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717 lines
23 KiB
C++
717 lines
23 KiB
C++
//
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// Atari2600.cpp
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// CLK
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//
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// Created by Thomas Harte on 14/07/2015.
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// Copyright © 2015 Thomas Harte. All rights reserved.
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//
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#include "Atari2600.hpp"
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#include <algorithm>
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#include <stdio.h>
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using namespace Atari2600;
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namespace {
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static const unsigned int horizontalTimerPeriod = 228;
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}
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Machine::Machine() :
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_horizontalTimer(0),
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_lastOutputStateDuration(0),
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_lastOutputState(OutputState::Sync),
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_piaTimerStatus(0xff),
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_rom(nullptr),
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_piaDataValue{0xff, 0xff},
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_tiaInputValue{0xff, 0xff},
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_upcomingEventsPointer(0)
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{
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memset(_collisions, 0xff, sizeof(_collisions));
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set_reset_line(true);
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}
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void Machine::setup_output(float aspect_ratio)
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{
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_crt = new Outputs::CRT::CRT(228, 1, 263, Outputs::CRT::ColourSpace::YIQ, 228, 1, 1);
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// this is the NTSC phase offset function; see below for PAL
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_crt->set_composite_sampling_function(
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"float composite_sample(usampler2D texID, vec2 coordinate, vec2 iCoordinate, float phase, float amplitude)"
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"{"
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"uint c = texture(texID, coordinate).r;"
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"uint y = c & 14u;"
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"uint iPhase = (c >> 4);"
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"float phaseOffset = 6.283185308 * float(iPhase - 1u) / 13.0;"
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"return (float(y) / 14.0) * (1.0 - amplitude) + step(1, iPhase) * amplitude * cos(phase + phaseOffset);"
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"}");
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_crt->set_output_device(Outputs::CRT::Television);
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}
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void Machine::switch_region()
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{
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// the PAL function
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_crt->set_composite_sampling_function(
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"float composite_sample(usampler2D texID, vec2 coordinate, vec2 iCoordinate, float phase, float amplitude)"
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"{"
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"uint c = texture(texID, coordinate).r;"
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"uint y = c & 14u;"
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"uint iPhase = (c >> 4);"
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"uint direction = iPhase & 1u;"
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"float phaseOffset = float(7u - direction) + (float(direction) - 0.5) * 2.0 * float(iPhase >> 1);"
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"phaseOffset *= 6.283185308 / 12.0;"
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"return (float(y) / 14.0) * (1.0 - amplitude) + step(4, (iPhase + 2u) & 15u) * amplitude * cos(phase + phaseOffset);"
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"}");
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_crt->set_new_timing(228, 312, Outputs::CRT::ColourSpace::YUV, 228, 1);
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}
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void Machine::close_output()
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{
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delete _crt;
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_crt = nullptr;
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}
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Machine::~Machine()
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{
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delete[] _rom;
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close_output();
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}
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void Machine::update_timers(int mask)
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{
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// unsigned int upcomingEventsPointerPlus1 = (_upcomingEventsPointer + 1)%number_of_upcoming_events;
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unsigned int upcomingEventsPointerPlus2 = (_upcomingEventsPointer + 4)%number_of_upcoming_events;
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unsigned int upcomingEventsPointerPlus3 = (_upcomingEventsPointer + 5)%number_of_upcoming_events;
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unsigned int upcomingEventsPointerPlus4 = (_upcomingEventsPointer + 6)%number_of_upcoming_events;
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// unsigned int upcomingEventsPointerPlus5 = (_upcomingEventsPointer + 5)%number_of_upcoming_events;
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// unsigned int upcomingEventsPointerPlus6 = (_upcomingEventsPointer + 6)%number_of_upcoming_events;
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// unsigned int upcomingEventsPointerPlus7 = (_upcomingEventsPointer + 7)%number_of_upcoming_events;
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// unsigned int upcomingEventsPointerPlus8 = (_upcomingEventsPointer + 8)%number_of_upcoming_events;
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// grab the background now, for display in four clocks
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if(mask & (1 << 5))
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{
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if(!(_horizontalTimer&3))
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{
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unsigned int offset = 4 + _horizontalTimer - (horizontalTimerPeriod - 160);
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_upcomingEvents[upcomingEventsPointerPlus2].updates |= Event::Action::Playfield;
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_upcomingEvents[upcomingEventsPointerPlus2].playfieldOutput = _playfield[(offset >> 2)%40];
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}
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}
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// the ball becomes visible whenever it hits zero, regardless of whether its status
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// is the result of a counter rollover or a programmatic reset
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if(mask & (1 << 4))
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{
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if(!_objectCounter[4])
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{
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_upcomingEvents[upcomingEventsPointerPlus2].updates |= Event::Action::ResetPixelCounter;
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_upcomingEvents[upcomingEventsPointerPlus2].pixelCounterMask |= (1 << 4);
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}
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_objectCounter[4] = (_objectCounter[4] + 1)%160;
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_pixelCounter[4] ++;
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}
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// check for player and missle triggers
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for(int c = 0; c < 4; c++)
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{
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if(mask & (1 << c))
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{
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// the players and missles become visible only upon overflow to zero, so schedule for
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// 5/6 clocks ahead from 159
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if(_objectCounter[c] == 159)
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{
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unsigned int actionSlot = (c < 2) ? upcomingEventsPointerPlus4 : upcomingEventsPointerPlus3;
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// unsigned int actionSlot = (c < 2) ? upcomingEventsPointerPlus6 : upcomingEventsPointerPlus5;
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_upcomingEvents[actionSlot].updates |= Event::Action::ResetPixelCounter;
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_upcomingEvents[actionSlot].pixelCounterMask |= (1 << c);
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}
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else
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{
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// otherwise visibility is determined by an appropriate repeat mask and hitting any of 12, 28 or 60,
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// in which case the counter reset (and hence the start of drawing) will occur in 4/5 cycles
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uint8_t repeatMask = _playerAndMissileSize[c&1] & 7;
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if(
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( _objectCounter[c] == 16 && ((repeatMask == 1) || (repeatMask == 3)) ) ||
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( _objectCounter[c] == 32 && ((repeatMask == 2) || (repeatMask == 3) || (repeatMask == 6)) ) ||
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( _objectCounter[c] == 64 && ((repeatMask == 4) || (repeatMask == 6)) )
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)
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{
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unsigned int actionSlot = (c < 2) ? upcomingEventsPointerPlus3 : upcomingEventsPointerPlus2;
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// unsigned int actionSlot = (c < 2) ? upcomingEventsPointerPlus5 : upcomingEventsPointerPlus4;
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_upcomingEvents[actionSlot].updates |= Event::Action::ResetPixelCounter;
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_upcomingEvents[actionSlot].pixelCounterMask |= (1 << c);
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}
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}
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}
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}
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for(int c = 0; c < 2; c++)
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{
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if(mask & (1 << c))
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{
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uint8_t repeatMask = _playerAndMissileSize[c] & 7;
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switch(repeatMask)
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{
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default:
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_pixelCounter[c] += 4;
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break;
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case 5:
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_pixelCounter[c] += 2;
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break;
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case 7:
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_pixelCounter[c] += 1;
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break;
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}
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_objectCounter[c] = (_objectCounter[c] + 1)%160;
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}
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if(mask & (1 << (c + 2)))
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{
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_objectCounter[c+2] = (_objectCounter[c+2] + 1)%160;
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_pixelCounter[c+2] ++;
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}
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}
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}
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uint8_t Machine::get_output_pixel()
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{
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unsigned int offset = _horizontalTimer - (horizontalTimerPeriod - 160);
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// get the playfield pixel and hence a proposed colour
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uint8_t playfieldColour = ((_playfieldControl&6) == 2) ? _playerColour[offset / 80] : _playfieldColour;
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// get the ball proposed state
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uint8_t ballPixel = 0;
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if(_ballGraphicsEnable&2) {
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int ballSize = 1 << ((_playfieldControl >> 4)&3);
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ballPixel = (_pixelCounter[4] < ballSize) ? 1 : 0;
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}
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// deal with the sprites
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uint8_t playerPixels[2] = {0, 0}, missilePixels[2] = {0, 0};
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for(int c = 0; c < 2; c++)
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{
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if(_playerGraphics[c]) {
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// figure out player colour
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int flipMask = (_playerReflection[c]&0x8) ? 0 : 7;
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if(_pixelCounter[c] < 32)
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playerPixels[c] = (_playerGraphics[_playerGraphicsSelector[c]][c] >> ((_pixelCounter[c] >> 2) ^ flipMask)) &1;
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}
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if((_missileGraphicsEnable[c]&2) && !(_missileGraphicsReset[c]&2)) {
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int missileSize = 1 << ((_playerAndMissileSize[c] >> 4)&3);
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missilePixels[c] = (_pixelCounter[c+2] < missileSize) ? 1 : 0;
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}
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}
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// accumulate collisions
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if(playerPixels[0] | playerPixels[1]) {
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_collisions[0] |= ((missilePixels[0] & playerPixels[1]) << 7) | ((missilePixels[0] & playerPixels[0]) << 6);
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_collisions[1] |= ((missilePixels[1] & playerPixels[0]) << 7) | ((missilePixels[1] & playerPixels[1]) << 6);
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_collisions[2] |= ((_playfieldOutput & playerPixels[0]) << 7) | ((ballPixel & playerPixels[0]) << 6);
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_collisions[3] |= ((_playfieldOutput & playerPixels[1]) << 7) | ((ballPixel & playerPixels[1]) << 6);
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_collisions[7] |= ((playerPixels[0] & playerPixels[1]) << 7);
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}
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if(_playfieldOutput | ballPixel) {
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_collisions[4] |= ((_playfieldOutput & missilePixels[0]) << 7) | ((ballPixel & missilePixels[0]) << 6);
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_collisions[5] |= ((_playfieldOutput & missilePixels[1]) << 7) | ((ballPixel & missilePixels[1]) << 6);
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_collisions[6] |= ((_playfieldOutput & ballPixel) << 7);
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}
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if(missilePixels[0] & missilePixels[1])
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_collisions[7] |= (1 << 6);
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// apply appropriate priority to pick a colour
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uint8_t playfieldPixel = _playfieldOutput;// | ballPixel;
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uint8_t outputColour = playfieldPixel ? playfieldColour : _backgroundColour;
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if(!(_playfieldControl&0x04) || !playfieldPixel) {
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if(missilePixels[1]) outputColour = _playerColour[1];
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if(missilePixels[0]) outputColour = _playerColour[0];
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// if(playerPixels[1] || missilePixels[1]) outputColour = _playerColour[1];
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// if(playerPixels[0] || missilePixels[0]) outputColour = _playerColour[0];
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}
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// return colour
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return outputColour;
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}
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// in imputing the knowledge that all we're dealing with is the rollover from 159 to 0,
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// this is faster than the straightforward +1)%160 per profiling
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//#define increment_object_counter(c) _objectCounter[c] = (_objectCounter[c]+1)&~((158-_objectCounter[c]) >> 8)
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void Machine::output_pixels(unsigned int count)
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{
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while(count--)
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{
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OutputState state;
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// determine which output state will be active in four cycles from now
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switch(_horizontalTimer >> 2)
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{
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case 56: case 0: case 1: case 2: state = OutputState::Blank; break;
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case 3: case 4: case 5: case 6: state = OutputState::Sync; break;
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case 7: case 8: case 9: case 10: state = OutputState::ColourBurst; break;
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case 11: case 12: case 13:
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case 14: case 15: state = OutputState::Blank; break;
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case 16: case 17: state = _vBlankExtend ? OutputState::Blank : OutputState::Pixel; break;
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default: state = OutputState::Pixel; break;
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}
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// grab background colour and schedule pixel counter resets
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if(state == OutputState::Pixel)
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update_timers(~0);
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// if vsync is enabled, output the opposite of the automatic hsync output
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if(_vSyncEnabled) {
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state = (state = OutputState::Sync) ? OutputState::Blank : OutputState::Sync;
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}
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// write that state as the one that will become effective in four clocks
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_upcomingEvents[(_upcomingEventsPointer+4)%number_of_upcoming_events].state = state;
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// apply any queued changes and flush the record
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if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::Playfield)
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_playfieldOutput = _upcomingEvents[_upcomingEventsPointer].playfieldOutput;
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if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::ResetPixelCounter)
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{
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for(int c = 0; c < 5; c++)
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{
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if(_upcomingEvents[_upcomingEventsPointer].pixelCounterMask & (1 << c))
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_pixelCounter[c] = 0;
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}
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_upcomingEvents[_upcomingEventsPointer].pixelCounterMask = 0;
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}
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if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveCompare)
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{
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for(int c = 0; c < 5; c++)
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{
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if(((_objectMotion[c] >> 4)^_hMoveCounter) == 7)
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{
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_hMoveFlags &= ~(1 << c);
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}
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}
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if(_hMoveFlags)
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{
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if(_hMoveCounter) _hMoveCounter--;
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_upcomingEvents[(_upcomingEventsPointer+4)%number_of_upcoming_events].updates |= Event::Action::HMoveCompare;
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_upcomingEvents[(_upcomingEventsPointer+2)%number_of_upcoming_events].updates |= Event::Action::HMoveDecrement;
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}
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}
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if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveDecrement)
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{
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update_timers(_hMoveFlags);
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}
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_upcomingEvents[_upcomingEventsPointer].updates = 0;
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// read that state
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state = _upcomingEvents[_upcomingEventsPointer].state;
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OutputState actingState = state;
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// honour the vertical blank flag
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if(_vBlankEnabled && state == OutputState::Pixel) {
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actingState = OutputState::Blank;
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}
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// decide what that means needs to be communicated to the CRT
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_lastOutputStateDuration++;
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if(actingState != _lastOutputState) {
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switch(_lastOutputState) {
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case OutputState::Blank: _crt->output_blank(_lastOutputStateDuration); break;
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case OutputState::Sync: _crt->output_sync(_lastOutputStateDuration); break;
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case OutputState::ColourBurst: _crt->output_colour_burst(_lastOutputStateDuration, 96, 0); break;
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case OutputState::Pixel: _crt->output_data(_lastOutputStateDuration, 1); break;
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}
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_lastOutputStateDuration = 0;
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_lastOutputState = actingState;
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if(actingState == OutputState::Pixel) {
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_outputBuffer = _crt->allocate_write_area(160);
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} else {
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_outputBuffer = nullptr;
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}
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}
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// decide on a pixel colour if that's what's happening
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if(state == OutputState::Pixel)
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{
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uint8_t colour = get_output_pixel();
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if(_outputBuffer)
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{
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*_outputBuffer = colour;
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_outputBuffer++;
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}
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}
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// advance
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_upcomingEventsPointer = (_upcomingEventsPointer + 1)%number_of_upcoming_events;
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// advance horizontal timer, perform reset actions if requested
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_horizontalTimer = (_horizontalTimer + 1) % horizontalTimerPeriod;
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if(!_horizontalTimer)
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{
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_vBlankExtend = false;
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set_ready_line(false);
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}
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}
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}
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unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value)
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{
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set_reset_line(false);
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uint8_t returnValue = 0xff;
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unsigned int cycles_run_for = 1;
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// this occurs as a feedback loop — the 2600 requests ready, then performs the cycles_run_for
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// leap to the end of ready only once ready is signalled — because on a 6502 ready doesn't take
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// effect until the next read; therefore it isn't safe to assume that signalling ready immediately
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// skips to the end of the line.
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if(operation == CPU6502::BusOperation::Ready) {
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unsigned int distance_to_end_of_ready = horizontalTimerPeriod - _horizontalTimer;
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cycles_run_for = distance_to_end_of_ready / 3;
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}
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output_pixels(cycles_run_for * 3);
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if(operation != CPU6502::BusOperation::Ready) {
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// check for a paging access
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if(_rom_size > 4096 && ((address & 0x1f00) == 0x1f00)) {
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uint8_t *base_ptr = _romPages[0];
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uint8_t first_paging_register = (uint8_t)(0xf8 - (_rom_size >> 14)*2);
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const uint8_t paging_register = address&0xff;
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if(paging_register >= first_paging_register) {
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const uint16_t selected_page = paging_register - first_paging_register;
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if(selected_page * 4096 < _rom_size) {
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base_ptr = &_rom[selected_page * 4096];
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}
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}
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if(base_ptr != _romPages[0]) {
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_romPages[0] = base_ptr;
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_romPages[1] = base_ptr + 1024;
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_romPages[2] = base_ptr + 2048;
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_romPages[3] = base_ptr + 3072;
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}
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}
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// check for a ROM read
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if((address&0x1000) && isReadOperation(operation)) {
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returnValue &= _romPages[(address >> 10)&3][address&1023];
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}
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// check for a RAM access
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if((address&0x1280) == 0x80) {
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if(isReadOperation(operation)) {
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returnValue &= _ram[address&0x7f];
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} else {
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_ram[address&0x7f] = *value;
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}
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}
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// check for a TIA access
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if(!(address&0x1080)) {
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if(isReadOperation(operation)) {
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const uint16_t decodedAddress = address & 0xf;
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switch(decodedAddress) {
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case 0x00: // missile 0 / player collisions
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case 0x01: // missile 1 / player collisions
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case 0x02: // player 0 / playfield / ball collisions
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case 0x03: // player 1 / playfield / ball collisions
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case 0x04: // missile 0 / playfield / ball collisions
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case 0x05: // missile 1 / playfield / ball collisions
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case 0x06: // ball / playfield collisions
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case 0x07: // player / player, missile / missile collisions
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returnValue &= _collisions[decodedAddress];
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break;
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case 0x08:
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case 0x09:
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case 0x0a:
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case 0x0b:
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// TODO: pot ports
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break;
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case 0x0c:
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case 0x0d:
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returnValue &= _tiaInputValue[decodedAddress - 0x0c];
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break;
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}
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} else {
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const uint16_t decodedAddress = address & 0x3f;
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switch(decodedAddress) {
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case 0x00:
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_vSyncEnabled = !!(*value & 0x02);
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break;
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case 0x01: _vBlankEnabled = !!(*value & 0x02); break;
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case 0x02:
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// printf("%d\n", _horizontalTimer);
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if(_horizontalTimer) set_ready_line(true);
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break;
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case 0x03:
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_horizontalTimer = 0;
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break;
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case 0x04:
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case 0x05: _playerAndMissileSize[decodedAddress - 0x04] = *value; break;
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case 0x06:
|
|
case 0x07: _playerColour[decodedAddress - 0x06] = *value; break;
|
|
case 0x08: _playfieldColour = *value; break;
|
|
case 0x09: _backgroundColour = *value; break;
|
|
|
|
case 0x0a: {
|
|
uint8_t old_playfield_control = _playfieldControl;
|
|
_playfieldControl = *value;
|
|
|
|
// did the mirroring bit change?
|
|
if((_playfieldControl^old_playfield_control)&1) {
|
|
if(_playfieldControl&1) {
|
|
for(int c = 0; c < 20; c++) _playfield[c+20] = _playfield[19-c];
|
|
} else {
|
|
memcpy(&_playfield[20], _playfield, 20);
|
|
}
|
|
}
|
|
} break;
|
|
case 0x0b:
|
|
case 0x0c: _playerReflection[decodedAddress - 0x0b] = *value; break;
|
|
|
|
case 0x0d:
|
|
_playfield[0] = ((*value) >> 4)&1;
|
|
_playfield[1] = ((*value) >> 5)&1;
|
|
_playfield[2] = ((*value) >> 6)&1;
|
|
_playfield[3] = (*value) >> 7;
|
|
|
|
if(_playfieldControl&1) {
|
|
for(int c = 0; c < 4; c++) _playfield[39-c] = _playfield[c];
|
|
} else {
|
|
memcpy(&_playfield[20], _playfield, 4);
|
|
}
|
|
break;
|
|
case 0x0e:
|
|
_playfield[4] = (*value) >> 7;
|
|
_playfield[5] = ((*value) >> 6)&1;
|
|
_playfield[6] = ((*value) >> 5)&1;
|
|
_playfield[7] = ((*value) >> 4)&1;
|
|
_playfield[8] = ((*value) >> 3)&1;
|
|
_playfield[9] = ((*value) >> 2)&1;
|
|
_playfield[10] = ((*value) >> 1)&1;
|
|
_playfield[11] = (*value)&1;
|
|
|
|
if(_playfieldControl&1) {
|
|
for(int c = 0; c < 8; c++) _playfield[35-c] = _playfield[c+4];
|
|
} else {
|
|
memcpy(&_playfield[24], &_playfield[4], 8);
|
|
}
|
|
break;
|
|
case 0x0f:
|
|
_playfield[19] = (*value) >> 7;
|
|
_playfield[18] = ((*value) >> 6)&1;
|
|
_playfield[17] = ((*value) >> 5)&1;
|
|
_playfield[16] = ((*value) >> 4)&1;
|
|
_playfield[15] = ((*value) >> 3)&1;
|
|
_playfield[14] = ((*value) >> 2)&1;
|
|
_playfield[13] = ((*value) >> 1)&1;
|
|
_playfield[12] = (*value)&1;
|
|
|
|
if(_playfieldControl&1) {
|
|
for(int c = 0; c < 8; c++) _playfield[27-c] = _playfield[c+12];
|
|
} else {
|
|
memcpy(&_playfield[32], &_playfield[12], 8);
|
|
}
|
|
break;
|
|
|
|
case 0x10: case 0x11: case 0x12: case 0x13:
|
|
case 0x14:
|
|
_objectCounter[decodedAddress - 0x10] = 0;
|
|
break;
|
|
|
|
case 0x1c:
|
|
_ballGraphicsEnable = _ballGraphicsEnableLatch;
|
|
case 0x1b: {
|
|
int index = decodedAddress - 0x1b;
|
|
_playerGraphics[0][index] = *value;
|
|
_playerGraphics[1][index^1] = _playerGraphics[0][index^1];
|
|
} break;
|
|
case 0x1d: _missileGraphicsEnable[0] = *value; break;
|
|
case 0x1e: _missileGraphicsEnable[1] = *value; break;
|
|
case 0x1f:
|
|
_ballGraphicsEnableLatch = *value;
|
|
if(!(_ballGraphicsEnableDelay&1))
|
|
_ballGraphicsEnable = _ballGraphicsEnableLatch;
|
|
break;
|
|
|
|
case 0x20:
|
|
case 0x21:
|
|
case 0x22:
|
|
case 0x23:
|
|
case 0x24:
|
|
_objectMotion[decodedAddress - 0x20] = *value;
|
|
break;
|
|
|
|
case 0x25: _playerGraphicsSelector[0] = (*value)&1; break;
|
|
case 0x26: _playerGraphicsSelector[1] = (*value)&1; break;
|
|
case 0x27: _ballGraphicsEnableDelay = *value; break;
|
|
|
|
case 0x28:
|
|
case 0x29:
|
|
if(!(*value&0x02) && _missileGraphicsReset[decodedAddress - 0x28]&0x02)
|
|
_objectCounter[decodedAddress - 0x26] = _objectCounter[decodedAddress - 0x28]; // TODO: +3 for normal, +6 for double, +10 for quad
|
|
_missileGraphicsReset[decodedAddress - 0x28] = *value;
|
|
break;
|
|
|
|
case 0x2a:
|
|
_vBlankExtend = true;
|
|
|
|
// clear any ongoing moves
|
|
if(_hMoveFlags)
|
|
{
|
|
for(int c = 0; c < number_of_upcoming_events; c++)
|
|
{
|
|
_upcomingEvents[c].updates &= ~(Event::Action::HMoveCompare | Event::Action::HMoveDecrement);
|
|
}
|
|
}
|
|
|
|
// schedule new moves
|
|
_hMoveFlags = 0x1f;
|
|
_hMoveCounter = 15;
|
|
|
|
// justification for +5: "we need to wait at least 71 [clocks] before the HMOVE operation is complete";
|
|
// which will take 16*4 + 2 = 66 cycles from the first compare, implying the first compare must be
|
|
// in five cycles from now
|
|
_upcomingEvents[(_upcomingEventsPointer + 5)%number_of_upcoming_events].updates |= Event::Action::HMoveCompare;
|
|
break;
|
|
case 0x2b:
|
|
_objectMotion[0] =
|
|
_objectMotion[1] =
|
|
_objectMotion[2] =
|
|
_objectMotion[3] =
|
|
_objectMotion[4] = 0;
|
|
break;
|
|
case 0x2c:
|
|
_collisions[0] = _collisions[1] = _collisions[2] =
|
|
_collisions[3] = _collisions[4] = _collisions[5] = 0x3f;
|
|
_collisions[6] = 0x7f;
|
|
_collisions[7] = 0x3f;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// check for a PIA access
|
|
if((address&0x1280) == 0x280) {
|
|
if(isReadOperation(operation)) {
|
|
const uint8_t decodedAddress = address & 0xf;
|
|
switch(address & 0xf) {
|
|
case 0x00:
|
|
case 0x02:
|
|
returnValue &= _piaDataValue[decodedAddress / 2];
|
|
break;
|
|
case 0x01:
|
|
case 0x03:
|
|
// TODO: port DDR
|
|
break;
|
|
case 0x04:
|
|
returnValue &= _piaTimerValue >> _piaTimerShift;
|
|
|
|
if(_writtenPiaTimerShift != _piaTimerShift) {
|
|
_piaTimerShift = _writtenPiaTimerShift;
|
|
_piaTimerValue <<= _writtenPiaTimerShift;
|
|
}
|
|
break;
|
|
case 0x05:
|
|
returnValue &= _piaTimerStatus;
|
|
_piaTimerStatus &= ~0x40;
|
|
break;
|
|
}
|
|
} else {
|
|
const uint8_t decodedAddress = address & 0x0f;
|
|
switch(decodedAddress) {
|
|
case 0x04:
|
|
case 0x05:
|
|
case 0x06:
|
|
case 0x07:
|
|
_writtenPiaTimerShift = _piaTimerShift = (decodedAddress - 0x04) * 3 + (decodedAddress / 0x07);
|
|
_piaTimerValue = (unsigned int)(*value << _piaTimerShift);
|
|
_piaTimerStatus &= ~0xc0;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if(isReadOperation(operation)) {
|
|
*value = returnValue;
|
|
}
|
|
}
|
|
|
|
if(_piaTimerValue >= cycles_run_for) {
|
|
_piaTimerValue -= cycles_run_for;
|
|
} else {
|
|
_piaTimerValue += 0xff - cycles_run_for;
|
|
_piaTimerShift = 0;
|
|
_piaTimerStatus |= 0xc0;
|
|
}
|
|
|
|
// output_pixels(cycles_run_for * 3);
|
|
|
|
return cycles_run_for;
|
|
}
|
|
|
|
void Machine::set_digital_input(Atari2600DigitalInput input, bool state)
|
|
{
|
|
switch (input) {
|
|
case Atari2600DigitalInputJoy1Up: if(state) _piaDataValue[0] &= ~0x10; else _piaDataValue[0] |= 0x10; break;
|
|
case Atari2600DigitalInputJoy1Down: if(state) _piaDataValue[0] &= ~0x20; else _piaDataValue[0] |= 0x20; break;
|
|
case Atari2600DigitalInputJoy1Left: if(state) _piaDataValue[0] &= ~0x40; else _piaDataValue[0] |= 0x40; break;
|
|
case Atari2600DigitalInputJoy1Right: if(state) _piaDataValue[0] &= ~0x80; else _piaDataValue[0] |= 0x80; break;
|
|
|
|
case Atari2600DigitalInputJoy2Up: if(state) _piaDataValue[0] &= ~0x01; else _piaDataValue[0] |= 0x01; break;
|
|
case Atari2600DigitalInputJoy2Down: if(state) _piaDataValue[0] &= ~0x02; else _piaDataValue[0] |= 0x02; break;
|
|
case Atari2600DigitalInputJoy2Left: if(state) _piaDataValue[0] &= ~0x04; else _piaDataValue[0] |= 0x04; break;
|
|
case Atari2600DigitalInputJoy2Right: if(state) _piaDataValue[0] &= ~0x08; else _piaDataValue[0] |= 0x08; break;
|
|
|
|
// TODO: latching
|
|
case Atari2600DigitalInputJoy1Fire: if(state) _tiaInputValue[0] &= ~0x80; else _tiaInputValue[0] |= 0x80; break;
|
|
case Atari2600DigitalInputJoy2Fire: if(state) _tiaInputValue[1] &= ~0x80; else _tiaInputValue[1] |= 0x80; break;
|
|
|
|
default: break;
|
|
}
|
|
}
|
|
|
|
void Machine::set_rom(size_t length, const uint8_t *data)
|
|
{
|
|
_rom_size = 1024;
|
|
while(_rom_size < length && _rom_size < 32768) _rom_size <<= 1;
|
|
|
|
delete[] _rom;
|
|
|
|
_rom = new uint8_t[_rom_size];
|
|
|
|
size_t offset = 0;
|
|
const size_t copy_step = std::min(_rom_size, length);
|
|
while(offset < _rom_size)
|
|
{
|
|
size_t copy_length = std::min(copy_step, _rom_size - offset);
|
|
memcpy(&_rom[offset], data, copy_length);
|
|
offset += copy_length;
|
|
}
|
|
|
|
size_t romMask = _rom_size - 1;
|
|
_romPages[0] = _rom;
|
|
_romPages[1] = &_rom[1024 & romMask];
|
|
_romPages[2] = &_rom[2048 & romMask];
|
|
_romPages[3] = &_rom[3072 & romMask];
|
|
}
|