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CLK/Machines/Atari2600/Atari2600.cpp

914 lines
28 KiB
C++

//
// Atari2600.cpp
// CLK
//
// Created by Thomas Harte on 14/07/2015.
// Copyright © 2015 Thomas Harte. All rights reserved.
//
#include "Atari2600.hpp"
#include <algorithm>
#include <stdio.h>
using namespace Atari2600;
namespace {
static const unsigned int horizontalTimerPeriod = 228;
static const double NTSC_clock_rate = 1194720;
static const double PAL_clock_rate = 1182298;
}
Machine::Machine() :
_horizontalTimer(0),
_lastOutputStateDuration(0),
_lastOutputState(OutputState::Sync),
_rom(nullptr),
_tiaInputValue{0xff, 0xff},
_upcomingEventsPointer(0),
_objectCounterPointer(0),
_stateByTime(_stateByExtendTime[0]),
_cycles_since_speaker_update(0),
_is_pal_region(false)
{
memset(_collisions, 0xff, sizeof(_collisions));
setup_reported_collisions();
for(int vbextend = 0; vbextend < 2; vbextend++)
{
for(int c = 0; c < 57; c++)
{
OutputState state;
// determine which output state will be active in four cycles from now
switch(c)
{
case 0: case 1: case 2: case 3: state = OutputState::Blank; break;
case 4: case 5: case 6: case 7: state = OutputState::Sync; break;
case 8: case 9: case 10: case 11: state = OutputState::ColourBurst; break;
case 12: case 13: case 14:
case 15: case 16: state = OutputState::Blank; break;
case 17: case 18: state = vbextend ? OutputState::Blank : OutputState::Pixel; break;
default: state = OutputState::Pixel; break;
}
_stateByExtendTime[vbextend][c] = state;
}
}
set_clock_rate(NTSC_clock_rate);
}
void Machine::setup_output(float aspect_ratio)
{
_speaker.reset(new Speaker);
_crt.reset(new Outputs::CRT::CRT(228, 1, 263, Outputs::CRT::ColourSpace::YIQ, 228, 1, 1));
_crt->set_output_device(Outputs::CRT::Television);
// this is the NTSC phase offset function; see below for PAL
_crt->set_composite_sampling_function(
"float composite_sample(usampler2D texID, vec2 coordinate, vec2 iCoordinate, float phase, float amplitude)"
"{"
"uint c = texture(texID, coordinate).r;"
"uint y = c & 14u;"
"uint iPhase = (c >> 4);"
"float phaseOffset = 6.283185308 * float(iPhase - 1u) / 13.0;"
"return mix(float(y) / 14.0, step(1, iPhase) * cos(phase + phaseOffset), amplitude);"
"}");
_speaker->set_input_rate((float)(get_clock_rate() / 38.0));
}
void Machine::switch_region()
{
// the PAL function
_crt->set_composite_sampling_function(
"float composite_sample(usampler2D texID, vec2 coordinate, vec2 iCoordinate, float phase, float amplitude)"
"{"
"uint c = texture(texID, coordinate).r;"
"uint y = c & 14u;"
"uint iPhase = (c >> 4);"
"uint direction = iPhase & 1u;"
"float phaseOffset = float(7u - direction) + (float(direction) - 0.5) * 2.0 * float(iPhase >> 1);"
"phaseOffset *= 6.283185308 / 12.0;"
"return mix(float(y) / 14.0, step(4, (iPhase + 2u) & 15u) * cos(phase + phaseOffset), amplitude);"
"}");
_crt->set_new_timing(228, 312, Outputs::CRT::ColourSpace::YUV, 228, 1);
_is_pal_region = true;
_speaker->set_input_rate((float)(get_clock_rate() / 38.0));
set_clock_rate(PAL_clock_rate);
}
void Machine::close_output()
{
_crt = nullptr;
}
Machine::~Machine()
{
delete[] _rom;
close_output();
}
void Machine::update_timers(int mask)
{
unsigned int upcomingPointerPlus4 = (_upcomingEventsPointer + 4)%number_of_upcoming_events;
_objectCounterPointer = (_objectCounterPointer + 1)%number_of_recorded_counters;
ObjectCounter *oneClockAgo = _objectCounter[(_objectCounterPointer - 1 + number_of_recorded_counters)%number_of_recorded_counters];
ObjectCounter *twoClocksAgo = _objectCounter[(_objectCounterPointer - 2 + number_of_recorded_counters)%number_of_recorded_counters];
ObjectCounter *now = _objectCounter[_objectCounterPointer];
// grab the background now, for application in four clocks
if(mask & (1 << 5) && !(_horizontalTimer&3))
{
unsigned int offset = 4 + _horizontalTimer - (horizontalTimerPeriod - 160);
_upcomingEvents[upcomingPointerPlus4].updates |= Event::Action::Playfield;
_upcomingEvents[upcomingPointerPlus4].playfieldPixel = _playfield[(offset >> 2)%40];
}
if(mask & (1 << 4))
{
// the ball becomes visible whenever it hits zero, regardless of whether its status
// is the result of a counter rollover or a programmatic reset, and there's a four
// clock delay on that triggering the start signal
now[4].count = (oneClockAgo[4].count + 1)%160;
now[4].pixel = oneClockAgo[4].pixel + 1;
if(!now[4].count) now[4].pixel = 0;
}
else
{
now[4] = oneClockAgo[4];
}
// check for player and missle triggers
for(int c = 0; c < 4; c++)
{
if(mask & (1 << c))
{
// update the count
now[c].count = (oneClockAgo[c].count + 1)%160;
uint8_t repeatMask = _playerAndMissileSize[c&1] & 7;
ObjectCounter *rollover;
ObjectCounter *equality;
if(c < 2)
{
// update the pixel
now[c].broad_pixel = oneClockAgo[c].broad_pixel + 1;
switch(repeatMask)
{
default: now[c].pixel = oneClockAgo[c].pixel + 1; break;
case 5: now[c].pixel = oneClockAgo[c].pixel + (now[c].broad_pixel&1); break;
case 7: now[c].pixel = oneClockAgo[c].pixel + (((now[c].broad_pixel | (now[c].broad_pixel >> 1))^1)&1); break;
}
// check for a rollover six clocks ago or equality five clocks ago
rollover = twoClocksAgo;
equality = oneClockAgo;
}
else
{
// update the pixel
now[c].pixel = oneClockAgo[c].pixel + 1;
// check for a rollover five clocks ago or equality four clocks ago
rollover = oneClockAgo;
equality = now;
}
if(
(rollover[c].count == 159) ||
(_hasSecondCopy[c&1] && equality[c].count == 16) ||
(_hasThirdCopy[c&1] && equality[c].count == 32) ||
(_hasFourthCopy[c&1] && equality[c].count == 64)
)
{
now[c].pixel = 0;
now[c].broad_pixel = 0;
}
}
else
{
now[c] = oneClockAgo[c];
}
}
}
uint8_t Machine::get_output_pixel()
{
ObjectCounter *now = _objectCounter[_objectCounterPointer];
// get the playfield pixel
unsigned int offset = _horizontalTimer - (horizontalTimerPeriod - 160);
uint8_t playfieldColour = ((_playfieldControl&6) == 2) ? _playerColour[offset / 80] : _playfieldColour;
// ball pixel
uint8_t ballPixel = 0;
if(now[4].pixel < _ballSize) {
ballPixel = _ballGraphicsEnable[_ballGraphicsSelector];
}
// determine the player and missile pixels
uint8_t playerPixels[2] = { 0, 0 };
uint8_t missilePixels[2] = { 0, 0 };
for(int c = 0; c < 2; c++)
{
if(_playerGraphics[c] && now[c].pixel < 8) {
playerPixels[c] = (_playerGraphics[_playerGraphicsSelector[c]][c] >> (now[c].pixel ^ _playerReflectionMask[c])) & 1;
}
if(!_missileGraphicsReset[c] && now[c+2].pixel < _missileSize[c]) {
missilePixels[c] = _missileGraphicsEnable[c];
}
}
// accumulate collisions
int pixel_mask = playerPixels[0] | (playerPixels[1] << 1) | (missilePixels[0] << 2) | (missilePixels[1] << 3) | (ballPixel << 4) | (_playfieldOutput << 5);
_collisions[0] |= _reportedCollisions[pixel_mask][0];
_collisions[1] |= _reportedCollisions[pixel_mask][1];
_collisions[2] |= _reportedCollisions[pixel_mask][2];
_collisions[3] |= _reportedCollisions[pixel_mask][3];
_collisions[4] |= _reportedCollisions[pixel_mask][4];
_collisions[5] |= _reportedCollisions[pixel_mask][5];
_collisions[6] |= _reportedCollisions[pixel_mask][6];
_collisions[7] |= _reportedCollisions[pixel_mask][7];
// apply appropriate priority to pick a colour
uint8_t playfieldPixel = _playfieldOutput | ballPixel;
uint8_t outputColour = playfieldPixel ? playfieldColour : _backgroundColour;
if(!(_playfieldControl&0x04) || !playfieldPixel) {
if(playerPixels[1] || missilePixels[1]) outputColour = _playerColour[1];
if(playerPixels[0] || missilePixels[0]) outputColour = _playerColour[0];
}
// return colour
return outputColour;
}
void Machine::setup_reported_collisions()
{
for(int c = 0; c < 64; c++)
{
memset(_reportedCollisions[c], 0, 8);
int playerPixels[2] = { c&1, (c >> 1)&1 };
int missilePixels[2] = { (c >> 2)&1, (c >> 3)&1 };
int ballPixel = (c >> 4)&1;
int playfieldPixel = (c >> 5)&1;
if(playerPixels[0] | playerPixels[1]) {
_reportedCollisions[c][0] |= ((missilePixels[0] & playerPixels[1]) << 7) | ((missilePixels[0] & playerPixels[0]) << 6);
_reportedCollisions[c][1] |= ((missilePixels[1] & playerPixels[0]) << 7) | ((missilePixels[1] & playerPixels[1]) << 6);
_reportedCollisions[c][2] |= ((playfieldPixel & playerPixels[0]) << 7) | ((ballPixel & playerPixels[0]) << 6);
_reportedCollisions[c][3] |= ((playfieldPixel & playerPixels[1]) << 7) | ((ballPixel & playerPixels[1]) << 6);
_reportedCollisions[c][7] |= ((playerPixels[0] & playerPixels[1]) << 7);
}
if(playfieldPixel | ballPixel) {
_reportedCollisions[c][4] |= ((playfieldPixel & missilePixels[0]) << 7) | ((ballPixel & missilePixels[0]) << 6);
_reportedCollisions[c][5] |= ((playfieldPixel & missilePixels[1]) << 7) | ((ballPixel & missilePixels[1]) << 6);
_reportedCollisions[c][6] |= ((playfieldPixel & ballPixel) << 7);
}
if(missilePixels[0] & missilePixels[1])
_reportedCollisions[c][7] |= (1 << 6);
}
}
void Machine::output_pixels(unsigned int count)
{
while(count--)
{
if(_upcomingEvents[_upcomingEventsPointer].updates)
{
// apply any queued changes and flush the record
if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveSetup)
{
// schedule an extended left border
_stateByTime = _stateByExtendTime[1];
// 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;
// follow-through into a compare immediately
_upcomingEvents[_upcomingEventsPointer].updates |= Event::Action::HMoveCompare;
}
if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveCompare)
{
for(int c = 0; c < 5; c++)
{
if(((_objectMotion[c] >> 4)^_hMoveCounter) == 7)
{
_hMoveFlags &= ~(1 << c);
}
}
if(_hMoveFlags)
{
if(_hMoveCounter) _hMoveCounter--;
_upcomingEvents[(_upcomingEventsPointer+4)%number_of_upcoming_events].updates |= Event::Action::HMoveCompare;
_upcomingEvents[(_upcomingEventsPointer+2)%number_of_upcoming_events].updates |= Event::Action::HMoveDecrement;
}
}
if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::HMoveDecrement)
{
update_timers(_hMoveFlags);
}
if(_upcomingEvents[_upcomingEventsPointer].updates & Event::Action::ResetCounter)
{
_objectCounter[_objectCounterPointer][_upcomingEvents[_upcomingEventsPointer].counter].count = 0;
}
// zero out current update event
_upcomingEvents[_upcomingEventsPointer].updates = 0;
}
// progress to next event
_upcomingEventsPointer = (_upcomingEventsPointer + 1)%number_of_upcoming_events;
// determine which output state is currently active
OutputState primary_state = _stateByTime[_horizontalTimer >> 2];
OutputState effective_state = primary_state;
// update pixel timers
if(primary_state == OutputState::Pixel) update_timers(~0);
// update the background chain
if(_horizontalTimer >= 64 && _horizontalTimer <= 160+64 && !(_horizontalTimer&3))
{
_playfieldOutput = _nextPlayfieldOutput;
_nextPlayfieldOutput = _playfield[(_horizontalTimer - 64) >> 2];
}
// if vsync is enabled, output the opposite of the automatic hsync output;
// also honour the vertical blank flag
if(_vSyncEnabled) {
effective_state = (effective_state = OutputState::Sync) ? OutputState::Blank : OutputState::Sync;
} else if(_vBlankEnabled && effective_state == OutputState::Pixel) {
effective_state = OutputState::Blank;
}
// decide what that means needs to be communicated to the CRT
_lastOutputStateDuration++;
if(effective_state != _lastOutputState) {
switch(_lastOutputState) {
case OutputState::Blank: _crt->output_blank(_lastOutputStateDuration); break;
case OutputState::Sync: _crt->output_sync(_lastOutputStateDuration); break;
case OutputState::ColourBurst: _crt->output_colour_burst(_lastOutputStateDuration, 96, 0); break;
case OutputState::Pixel: _crt->output_data(_lastOutputStateDuration, 1); break;
}
_lastOutputStateDuration = 0;
_lastOutputState = effective_state;
if(effective_state == OutputState::Pixel) {
_outputBuffer = _crt->allocate_write_area(160);
} else {
_outputBuffer = nullptr;
}
}
// decide on a pixel colour if that's what's happening
if(effective_state == OutputState::Pixel)
{
uint8_t colour = get_output_pixel();
if(_outputBuffer)
{
*_outputBuffer = colour;
_outputBuffer++;
}
}
// advance horizontal timer, perform reset actions if desired
_horizontalTimer = (_horizontalTimer + 1) % horizontalTimerPeriod;
if(!_horizontalTimer)
{
// switch back to a normal length left border
_stateByTime = _stateByExtendTime[0];
set_ready_line(false);
}
}
}
unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value)
{
uint8_t returnValue = 0xff;
unsigned int cycles_run_for = 3;
// this occurs as a feedback loop — the 2600 requests ready, then performs the cycles_run_for
// leap to the end of ready only once ready is signalled — because on a 6502 ready doesn't take
// effect until the next read; therefore it isn't safe to assume that signalling ready immediately
// skips to the end of the line.
if(operation == CPU6502::BusOperation::Ready) {
unsigned int distance_to_end_of_ready = horizontalTimerPeriod - _horizontalTimer;
cycles_run_for = distance_to_end_of_ready;
}
output_pixels(cycles_run_for);
_cycles_since_speaker_update += cycles_run_for;
if(operation != CPU6502::BusOperation::Ready) {
// check for a paging access
if(_rom_size > 4096 && ((address & 0x1f00) == 0x1f00)) {
uint8_t *base_ptr = _romPages[0];
uint8_t first_paging_register = (uint8_t)(0xf8 - (_rom_size >> 14)*2);
const uint8_t paging_register = address&0xff;
if(paging_register >= first_paging_register) {
const uint16_t selected_page = paging_register - first_paging_register;
if(selected_page * 4096 < _rom_size) {
base_ptr = &_rom[selected_page * 4096];
}
}
if(base_ptr != _romPages[0]) {
_romPages[0] = base_ptr;
_romPages[1] = base_ptr + 1024;
_romPages[2] = base_ptr + 2048;
_romPages[3] = base_ptr + 3072;
}
}
// check for a ROM read
if((address&0x1000) && isReadOperation(operation)) {
returnValue &= _romPages[(address >> 10)&3][address&1023];
}
// check for a RAM access
if((address&0x1280) == 0x80) {
if(isReadOperation(operation)) {
returnValue &= _mos6532.get_ram(address);
} else {
_mos6532.set_ram(address, *value);
}
}
// check for a TIA access
if(!(address&0x1080)) {
if(isReadOperation(operation)) {
const uint16_t decodedAddress = address & 0xf;
switch(decodedAddress) {
case 0x00: // missile 0 / player collisions
case 0x01: // missile 1 / player collisions
case 0x02: // player 0 / playfield / ball collisions
case 0x03: // player 1 / playfield / ball collisions
case 0x04: // missile 0 / playfield / ball collisions
case 0x05: // missile 1 / playfield / ball collisions
case 0x06: // ball / playfield collisions
case 0x07: // player / player, missile / missile collisions
returnValue &= _collisions[decodedAddress];
break;
case 0x08:
case 0x09:
case 0x0a:
case 0x0b:
// TODO: pot ports
break;
case 0x0c:
case 0x0d:
returnValue &= _tiaInputValue[decodedAddress - 0x0c];
break;
}
} else {
const uint16_t decodedAddress = address & 0x3f;
switch(decodedAddress) {
case 0x00:
_vSyncEnabled = !!(*value & 0x02);
break;
case 0x01: _vBlankEnabled = !!(*value & 0x02); break;
case 0x02:
if(_horizontalTimer) set_ready_line(true);
break;
case 0x03:
// Reset is delayed by four cycles.
_horizontalTimer = horizontalTimerPeriod - 4;
// TODO: audio will now be out of synchronisation — fix
break;
case 0x04:
case 0x05: {
int entry = decodedAddress - 0x04;
_playerAndMissileSize[entry] = *value;
_missileSize[entry] = 1 << ((*value >> 4)&3);
uint8_t repeatMask = (*value)&7;
_hasSecondCopy[entry] = (repeatMask == 1) || (repeatMask == 3);
_hasThirdCopy[entry] = (repeatMask == 2) || (repeatMask == 3) || (repeatMask == 6);
_hasFourthCopy[entry] = (repeatMask == 4) || (repeatMask == 6);
} break;
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;
_ballSize = 1 << ((_playfieldControl >> 4)&3);
// 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: _playerReflectionMask[decodedAddress - 0x0b] = (*value)&8 ? 0 : 7; 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:
_upcomingEvents[(_upcomingEventsPointer + 4)%number_of_upcoming_events].updates |= Event::Action::ResetCounter;
_upcomingEvents[(_upcomingEventsPointer + 4)%number_of_upcoming_events].counter = decodedAddress - 0x10;
break;
case 0x15: case 0x16:
update_audio();
_speaker->set_control(decodedAddress - 0x15, *value);
break;
case 0x17: case 0x18:
update_audio();
_speaker->set_divider(decodedAddress - 0x17, *value);
break;
case 0x19: case 0x1a:
update_audio();
_speaker->set_volume(decodedAddress - 0x19, *value);
break;
case 0x1c:
_ballGraphicsEnable[1] = _ballGraphicsEnable[0];
case 0x1b: {
int index = decodedAddress - 0x1b;
_playerGraphics[0][index] = *value;
_playerGraphics[1][index^1] = _playerGraphics[0][index^1];
} break;
case 0x1d:
case 0x1e:
_missileGraphicsEnable[decodedAddress - 0x1d] = ((*value) >> 1)&1;
// printf("e:%02x <- %c\n", decodedAddress - 0x1d, ((*value)&1) ? 'E' : '-');
break;
case 0x1f:
_ballGraphicsEnable[0] = ((*value) >> 1)&1;
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: _ballGraphicsSelector = (*value)&1; break;
case 0x28:
case 0x29:
{
// TODO: this should properly mean setting a flag and propagating later, I think?
int index = decodedAddress - 0x28;
if(!(*value&0x02) && _missileGraphicsReset[index])
{
_objectCounter[_objectCounterPointer][index + 2].count = _objectCounter[_objectCounterPointer][index].count;
uint8_t repeatMask = _playerAndMissileSize[index] & 7;
int extra_offset;
switch(repeatMask)
{
default: extra_offset = 3; break;
case 5: extra_offset = 6; break;
case 7: extra_offset = 10; break;
}
_objectCounter[_objectCounterPointer][index + 2].count = (_objectCounter[_objectCounterPointer][index + 2].count + extra_offset)%160;
}
_missileGraphicsReset[index] = !!((*value) & 0x02);
// printf("r:%02x <- %c\n", decodedAddress - 0x28, ((*value)&2) ? 'R' : '-');
}
break;
case 0x2a: {
// 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
// int start_pause = ((_horizontalTimer + 3)&3) + 4;
_upcomingEvents[(_upcomingEventsPointer + 5)%number_of_upcoming_events].updates |= Event::Action::HMoveSetup;
} 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)) {
returnValue &= _mos6532.get_register(address);
} else {
_mos6532.set_register(address, *value);
}
}
if(isReadOperation(operation)) {
*value = returnValue;
}
}
_mos6532.run_for_cycles(cycles_run_for / 3);
return cycles_run_for / 3;
}
void Machine::set_digital_input(Atari2600DigitalInput input, bool state)
{
switch (input) {
case Atari2600DigitalInputJoy1Up: _mos6532.update_port_input(0, 0x10, state); break;
case Atari2600DigitalInputJoy1Down: _mos6532.update_port_input(0, 0x20, state); break;
case Atari2600DigitalInputJoy1Left: _mos6532.update_port_input(0, 0x40, state); break;
case Atari2600DigitalInputJoy1Right: _mos6532.update_port_input(0, 0x80, state); break;
case Atari2600DigitalInputJoy2Up: _mos6532.update_port_input(0, 0x01, state); break;
case Atari2600DigitalInputJoy2Down: _mos6532.update_port_input(0, 0x02, state); break;
case Atari2600DigitalInputJoy2Left: _mos6532.update_port_input(0, 0x04, state); break;
case Atari2600DigitalInputJoy2Right: _mos6532.update_port_input(0, 0x08, state); 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_switch_is_enabled(Atari2600Switch input, bool state)
{
switch(input) {
case Atari2600SwitchReset: _mos6532.update_port_input(1, 0x01, state); break;
case Atari2600SwitchSelect: _mos6532.update_port_input(1, 0x02, state); break;
case Atari2600SwitchColour: _mos6532.update_port_input(1, 0x08, state); break;
case Atari2600SwitchLeftPlayerDifficulty: _mos6532.update_port_input(1, 0x40, state); break;
case Atari2600SwitchRightPlayerDifficulty: _mos6532.update_port_input(1, 0x80, state); 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];
}
#pragma mark - Audio
void Machine::update_audio()
{
unsigned int audio_cycles = _cycles_since_speaker_update / 114;
// static unsigned int total_cycles = 0;
// total_cycles += audio_cycles;
// static time_t logged_time = 0;
// time_t time_now = time(nullptr);
// if(time_now - logged_time > 0)
// {
// printf("[s] %ld : %d\n", time_now - logged_time, total_cycles);
// total_cycles = 0;
// logged_time = time_now;
// }
_speaker->run_for_cycles(audio_cycles);
_cycles_since_speaker_update %= 114;
}
void Machine::synchronise()
{
update_audio();
}
Atari2600::Speaker::Speaker()
{
_poly4_counter[0] = _poly4_counter[1] = 0x00f;
_poly5_counter[0] = _poly5_counter[1] = 0x01f;
_poly9_counter[0] = _poly9_counter[1] = 0x1ff;
}
Atari2600::Speaker::~Speaker()
{
}
void Atari2600::Speaker::set_volume(int channel, uint8_t volume)
{
_volume[channel] = volume & 0xf;
}
void Atari2600::Speaker::set_divider(int channel, uint8_t divider)
{
_divider[channel] = divider & 0x1f;
_divider_counter[channel] = 0;
}
void Atari2600::Speaker::set_control(int channel, uint8_t control)
{
_control[channel] = control & 0xf;
}
#define advance_poly4(c) _poly4_counter[channel] = (_poly4_counter[channel] >> 1) | (((_poly4_counter[channel] << 3) ^ (_poly4_counter[channel] << 2))&0x008)
#define advance_poly5(c) _poly5_counter[channel] = (_poly5_counter[channel] >> 1) | (((_poly5_counter[channel] << 4) ^ (_poly5_counter[channel] << 2))&0x010)
#define advance_poly9(c) _poly9_counter[channel] = (_poly9_counter[channel] >> 1) | (((_poly9_counter[channel] << 4) ^ (_poly9_counter[channel] << 8))&0x100)
void Atari2600::Speaker::get_samples(unsigned int number_of_samples, int16_t *target)
{
for(unsigned int c = 0; c < number_of_samples; c++)
{
target[c] = 0;
for(int channel = 0; channel < 2; channel++)
{
_divider_counter[channel] ++;
int level = 0;
switch(_control[channel])
{
case 0x0: case 0xb: // constant 1
level = 1;
break;
case 0x4: case 0x5: // div2 tone
level = (_divider_counter[channel] / (_divider[channel]+1))&1;
break;
case 0xc: case 0xd: // div6 tone
level = (_divider_counter[channel] / ((_divider[channel]+1)*3))&1;
break;
case 0x6: case 0xa: // div31 tone
level = (_divider_counter[channel] / (_divider[channel]+1))%30 <= 18;
break;
case 0xe: // div93 tone
level = (_divider_counter[channel] / ((_divider[channel]+1)*3))%30 <= 18;
break;
case 0x1: // 4-bit poly
level = _poly4_counter[channel]&1;
if(_divider_counter[channel] == _divider[channel]+1)
{
_divider_counter[channel] = 0;
advance_poly4(channel);
}
break;
case 0x2: // 4-bit poly div31
level = _poly4_counter[channel]&1;
if(_divider_counter[channel]%(30*(_divider[channel]+1)) == 18)
{
advance_poly4(channel);
}
break;
case 0x3: // 5/4-bit poly
level = _output_state[channel];
if(_divider_counter[channel] == _divider[channel]+1)
{
if(_poly5_counter[channel]&1)
{
_output_state[channel] = _poly4_counter[channel]&1;
advance_poly4(channel);
}
advance_poly5(channel);
}
break;
case 0x7: case 0x9: // 5-bit poly
level = _poly5_counter[channel]&1;
if(_divider_counter[channel] == _divider[channel]+1)
{
_divider_counter[channel] = 0;
advance_poly5(channel);
}
break;
case 0xf: // 5-bit poly div6
level = _poly5_counter[channel]&1;
if(_divider_counter[channel] == (_divider[channel]+1)*3)
{
_divider_counter[channel] = 0;
advance_poly5(channel);
}
break;
case 0x8: // 9-bit poly
level = _poly9_counter[channel]&1;
if(_divider_counter[channel] == _divider[channel]+1)
{
_divider_counter[channel] = 0;
advance_poly9(channel);
}
break;
}
target[c] += _volume[channel] * 1024 * level;
}
}
}