ENEE350 Computer Organization Lecture-9 Return to lecture notes I went over Vesp 2.0:
/*****************************************************************************/ /* VESP COMPUTER-2.0 * /* Author: A. Yavuz Oruc * /* Copyright © 2000,2004. * /* 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 Sabatech Corporation. * * /*Neither Sabatech 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.h> #include <iomanip.h> #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(void); 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,lor,shl,shr,mxf,mxt; } architecture; architecture vesp; int j=1; int main(void) {int address = 0,i = 0,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; char filename[16]; 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; cout << "Enter 0 to type in your program or 1 to read it from a file: "; cin >> action; if(action != 0) {cout << "Enter the file name: "; cin >> filename; if( (file = fopen(filename,"r")) != NULL) { while (fscanf(file,"%x",&instruction) != EOF && address < 8192 ) { vesp.MEMORY[address] = instruction; address = address + 1; /* cout << hex << address << "\n"; */ } } fclose(file); } 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 << "Enter the file name: "; cin >> filename; if( (file = fopen(filename,"w")) != NULL) {address = vesp.PC; while (address < progend ) { fprintf(file,"%4X\n",vesp.MEMORY[address]); //fputs("\n",file); address = address + 1; } } fclose(file); } 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(); 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(void) { //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 cout << "MAR = "; printf("%04X",vesp.MAR); cout << ", "; vesp.IR = vesp.MEMORY[vesp.MAR]; vesp.clock = vesp.clock +1; cout << "IR = "; printf("%04X",vesp.IR); cout << ", "; } 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 << "MXP\n"; break; case 15: cout << "MXM\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.lor = 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; } }