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https://github.com/TomHarte/CLK.git
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Made an attempt to adjust the 6560 to a model compatible with that advocated by the available documentation. Exact decision timing may need further work.
This commit is contained in:
Thomas Harte
parent
106e56600d
commit
b753690d5e
@ -60,31 +60,31 @@ MOS6560::MOS6560() :
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void MOS6560::set_register(int address, uint8_t value)
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{
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address &= 0xf;
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_registers[address] = value;
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_registers.direct_values[address] = value;
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switch(address)
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{
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case 0x0:
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_interlaced = !!(value&0x80);
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_first_column_location = value & 0x7f;
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_registers.interlaced = !!(value&0x80);
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_registers.first_column_location = value & 0x7f;
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break;
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case 0x1:
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_first_row_location = value;
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_registers.first_row_location = value;
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break;
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case 0x2:
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_number_of_columns = value & 0x7f;
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_video_matrix_start_address = (uint16_t)((_video_matrix_start_address & 0x3c00) | ((value & 0x80) << 2));
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_registers.number_of_columns = value & 0x7f;
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_registers.video_matrix_start_address = (uint16_t)((_registers.video_matrix_start_address & 0x3c00) | ((value & 0x80) << 2));
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break;
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case 0x3:
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_number_of_rows = (value >> 1)&0x3f;
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_tall_characters = !!(value&0x01);
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_registers.number_of_rows = (value >> 1)&0x3f;
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_registers.tall_characters = !!(value&0x01);
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break;
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case 0x5:
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_character_cell_start_address = (uint16_t)((value & 0x0f) << 10);
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_video_matrix_start_address = (uint16_t)((_video_matrix_start_address & 0x0200) | ((value & 0xf0) << 6));
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_registers.character_cell_start_address = (uint16_t)((value & 0x0f) << 10);
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_registers.video_matrix_start_address = (uint16_t)((_registers.video_matrix_start_address & 0x0200) | ((value & 0xf0) << 6));
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break;
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case 0xa:
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@ -97,7 +97,7 @@ void MOS6560::set_register(int address, uint8_t value)
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case 0xe:
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update_audio();
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_auxiliary_colour = _colours[value >> 4];
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_registers.auxiliary_colour = _colours[value >> 4];
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_speaker.set_volume(value & 0xf);
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break;
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@ -107,9 +107,9 @@ void MOS6560::set_register(int address, uint8_t value)
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output_border(_cycles_in_state * 4);
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_cycles_in_state = 0;
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}
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_invertedCells = !((value >> 3)&1);
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_borderColour = _colours[value & 0x07];
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_backgroundColour = _colours[value >> 4];
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_registers.invertedCells = !((value >> 3)&1);
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_registers.borderColour = _colours[value & 0x07];
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_registers.backgroundColour = _colours[value >> 4];
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break;
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// TODO: audio, primarily
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@ -124,8 +124,8 @@ uint8_t MOS6560::get_register(int address)
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address &= 0xf;
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switch(address)
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{
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default: return _registers[address];
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case 0x03: return (uint8_t)(_vertical_counter << 7) | (_registers[3] & 0x7f);
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default: return _registers.direct_values[address];
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case 0x03: return (uint8_t)(_vertical_counter << 7) | (_registers.direct_values[3] & 0x7f);
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case 0x04: return (_vertical_counter >> 1) & 0xff;
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}
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}
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@ -133,7 +133,7 @@ uint8_t MOS6560::get_register(int address)
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void MOS6560::output_border(unsigned int number_of_cycles)
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{
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uint8_t *colour_pointer = _crt->allocate_write_area(1);
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if(colour_pointer) *colour_pointer = _borderColour;
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if(colour_pointer) *colour_pointer = _registers.borderColour;
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_crt->output_level(number_of_cycles);
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}
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@ -144,64 +144,62 @@ uint16_t MOS6560::get_address()
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// keep track of internal time relative to this scanline
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_horizontal_counter++;
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// check for end of scanline
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if(_horizontal_counter == 65)
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{
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_horizontal_counter = 0;
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_vertical_counter++;
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_column_counter = -1;
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if(_vertical_counter == (_interlaced ? (_is_odd_frame ? 262 : 263) : 261))
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if(_horizontal_drawing_latch)
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{
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_is_odd_frame ^= true;
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_vertical_counter = 0;
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_row_counter = -1;
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}
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if(_row_counter >= 0)
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{
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_row_counter++;
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if(_row_counter == _number_of_rows*(_tall_characters ? 16 : 8)) _row_counter = -1;
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}
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else if(_vertical_counter == _first_row_location * 2)
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{
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_video_matrix_line_address_counter = _video_matrix_start_address;
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_row_counter = 0;
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}
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}
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if(_column_counter >= 0)
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{
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_column_counter++;
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if(_column_counter == _number_of_columns*2)
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{
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_column_counter = -1;
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if((_row_counter&(_tall_characters ? 15 : 7)) == (_tall_characters ? 15 : 7))
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{
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_video_matrix_line_address_counter = _video_matrix_address_counter;
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_current_character_row++;
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if(
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(_current_character_row == 16) ||
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(_current_character_row == 8 && !_registers.tall_characters)
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) {
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_current_character_row = 0;
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_video_matrix_address_counter += _columns_this_line;
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_current_row++;
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}
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_current_column = 0;
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_columns_this_line = -1;
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}
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_horizontal_counter = 0;
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_horizontal_drawing_latch = false;
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_vertical_counter ++;
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if(_vertical_counter == (_registers.interlaced ? (_is_odd_frame ? 262 : 263) : 261))
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{
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_vertical_counter = 0;
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_is_odd_frame ^= true;
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_current_row = 0;
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_rows_this_field = -1;
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_vertical_drawing_latch = false;
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_video_matrix_address_counter = 0;
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_current_character_row = 0;
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}
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}
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else if(_horizontal_counter == _first_column_location)
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{
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_column_counter = 0;
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_video_matrix_address_counter = _video_matrix_line_address_counter;
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}
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// check for vertical starting events
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if(_vertical_drawing_latch && _rows_this_field < 0) _rows_this_field = _registers.number_of_rows;
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_vertical_drawing_latch |= _registers.first_row_location == (_vertical_counter >> 1); // TODO: this test should be delayed a cycle
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// check for horizontal starting events
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if(_horizontal_drawing_latch && _columns_this_line < 0) _columns_this_line = _registers.number_of_columns;
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_horizontal_drawing_latch |=
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_vertical_drawing_latch && (_current_row < _rows_this_field) && (_horizontal_counter == _registers.first_column_location);
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// determine output state; colour burst and sync timing are currently a guess
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if(_horizontal_counter > 61) _this_state = State::ColourBurst;
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else if(_horizontal_counter > 57) _this_state = State::Sync;
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else
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{
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_this_state = (_column_counter >= 0 && _row_counter >= 0) ? State::Pixels : State::Border;
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_this_state = (_horizontal_drawing_latch && _current_column < _columns_this_line*2) ? State::Pixels : State::Border;
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}
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// apply vertical sync
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if(
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(_vertical_counter < 3 && (_is_odd_frame || !_interlaced)) ||
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(_interlaced &&
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(_vertical_counter < 3 && (_is_odd_frame || !_registers.interlaced)) ||
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(_registers.interlaced &&
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(
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(_vertical_counter == 0 && _horizontal_counter > 32) ||
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(_vertical_counter == 1) || (_vertical_counter == 2) ||
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@ -235,7 +233,7 @@ uint16_t MOS6560::get_address()
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if(_this_state == State::Pixels)
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{
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/*
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Per http://tinyvga.com/6561 :
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Per http:tinyvga.com/6561 :
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The basic video timing is very simple. For
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every character the VIC-I is about to display, it first fetches the
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@ -248,15 +246,13 @@ uint16_t MOS6560::get_address()
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reading from unconnected address space, such as $9100-$910f, you can
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read the data fetched by the videochip on the previous clock cycle.)
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*/
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if(_column_counter&1)
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if(_current_column&1)
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{
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return _character_cell_start_address + (_character_code*(_tall_characters ? 16 : 8)) + (_row_counter&(_tall_characters ? 15 : 7));
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return _registers.character_cell_start_address + (_character_code*(_registers.tall_characters ? 16 : 8)) + _current_character_row;
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}
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else
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{
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uint16_t result = _video_matrix_address_counter;
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_video_matrix_address_counter++;
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return result;
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return (uint16_t)(_registers.video_matrix_start_address + _video_matrix_address_counter + (_current_column >> 1));
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}
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}
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@ -271,7 +267,7 @@ void MOS6560::set_graphics_value(uint8_t value, uint8_t colour_value)
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// and to adjust the signalling to the CRT above?
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if(_this_state == State::Pixels)
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{
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if(_column_counter&1)
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if(_current_column&1)
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{
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_character_value = value;
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@ -281,14 +277,14 @@ void MOS6560::set_graphics_value(uint8_t value, uint8_t colour_value)
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if(!(_character_colour&0x8))
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{
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uint8_t colours[2];
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if(_invertedCells)
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if(_registers.invertedCells)
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{
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colours[0] = cell_colour;
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colours[1] = _backgroundColour;
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colours[1] = _registers.backgroundColour;
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}
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else
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{
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colours[0] = _backgroundColour;
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colours[0] = _registers.backgroundColour;
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colours[1] = cell_colour;
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}
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pixel_pointer[0] = colours[(_character_value >> 7)&1];
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@ -302,7 +298,7 @@ void MOS6560::set_graphics_value(uint8_t value, uint8_t colour_value)
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}
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else
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{
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uint8_t colours[4] = {_backgroundColour, _borderColour, cell_colour, _auxiliary_colour};
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uint8_t colours[4] = {_registers.backgroundColour, _registers.borderColour, cell_colour, _registers.auxiliary_colour};
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pixel_pointer[0] =
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pixel_pointer[1] = colours[(_character_value >> 6)&3];
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pixel_pointer[2] =
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@ -320,6 +316,7 @@ void MOS6560::set_graphics_value(uint8_t value, uint8_t colour_value)
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_character_code = value;
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_character_colour = colour_value;
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}
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_current_column++;
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}
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}
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@ -56,6 +56,8 @@ class MOS6560 {
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private:
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std::unique_ptr<Outputs::CRT::CRT> _crt;
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// audio state
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class Speaker: public ::Outputs::Filter<Speaker> {
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public:
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Speaker();
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@ -72,38 +74,55 @@ class MOS6560 {
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uint8_t _control_registers[4];
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uint8_t _volume;
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} _speaker;
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unsigned int _cycles_since_speaker_update;
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void update_audio();
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bool _interlaced, _tall_characters;
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uint8_t _first_column_location, _first_row_location;
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uint8_t _number_of_columns, _number_of_rows;
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uint16_t _character_cell_start_address, _video_matrix_start_address;
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uint8_t _backgroundColour, _borderColour, _auxiliary_colour;
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bool _invertedCells;
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// register state
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struct {
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bool interlaced, tall_characters;
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uint8_t first_column_location, first_row_location;
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uint8_t number_of_columns, number_of_rows;
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uint16_t character_cell_start_address, video_matrix_start_address;
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uint8_t backgroundColour, borderColour, auxiliary_colour;
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bool invertedCells;
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int _horizontal_counter, _vertical_counter;
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bool _did_output_graphics;
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int _column_counter, _row_counter;
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uint16_t _video_matrix_address_counter, _video_matrix_line_address_counter;
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uint8_t direct_values[16];
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} _registers;
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// output state
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enum State {
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Sync, ColourBurst, Border, Pixels
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} _this_state, _output_state;
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unsigned int _cycles_in_state;
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// counters that cover an entire field
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int _horizontal_counter, _vertical_counter;
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// latches dictating start and length of drawing
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bool _vertical_drawing_latch, _horizontal_drawing_latch;
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int _rows_this_field, _columns_this_line;
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// current drawing position counter
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int _current_column;
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int _current_row;
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uint16_t _current_character_row;
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uint16_t _video_matrix_address_counter;
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// address counters
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// uint16_t _
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// int _column_counter, _row_counter;
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// uint16_t _video_matrix_address_counter, _video_matrix_line_address_counter;
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// data latched from the bus
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uint8_t _character_code, _character_colour, _character_value;
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uint8_t *pixel_pointer;
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uint8_t _registers[16];
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uint8_t _colours[16];
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bool _is_odd_frame;
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void output_border(unsigned int number_of_cycles);
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// lookup table from 6560 colour index to appropriate PAL/NTSC value
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uint8_t _colours[16];
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unsigned int _cycles_since_speaker_update;
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void update_audio();
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uint8_t *pixel_pointer;
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void output_border(unsigned int number_of_cycles);
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};
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}
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