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408 lines
13 KiB
C++
408 lines
13 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 double NTSC_clock_rate = 1194720;
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static const double PAL_clock_rate = 1182298;
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}
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Machine::Machine() :
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rom_(nullptr),
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rom_pages_{nullptr, nullptr, nullptr, nullptr},
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tia_input_value_{0xff, 0xff},
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cycles_since_speaker_update_(0),
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cycles_since_video_update_(0),
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cycles_since_6532_update_(0),
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frame_record_pointer_(0),
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is_ntsc_(true)
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{
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set_clock_rate(NTSC_clock_rate);
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}
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void Machine::setup_output(float aspect_ratio)
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{
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tia_.reset(new TIA);
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speaker_.reset(new Speaker);
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speaker_->set_input_rate((float)(get_clock_rate() / 38.0));
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tia_->get_crt()->set_delegate(this);
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}
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void Machine::close_output()
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{
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tia_ = nullptr;
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speaker_ = 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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unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value)
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{
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uint8_t returnValue = 0xff;
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unsigned int cycles_run_for = 3;
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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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cycles_run_for = (unsigned int)tia_->get_cycles_until_horizontal_blank(cycles_since_video_update_);
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cycles_since_speaker_update_ += cycles_run_for;
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cycles_since_video_update_ += cycles_run_for;
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cycles_since_6532_update_ += (cycles_run_for / 3);
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if(operation != CPU6502::BusOperation::Ready) {
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uint16_t masked_address = address & 0x1fff;
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// check for potential paging
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switch(paging_model_) {
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default:
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// check for an Atari paging access
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if(rom_size_ > 4096 && ((address & 0x1f00) == 0x1f00)) {
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uint8_t *base_ptr = rom_pages_[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 != rom_pages_[0]) {
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rom_pages_[0] = base_ptr;
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rom_pages_[1] = base_ptr + 1024;
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rom_pages_[2] = base_ptr + 2048;
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rom_pages_[3] = base_ptr + 3072;
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}
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}
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break;
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case StaticAnalyser::Atari2600PagingModel::ParkerBros:
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if(masked_address >= 0x1fe0 && masked_address < 0x1ff8) {
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int slot = (masked_address >> 3) & 3;
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int target = masked_address & 7;
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rom_pages_[slot] = &rom_[target * 1024];
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}
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break;
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}
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// check for a ROM read
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if(address&0x1000)
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{
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// check for a RAM access
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bool was_ram_access = false;
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if(has_ram_) {
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if(masked_address >= ram_write_start_ && masked_address < ram_.size() + ram_write_start_) {
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ram_[masked_address & ram_.size() - 1] = *value;
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was_ram_access = true;
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} else if(masked_address >= ram_read_start_ && masked_address < ram_.size() + ram_read_start_) {
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returnValue &= ram_[masked_address & ram_.size() - 1];
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was_ram_access = true;
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}
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}
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if(isReadOperation(operation) && !was_ram_access) {
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returnValue &= rom_pages_[(address >> 10)&3][address&1023];
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}
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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 &= mos6532_.get_ram(address);
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} else {
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mos6532_.set_ram(address, *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 &= tia_->get_collision_flags(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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returnValue &= 0;
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break;
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case 0x0c:
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case 0x0d:
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returnValue &= tia_input_value_[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: update_video(); tia_->set_sync(*value & 0x02); break;
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case 0x01: update_video(); tia_->set_blank(*value & 0x02); break;
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case 0x02: set_ready_line(true); break;
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case 0x03: update_video(); tia_->reset_horizontal_counter(); break;
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// TODO: audio will now be out of synchronisation — fix
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case 0x04:
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case 0x05: update_video(); tia_->set_player_number_and_size(decodedAddress - 0x04, *value); break;
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case 0x06:
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case 0x07: update_video(); tia_->set_player_missile_colour(decodedAddress - 0x06, *value); break;
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case 0x08: update_video(); tia_->set_playfield_ball_colour(*value); break;
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case 0x09: update_video(); tia_->set_background_colour(*value); break;
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case 0x0a: update_video(); tia_->set_playfield_control_and_ball_size(*value); break;
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case 0x0b:
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case 0x0c: update_video(); tia_->set_player_reflected(decodedAddress - 0x0b, !((*value)&8)); break;
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case 0x0d:
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case 0x0e:
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case 0x0f: update_video(); tia_->set_playfield(decodedAddress - 0x0d, *value); break;
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case 0x10:
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case 0x11: update_video(); tia_->set_player_position(decodedAddress - 0x10); break;
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case 0x12:
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case 0x13: update_video(); tia_->set_missile_position(decodedAddress - 0x12); break;
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case 0x14: update_video(); tia_->set_ball_position(); break;
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case 0x1b:
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case 0x1c: update_video(); tia_->set_player_graphic(decodedAddress - 0x1b, *value); break;
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case 0x1d:
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case 0x1e: update_video(); tia_->set_missile_enable(decodedAddress - 0x1d, (*value)&2); break;
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case 0x1f: update_video(); tia_->set_ball_enable((*value)&2); break;
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case 0x20:
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case 0x21: update_video(); tia_->set_player_motion(decodedAddress - 0x20, *value); break;
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case 0x22:
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case 0x23: update_video(); tia_->set_missile_motion(decodedAddress - 0x22, *value); break;
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case 0x24: update_video(); tia_->set_ball_motion(*value); break;
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case 0x25:
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case 0x26: tia_->set_player_delay(decodedAddress - 0x25, (*value)&1); break;
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case 0x27: tia_->set_ball_delay((*value)&1); break;
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case 0x28:
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case 0x29: update_video(); tia_->set_missile_position_to_player(decodedAddress - 0x28, (*value)&2); break;
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case 0x2a: update_video(); tia_->move(); break;
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case 0x2b: update_video(); tia_->clear_motion(); break;
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case 0x2c: update_video(); tia_->clear_collision_flags(); break;
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case 0x15:
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case 0x16: update_audio(); speaker_->set_control(decodedAddress - 0x15, *value); break;
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case 0x17:
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case 0x18: update_audio(); speaker_->set_divider(decodedAddress - 0x17, *value); break;
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case 0x19:
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case 0x1a: update_audio(); speaker_->set_volume(decodedAddress - 0x19, *value); break;
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case 0x3f:
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if(paging_model_ == StaticAnalyser::Atari2600PagingModel::Tigervision && (masked_address == 0x3f))
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{
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int selected_page = (*value) % (rom_size_ / 2048);
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rom_pages_[0] = &rom_[selected_page * 2048];
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rom_pages_[1] = rom_pages_[0] + 1024;
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}
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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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update_6532();
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if(isReadOperation(operation)) {
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returnValue &= mos6532_.get_register(address);
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} else {
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mos6532_.set_register(address, *value);
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}
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}
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if(isReadOperation(operation)) {
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*value = returnValue;
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}
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}
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if(!tia_->get_cycles_until_horizontal_blank(cycles_since_video_update_)) set_ready_line(false);
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return cycles_run_for / 3;
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}
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void Machine::set_digital_input(Atari2600DigitalInput input, bool state)
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{
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switch (input) {
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case Atari2600DigitalInputJoy1Up: mos6532_.update_port_input(0, 0x10, state); break;
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case Atari2600DigitalInputJoy1Down: mos6532_.update_port_input(0, 0x20, state); break;
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case Atari2600DigitalInputJoy1Left: mos6532_.update_port_input(0, 0x40, state); break;
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case Atari2600DigitalInputJoy1Right: mos6532_.update_port_input(0, 0x80, state); break;
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case Atari2600DigitalInputJoy2Up: mos6532_.update_port_input(0, 0x01, state); break;
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case Atari2600DigitalInputJoy2Down: mos6532_.update_port_input(0, 0x02, state); break;
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case Atari2600DigitalInputJoy2Left: mos6532_.update_port_input(0, 0x04, state); break;
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case Atari2600DigitalInputJoy2Right: mos6532_.update_port_input(0, 0x08, state); break;
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// TODO: latching
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case Atari2600DigitalInputJoy1Fire: if(state) tia_input_value_[0] &= ~0x80; else tia_input_value_[0] |= 0x80; break;
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case Atari2600DigitalInputJoy2Fire: if(state) tia_input_value_[1] &= ~0x80; else tia_input_value_[1] |= 0x80; break;
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default: break;
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}
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}
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void Machine::set_switch_is_enabled(Atari2600Switch input, bool state)
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{
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switch(input) {
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case Atari2600SwitchReset: mos6532_.update_port_input(1, 0x01, state); break;
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case Atari2600SwitchSelect: mos6532_.update_port_input(1, 0x02, state); break;
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case Atari2600SwitchColour: mos6532_.update_port_input(1, 0x08, state); break;
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case Atari2600SwitchLeftPlayerDifficulty: mos6532_.update_port_input(1, 0x40, state); break;
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case Atari2600SwitchRightPlayerDifficulty: mos6532_.update_port_input(1, 0x80, state); break;
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}
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}
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void Machine::configure_as_target(const StaticAnalyser::Target &target)
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{
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if(!target.cartridges.front()->get_segments().size()) return;
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Storage::Cartridge::Cartridge::Segment segment = target.cartridges.front()->get_segments().front();
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size_t length = segment.data.size();
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rom_size_ = 1024;
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while(rom_size_ < length && rom_size_ < 32768) rom_size_ <<= 1;
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delete[] rom_;
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rom_ = new uint8_t[rom_size_];
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size_t offset = 0;
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const size_t copy_step = std::min(rom_size_, length);
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while(offset < rom_size_)
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{
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size_t copy_length = std::min(copy_step, rom_size_ - offset);
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memcpy(&rom_[offset], &segment.data[0], copy_length);
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offset += copy_length;
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}
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// On a real paged cartridge, any page may initially be visible. Various homebrew authors appear to have
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// decided the last page will always be initially visible. So do that.
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size_t rom_mask = rom_size_ - 1;
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uint8_t *rom_base = rom_;
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if(rom_size_ > 4096) rom_base = &rom_[rom_size_ - 4096];
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rom_pages_[0] = rom_base;
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rom_pages_[1] = &rom_base[1024 & rom_mask];
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rom_pages_[2] = &rom_base[2048 & rom_mask];
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rom_pages_[3] = &rom_base[3072 & rom_mask];
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switch(target.atari.paging_model)
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{
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default:
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if(target.atari.uses_superchip)
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{
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ram_.resize(128);
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has_ram_ = true;
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ram_write_start_ = 0x1000;
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ram_read_start_ = 0x1080;
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}
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break;
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case StaticAnalyser::Atari2600PagingModel::CommaVid:
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ram_.resize(1024);
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has_ram_ = true;
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ram_write_start_ = 0x1400;
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ram_read_start_ = 0x1000;
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break;
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}
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paging_model_ = target.atari.paging_model;
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}
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#pragma mark - Audio and Video
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void Machine::update_audio()
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{
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unsigned int audio_cycles = cycles_since_speaker_update_ / 114;
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speaker_->run_for_cycles(audio_cycles);
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cycles_since_speaker_update_ %= 114;
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}
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void Machine::update_video()
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{
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tia_->run_for_cycles((int)cycles_since_video_update_);
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cycles_since_video_update_ = 0;
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}
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void Machine::update_6532()
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{
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mos6532_.run_for_cycles(cycles_since_6532_update_);
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cycles_since_6532_update_ = 0;
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}
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void Machine::synchronise()
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{
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update_audio();
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update_video();
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speaker_->flush();
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}
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#pragma mark - CRT delegate
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void Machine::crt_did_end_batch_of_frames(Outputs::CRT::CRT *crt, unsigned int number_of_frames, unsigned int number_of_unexpected_vertical_syncs)
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{
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const size_t number_of_frame_records = sizeof(frame_records_) / sizeof(frame_records_[0]);
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frame_records_[frame_record_pointer_ % number_of_frame_records].number_of_frames = number_of_frames;
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frame_records_[frame_record_pointer_ % number_of_frame_records].number_of_unexpected_vertical_syncs = number_of_unexpected_vertical_syncs;
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frame_record_pointer_ ++;
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if(frame_record_pointer_ >= 6)
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{
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unsigned int total_number_of_frames = 0;
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unsigned int total_number_of_unexpected_vertical_syncs = 0;
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for(size_t c = 0; c < number_of_frame_records; c++)
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{
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total_number_of_frames += frame_records_[c].number_of_frames;
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total_number_of_unexpected_vertical_syncs += frame_records_[c].number_of_unexpected_vertical_syncs;
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}
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if(total_number_of_unexpected_vertical_syncs >= total_number_of_frames >> 1)
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{
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for(size_t c = 0; c < number_of_frame_records; c++)
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{
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frame_records_[c].number_of_frames = 0;
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frame_records_[c].number_of_unexpected_vertical_syncs = 0;
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}
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is_ntsc_ ^= true;
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double clock_rate;
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if(is_ntsc_)
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{
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clock_rate = NTSC_clock_rate;
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tia_->set_output_mode(TIA::OutputMode::NTSC);
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}
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else
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{
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clock_rate = PAL_clock_rate;
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tia_->set_output_mode(TIA::OutputMode::PAL);
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}
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speaker_->set_input_rate((float)(clock_rate / 38.0));
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speaker_->set_high_frequency_cut_off((float)(clock_rate / (38.0 * 2.0)));
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set_clock_rate(clock_rate);
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}
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}
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}
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