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CLK/Components/6560/6560.cpp
2016-06-23 20:43:29 -04:00

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//
// 6560.cpp
// Clock Signal
//
// Created by Thomas Harte on 05/06/2016.
// Copyright © 2016 Thomas Harte. All rights reserved.
//
#include "6560.hpp"
using namespace MOS;
MOS6560::MOS6560() :
_crt(new Outputs::CRT::CRT(65*4, 4, Outputs::CRT::NTSC60, 1)),
_horizontal_counter(0),
_vertical_counter(0),
_cycles_since_speaker_update(0),
_is_odd_frame(false)
{
_crt->set_composite_sampling_function(
"float composite_sample(usampler2D texID, vec2 coordinate, vec2 iCoordinate, float phase, float amplitude)"
"{"
"uint c = texture(texID, coordinate).r;"
"float y = float(c >> 4) / 4.0;"
"uint yC = c & 15u;"
"float phaseOffset = 6.283185308 * float(yC) / 16.0;"
"float chroma = cos(phase + phaseOffset);"
"return mix(y, step(yC, 14) * chroma, amplitude);"
"}");
// default to NTSC
set_output_mode(OutputMode::NTSC);
// show only the centre
_crt->set_visible_area(_crt->get_rect_for_area(16, 237, 11*4, 55*4, 4.0f / 3.0f));
_speaker.set_input_rate(255681.75); // assuming NTSC; clock rate / 4
}
void MOS6560::set_output_mode(OutputMode output_mode)
{
uint8_t luminances[16] = { // range is 04
0, 4, 1, 3, 2, 2, 1, 3,
2, 1, 2, 1, 2, 3, 2, 3
};
uint8_t pal_chrominances[16] = { // range is 015; 15 is a special case meaning "no chrominance"
15, 15, 5, 13, 2, 10, 0, 8,
6, 7, 5, 13, 2, 10, 0, 8,
};
uint8_t ntsc_chrominances[16] = {
15, 15, 2, 10, 4, 12, 6, 14,
0, 8, 2, 10, 4, 12, 6, 14,
};
uint8_t *chrominances;
Outputs::CRT::DisplayType display_type;
switch(output_mode)
{
case OutputMode::PAL:
chrominances = pal_chrominances;
display_type = Outputs::CRT::PAL50;
_timing.cycles_per_line = 71;
_timing.lines_per_progressive_field = 312;
_timing.supports_interlacing = false;
break;
case OutputMode::NTSC:
chrominances = ntsc_chrominances;
display_type = Outputs::CRT::NTSC60;
_timing.cycles_per_line = 65;
_timing.lines_per_progressive_field = 261;
_timing.supports_interlacing = true;
break;
}
_crt->set_new_display_type((unsigned int)(_timing.cycles_per_line*4), display_type);
for(int c = 0; c < 16; c++)
{
_colours[c] = (uint8_t)((luminances[c] << 4) | chrominances[c]);
}
}
// TODO: set clock rate
void MOS6560::set_register(int address, uint8_t value)
{
address &= 0xf;
_registers.direct_values[address] = value;
switch(address)
{
case 0x0:
_registers.interlaced = !!(value&0x80) && _timing.supports_interlacing;
_registers.first_column_location = value & 0x7f;
break;
case 0x1:
_registers.first_row_location = value;
break;
case 0x2:
_registers.number_of_columns = value & 0x7f;
_registers.video_matrix_start_address = (uint16_t)((_registers.video_matrix_start_address & 0x3c00) | ((value & 0x80) << 2));
break;
case 0x3:
_registers.number_of_rows = (value >> 1)&0x3f;
_registers.tall_characters = !!(value&0x01);
break;
case 0x5:
_registers.character_cell_start_address = (uint16_t)((value & 0x0f) << 10);
_registers.video_matrix_start_address = (uint16_t)((_registers.video_matrix_start_address & 0x0200) | ((value & 0xf0) << 6));
break;
case 0xa:
case 0xb:
case 0xc:
case 0xd:
update_audio();
_speaker.set_control(address - 0xa, value);
break;
case 0xe:
update_audio();
_registers.auxiliary_colour = _colours[value >> 4];
_speaker.set_volume(value & 0xf);
break;
case 0xf:
if(_this_state == State::Border)
{
output_border(_cycles_in_state * 4);
_cycles_in_state = 0;
}
_registers.invertedCells = !((value >> 3)&1);
_registers.borderColour = _colours[value & 0x07];
_registers.backgroundColour = _colours[value >> 4];
break;
// TODO: the lightpen, etc
default:
break;
}
}
uint8_t MOS6560::get_register(int address)
{
address &= 0xf;
switch(address)
{
default: return _registers.direct_values[address];
case 0x03: return (uint8_t)(_vertical_counter << 7) | (_registers.direct_values[3] & 0x7f);
case 0x04: return (_vertical_counter >> 1) & 0xff;
}
}
void MOS6560::output_border(unsigned int number_of_cycles)
{
uint8_t *colour_pointer = _crt->allocate_write_area(1);
if(colour_pointer) *colour_pointer = _registers.borderColour;
_crt->output_level(number_of_cycles);
}
uint16_t MOS6560::get_address()
{
// keep track of the amount of time since the speaker was updated; lazy updates are applied
_cycles_since_speaker_update++;
// keep an old copy of the vertical count because that test is a cycle later than the actual changes
int previous_vertical_counter = _vertical_counter;
// keep track of internal time relative to this scanline
_horizontal_counter++;
if(_horizontal_counter == _timing.cycles_per_line)
{
if(_horizontal_drawing_latch)
{
_current_character_row++;
if(
(_current_character_row == 16) ||
(_current_character_row == 8 && !_registers.tall_characters)
) {
_current_character_row = 0;
_current_row++;
}
_pixel_line_cycle = -1;
_columns_this_line = -1;
_column_counter = -1;
}
_horizontal_counter = 0;
_horizontal_drawing_latch = false;
_vertical_counter ++;
if(_vertical_counter == (_registers.interlaced ? (_is_odd_frame ? 262 : 263) : _timing.lines_per_progressive_field))
{
_vertical_counter = 0;
_is_odd_frame ^= true;
_current_row = 0;
_rows_this_field = -1;
_vertical_drawing_latch = false;
_base_video_matrix_address_counter = 0;
_current_character_row = 0;
}
}
// check for vertical starting events
_vertical_drawing_latch |= _registers.first_row_location == (previous_vertical_counter >> 1);
_horizontal_drawing_latch |= _vertical_drawing_latch && (_horizontal_counter == _registers.first_column_location);
if(_pixel_line_cycle >= 0) _pixel_line_cycle++;
switch(_pixel_line_cycle)
{
case -1:
if(_horizontal_drawing_latch)
{
_pixel_line_cycle = 0;
_video_matrix_address_counter = _base_video_matrix_address_counter;
}
break;
case 1: _columns_this_line = _registers.number_of_columns; break;
case 2: if(_rows_this_field < 0) _rows_this_field = _registers.number_of_rows; break;
case 3: if(_current_row < _rows_this_field) _column_counter = 0; break;
}
uint16_t fetch_address = 0x1c;
if(_column_counter >= 0 && _column_counter < _columns_this_line*2)
{
if(_column_counter&1)
{
fetch_address = _registers.character_cell_start_address + (_character_code*(_registers.tall_characters ? 16 : 8)) + _current_character_row;
}
else
{
fetch_address = (uint16_t)(_registers.video_matrix_start_address + _video_matrix_address_counter);
_video_matrix_address_counter++;
if(
(_current_character_row == 15) ||
(_current_character_row == 7 && !_registers.tall_characters)
) {
_base_video_matrix_address_counter = _video_matrix_address_counter;
}
}
}
return fetch_address;
}
void MOS6560::set_graphics_value(uint8_t value, uint8_t colour_value)
{
// TODO: there should be a further two-cycle delay on pixels being output; the reverse bit should
// divide the byte it is set for 3:1 and then continue as usual.
// determine output state; colour burst and sync timing are currently a guess
if(_horizontal_counter > _timing.cycles_per_line-4) _this_state = State::ColourBurst;
else if(_horizontal_counter > _timing.cycles_per_line-7) _this_state = State::Sync;
else
{
_this_state = (_column_counter >= 0 && _column_counter < _columns_this_line*2) ? State::Pixels : State::Border;
}
// apply vertical sync
if(
(_vertical_counter < 3 && (_is_odd_frame || !_registers.interlaced)) ||
(_registers.interlaced &&
(
(_vertical_counter == 0 && _horizontal_counter > 32) ||
(_vertical_counter == 1) || (_vertical_counter == 2) ||
(_vertical_counter == 3 && _horizontal_counter <= 32)
)
))
_this_state = State::Sync;
// update the CRT
if(_this_state != _output_state)
{
switch(_output_state)
{
case State::Sync: _crt->output_sync(_cycles_in_state * 4); break;
case State::ColourBurst: _crt->output_colour_burst(_cycles_in_state * 4, _is_odd_frame ? 128 : 0, 0); break;
case State::Border: output_border(_cycles_in_state * 4); break;
case State::Pixels: _crt->output_data(_cycles_in_state * 4, 1); break;
}
_output_state = _this_state;
_cycles_in_state = 0;
pixel_pointer = nullptr;
if(_output_state == State::Pixels)
{
pixel_pointer = _crt->allocate_write_area(260);
}
}
_cycles_in_state++;
if(_this_state == State::Pixels)
{
if(_column_counter&1)
{
_character_value = value;
if(pixel_pointer)
{
uint8_t cell_colour = _colours[_character_colour & 0x7];
if(!(_character_colour&0x8))
{
uint8_t colours[2];
if(_registers.invertedCells)
{
colours[0] = cell_colour;
colours[1] = _registers.backgroundColour;
}
else
{
colours[0] = _registers.backgroundColour;
colours[1] = cell_colour;
}
pixel_pointer[0] = colours[(_character_value >> 7)&1];
pixel_pointer[1] = colours[(_character_value >> 6)&1];
pixel_pointer[2] = colours[(_character_value >> 5)&1];
pixel_pointer[3] = colours[(_character_value >> 4)&1];
pixel_pointer[4] = colours[(_character_value >> 3)&1];
pixel_pointer[5] = colours[(_character_value >> 2)&1];
pixel_pointer[6] = colours[(_character_value >> 1)&1];
pixel_pointer[7] = colours[(_character_value >> 0)&1];
}
else
{
uint8_t colours[4] = {_registers.backgroundColour, _registers.borderColour, cell_colour, _registers.auxiliary_colour};
pixel_pointer[0] =
pixel_pointer[1] = colours[(_character_value >> 6)&3];
pixel_pointer[2] =
pixel_pointer[3] = colours[(_character_value >> 4)&3];
pixel_pointer[4] =
pixel_pointer[5] = colours[(_character_value >> 2)&3];
pixel_pointer[6] =
pixel_pointer[7] = colours[(_character_value >> 0)&3];
}
pixel_pointer += 8;
}
}
else
{
_character_code = value;
_character_colour = colour_value;
}
_column_counter++;
}
}
void MOS6560::update_audio()
{
_speaker.run_for_cycles(_cycles_since_speaker_update >> 2);
_cycles_since_speaker_update &= 3;
}
#pragma mark - Audio
MOS6560::Speaker::Speaker() :
_volume(0),
_control_registers{0, 0, 0, 0},
_shift_registers{0, 0, 0, 0},
_counters{2, 1, 0, 0} // create a slight phase offset for the three channels
{}
void MOS6560::Speaker::set_volume(uint8_t volume)
{
_volume = volume;
}
void MOS6560::Speaker::set_control(int channel, uint8_t value)
{
_control_registers[channel] = value;
}
// Source: VICE. Not original.
static uint8_t noise_pattern[] = {
0x07, 0x1e, 0x1e, 0x1c, 0x1c, 0x3e, 0x3c, 0x38, 0x78, 0xf8, 0x7c, 0x1e, 0x1f, 0x8f, 0x07, 0x07,
0xc1, 0xc0, 0xe0, 0xf1, 0xe0, 0xf0, 0xe3, 0xe1, 0xc0, 0xe0, 0x78, 0x7e, 0x3c, 0x38, 0xe0, 0xe1,
0xc3, 0xc3, 0x87, 0xc7, 0x07, 0x1e, 0x1c, 0x1f, 0x0e, 0x0e, 0x1e, 0x0e, 0x0f, 0x0f, 0xc3, 0xc3,
0xf1, 0xe1, 0xe3, 0xc1, 0xe3, 0xc3, 0xc3, 0xfc, 0x3c, 0x1e, 0x0f, 0x83, 0xc3, 0xc1, 0xc1, 0xc3,
0xc3, 0xc7, 0x87, 0x87, 0xc7, 0x0f, 0x0e, 0x3c, 0x7c, 0x78, 0x3c, 0x3c, 0x3c, 0x38, 0x3e, 0x1c,
0x7c, 0x1e, 0x3c, 0x0f, 0x0e, 0x3e, 0x78, 0xf0, 0xf0, 0xe0, 0xe1, 0xf1, 0xc1, 0xc3, 0xc7, 0xc3,
0xe1, 0xf1, 0xe0, 0xe1, 0xf0, 0xf1, 0xe3, 0xc0, 0xf0, 0xe0, 0xf8, 0x70, 0xe3, 0x87, 0x87, 0xc0,
0xf0, 0xe0, 0xf1, 0xe1, 0xe1, 0xc7, 0x83, 0x87, 0x83, 0x8f, 0x87, 0x87, 0xc7, 0x83, 0xc3, 0x83,
0xc3, 0xf1, 0xe1, 0xc3, 0xc7, 0x81, 0xcf, 0x87, 0x03, 0x87, 0xc7, 0xc7, 0x87, 0x83, 0xe1, 0xc3,
0x07, 0xc3, 0x87, 0x87, 0x07, 0x87, 0xc3, 0x87, 0x83, 0xe1, 0xc3, 0xc7, 0xc3, 0x87, 0x87, 0x8f,
0x0f, 0x87, 0x87, 0x0f, 0xcf, 0x1f, 0x87, 0x8e, 0x0e, 0x07, 0x81, 0xc3, 0xe3, 0xc1, 0xe0, 0xf0,
0xe0, 0xe3, 0x83, 0x87, 0x07, 0x87, 0x8e, 0x1e, 0x0f, 0x07, 0x87, 0x8f, 0x1f, 0x07, 0x87, 0xc1,
0xf0, 0xe1, 0xe1, 0xe3, 0xc7, 0x0f, 0x03, 0x8f, 0x87, 0x0e, 0x1e, 0x1e, 0x0f, 0x87, 0x87, 0x0f,
0x87, 0x1f, 0x0f, 0xc3, 0xc3, 0xf0, 0xf8, 0xf0, 0x70, 0xf1, 0xf0, 0xf0, 0xe1, 0xf0, 0xe0, 0x78,
0x7c, 0x78, 0x7c, 0x70, 0x71, 0xe1, 0xe1, 0xc3, 0xc3, 0xc7, 0x87, 0x1c, 0x3c, 0x3c, 0x1c, 0x3c,
0x7c, 0x1e, 0x1e, 0x1e, 0x1c, 0x3c, 0x78, 0xf8, 0xf8, 0xe1, 0xc3, 0x87, 0x1e, 0x1e, 0x3c, 0x3e,
0x0f, 0x0f, 0x87, 0x1f, 0x8e, 0x0f, 0x0f, 0x8e, 0x1e, 0x1e, 0x1e, 0x1e, 0x0f, 0x0f, 0x8f, 0x87,
0x87, 0xc3, 0x83, 0xc1, 0xe1, 0xc3, 0xc1, 0xc3, 0xc7, 0x8f, 0x0f, 0x0f, 0x0f, 0x0f, 0x83, 0xc7,
0xc3, 0xc1, 0xe1, 0xe0, 0xf8, 0x3e, 0x3c, 0x3c, 0x3c, 0x3c, 0x3c, 0x78, 0x3e, 0x1e, 0x1e, 0x1e,
0x0f, 0x0f, 0x0f, 0x1e, 0x0e, 0x1e, 0x1e, 0x0f, 0x0f, 0x87, 0x1f, 0x87, 0x87, 0x1c, 0x3e, 0x1f,
0x0f, 0x0f, 0x8e, 0x3e, 0x0e, 0x3e, 0x1e, 0x1c, 0x3c, 0x7c, 0xfc, 0x38, 0x78, 0x78, 0x38, 0x78,
0x70, 0xf8, 0x7c, 0x1e, 0x3c, 0x3c, 0x30, 0xf1, 0xf0, 0x70, 0x70, 0xe0, 0xf8, 0xf0, 0xf8, 0x78,
0x78, 0x71, 0xe1, 0xf0, 0xe3, 0xc1, 0xf0, 0x71, 0xe3, 0xc7, 0x87, 0x8e, 0x3e, 0x0e, 0x1e, 0x3e,
0x0f, 0x07, 0x87, 0x0c, 0x3e, 0x0f, 0x87, 0x0f, 0x1e, 0x3c, 0x3c, 0x38, 0x78, 0xf1, 0xe7, 0xc3,
0xc3, 0xc7, 0x8e, 0x3c, 0x38, 0xf0, 0xe0, 0x7e, 0x1e, 0x3e, 0x0e, 0x0f, 0x0f, 0x0f, 0x03, 0xc3,
0xc3, 0xc7, 0x87, 0x1f, 0x0e, 0x1e, 0x1c, 0x3c, 0x3c, 0x0f, 0x07, 0x07, 0xc7, 0xc7, 0x87, 0x87,
0x8f, 0x0f, 0xc0, 0xf0, 0xf8, 0x60, 0xf0, 0xf0, 0xe1, 0xe3, 0xe3, 0xc3, 0xc3, 0xc3, 0x87, 0x0f,
0x87, 0x8e, 0x1e, 0x1e, 0x3f, 0x1e, 0x0e, 0x1c, 0x3c, 0x7e, 0x1e, 0x3c, 0x38, 0x78, 0x78, 0x78,
0x38, 0x78, 0x3c, 0xe1, 0xe3, 0x8f, 0x1f, 0x1c, 0x78, 0x70, 0x7e, 0x0f, 0x87, 0x07, 0xc3, 0xc7,
0x0f, 0x1e, 0x3c, 0x0e, 0x0f, 0x0e, 0x1e, 0x03, 0xf0, 0xf0, 0xf1, 0xe3, 0xc1, 0xc7, 0xc0, 0xe1,
0xe1, 0xe1, 0xe1, 0xe0, 0x70, 0xe1, 0xf0, 0x78, 0x70, 0xe3, 0xc7, 0x0f, 0xc1, 0xe1, 0xe3, 0xc3,
0xc0, 0xf0, 0xfc, 0x1c, 0x3c, 0x70, 0xf8, 0x70, 0xf8, 0x78, 0x3c, 0x70, 0xf0, 0x78, 0x70, 0x7c,
0x7c, 0x3c, 0x38, 0x1e, 0x3e, 0x3c, 0x7e, 0x07, 0x83, 0xc7, 0xc1, 0xc1, 0xe1, 0xc3, 0xc3, 0xc3,
0xe1, 0xe1, 0xf0, 0x78, 0x7c, 0x3e, 0x0f, 0x1f, 0x07, 0x8f, 0x0f, 0x83, 0x87, 0xc1, 0xe3, 0xe3,
0xc3, 0xc3, 0xe1, 0xf0, 0xf8, 0xf0, 0x3c, 0x7c, 0x3c, 0x0f, 0x8e, 0x0e, 0x1f, 0x1f, 0x0e, 0x3c,
0x38, 0x78, 0x70, 0x70, 0xf0, 0xf0, 0xf8, 0x70, 0x70, 0x78, 0x38, 0x3c, 0x70, 0xe0, 0xf0, 0x78,
0xf1, 0xf0, 0x78, 0x3e, 0x3c, 0x0f, 0x07, 0x0e, 0x3e, 0x1e, 0x3f, 0x1e, 0x0e, 0x0f, 0x87, 0x87,
0x07, 0x0f, 0x07, 0xc7, 0x8f, 0x0f, 0x87, 0x1e, 0x1e, 0x1f, 0x1e, 0x1e, 0x3c, 0x1e, 0x1c, 0x3e,
0x0f, 0x03, 0xc3, 0x81, 0xe0, 0xf0, 0xfc, 0x38, 0x3c, 0x3e, 0x0e, 0x1e, 0x1c, 0x7c, 0x1e, 0x1f,
0x0e, 0x3e, 0x1c, 0x78, 0x78, 0x7c, 0x1e, 0x3e, 0x1e, 0x3c, 0x1f, 0x0f, 0x1f, 0x0f, 0x0f, 0x8f,
0x1c, 0x3c, 0x78, 0xf8, 0xf0, 0xf8, 0x70, 0xf0, 0x78, 0x78, 0x3c, 0x3c, 0x78, 0x3c, 0x1f, 0x0f,
0x07, 0x86, 0x1c, 0x1e, 0x1c, 0x1e, 0x1e, 0x1f, 0x03, 0xc3, 0xc7, 0x8e, 0x3c, 0x3c, 0x1c, 0x18,
0xf0, 0xe1, 0xc3, 0xe1, 0xc1, 0xe1, 0xe3, 0xc3, 0xc3, 0xe3, 0xc3, 0x83, 0x87, 0x83, 0x87, 0x0f,
0x07, 0x07, 0xe1, 0xe1, 0xe0, 0x7c, 0x78, 0x38, 0x78, 0x78, 0x3c, 0x1f, 0x0f, 0x8f, 0x0e, 0x07,
0x0f, 0x07, 0x83, 0xc3, 0xc3, 0x81, 0xf0, 0xf8, 0xf1, 0xe0, 0xe3, 0xc7, 0x1c, 0x3e, 0x1e, 0x0f,
0x0f, 0xc3, 0xf0, 0xf0, 0xe3, 0x83, 0xc3, 0xc7, 0x07, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x07, 0x87,
0x0f, 0x0f, 0x0e, 0x0f, 0x0f, 0x1e, 0x0f, 0x0f, 0x87, 0x87, 0x87, 0x8f, 0xc7, 0xc7, 0x83, 0x83,
0xc3, 0xc7, 0x8f, 0x87, 0x07, 0xc3, 0x8e, 0x1e, 0x38, 0x3e, 0x3c, 0x38, 0x7c, 0x1f, 0x1c, 0x38,
0x3c, 0x78, 0x7c, 0x1e, 0x1c, 0x3c, 0x3f, 0x1e, 0x0e, 0x3e, 0x1c, 0x3c, 0x1f, 0x0f, 0x07, 0xc3,
0xe3, 0x83, 0x87, 0x81, 0xc1, 0xe3, 0xcf, 0x0e, 0x0f, 0x1e, 0x3e, 0x1e, 0x1f, 0x0f, 0x8f, 0xc3,
0x87, 0x0e, 0x03, 0xf0, 0xf0, 0x70, 0xe0, 0xe1, 0xe1, 0xc7, 0x8e, 0x0f, 0x0f, 0x1e, 0x0e, 0x1e,
0x1f, 0x1c, 0x78, 0xf0, 0xf1, 0xf1, 0xe0, 0xf1, 0xe1, 0xe1, 0xe0, 0xe0, 0xf1, 0xc1, 0xf0, 0x71,
0xe1, 0xc3, 0x83, 0xc7, 0x83, 0xe1, 0xe1, 0xf8, 0x70, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0x70, 0xf8,
0x70, 0x70, 0x61, 0xe0, 0xf0, 0xe1, 0xe0, 0x78, 0x71, 0xe0, 0xf0, 0xf8, 0x38, 0x1e, 0x1c, 0x38,
0x70, 0xf8, 0x60, 0x78, 0x38, 0x3c, 0x3f, 0x1f, 0x0f, 0x1f, 0x0f, 0x1f, 0x87, 0x87, 0x83, 0x87,
0x83, 0xe1, 0xe1, 0xf0, 0x78, 0xf1, 0xf0, 0x70, 0x38, 0x38, 0x70, 0xe0, 0xe3, 0xc0, 0xe0, 0xf8,
0x78, 0x78, 0xf8, 0x38, 0xf1, 0xe1, 0xe1, 0xc3, 0x87, 0x87, 0x0e, 0x1e, 0x1f, 0x0e, 0x0e, 0x0f,
0x0f, 0x87, 0xc3, 0x87, 0x07, 0x83, 0xc0, 0xf0, 0x38, 0x3c, 0x3c, 0x38, 0xf0, 0xfc, 0x3e, 0x1e,
0x1c, 0x1c, 0x38, 0x70, 0xf0, 0xf1, 0xe0, 0xf0, 0xe0, 0xe0, 0xf1, 0xe3, 0xe0, 0xe1, 0xf0, 0xf0,
0x78, 0x7c, 0x78, 0x3c, 0x78, 0x78, 0x38, 0x78, 0x78, 0x78, 0x78, 0x70, 0xe3, 0x83, 0x83, 0xe0,
0xc3, 0xc1, 0xe1, 0xc1, 0xc1, 0xc1, 0xe3, 0xc3, 0xc7, 0x1e, 0x0e, 0x1f, 0x1e, 0x1e, 0x0f, 0x0f,
0x0e, 0x0e, 0x0e, 0x07, 0x83, 0x87, 0x87, 0x0e, 0x07, 0x8f, 0x0f, 0x0f, 0x0f, 0x0e, 0x1c, 0x70,
0xe1, 0xe0, 0x71, 0xc1, 0x83, 0x83, 0x87, 0x0f, 0x1e, 0x18, 0x78, 0x78, 0x7c, 0x3e, 0x1c, 0x38,
0xf0, 0xe1, 0xe0, 0x78, 0x70, 0x38, 0x3c, 0x3e, 0x1e, 0x3c, 0x1e, 0x1c, 0x70, 0x3c, 0x38, 0x3f,
};
#define shift(r) _shift_registers[r] = (_shift_registers[r] << 1) | (((_shift_registers[r]^0x80)&_control_registers[r]) >> 7);
#define increment(r) _shift_registers[r] = (_shift_registers[r]+1)%8191;
#define update(r, m, up) _counters[r]++; if((_counters[r] >> m) == 0x7f) { up(r); _counters[r] = _control_registers[r]&0x7f; }
void MOS6560::Speaker::get_samples(unsigned int number_of_samples, int16_t *target)
{
for(unsigned int c = 0; c < number_of_samples; c++)
{
update(0, 2, shift);
update(1, 1, shift);
update(2, 0, shift);
update(3, 1, increment);
// this sums the output of all three sounds channels plus a DC offset for volume;
// TODO: what's the real ratio of this stuff?
target[c] = (
(_shift_registers[0]&1) +
(_shift_registers[1]&1) +
(_shift_registers[2]&1) +
((noise_pattern[_shift_registers[3] >> 3] >> (_shift_registers[3]&7))&(_control_registers[3] >> 7)&1)
) * _volume * 700 + _volume * 44;
}
}
void MOS6560::Speaker::skip_samples(unsigned int number_of_samples)
{
for(unsigned int c = 0; c < number_of_samples; c++)
{
update(0, 2, shift);
update(1, 1, shift);
update(2, 0, shift);
update(3, 1, increment);
}
}
#undef shift
#undef increment
#undef update