203 lines
4.0 KiB
C++
203 lines
4.0 KiB
C++
/*
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* File: Cpu6502.cpp
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* Author: Christopher
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*
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* Created on December 12, 2013, 10:14 PM
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*/
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#include "Cpu6502.h"
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#include "TransNetwork.h"
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#include "trans.h"
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#include "addressbus.h"
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#include "Trace.h"
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#include <iostream>
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#include "StateCalculator.h"
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#define TRACEREG 1
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//#define TRACESEG 1
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//#define TRACEMEM 1
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#ifdef TRACEREG
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#define dumpRegs() this->trace.dumpRegisters()
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#else
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#define dumpRegs()
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#endif
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#ifdef TRACESEG
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#define dumpSegs() dumpSegments()
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#else
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#define dumpSegs()
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#endif
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void Cpu6502::powerOn() {
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std::cout << "initial state" << std::endl;
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dumpRegs();
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dumpSegs();
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/*
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* Since we use segs[CLK0].on as our own
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* temporary variable (see "step" method), we
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* need to initialize it here, to "phase one".
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*/
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n->CLK0->on = true;
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std::cout << "setting input pins..." << std::endl;
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initPins();
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std::cout << "initial full calculation..." << std::endl;
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recalc(segs.all());
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dumpRegs();
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dumpSegs();
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}
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void Cpu6502::setSeg(Segment* s, bool on) {
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s->set(on);
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}
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void Cpu6502::recalc(Segment* s) {
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StateCalculator::recalc(s);
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}
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void Cpu6502::recalc(std::set<Segment*> s) {
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StateCalculator::recalc(s);
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}
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void Cpu6502::initPins() {
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// set voltage supply and ground.
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setSeg(n->VCC, true);
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setSeg(n->VSS, false);
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// don't do the set-overflow overriding functionality
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setSeg(n->SO, false);
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// ready to run (i.e., do not do single-stepping of instructions)
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setSeg(n->RDY, true);
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// pull up to indicate that we are not interrupting now
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setSeg(n->IRQ, true);
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setSeg(n->NMI, true);
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/*
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* RES_BAR pin means "not resetting". Since it is a negated pin, pulling it low means "resetting"
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* and pulling it high means "not resetting" or equivalently "running".
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*/
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/*
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* RES_BAR false: resetting now (i.e., in power-up now; pull high to begin normal operation)
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* We want to hold RES_BAR low for a while, indicating power-up phase during which the
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* CPU does not start up normal operations yet. The caller can set RES_BAR high (by calling
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* reset) whenever he is ready to start the CPU running.
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*/
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setSeg(n->RES, false);
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}
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void Cpu6502::reset() {
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setSeg(n->RES, true);
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recalc(n->RES);
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}
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void Cpu6502::tick() {
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step();
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step();
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}
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void Cpu6502::step() {
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/*
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* We cheat a little bit here: instead of requiring the
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* caller to toggle clock-zero pin, we let him just call
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* "step" and *we* keep track of which phase we are in.
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* To do this, we just use the CLK0 segment value (as
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* a kind of temporary variable), and just toggle it in
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* order to know which phase we are going into.
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*
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* The real 6502, of course, does not do this.
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*/
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const bool nextPhase = !n->CLK0->on;
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clock(nextPhase);
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rw();
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dumpRegs();
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dumpSegs();
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}
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void Cpu6502::clock(bool phase) {
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setSeg(n->CLK0, phase);
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recalc(n->CLK0);
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}
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void Cpu6502::rw() {
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// database read/write happens during Clock Phase 2 (only)
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if (n->CLK2OUT->on) {
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readBus();
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std::set<Segment*> s;
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segs.addDataToRecalc(s);
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recalc(s);
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writeBus();
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}
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}
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void Cpu6502::readBus() {
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if (this->transNetwork.segs.c->RW->on) {
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this->transNetwork.segs.setDataSegs(read(this->transNetwork.segs.rAddr()));
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}
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}
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void Cpu6502::writeBus() {
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if (!this->transNetwork.segs.c->RW->on) {
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write(this->transNetwork.segs.rAddr(), this->transNetwork.segs.rData());
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}
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}
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unsigned char Cpu6502::read(unsigned short addr) {
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const unsigned char x = this->addressBus.read(addr);
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#ifdef TRACEMEM
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std::cout << "-------------------------------------------------- ";
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pHex(x);
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std::cout << "<";
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pHexw(addr);
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std::cout << std::endl;
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#endif
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return x;
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}
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void Cpu6502::write(unsigned short addr, unsigned char data) {
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this->addressBus.write(addr, data);
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#ifdef TRACEMEM
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std::cout << "-------------------------------------------------- ";
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pHex(data);
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std::cout << ">";
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pHexw(addr);
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std::cout << std::endl;
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#endif
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}
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