWelcome to Vesp 2.0\n\n";
while(1) {vesp.reset = false; //AYO: vesp keeps running unless it is reset.
//AYO: Input program, diplay registers or memory
cin.clear();
cout << "\nType \n 0 to enter a program\n "
<< "1 to display registers\n 2 to display memory: ";
cin >> action2;
cin.clear();
cout << "\n";
//AYO: Read the program, display it, and execute it.
if(action2 == 0)
{progend = readprogram(); displayprogram(progend);
//AYO: Step through or execute the program.
while(vesp.reset == 0)
{cout << "\nEnter 0 if you wish to execute the program, 1 to step it, ";
cout << "2 to exit to the main menu: ";
cin.clear(); cin >> action2;
switch(action2)
{case 0: cout << "Enter 0 for a brief trace 1 for long trace: "; cin.clear(); cin >> action;
cout << "\n";
while(vesp.reset == 0) maincycle(action); break;
case 1: maincycle(1); break;
case 2: vesp.reset = true; break;
}
}
//AYO: Display the number of instructions and clock cycles executed.
if(action2 != 2)
{cout << "The number of instructions executed = " << dec << j-1 << "\n";
cout << "The number of clock cycles used = " << dec << vesp.clock << "\n";
j = 1; vesp.clock = 0;
}
}
if (action2 == 1) displayregisters();
if (action2 == 2) displaymemory();
//if (action == 3) readprogram();
}
}
void initialize(void)
{vesp.PC = vesp.MEMORY[0] = vesp.MEMORY[1] = vesp.IR = 0;
vesp.reset = 0; vesp.clock = 0;
}
int readprogram(void)
{int address,instruction,progend,action,i;
char longfilename[100] ="/UMD-Web-Dreamweaver/teaching/courses/enee350/vesp-source-code/vesp2.0X/", filename[25];
//The above path needs to be changed if the file is located in another directory.
FILE *file;
do{ cout << "Enter your program's starting "
<< "address ( >= 3) as a 3-digit hex number: ";
cin >> hex >> vesp.PC;
} while (vesp.PC < 3);
address = vesp.PC; action = -1;
cout << "\n";
do { cout << "Enter 0 to type in your program or 1 to read it from a file: ";
cin >> action;
} while (action != 0 && action != 1);
if(action == 1)
{cout << "\nEnter the file name: "; cin >> filename;
file = fopen(filename,"r");
if( file != NULL)
{
while (fscanf(file,"%x",&instruction) != EOF && address < 8192 )
{
vesp.MEMORY[address] = instruction; address = address + 1;
}
fclose(file);
}
else
{for (i=0; i <= 24; i++) longfilename[i+72] = filename[i];
file = fopen(longfilename,"r");
if( file != NULL)
{
while (fscanf(file,"%x",&instruction) != EOF && address < 8192 )
{vesp.MEMORY[address] = instruction; address = address + 1;}
fclose(file);
}
else
{cout << "The file is not found. Check if file to be opened is in the program directory... \n"; exit(1);}
}
}
else
do {cin.clear();
cout << "Enter instruction "
<< (address -vesp.PC)
<< " using a 4-digit hex number" << "\n";
cout << "Or type -1 to end your program: ";
cin >> hex >> instruction; //AYO: read it in hex.
vesp.MEMORY[address] = instruction;
address = address + 1;
}
while ( ( vesp.MEMORY[address-1] != -1 ) && (address < 8192)); //AYO: -1 marks the end.
if (address >= 4096)
{cout << "Memory overflow,"
<< "Please quit from the file menu and restart me!";
return address-1;}
progend = address - 1;
//save the program into a file cout << "Enter 0 to continue, 1 to save your program into a file: "; cin >> action;
if(action == 1)
{cout << "\nEnter the file name: "; cin >> filename;
cout << hex;
file = fopen(filename,"w");
if( file != NULL)
{address = vesp.PC;
while (address <= progend )
{
fprintf(file,"%04X\n",vesp.MEMORY[address]);
address = address + 1;
}
fclose(file);
}
else
{for (i=0; i <= 24; i++) longfilename[i+72] = filename[i];
file = fopen(longfilename,"w");
if( file != NULL)
{address = vesp.PC;
cout << hex;
while (address <= progend )
{
fprintf(file,"%04X\n",vesp.MEMORY[address]);
address = address + 1;
}
fclose(file);
}
else
{cout << "The file is not found. Check if file to be opened is in the program directory... \n"; exit(1);}
}
}
return progend;
}
void displayprogram(int progend)
{int i;
cout << "\nHere is your program: \n\n";
for (i = vesp.PC; i<= progend; i++)
{
cout << "Location "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << i << ": "; //AYO: display it in uppercase hex.
cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << (0x0000FFFF & vesp.MEMORY[i]) << "\n";
}
}
void displayregisters(void)
{
cout << "A = "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << (0x0000FFFF & vesp.MEMORY[0])<< ", ";
cout << "B = "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << (0x0000FFFF & vesp.MEMORY[1])<< ", ";
cout << "Z = " << vesp.Z << ", ";
cout << "S = " << vesp.S << ", ";
cout << "C = " << vesp.C << ", ";
cout << "F = " << vesp.F << "\n";
cout << "MAR = "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << vesp.MAR << ", ";
cout << "PC = "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << vesp.PC << ", ";
cout << "IR = "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << vesp.IR << ", ";
cout << "reset = " << vesp.reset << "\n";
}
void displaymemory(void)
{int location1,location2,i;
cout << "Enter the first address (3 hex digits): ";
cin.clear();
cin >> hex >> location1;
cin.clear();
cout << "Enter the last address: (3 hex digits): ";
cin.clear();
cin >> hex >> location2;
cin.clear();
for (i = location1; i <= location2; i++)
{cout << "Location "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << i << " : ";
cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << (0x0000FFFF & vesp.MEMORY[i]); cout << "\n";
}
}
void maincycle(int trace)
{ cout << "Machine Cycle " << j << ": ";
j = j+1;
//AYO: Fetch Step
cout << "PC = "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << (vesp.PC & 0x0FFF) << ", ";
cout << "\nFETCH SUBCYCLE\n";
fetch(trace);
cout << "\nClock cycle = " << vesp.clock << "\n";
//AYO: Decode Step
cout << "DECODE SUBCYCLE\n";
decode();
cout << "Clock cycle = " << vesp.clock << "\n";
//AYO: Execute Step
cout << "EXECUTE SUBCYCLE";
vesp.add = vesp.cmp = 0;
execute();
cout << "\nClock cycle = " << vesp.clock << "\n\n";
//AYO: Display the registers
if(trace == 1)
{
displayregisters();
cout << "add = " << vesp.add << " ";
cout << "complement = " << vesp.cmp << "\n\n";
if( (vesp.IR >> 12 ) == 2 || (vesp.IR >> 12 ) == 3)
{cout << "Memory[";
cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << (vesp.IR & 0x0FFF) << "] = ";
cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << (0x0000FFFF & vesp.MEMORY[vesp.IR & 0x0FFF])<< "\n\n";
}
}
}
void fetch(int trace)
{ //clock cycle 1. Load next instruction's address into MAR.
vesp.MAR = vesp.PC; vesp.clock = vesp.clock +1;
vesp.PC = vesp.PC +1; //Increment PC.
//clock cycle 2. Fetch the next Instruction into IR
if(trace == 1)
{cout << "MAR = "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << vesp.MAR << ", ";}
vesp.IR = vesp.MEMORY[vesp.MAR]; vesp.clock = vesp.clock +1;
if(trace == 1)
{cout << "IR = "; cout.fill('0'); cout.width(4); cout.setf(ios::uppercase);
cout << hex << vesp.IR << ", ";}
}
void decode(void)
{cout << "Decoded instruction is: ";
switch( vesp.IR >> 12)
{//Add //Complement
case 0: cout << "ADD\n"; break; case 1: cout << "CMP\n"; break;
//Load //Move
case 2: cout << "LDA\n"; break; case 3: cout << "MOV\n"; break;
//Jump //Jump if A = 0
case 4: cout << "JMP\n"; break; case 5: cout << "JEZ\n"; break;
//Jump if A > 0 //Halt
case 6: cout << "JPS\n"; break; case 7: cout << "HLT\n"; break;
//Increment //Decrement
case 8: cout << "INC\n"; break; case 9: cout << "DEC\n"; break;
//And //Or
case 10: cout << "AND\n"; break; case 11: cout << "IOR\n"; break;
//Shift left //Shift right
case 12: cout << "SHL\n"; break; case 13: cout << "SHR\n"; break;
//Add with IX+ //Add with IX-
case 14: cout << "MXF\n"; break; case 15: cout << "MXT\n"; break;
}
}
void execute(void)
{ short temp;
switch(vesp.IR >> 12)
{//clock cycle 3.
//Add
case 0:
temp = vesp.MEMORY[0] + vesp.MEMORY[1]; vesp.clock = vesp.clock +1;
if(vesp.MEMORY[0] > 0 && vesp.MEMORY[1] > 0 && temp < 0 ||
vesp.MEMORY[0] < 0 && vesp.MEMORY[1] < 0 && temp >= 0)
vesp.F = 1; else vesp.F = 0; //AYO: Set Overflow Flag
if (vesp.MEMORY[0] < 0 && vesp.MEMORY[1] < 0 || temp > 0 &&
(vesp.MEMORY[0] < 0 && vesp.MEMORY[1] > 0 || vesp.MEMORY[0] > 0 && vesp.MEMORY[1] < 0))
vesp.C = 1; else vesp.C = 0; //AYO: Set Carry Flag
vesp.MEMORY[0] = temp; //Save the sum in MEMORY[0]
//AYO: Set Zero Flag
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
//AYO: Set Sign Flag
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15; vesp.add = 1; break;
//Complement
case 1: vesp.MEMORY[0] = ~vesp.MEMORY[0];
vesp.clock = vesp.clock +1;
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15;
vesp.cmp = 1; break;
//Load
case 2: vesp.MAR += 1;
vesp.clock = vesp.clock +1;
vesp.MDR = vesp.MEMORY[vesp.MAR];
vesp.MAR = vesp.IR&0x0FFF; //without an extra clock
vesp.clock = vesp.clock +1;
vesp.MEMORY[vesp.MAR] = vesp.MDR;
vesp.clock = vesp.clock +1; vesp.lda = 1;
//AYO: Set Zero Flag
if(vesp.MAR == 0 && vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
//AYO: Set Sign Flag
if(vesp.MAR == 0)
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15;
vesp.PC = vesp.PC + 1; break;
//Move
case 3: vesp.MAR += 1;
vesp.clock = vesp.clock +1;
vesp.MDR = vesp.MEMORY[vesp.MAR];
vesp.clock = vesp.clock +1;
vesp.MAR = vesp.MDR;
vesp.clock = vesp.clock +1;
vesp.MDR = vesp.MEMORY[vesp.MAR];
vesp.MAR = vesp.IR&0x0FFF; //without an extra clock
vesp.clock = vesp.clock +1;
vesp.MEMORY[vesp.MAR] = vesp.MDR;
vesp.clock = vesp.clock + 1; vesp.mov = 1;
//AYO: Set Zero Flag
if(vesp.MAR == 0 && vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
//AYO: Set Sign Flag
if(vesp.MAR == 0)
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15;
vesp.PC = vesp.PC + 1; break;
//Jump
case 4: vesp.PC = vesp.IR & 0x1FFF; vesp.jmp = 1;
vesp.clock = vesp.clock +1; break;
//Jump if A is 0
case 5: if (vesp.MEMORY[0] == 0)
{vesp.PC = vesp.IR & 0x0FFF;} vesp.jez = 1;
vesp.clock = vesp.clock +1; break;
//Jump if A is > 0
case 6: if (vesp.MEMORY[0] > 0)
{vesp.PC = vesp.IR & 0x0FFF;} vesp.jps = 1;
vesp.clock = vesp.clock +1; break;
//Halt
case 7: vesp.reset = true; vesp.clock = vesp.clock +1; break;
//INC
case 8:
temp = vesp.MEMORY[0] + 1; vesp.clock = vesp.clock +1;
if(vesp.MEMORY[0] > 0 && vesp.MEMORY[1] > 0 && temp < 0 ||
vesp.MEMORY[0] < 0 && vesp.MEMORY[1] < 0 && temp >= 0)
vesp.F = 1; else vesp.F = 0; //AYO: Set Overflow Flag
if (vesp.MEMORY[0] < 0 && vesp.MEMORY[1] < 0 || temp > 0 &&
(vesp.MEMORY[0] < 0 && vesp.MEMORY[1] > 0 || vesp.MEMORY[0] > 0 && vesp.MEMORY[1] < 0))
vesp.C = 1; else vesp.C = 0; //AYO: Set Carry Flag
vesp.MEMORY[0] = temp; //Save the sum in MEMORY[0]
//AYO: Set Zero Flag
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
//AYO: Set Sign Flag
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15; vesp.inc = 1; break;
//AYO: In this implementation, vesp.inc is just symbolically set to 1.
//In a bus implementation, the input bus must be loaded with 1 and the
//vesp's computation engine must be programmed to add its operands.
//DEC
case 9:
temp = vesp.MEMORY[0] - 1; vesp.clock = vesp.clock +1;
if(vesp.MEMORY[0] > 0 && vesp.MEMORY[1] > 0 && temp < 0 ||
vesp.MEMORY[0] < 0 && vesp.MEMORY[1] < 0 && temp >= 0)
vesp.F = 1; else vesp.F = 0; //AYO: Set Overflow Flag
if (vesp.MEMORY[0] < 0 && vesp.MEMORY[1] < 0 || temp > 0 &&
(vesp.MEMORY[0] < 0 && vesp.MEMORY[1] > 0 || vesp.MEMORY[0] > 0 && vesp.MEMORY[1] < 0))
vesp.C = 1; else vesp.C = 0; //AYO: Set Carry Flag
vesp.MEMORY[0] = temp; //Save the sum in MEMORY[0]
//AYO: Set Zero Flag
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
//AYO: Set Sign Flag
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15; vesp.dec = 1; break;
//AYO: In this implementation, vesp.dec is just symbolically set to 1.
//In a bus implementation, the input bus must be loaded with 1 and complemented;
// carry-in must be set to vesp.dec, and the vesp's computation engine
// must be programmed to add its operands.
//AND
case 10:
temp = vesp.MEMORY[0] & vesp.MEMORY[1]; vesp.clock = vesp.clock +1;
vesp.MEMORY[0] = temp; //Save the sum in MEMORY[0]
//AYO: Set Zero Flag
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0; vesp.lnd = 1; break;
//IOR
case 11:
temp = vesp.MEMORY[0] | vesp.MEMORY[1]; vesp.clock = vesp.clock +1;
vesp.MEMORY[0] = temp; //Save the sum in MEMORY[0]
//AYO: Set Zero Flag
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0; vesp.ior = 1; break;
//SHL
case 12:
temp = vesp.MEMORY[0] << 1; vesp.clock = vesp.clock +1;
vesp.MEMORY[0] = temp; //Save the sum in MEMORY[0]
//AYO: Set Zero Flag
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
//AYO: Set Sign Flag
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15; vesp.shl = 1; break;
//SHR
case 13:
temp = vesp.MEMORY[0] >> 1; vesp.clock = vesp.clock +1;
vesp.MEMORY[0] = temp; //Save the sum in MEMORY[0]
//AYO: Set Zero Flag
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
//AYO: Set Sign Flag
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15; vesp.shr = 1; break;
//MXF (index is used to copy a list of operands into a location one at a time.)
case 14:
vesp.MAR = vesp.MEMORY[2]; // read the next operand
vesp.clock = vesp.clock +1;
vesp.MDR = vesp.MEMORY[vesp.MAR];
vesp.MAR = vesp.IR&0x0FFF; //without an extra clock
vesp.clock = vesp.clock +1;
vesp.MEMORY[vesp.MAR] = vesp.MDR; // move the operand to the specified address
vesp.MEMORY[2]++; //without an extra clock
vesp.clock = vesp.clock +1;
//AYO: Set Zero Flag
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
//AYO: Set Sign Flag
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15; vesp.mxf = 1; break;
//MXT (index is used to copy an operand to a set of locations one at a time.)
case 15:
vesp.MAR = vesp.IR&0x0FFF; // read the operand
vesp.clock = vesp.clock +1;
vesp.MDR = vesp.MEMORY[vesp.MAR];
vesp.MAR = vesp.MEMORY[2]; //without an extra clock
vesp.clock = vesp.clock +1;
vesp.MEMORY[vesp.MAR] = vesp.MDR; //move the operand to the next location
vesp.MEMORY[2]++; //without an extra clock
vesp.clock = vesp.clock +1;
//AYO: Set Zero Flag
if(vesp.MEMORY[0] == 0) vesp.Z = 1; else vesp.Z = 0;
//AYO: Set Sign Flag
vesp.S = (vesp.MEMORY[0] & 0x8000 ) >> 15; vesp.mxt = 1; break;
}
}
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Last modified by A. Yavuz Oruç on
Tuesday, February 19, 2008 2:14 AM