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531 lines
16 KiB
C++
531 lines
16 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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static const char atari2600DataType[] = "Atari2600";
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static const int horizontalTimerReload = 227;
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Machine::Machine()
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{
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_timestamp = 0;
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_horizontalTimer = 0;
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_lastOutputStateDuration = 0;
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_lastOutputState = OutputState::Sync;
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_crt = new Outputs::CRT(228, 262, 1, 4);
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_piaTimerStatus = 0xff;
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memset(_collisions, 0xff, sizeof(_collisions));
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_rom = nullptr;
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_hMoveWillCount = false;
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setup6502();
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set_reset_line(true);
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}
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Machine::~Machine()
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{
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delete[] _rom;
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delete _crt;
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}
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void Machine::switch_region()
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{
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_crt->set_new_timing(228, 312);
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}
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void Machine::get_output_pixel(uint8_t *pixel, int offset)
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{
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const uint8_t palette[16][3] =
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{
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{255, 255, 255}, {253, 250, 115}, {236, 199, 125}, {252, 187, 151},
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{252, 180, 181}, {235, 177, 223}, {211, 178, 250}, {187, 182, 250},
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{164, 186, 250}, {166, 201, 250}, {164, 224, 251}, {165, 251, 213},
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{185, 251, 187}, {201, 250, 168}, {225, 235, 160}, {252, 223, 145}
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};
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const uint8_t alphaValues[8] =
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{
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// 0, 64, 108, 144, 176, 200, 220, 255
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// };
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//
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// {
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69, 134, 108, 161, 186, 210, 235, 255
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};
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// get the playfield pixel and hence a proposed colour
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const int x = offset >> 2;
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const int mirrored = (x / 20) & (_playfieldControl&1);
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const int index = mirrored ? 39 - x : (x%20);
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uint8_t playfieldPixel = _playfield[index];
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uint8_t playfieldColour = ((_playfieldControl&6) == 2) ? _playerColour[x / 20] : _playfieldColour;
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// get player and missile proposed pixels
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uint8_t playerPixels[2], missilePixels[2];
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for(int c = 0; c < 2; c++)
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{
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// figure out player colour
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int flipMask = (_playerReflection[c]&0x8) ? 0 : 7;
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int relativeTimer = _objectCounter[c] - 5;
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switch (_playerAndMissileSize[c]&7)
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{
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case 0: break;
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case 1:
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if (relativeTimer >= 16) relativeTimer -= 16;
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break;
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case 2:
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if (relativeTimer >= 32) relativeTimer -= 32;
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break;
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case 3:
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if (relativeTimer >= 32) relativeTimer -= 32;
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else if (relativeTimer >= 16) relativeTimer -= 16;
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break;
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case 4:
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if (relativeTimer >= 64) relativeTimer -= 64;
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break;
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case 5:
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relativeTimer >>= 1;
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break;
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case 6:
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if (relativeTimer >= 64) relativeTimer -= 64;
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else if (relativeTimer >= 32) relativeTimer -= 32;
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break;
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case 7:
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relativeTimer >>= 2;
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break;
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}
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if(relativeTimer >= 0 && relativeTimer < 8)
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playerPixels[c] = (_playerGraphics[c] >> (relativeTimer ^ flipMask)) &1;
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else
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playerPixels[c] = 0;
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// figure out missile colour
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int missileIndex = _objectCounter[2+c] - 4;
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int missileSize = 1 << ((_playerAndMissileSize[c] >> 4)&3);
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missilePixels[c] = (missileIndex >= 0 && missileIndex < missileSize && (_missileGraphicsEnable[c]&2) && !(_missileGraphicsReset[c]&2)) ? 1 : 0;
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}
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// get the ball proposed colour
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uint8_t ballPixel;
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int ballIndex = _objectCounter[4] - 4;
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int ballSize = 1 << ((_playfieldControl >> 4)&3);
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ballPixel = (ballIndex >= 0 && ballIndex < ballSize && (_ballGraphicsEnable&2)) ? 1 : 0;
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// accumulate collisions
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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] |= ((playfieldPixel & playerPixels[0]) << 7) | ((ballPixel & playerPixels[0]) << 6);
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_collisions[3] |= ((playfieldPixel & playerPixels[1]) << 7) | ((ballPixel & playerPixels[1]) << 6);
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_collisions[4] |= ((playfieldPixel & missilePixels[0]) << 7) | ((ballPixel & missilePixels[0]) << 6);
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_collisions[5] |= ((playfieldPixel & missilePixels[1]) << 7) | ((ballPixel & missilePixels[1]) << 6);
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_collisions[6] |= ((playfieldPixel & ballPixel) << 7);
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_collisions[7] |= ((playerPixels[0] & playerPixels[1]) << 7) | ((missilePixels[0] & missilePixels[1]) << 6);
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// apply appropriate priority to pick a colour
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playfieldPixel |= ballPixel;
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uint8_t outputColour = playfieldPixel ? playfieldColour : _backgroundColour;
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if(!(_playfieldControl&0x04) || !playfieldPixel) {
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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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// map that colour to an RGBA
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pixel[0] = palette[outputColour >> 4][0];
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pixel[1] = palette[outputColour >> 4][1];
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pixel[2] = palette[outputColour >> 4][2];
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pixel[3] = alphaValues[(outputColour >> 1)&7];
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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(int count)
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{
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const int32_t start_of_sync = 214;
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const int32_t end_of_sync = 198;
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while(count--)
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{
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OutputState state;
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// update hmove
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if (!(_horizontalTimer&3)) {
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if(_hMoveFlags) {
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const uint8_t counterValue = _hMoveCounter ^ 0x7;
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for(int c = 0; c < 5; c++) {
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if (counterValue == (_objectMotion[c] >> 4)) _hMoveFlags &= ~(1 << c);
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if (_hMoveFlags&(1 << c)) increment_object_counter(c);
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}
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}
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if(_hMoveIsCounting) {
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_hMoveIsCounting = !!_hMoveCounter;
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_hMoveCounter = (_hMoveCounter-1)&0xf;
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}
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}
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// logic: if in vsync, output that; otherwise if in vblank then output that;
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// otherwise output a pixel
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if(_vSyncEnabled) {
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state = (_horizontalTimer < start_of_sync) ? OutputState::Sync : OutputState::Blank;
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} else {
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// blank is decoded as 68 counts; sync and colour burst as 16 counts
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// 4 blank
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// 4 sync
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// 9 'blank'; colour burst after 4
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// 40 pixels
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// it'll be about 43 cycles from start of hsync to start of visible frame, so...
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// guesses, until I can find information: 26 cycles blank, 16 sync, 40 blank, 160 pixels
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if (_horizontalTimer < (_vBlankExtend ? 152 : 160)) {
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if(_vBlankEnabled) {
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state = OutputState::Blank;
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} else {
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state = OutputState::Pixel;
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}
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}
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else if (_horizontalTimer < end_of_sync) state = OutputState::Blank;
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else if (_horizontalTimer < start_of_sync) state = OutputState::Sync;
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else state = OutputState::Blank;
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}
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_lastOutputStateDuration++;
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if(state != _lastOutputState)
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{
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switch(_lastOutputState)
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{
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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::Pixel: _crt->output_data(_lastOutputStateDuration, atari2600DataType); break;
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}
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_lastOutputStateDuration = 0;
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_lastOutputState = state;
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if(state == OutputState::Pixel)
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{
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_vBlankExtend = false;
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_crt->allocate_write_area(160);
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_outputBuffer = _crt->get_write_target_for_buffer(0);
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} else {
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_outputBuffer = nullptr;
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}
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}
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if(state == OutputState::Pixel)//_horizontalTimer < (_vBlankExtend ? 152 : 160))
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{
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if(_outputBuffer)
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get_output_pixel(&_outputBuffer[_lastOutputStateDuration * 4], 159 - _horizontalTimer);
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// increment all graphics counters
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increment_object_counter(0);
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increment_object_counter(1);
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increment_object_counter(2);
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increment_object_counter(3);
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increment_object_counter(4);
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}
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// assumption here: signed shifts right; otherwise it's just
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// an attempt to avoid both the % operator and a conditional
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_horizontalTimer--;
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const int32_t sign_extension = _horizontalTimer >> 31;
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_horizontalTimer = (_horizontalTimer&~sign_extension) | (sign_extension&horizontalTimerReload);
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_timestamp ++;
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}
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}
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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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int cycles_run_for = 1;
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const int32_t ready_line_disable_time = 227;//horizontalTimerReload;
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if(operation == CPU6502::BusOperation::Ready) {
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int32_t distance_to_end_of_ready = (_horizontalTimer - ready_line_disable_time + horizontalTimerReload + 1)%(horizontalTimerReload + 1);
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cycles_run_for = distance_to_end_of_ready / 3;
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output_pixels(distance_to_end_of_ready);
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} else {
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output_pixels(3);
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}
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if(_hMoveWillCount) {
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_hMoveCounter = 0x0f;
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_hMoveFlags = 0x1f;
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_hMoveIsCounting = true;
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_hMoveWillCount = false;
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}
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if(_horizontalTimer == ready_line_disable_time)
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set_ready_line(false);
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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 = 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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// TODO: inputs
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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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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:
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case 0x07: _playerColour[decodedAddress - 0x06] = *value; break;
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case 0x08: _playfieldColour = *value; break;
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case 0x09: _backgroundColour = *value; break;
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case 0x0a: _playfieldControl = *value; break;
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case 0x0b:
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case 0x0c: _playerReflection[decodedAddress - 0x0b] = *value; break;
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case 0x0d:
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_playfield[0] = ((*value) >> 4)&1;
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_playfield[1] = ((*value) >> 5)&1;
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_playfield[2] = ((*value) >> 6)&1;
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_playfield[3] = (*value) >> 7;
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break;
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case 0x0e:
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_playfield[4] = (*value) >> 7;
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_playfield[5] = ((*value) >> 6)&1;
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_playfield[6] = ((*value) >> 5)&1;
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_playfield[7] = ((*value) >> 4)&1;
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_playfield[8] = ((*value) >> 3)&1;
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_playfield[9] = ((*value) >> 2)&1;
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_playfield[10] = ((*value) >> 1)&1;
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_playfield[11] = (*value)&1;
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break;
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case 0x0f:
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_playfield[19] = (*value) >> 7;
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_playfield[18] = ((*value) >> 6)&1;
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_playfield[17] = ((*value) >> 5)&1;
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_playfield[16] = ((*value) >> 4)&1;
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_playfield[15] = ((*value) >> 3)&1;
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_playfield[14] = ((*value) >> 2)&1;
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_playfield[13] = ((*value) >> 1)&1;
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_playfield[12] = (*value)&1;
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break;
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case 0x10: case 0x11: case 0x12: case 0x13:
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case 0x14: _objectCounter[decodedAddress - 0x10] = 0; break;
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case 0x1c:
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_ballGraphicsEnable = _ballGraphicsEnableLatch;
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case 0x1b: {
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int index = decodedAddress - 0x1b;
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_playerGraphicsLatch[index] = *value;
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if(!(_playerGraphicsLatchEnable[index]&1))
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_playerGraphics[index] = _playerGraphicsLatch[index];
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_playerGraphics[index^1] = _playerGraphicsLatch[index^1];
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} break;
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case 0x1d: _missileGraphicsEnable[0] = *value; break;
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case 0x1e: _missileGraphicsEnable[1] = *value; break;
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case 0x1f:
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_ballGraphicsEnableLatch = *value;
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if(!(_ballGraphicsEnableDelay&1))
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_ballGraphicsEnable = _ballGraphicsEnableLatch;
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break;
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case 0x20:
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case 0x21:
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case 0x22:
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case 0x23:
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case 0x24:
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_objectMotion[decodedAddress - 0x20] = *value;
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break;
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case 0x25: _playerGraphicsLatchEnable[0] = *value; break;
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case 0x26: _playerGraphicsLatchEnable[1] = *value; break;
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case 0x27: _ballGraphicsEnableDelay = *value; break;
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case 0x28:
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case 0x29:
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if (!(*value&0x02) && _missileGraphicsReset[decodedAddress - 0x28]&0x02)
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_objectCounter[decodedAddress - 0x26] = _objectCounter[decodedAddress - 0x28]; // TODO: +3 for normal, +6 for double, +10 for quad
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_missileGraphicsReset[decodedAddress - 0x28] = *value;
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break;
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case 0x2a:
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_vBlankExtend = true;
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_hMoveWillCount = true;
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break;
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case 0x2b:
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_objectMotion[0] =
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_objectMotion[1] =
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_objectMotion[2] =
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_objectMotion[3] =
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_objectMotion[4] = 0;
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break;
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case 0x2c:
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_collisions[0] = _collisions[1] = _collisions[2] =
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_collisions[3] = _collisions[4] = _collisions[5] = 0x3f;
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_collisions[6] = 0x7f;
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_collisions[7] = 0x3f;
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break;
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}
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}
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}
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// check for a PIA access
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if ((address&0x1280) == 0x280) {
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if(isReadOperation(operation)) {
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switch(address & 0xf) {
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case 0x00:
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// TODO: port A read
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break;
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case 0x01:
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// TODO: port A DDR
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break;
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case 0x02:
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// TODO: port B read
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break;
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case 0x03:
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// TODO: port B DDR
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break;
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case 0x04:
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returnValue &= _piaTimerValue >> _piaTimerShift;
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if(_writtenPiaTimerShift != _piaTimerShift) {
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_piaTimerShift = _writtenPiaTimerShift;
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_piaTimerValue <<= _writtenPiaTimerShift;
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}
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break;
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case 0x05:
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returnValue &= _piaTimerStatus;
|
|
_piaTimerStatus &= ~0x40;
|
|
break;
|
|
}
|
|
} else {
|
|
switch(address & 0x0f) {
|
|
case 0x04: _writtenPiaTimerShift = _piaTimerShift = 0; _piaTimerValue = *value << 0; _piaTimerStatus &= ~0xc0; break;
|
|
case 0x05: _writtenPiaTimerShift = _piaTimerShift = 3; _piaTimerValue = *value << 3; _piaTimerStatus &= ~0xc0; break;
|
|
case 0x06: _writtenPiaTimerShift = _piaTimerShift = 6; _piaTimerValue = *value << 6; _piaTimerStatus &= ~0xc0; break;
|
|
case 0x07: _writtenPiaTimerShift = _piaTimerShift = 10; _piaTimerValue = *value << 10; _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;
|
|
}
|
|
|
|
return cycles_run_for;
|
|
}
|
|
|
|
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];
|
|
memcpy(_rom, data, std::min(_rom_size, 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];
|
|
}
|