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708 lines
19 KiB
C++
708 lines
19 KiB
C++
//
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// Electron.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 03/01/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#include "Electron.hpp"
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#include <algorithm>
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using namespace Electron;
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static const unsigned int cycles_per_line = 128;
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static const unsigned int cycles_per_frame = 312*cycles_per_line;
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static const unsigned int crt_cycles_multiplier = 8;
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static const unsigned int crt_cycles_per_line = crt_cycles_multiplier * cycles_per_line;
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const int first_graphics_line = 28;
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Machine::Machine() :
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_interruptControl(0),
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_frameCycles(0),
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_displayOutputPosition(0),
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_audioOutputPosition(0),
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_audioOutputPositionError(0),
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_currentOutputLine(0),
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_crt(Outputs::CRT(crt_cycles_per_line, Outputs::CRT::DisplayType::PAL50, 1, 1))
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{
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memset(_keyStates, 0, sizeof(_keyStates));
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memset(_palette, 0xf, sizeof(_palette));
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_interruptStatus = 0x02;
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for(int c = 0; c < 16; c++)
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memset(_roms[c], 0xff, 16384);
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_speaker.set_input_rate(125000);
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_tape.set_delegate(this);
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}
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Machine::~Machine()
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{
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}
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unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value)
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{
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unsigned int cycles = 1;
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if(address < 0x8000)
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{
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if(isReadOperation(operation))
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{
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*value = _ram[address];
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}
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else
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{
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// If we're still before the display will start to be painted, or the address is
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// less than both the current line address and 0x3000, (the minimum screen mode
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// base address) then there's no way this write can affect the current frame. Sp
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// no need to flush the display. Otherwise, output up until now so that any
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// write doesn't have retroactive effect on the video output.
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if(!(
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(_frameCycles < first_graphics_line * cycles_per_line) ||
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(address < _startLineAddress && address < 0x3000)
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))
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update_display();
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_ram[address] = *value;
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}
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// for the entire frame, RAM is accessible only on odd cycles; in modes below 4
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// it's also accessible only outside of the pixel regions
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cycles += (_frameCycles&1)^1;
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if(_screenMode < 4)
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{
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const int current_line = _frameCycles >> 7;
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const int line_position = _frameCycles & 127;
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if(current_line >= first_graphics_line && current_line < first_graphics_line+256 && line_position >= 24 && line_position < 104)
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cycles = (unsigned int)(104 - line_position);
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}
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}
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else
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{
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if(address >= 0xc000)
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{
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if((address & 0xff00) == 0xfe00)
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{
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// printf("%c: %02x: ", isReadOperation(operation) ? 'r' : 'w', *value);
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switch(address&0xf)
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{
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case 0x0:
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if(isReadOperation(operation))
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{
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*value = _interruptStatus;
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_interruptStatus &= ~0x02;
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}
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else
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{
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_interruptControl = *value;
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evaluate_interrupts();
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}
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break;
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case 0x1:
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break;
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case 0x2:
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printf("%02x to [2] mutates %04x ", *value, _startScreenAddress);
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_startScreenAddress = (_startScreenAddress & 0xfe00) | (uint16_t)(((*value) & 0xe0) << 1);
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printf("into %04x\n", _startScreenAddress);
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break;
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case 0x3:
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printf("%02x to [3] mutates %04x ", *value, _startScreenAddress);
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_startScreenAddress = (_startScreenAddress & 0x01ff) | (uint16_t)(((*value) & 0x3f) << 9);
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printf("into %04x\n", _startScreenAddress);
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break;
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case 0x4:
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if(isReadOperation(operation))
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{
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*value = _tape.get_data_register();
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_tape.clear_interrupts(Interrupt::TransmitDataEmpty);
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}
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else
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{
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_tape.set_data_register(*value);
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_tape.clear_interrupts(Interrupt::ReceiveDataFull);
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}
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break;
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case 0x5:
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if(!isReadOperation(operation))
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{
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const uint8_t interruptDisable = (*value)&0xf0;
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if( interruptDisable )
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{
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if( interruptDisable&0x10 ) _interruptStatus &= ~Interrupt::DisplayEnd;
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if( interruptDisable&0x20 ) _interruptStatus &= ~Interrupt::RealTimeClock;
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if( interruptDisable&0x40 ) _interruptStatus &= ~Interrupt::HighToneDetect;
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evaluate_interrupts();
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// TODO: NMI (?)
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}
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// else
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{
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uint8_t nextROM = (*value)&0xf;
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// if(nextROM&0x08)
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// {
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// _activeRom = (Electron::ROMSlot)(nextROM&0x0e);
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// printf("%d -> Paged %d\n", nextROM, _activeRom);
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// }
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if(((_activeRom&12) != 8) || (nextROM&8))
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{
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_activeRom = (Electron::ROMSlot)nextROM;
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}
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// else
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// {
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// printf("Ignored!");
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// }
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// printf("%d -> Paged %d\n", nextROM, _activeRom);
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}
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}
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break;
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case 0x6:
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if(!isReadOperation(operation))
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{
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update_audio();
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_speaker.set_divider(*value);
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_tape.set_counter(*value);
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}
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break;
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case 0x7:
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if(!isReadOperation(operation))
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{
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// update screen mode
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uint8_t new_screen_mode = ((*value) >> 3)&7;
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if(new_screen_mode == 7) new_screen_mode = 4;
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if(new_screen_mode != _screenMode)
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{
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update_display();
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_screenMode = new_screen_mode;
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switch(_screenMode)
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{
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case 0: case 1: case 2: _screenModeBaseAddress = 0x3000; break;
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case 3: _screenModeBaseAddress = 0x4000; break;
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case 4: case 5: _screenModeBaseAddress = 0x5800; break;
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case 6: _screenModeBaseAddress = 0x6000; break;
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}
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}
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// update speaker mode
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bool new_speaker_is_enabled = (*value & 6) == 2;
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if(new_speaker_is_enabled != _speaker.get_is_enabled())
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{
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update_audio();
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_speaker.set_is_enabled(new_speaker_is_enabled);
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_tape.set_is_enabled(!new_speaker_is_enabled);
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}
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_tape.set_is_running(((*value)&0x40) ? true : false);
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_tape.set_is_in_input_mode(((*value)&0x04) ? false : true);
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// TODO: caps lock LED
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}
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break;
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default:
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{
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if(!isReadOperation(operation))
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{
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update_display();
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static const int registers[4][4] = {
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{10, 8, 2, 0},
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{14, 12, 6, 4},
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{15, 13, 7, 5},
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{11, 9, 3, 1},
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};
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const int index = (address >> 1)&3;
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const uint8_t colour = ~(*value);
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if(address&1)
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{
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_palette[registers[index][0]] = (_palette[registers[index][0]]&3) | ((colour >> 1)&4);
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_palette[registers[index][1]] = (_palette[registers[index][1]]&3) | ((colour >> 0)&4);
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_palette[registers[index][2]] = (_palette[registers[index][2]]&3) | ((colour << 1)&4);
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_palette[registers[index][3]] = (_palette[registers[index][3]]&3) | ((colour << 2)&4);
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_palette[registers[index][2]] = (_palette[registers[index][2]]&5) | ((colour >> 4)&2);
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_palette[registers[index][3]] = (_palette[registers[index][3]]&5) | ((colour >> 3)&2);
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}
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else
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{
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_palette[registers[index][0]] = (_palette[registers[index][0]]&6) | ((colour >> 7)&1);
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_palette[registers[index][1]] = (_palette[registers[index][1]]&6) | ((colour >> 6)&1);
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_palette[registers[index][2]] = (_palette[registers[index][2]]&6) | ((colour >> 5)&1);
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_palette[registers[index][3]] = (_palette[registers[index][3]]&6) | ((colour >> 4)&1);
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_palette[registers[index][0]] = (_palette[registers[index][0]]&5) | ((colour >> 2)&2);
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_palette[registers[index][1]] = (_palette[registers[index][1]]&5) | ((colour >> 1)&2);
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}
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}
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}
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break;
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}
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}
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else
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{
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if(isReadOperation(operation))
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*value = _os[address & 16383];
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}
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}
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else
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{
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if(isReadOperation(operation))
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{
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switch(_activeRom)
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{
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case ROMSlotKeyboard:
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case ROMSlotKeyboard+1:
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*value = 0xf0;
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for(int address_line = 0; address_line < 14; address_line++)
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{
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if(!(address&(1 << address_line))) *value |= _keyStates[address_line];
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}
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break;
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default:
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*value = _roms[_activeRom][address & 16383];
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break;
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}
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}
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}
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}
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// if(operation == CPU6502::BusOperation::ReadOpcode)
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// {
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// printf("%04x: %02x (%d)\n", address, *value, _frameCycles);
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// }
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_frameCycles += cycles;
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switch(_frameCycles)
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{
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case 64*128:
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case 196*128:
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update_audio();
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break;
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case 128*128:
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update_audio();
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signal_interrupt(Interrupt::RealTimeClock);
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break;
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case 284*128:
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update_audio();
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signal_interrupt(Interrupt::DisplayEnd);
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break;
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case cycles_per_frame:
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update_display();
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update_audio();
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_frameCycles = 0;
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_displayOutputPosition = 0;
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_audioOutputPosition = 0;
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_currentOutputLine = 0;
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break;
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}
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_tape.run_for_cycles(cycles);
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return cycles;
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}
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void Machine::set_tape(std::shared_ptr<Storage::Tape> tape)
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{
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_tape.set_tape(tape);
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}
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void Machine::set_rom(ROMSlot slot, size_t length, const uint8_t *data)
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{
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uint8_t *target = nullptr;
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switch(slot)
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{
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case ROMSlotOS: target = _os; break;
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default: target = _roms[slot]; break;
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}
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memcpy(target, data, std::min((size_t)16384, length));
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}
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inline void Machine::signal_interrupt(Electron::Interrupt interrupt)
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{
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_interruptStatus |= interrupt;
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evaluate_interrupts();
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}
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void Machine::tape_did_change_interrupt_status(Tape *tape)
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{
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_interruptStatus = (_interruptStatus & ~(Interrupt::TransmitDataEmpty | Interrupt::ReceiveDataFull | Interrupt::HighToneDetect)) | _tape.get_interrupt_status();
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evaluate_interrupts();
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}
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inline void Machine::evaluate_interrupts()
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{
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if(_interruptStatus & _interruptControl)
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{
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_interruptStatus |= 1;
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}
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else
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{
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_interruptStatus &= ~1;
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}
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set_irq_line(_interruptStatus & 1);
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}
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inline void Machine::update_audio()
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{
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int difference = _frameCycles - _audioOutputPosition;
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_audioOutputPosition = _frameCycles;
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_speaker.run_for_cycles((_audioOutputPositionError + difference) >> 4);
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_audioOutputPositionError = (_audioOutputPositionError + difference)&15;
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}
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inline void Machine::update_display()
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{
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const int lines_of_hsync = 3;
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const int end_of_hsync = lines_of_hsync * cycles_per_line;
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if(_frameCycles >= end_of_hsync)
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{
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// assert sync for the first three lines of the display, with a break at the end for horizontal alignment
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if(_displayOutputPosition < end_of_hsync)
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{
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for(int c = 0; c < lines_of_hsync; c++)
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{
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_crt.output_sync(119 * crt_cycles_multiplier);
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_crt.output_blank(9 * crt_cycles_multiplier);
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}
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_displayOutputPosition = end_of_hsync;
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}
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while(_displayOutputPosition >= end_of_hsync && _displayOutputPosition < _frameCycles)
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{
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const int current_line = _displayOutputPosition >> 7;
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const int line_position = _displayOutputPosition & 127;
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// all lines then start with 9 cycles of sync
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if(!line_position)
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{
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_crt.output_sync(9 * crt_cycles_multiplier);
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_displayOutputPosition += 9;
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}
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else
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{
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bool isBlankLine =
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((_screenMode == 3) || (_screenMode == 6)) ?
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((current_line < first_graphics_line || current_line >= first_graphics_line+248) || (((current_line - first_graphics_line)%10) > 7)) :
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((current_line < first_graphics_line || current_line >= first_graphics_line+256));
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if(isBlankLine)
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{
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if(line_position == 9)
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{
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_crt.output_blank(119 * crt_cycles_multiplier);
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_displayOutputPosition += 119;
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}
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}
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else
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{
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// there are then 15 cycles of blank, 80 cycles of pixels, and 24 further cycles of blank
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if(line_position == 9)
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{
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_crt.output_blank(15 * crt_cycles_multiplier);
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_displayOutputPosition += 15;
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switch(_screenMode)
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{
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case 0: case 3: _currentOutputDivider = 1; break;
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case 1: case 4: case 6: _currentOutputDivider = 2; break;
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case 2: case 5: _currentOutputDivider = 4; break;
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}
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_crt.allocate_write_area(80 * crt_cycles_multiplier / _currentOutputDivider);
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_currentLine = _writePointer = (uint8_t *)_crt.get_write_target_for_buffer(0);
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if(current_line == first_graphics_line)
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_startLineAddress = _startScreenAddress;
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_currentScreenAddress = _startLineAddress;
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}
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if(line_position >= 24 && line_position < 104)
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{
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// determine whether the pixel clock divider has changed; if so write out the old
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// data and start a new run
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unsigned int newDivider = 0;
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switch(_screenMode)
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{
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case 0: case 3: newDivider = 1; break;
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case 1: case 4: case 6: newDivider = 2; break;
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case 2: case 5: newDivider = 4; break;
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}
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if(newDivider != _currentOutputDivider)
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{
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_crt.output_data((unsigned int)((_writePointer - _currentLine) * _currentOutputDivider * crt_cycles_multiplier), _currentOutputDivider);
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_currentOutputDivider = newDivider;
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_crt.allocate_write_area((int)((104 - (unsigned int)line_position) * crt_cycles_multiplier / _currentOutputDivider));
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_currentLine = _writePointer = (uint8_t *)_crt.get_write_target_for_buffer(0);
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}
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int pixels_to_output = std::min(_frameCycles - _displayOutputPosition, 104 - line_position);
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_displayOutputPosition += pixels_to_output;
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if(_screenMode >= 4)
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{
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// just shifting wouldn't be enough if both
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if(_displayOutputPosition&1) pixels_to_output++;
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pixels_to_output >>= 1;
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}
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#define GetNextPixels() \
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if(_currentScreenAddress&32768)\
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{\
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_currentScreenAddress = _screenModeBaseAddress + (_currentScreenAddress&32767);\
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}\
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uint8_t pixels = _ram[_currentScreenAddress];\
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_currentScreenAddress = _currentScreenAddress+8
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if(pixels_to_output && _writePointer)
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{
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switch(_screenMode)
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{
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default:
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case 0: case 3: case 4: case 6:
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while(pixels_to_output--)
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{
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GetNextPixels();
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_writePointer[0] = _palette[(pixels&0x80) >> 4];
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_writePointer[1] = _palette[(pixels&0x40) >> 3];
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_writePointer[2] = _palette[(pixels&0x20) >> 2];
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_writePointer[3] = _palette[(pixels&0x10) >> 1];
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_writePointer[4] = _palette[(pixels&0x08) >> 0];
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_writePointer[5] = _palette[(pixels&0x04) << 1];
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_writePointer[6] = _palette[(pixels&0x02) << 2];
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_writePointer[7] = _palette[(pixels&0x01) << 3];
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_writePointer += 8;
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}
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break;
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case 1:
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case 5:
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while(pixels_to_output--)
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{
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GetNextPixels();
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_writePointer[0] = _palette[((pixels&0x80) >> 4) | ((pixels&0x08) >> 2)];
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_writePointer[1] = _palette[((pixels&0x40) >> 3) | ((pixels&0x04) >> 1)];
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_writePointer[2] = _palette[((pixels&0x20) >> 2) | ((pixels&0x02) >> 0)];
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_writePointer[3] = _palette[((pixels&0x10) >> 1) | ((pixels&0x01) << 1)];
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_writePointer += 4;
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}
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break;
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case 2:
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while(pixels_to_output--)
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{
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GetNextPixels();
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_writePointer[0] = _palette[((pixels&0x80) >> 4) | ((pixels&0x20) >> 3) | ((pixels&0x08) >> 2) | ((pixels&0x02) >> 1)];
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_writePointer[1] = _palette[((pixels&0x40) >> 3) | ((pixels&0x10) >> 2) | ((pixels&0x04) >> 1) | ((pixels&0x01) >> 0)];
|
|
_writePointer += 2;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
#undef GetNextPixels
|
|
|
|
if(line_position == 104)
|
|
{
|
|
_currentOutputLine++;
|
|
if(!(_currentOutputLine&7))
|
|
{
|
|
_startLineAddress += ((_screenMode < 4) ? 80 : 40)*8 - 7;
|
|
}
|
|
else
|
|
_startLineAddress++;
|
|
|
|
if(_writePointer)
|
|
_crt.output_data((unsigned int)((_writePointer - _currentLine) * _currentOutputDivider), _currentOutputDivider);
|
|
else
|
|
_crt.output_data(80 * crt_cycles_multiplier, _currentOutputDivider);
|
|
_crt.output_blank(24 * crt_cycles_multiplier);
|
|
_displayOutputPosition += 24;
|
|
_currentLine = nullptr;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
const char *Machine::get_signal_decoder()
|
|
{
|
|
return
|
|
"vec4 sample(vec2 coordinate)\n"
|
|
"{\n"
|
|
"float texValue = texture(texID, coordinate).r;\n"
|
|
"return vec4( step(4.0/256.0, mod(texValue, 8.0/256.0)), step(2.0/256.0, mod(texValue, 4.0/256.0)), step(1.0/256.0, mod(texValue, 2.0/256.0)), 1.0);\n"
|
|
"}";
|
|
}
|
|
|
|
void Machine::set_key_state(Key key, bool isPressed)
|
|
{
|
|
if(key == KeyBreak)
|
|
{
|
|
set_reset_line(isPressed);
|
|
}
|
|
else
|
|
{
|
|
if(isPressed)
|
|
_keyStates[key >> 4] |= key&0xf;
|
|
else
|
|
_keyStates[key >> 4] &= ~(key&0xf);
|
|
}
|
|
}
|
|
|
|
/*
|
|
Speaker
|
|
*/
|
|
|
|
void Speaker::get_samples(unsigned int number_of_samples, int16_t *target)
|
|
{
|
|
if(!_is_enabled)
|
|
{
|
|
*target = 0;
|
|
}
|
|
else
|
|
{
|
|
*target = _output_level;
|
|
}
|
|
skip_samples(number_of_samples);
|
|
}
|
|
|
|
void Speaker::skip_samples(unsigned int number_of_samples)
|
|
{
|
|
while(number_of_samples--)
|
|
{
|
|
_counter ++;
|
|
if(_counter > _divider)
|
|
{
|
|
_counter = 0;
|
|
_output_level ^= 8192;
|
|
}
|
|
}
|
|
}
|
|
|
|
void Speaker::set_divider(uint8_t divider)
|
|
{
|
|
_divider = divider;
|
|
}
|
|
|
|
void Speaker::set_is_enabled(bool is_enabled)
|
|
{
|
|
_is_enabled = is_enabled;
|
|
_counter = 0;
|
|
}
|
|
|
|
/*
|
|
Tape
|
|
*/
|
|
|
|
Tape::Tape() : _is_running(false), _data_register(0), _delegate(nullptr) {}
|
|
|
|
void Tape::set_tape(std::shared_ptr<Storage::Tape> tape)
|
|
{
|
|
_tape = tape;
|
|
get_next_tape_pulse();
|
|
}
|
|
|
|
inline void Tape::get_next_tape_pulse()
|
|
{
|
|
_time_into_pulse = 0;
|
|
_current_pulse = _tape->get_next_pulse();
|
|
if(_pulse_stepper == nullptr || _current_pulse.length.clock_rate != _pulse_stepper->get_output_rate())
|
|
{
|
|
_pulse_stepper = std::shared_ptr<SignalProcessing::Stepper>(new SignalProcessing::Stepper(_current_pulse.length.clock_rate, 2000000));
|
|
}
|
|
}
|
|
|
|
inline void Tape::push_tape_bit(uint16_t bit)
|
|
{
|
|
_data_register = (uint16_t)((_data_register >> 1) | (bit << 10));
|
|
|
|
uint8_t old_interrupt_status = _interrupt_status;
|
|
|
|
if(_bits_since_start)
|
|
{
|
|
_bits_since_start--;
|
|
|
|
if(_bits_since_start == 7)
|
|
{
|
|
_interrupt_status &= ~Interrupt::TransmitDataEmpty;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if((_data_register&0x3) == 0x1)
|
|
{
|
|
_interrupt_status |= Interrupt::TransmitDataEmpty;
|
|
_bits_since_start = 9;
|
|
}
|
|
|
|
if(_data_register == 0x3ff)
|
|
_interrupt_status |= Interrupt::HighToneDetect;
|
|
else
|
|
_interrupt_status &= ~Interrupt::HighToneDetect;
|
|
}
|
|
|
|
if(old_interrupt_status != _interrupt_status && _delegate) _delegate->tape_did_change_interrupt_status(this);
|
|
}
|
|
|
|
inline void Tape::clear_interrupts(uint8_t interrupts)
|
|
{
|
|
if(_interrupt_status & interrupts)
|
|
{
|
|
_interrupt_status &= ~interrupts;
|
|
if(_delegate) _delegate->tape_did_change_interrupt_status(this);
|
|
}
|
|
}
|
|
|
|
inline void Tape::run_for_cycles(unsigned int number_of_cycles)
|
|
{
|
|
if(_is_running && _is_enabled && _tape != nullptr)
|
|
{
|
|
while(number_of_cycles--)
|
|
{
|
|
_time_into_pulse += (unsigned int)_pulse_stepper->step();
|
|
if(_time_into_pulse == _current_pulse.length.length)
|
|
{
|
|
get_next_tape_pulse();
|
|
|
|
_crossings[0] = _crossings[1];
|
|
_crossings[1] = _crossings[2];
|
|
_crossings[2] = _crossings[3];
|
|
|
|
_crossings[3] = Tape::Unrecognised;
|
|
if(_current_pulse.type != Storage::Tape::Pulse::Zero)
|
|
{
|
|
float pulse_length = (float)_current_pulse.length.length / (float)_current_pulse.length.clock_rate;
|
|
if(pulse_length > 0.4 / 2400.0 && pulse_length < 0.6 / 2400.0) _crossings[3] = Tape::Short;
|
|
if(pulse_length > 0.4 / 1200.0 && pulse_length < 0.6 / 1200.0) _crossings[3] = Tape::Long;
|
|
}
|
|
|
|
if(_crossings[0] == Tape::Long && _crossings[1] == Tape::Long)
|
|
{
|
|
push_tape_bit(0);
|
|
_crossings[1] = Tape::Unrecognised;
|
|
}
|
|
else
|
|
{
|
|
if(_crossings[0] == Tape::Short && _crossings[1] == Tape::Short && _crossings[2] == Tape::Short && _crossings[3] == Tape::Short)
|
|
{
|
|
push_tape_bit(1);
|
|
_crossings[3] = Tape::Unrecognised;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|