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Switches to an overt active/inactive state machine.

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This commit is contained in:
Thomas Harte 2021-06-24 18:34:21 -04:00
parent 6c8b23e708
commit f98888824d
2 changed files with 233 additions and 190 deletions
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399
Machines/Enterprise/Nick.cpp
View File

@ -52,7 +52,9 @@ void Nick::write(uint16_t address, uint8_t value) {
}
break;
case 1:
flush_border();
if(output_type_ == OutputType::Border) {
set_output_type(OutputType::Border, true);
}
border_colour_ = mapped_colour(value);
break;
case 2:
@ -68,7 +70,7 @@ void Nick::write(uint16_t address, uint8_t value) {
// I'm unclear whether I should also reset the horizontal counter
// (i.e. completely abandon current video phase).
lines_remaining_ = 0xff;
line_parameters_[1] |= 1;
should_reload_line_parameters_ = true;
}
line_parameter_control_ = value & 0xc0;
break;
@ -79,9 +81,15 @@ uint8_t Nick::read([[maybe_unused]] uint16_t address) {
return 0xff;
}
//int c;
void Nick::run_for(Cycles duration) {
constexpr int line_length = 912;
#define check_margins() \
if(window == left_margin_) is_sync_or_pixels_ = true; \
if(window == right_margin_) is_sync_or_pixels_ = false;
int clocks_remaining = duration.as<int>();
while(clocks_remaining) {
// Determine how many cycles are left this line.
@ -98,162 +106,197 @@ void Nick::run_for(Cycles duration) {
// Do nothing if a window boundary isn't crossed.
if(window == end_window) continue;
// If this is within the first 8 cycles of the line, [possibly] fetch
// the relevant part of the line parameters.
if(should_reload_line_parameters_ && window < 8) {
int fetch_spot = window;
while(fetch_spot < end_window && fetch_spot < 8) {
line_parameters_[(fetch_spot << 1)] = ram_[line_parameter_pointer_];
line_parameters_[(fetch_spot << 1) + 1] = ram_[line_parameter_pointer_ + 1];
line_parameter_pointer_ += 2;
++fetch_spot;
}
// TODO: when exactly does the interrupt output change? Am I a window too late? Or two too early?
// Special: set mode as soon as it's known. It'll be needed at the end of HSYNC.
if(window < 2 && fetch_spot >= 2) {
// Set length of mode line.
lines_remaining_ = line_parameters_[0];
// Set the new interrupt line output.
interrupt_line_ = line_parameters_[1] & 0x80;
// Determine the margins.
left_margin_ = line_parameters_[2] & 0x3f;
right_margin_ = line_parameters_[3] & 0x3f;
// Determine the mode and depth, and hence the column size.
mode_ = Mode((line_parameters_[1] >> 1)&7);
bpp_ = 1 << ((line_parameters_[1] >> 5)&3);
switch(mode_) {
default:
case Mode::Pixel: column_size_ = 16 / bpp_; break;
case Mode::CH64:
case Mode::CH128:
case Mode::CH256:
case Mode::LPixel: column_size_ = 8 / bpp_; break;
case Mode::Attr: column_size_ = 8; break;
}
// Act as if proper state transitions had occurred while HSYNC is being output.
if(mode_ == Mode::Vsync) {
state_ = State::Blank;
} else {
// The first ten windows are occupied by the horizontal sync and
// colour burst; if left signalled before then, begin in pixels.
state_ = left_margin_ > 10 ? State::Border : State::Pixels;
}
}
// If all parameters have been loaded, set appropriate fields.
if(fetch_spot == 8) {
should_reload_line_parameters_ = false;
// Determine the line data pointers.
line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
line_data_pointer_[1] = uint16_t(line_parameters_[6] | (line_parameters_[7] << 8));
// Populate the first eight colours of the palette.
for(int c = 0; c < 8; c++) {
palette_[c] = mapped_colour(line_parameters_[8 + c]);
}
switch(mode_) {
default:
assert(false);
case Mode::Vsync:
break;
// NB: LSBALT/MSBALT and ALTIND0/ALTIND1 appear to have opposite effects on palette selection.
case Mode::Pixel:
case Mode::LPixel:
// Use MSBALT and LSBALT to pick the alt_ind_palettes.
//
// LSBALT = b6 of params[2], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
// MSBALT = b7 of params[2], if set => character codes with bit 7 set should use palette indices 2 and 3.
two_colour_mask_ = 0xff &~ (((line_parameters_[2]&0x80) >> 7) | ((line_parameters_[2]&0x40) << 1));
alt_ind_palettes[0] = palette_;
alt_ind_palettes[2] = alt_ind_palettes[0] + ((line_parameters_[2] & 0x80) ? 2 : 0);
alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[2] & 0x40) ? 4 : 0);
alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[2] & 0x40) ? 4 : 0);
line_data_per_column_increments_[0] = 1 + (mode_ == Mode::Pixel);
line_data_per_column_increments_[1] = 0;
break;
case Mode::CH64:
case Mode::CH128:
case Mode::CH256:
// Use ALTIND0 and ALTIND1 to pick the alt_ind_palettes.
//
// ALTIND1 = b6 of params[3], if set => character codes with bit 7 set should use palette indices 2 and 3.
// ALTIND0 = b7 of params[3], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
alt_ind_palettes[0] = palette_;
alt_ind_palettes[2] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x40) ? 2 : 0);
alt_ind_palettes[1] = alt_ind_palettes[0] + ((line_parameters_[3] & 0x80) ? 4 : 0);
alt_ind_palettes[3] = alt_ind_palettes[2] + ((line_parameters_[3] & 0x80) ? 4 : 0);
line_data_per_column_increments_[0] = 1;
line_data_per_column_increments_[1] = 0;
break;
case Mode::Attr:
line_data_per_column_increments_[0] = 1;
line_data_per_column_increments_[1] = 1;
break;
}
}
}
// HSYNC is signalled for four windows at the start of the line.
// I currently belive this happens regardless of Vsync mode.
if(window < 4 && end_window >= 4) {
crt_.output_sync(4*16);
window = 4;
// I currently believe this happens regardless of Vsync mode.
//
// This is also when the non-palette line parameters
// are loaded, if appropriate.
if(!window) set_output_type(OutputType::Sync);
while(window < 4 && window < end_window) {
if(should_reload_line_parameters_) {
switch(window) {
// First slot: line count, mode and interrupt flag.
case 0:
assert(!(line_parameter_pointer_&0xf));
lines_remaining_ = ram_[line_parameter_pointer_];
++line_parameter_pointer_;
// Set the new interrupt line output.
interrupt_line_ = ram_[line_parameter_pointer_] & 0x80;
// Determine the mode and depth, and hence the column size.
mode_ = Mode((ram_[line_parameter_pointer_] >> 1)&7);
bpp_ = 1 << ((ram_[line_parameter_pointer_] >> 5)&3);
switch(mode_) {
default:
case Mode::Pixel:
column_size_ = 16 / bpp_;
line_data_per_column_increments_[0] = 2;
line_data_per_column_increments_[1] = 0;
break;
case Mode::LPixel:
column_size_ = 8 / bpp_;
line_data_per_column_increments_[0] = 1;
line_data_per_column_increments_[1] = 0;
break;
case Mode::CH64:
case Mode::CH128:
case Mode::CH256:
column_size_ = 8;
line_data_per_column_increments_[0] = 1;
line_data_per_column_increments_[1] = 0;
break;
case Mode::Attr:
column_size_ = 8;
line_data_per_column_increments_[0] = 1;
line_data_per_column_increments_[1] = 1;
break;
}
vres_ = ram_[line_parameter_pointer_] & 0x10;
reload_line_parameter_pointer_ = ram_[line_parameter_pointer_] & 0x01;
++line_parameter_pointer_;
break;
// Second slot: margins and ALT/IND bits.
case 1:
// Determine the margins.
left_margin_ = ram_[line_parameter_pointer_] & 0x3f;
right_margin_ = ram_[(line_parameter_pointer_+1) & 0xffff] & 0x3f;
// Set up the alternative palettes,
switch(mode_) {
default:
break;
// NB: LSBALT/MSBALT and ALTIND0/ALTIND1 appear to have opposite effects on palette selection.
case Mode::Pixel:
case Mode::LPixel: {
const uint8_t flags = ram_[line_parameter_pointer_];
// Use MSBALT and LSBALT to pick the alt_ind_palettes.
//
// LSBALT = b6 of params[2], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
// MSBALT = b7 of params[2], if set => character codes with bit 7 set should use palette indices 2 and 3.
two_colour_mask_ = 0xff &~ (((flags&0x80) >> 7) | ((flags&0x40) << 1));
alt_ind_palettes[0] = palette_;
alt_ind_palettes[2] = alt_ind_palettes[0] + ((flags & 0x80) ? 2 : 0);
alt_ind_palettes[1] = alt_ind_palettes[0] + ((flags & 0x40) ? 4 : 0);
alt_ind_palettes[3] = alt_ind_palettes[2] + ((flags & 0x40) ? 4 : 0);
} break;
case Mode::CH64:
case Mode::CH128:
case Mode::CH256: {
const uint8_t flags = ram_[(line_parameter_pointer_+1) & 0xffff];
// Use ALTIND0 and ALTIND1 to pick the alt_ind_palettes.
//
// ALTIND1 = b6 of params[3], if set => character codes with bit 7 set should use palette indices 2 and 3.
// ALTIND0 = b7 of params[3], if set => character codes with bit 6 set should use palette indices 4... instead of 0... .
alt_ind_palettes[0] = palette_;
alt_ind_palettes[2] = alt_ind_palettes[0] + ((flags & 0x40) ? 2 : 0);
alt_ind_palettes[1] = alt_ind_palettes[0] + ((flags & 0x80) ? 4 : 0);
alt_ind_palettes[3] = alt_ind_palettes[2] + ((flags & 0x80) ? 4 : 0);
} break;
}
line_parameter_pointer_ += 2;
break;
// Third slot: Line data pointer 1.
case 2:
start_line_data_pointer_[0] = ram_[line_parameter_pointer_];
++line_parameter_pointer_;
start_line_data_pointer_[0] |= ram_[line_parameter_pointer_] << 8;
++line_parameter_pointer_;
line_data_pointer_[0] = start_line_data_pointer_[0];
break;
// Fourth slot: Line data pointer 2.
case 3:
start_line_data_pointer_[1] = ram_[line_parameter_pointer_];
++line_parameter_pointer_;
start_line_data_pointer_[1] |= ram_[line_parameter_pointer_] << 8;
++line_parameter_pointer_;
line_data_pointer_[1] = start_line_data_pointer_[1];
break;
}
}
++output_duration_;
++window;
check_margins();
}
if(window == 4) {
if(mode_ == Mode::Vsync) {
// Skip the palette.
if(should_reload_line_parameters_) line_parameter_pointer_ += 8;
should_reload_line_parameters_ = false;
set_output_type(is_sync_or_pixels_ ? OutputType::Sync : OutputType::Blank);
} else {
set_output_type(OutputType::Blank);
}
}
// Deal with vsync mode out here.
if(mode_ == Mode::Vsync) {
if(window >= 4) {
while(window < end_window) {
// Skip straight to the next event.
int next_event = end_window;
if(window < left_margin_) next_event = std::min(next_event, left_margin_);
if(window < right_margin_) next_event = std::min(next_event, right_margin_);
if(state_ == State::Blank) {
crt_.output_blank((next_event - window)*16);
} else {
crt_.output_sync((next_event - window)*16);
}
output_duration_ += next_event - window;
window = next_event;
if(window == left_margin_) state_ = State::Sync;
if(window == right_margin_) state_ = State::Blank;
check_margins();
set_output_type(is_sync_or_pixels_ ? OutputType::Sync : OutputType::Blank);
}
}
} else {
// If present then the colour burst is output for the period from
// the start of window 6 to the end of window 10.
if(window < 10 && end_window >= 10) {
crt_.output_blank(2*16);
crt_.output_colour_burst(4*16, 0); // TODO: try to determine actual phase.
window = 10;
//
// The first 8 palette entries also need to be fetched here.
while(window < 10 && window < end_window) {
if(window == 6) {
set_output_type(OutputType::ColourBurst);
}
if(should_reload_line_parameters_ && window < 8) {
const int base = (window - 4) << 1;
palette_[base] = mapped_colour(ram_[line_parameter_pointer_]);
++line_parameter_pointer_;
palette_[base+1] = mapped_colour(ram_[line_parameter_pointer_]);
++line_parameter_pointer_;
} else {
should_reload_line_parameters_ = false;
}
++output_duration_;
++window;
}
if(window >= 10) {
if(window == 10) set_output_type(is_sync_or_pixels_ ? OutputType::Pixels : OutputType::Border);
while(window < end_window) {
int next_event = end_window;
if(window < left_margin_) next_event = std::min(next_event, left_margin_);
if(window < right_margin_) next_event = std::min(next_event, right_margin_);
if(state_ == State::Border) {
border_duration_ += next_event - window;
} else {
if(is_sync_or_pixels_) {
#define DispatchBpp(func) \
switch(bpp_) { \
default: \
@ -272,8 +315,10 @@ void Nick::run_for(Cycles duration) {
int columns_remaining = next_event - window;
while(columns_remaining) {
if(!allocated_pointer_) {
flush_pixels();
if(!pixel_pointer_) {
if(output_duration_) {
set_output_type(OutputType::Pixels, true);
}
pixel_pointer_ = allocated_pointer_ = reinterpret_cast<uint16_t *>(crt_.begin_data(allocation_size));
}
@ -291,9 +336,9 @@ void Nick::run_for(Cycles duration) {
}
pixel_pointer_ += output_duration * column_size_;
pixel_duration_ += output_duration;
output_duration_ += output_duration;
if(pixel_pointer_ - allocated_pointer_ == allocation_size) {
flush_pixels();
set_output_type(OutputType::Pixels, true);
}
columns_remaining -= output_duration;
} else {
@ -302,14 +347,11 @@ void Nick::run_for(Cycles duration) {
line_data_pointer_[0] += columns_remaining * line_data_per_column_increments_[0];
line_data_pointer_[1] += columns_remaining * line_data_per_column_increments_[1];
// Advance pixel pointer, so as to be able to supply something
// convincing to the CRT as to the number of samples that would have
// been provided, and skip asking for further allocations for now.
pixel_pointer_ += columns_remaining * column_size_;
pixel_duration_ += columns_remaining;
output_duration_ += columns_remaining;
columns_remaining = 0;
}
}
#undef attr
#undef ch64
#undef ch128
@ -317,38 +359,26 @@ void Nick::run_for(Cycles duration) {
#undef pixel
#undef lpixel
#undef DispatchBpp
} else {
output_duration_ += next_event - window;
}
window = next_event;
if(window == left_margin_) {
flush_border();
state_ = State::Pixels;
}
if(window == right_margin_) {
flush_pixels();
state_ = State::Border;
}
}
}
// Finish up the line.
if(!horizontal_counter_) {
if(state_ == State::Border) {
flush_border();
} else {
flush_pixels();
check_margins();
set_output_type(is_sync_or_pixels_ ? OutputType::Pixels : OutputType::Border);
}
}
}
// Check for end of line.
if(!horizontal_counter_) {
// ++c;
++lines_remaining_;
if(!lines_remaining_) {
should_reload_line_parameters_ = true;
// Check for end-of-frame.
if(line_parameters_[1] & 1) {
if(reload_line_parameter_pointer_) {
line_parameter_pointer_ = line_parameter_base_;
}
}
@ -359,22 +389,22 @@ void Nick::run_for(Cycles duration) {
case Mode::CH64:
case Mode::CH128:
case Mode::CH256:
line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
line_data_pointer_[0] = start_line_data_pointer_[0];
++line_data_pointer_[1];
break;
case Mode::Attr:
// Reload the attribute address if VRES is set.
if(line_parameters_[1] & 0x10) {
line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
if(vres_) {
line_data_pointer_[0] = start_line_data_pointer_[0];
}
break;
case Mode::Pixel:
case Mode::LPixel:
// If VRES is clear, reload the pixel address.
if(!(line_parameters_[1] & 0x10)) {
line_data_pointer_[0] = uint16_t(line_parameters_[4] | (line_parameters_[5] << 8));
if(!vres_) {
line_data_pointer_[0] = start_line_data_pointer_[0];
}
break;
}
@ -382,21 +412,32 @@ void Nick::run_for(Cycles duration) {
}
}
void Nick::flush_border() {
if(!border_duration_) return;
void Nick::set_output_type(OutputType type, bool force_flush) {
if(type == output_type_ && !force_flush) {
return;
}
if(output_duration_) {
switch(output_type_) {
case OutputType::Border: {
uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
if(colour_pointer) *colour_pointer = border_colour_;
crt_.output_level(output_duration_*16);
} break;
uint16_t *const colour_pointer = reinterpret_cast<uint16_t *>(crt_.begin_data(1));
if(colour_pointer) *colour_pointer = border_colour_;
crt_.output_level(border_duration_*16);
border_duration_ = 0;
}
case OutputType::Pixels: {
crt_.output_data(output_duration_*16, size_t(output_duration_*column_size_));
pixel_pointer_ = nullptr;
allocated_pointer_ = nullptr;
} break;
void Nick::flush_pixels() {
if(!pixel_duration_) return;
crt_.output_data(pixel_duration_*16, size_t(pixel_pointer_ - allocated_pointer_));
pixel_duration_ = 0;
pixel_pointer_ = nullptr;
allocated_pointer_ = nullptr;
case OutputType::Sync: crt_.output_sync(output_duration_*16); break;
case OutputType::Blank: crt_.output_blank(output_duration_*16); break;
case OutputType::ColourBurst: crt_.output_colour_burst(output_duration_*16, 0); break;
}
}
output_duration_ = 0;
output_type_ = type;
}
// MARK: - Sequence points.

24
Machines/Enterprise/Nick.hpp
View File

@ -49,9 +49,9 @@ class Nick {
// Ephemerals, related to current video position.
int horizontal_counter_ = 0;
uint16_t line_parameter_pointer_ = 0x0000;
uint8_t line_parameters_[16];
bool should_reload_line_parameters_ = true;
uint16_t line_data_pointer_[2];
uint16_t start_line_data_pointer_[2];
// Current mode line parameters.
uint8_t lines_remaining_ = 0x00;
@ -68,27 +68,29 @@ class Nick {
Unused,
LPixel,
} mode_ = Mode::Vsync;
enum class State {
Sync,
Border,
Pixels,
Blank,
} state_ = State::Sync;
bool is_sync_or_pixels_ = false;
int bpp_ = 0;
int column_size_ = 0;
bool interrupt_line_ = true;
int line_data_per_column_increments_[2] = {0, 0};
bool vres_ = false;
bool reload_line_parameter_pointer_ = false;
// An accumulator for border output regions.
int border_duration_ = 0;
void flush_border();
// The destination for new pixels.
static constexpr int allocation_size = 80;
static constexpr int allocation_size = 320;
static_assert((allocation_size % 16) == 0, "Allocation size must be a multiple of 16");
uint16_t *pixel_pointer_ = nullptr, *allocated_pointer_ = nullptr;
int pixel_duration_ = 0;
void flush_pixels();
// Output transitions.
enum class OutputType {
Sync, Blank, Pixels, Border, ColourBurst
};
void set_output_type(OutputType, bool force_flush = false);
int output_duration_ = 0;
OutputType output_type_ = OutputType::Sync;
// Current palette.
uint16_t palette_[16]{};