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CLK/Machines/Enterprise/Nick.hpp
2021-07-03 19:10:29 -04:00

127 lines
3.6 KiB
C++

//
// Nick.hpp
// Clock Signal
//
// Created by Thomas Harte on 14/06/2021.
// Copyright © 2021 Thomas Harte. All rights reserved.
//
#ifndef Nick_hpp
#define Nick_hpp
#include <cstdint>
#include "../../ClockReceiver/ClockReceiver.hpp"
#include "../../Outputs/CRT/CRT.hpp"
namespace Enterprise {
class Nick {
public:
Nick(const uint8_t *ram);
/// Writes to a Nick register; only the low two bits are decoded.
void write(uint16_t address, uint8_t value);
/// Reads from the Nick range. Nobody seems to be completely clear what
/// this should return; I've set it up to return the last fetched video or mode
/// line byte during periods when those things are being fetched, 0xff at all
/// other times. Including during refresh, since I don't know what addresses
/// are generated then.
///
/// This likely isn't accurate, but is the most accurate guess I could make.
uint8_t read();
void run_for(Cycles);
Cycles get_time_until_z80_slot(Cycles after_period) const;
void set_scan_target(Outputs::Display::ScanTarget *scan_target);
Outputs::Display::ScanStatus get_scaled_scan_status() const;
/// @returns The amount of time until the next potential change in interrupt output.
Cycles get_next_sequence_point() const;
/*!
@returns The current state of the interrupt line — @c true for active;
@c false for inactive.
*/
inline bool get_interrupt_line() const {
return interrupt_line_;
}
/// Sets the type of output.
void set_display_type(Outputs::Display::DisplayType);
/// Gets the type of output.
Outputs::Display::DisplayType get_display_type() const;
private:
Outputs::CRT::CRT crt_;
const uint8_t *const ram_;
// CPU-provided state.
uint8_t line_parameter_control_ = 0xc0;
uint16_t line_parameter_base_ = 0x0000;
uint16_t border_colour_ = 0;
// Ephemerals, related to current video position.
int horizontal_counter_ = 0;
uint16_t line_parameter_pointer_ = 0x0000;
bool should_reload_line_parameters_ = true;
uint16_t line_data_pointer_[2];
uint16_t start_line_data_pointer_[2];
mutable uint8_t last_read_ = 0xff;
// Current mode line parameters.
uint8_t lines_remaining_ = 0x00;
uint8_t two_colour_mask_ = 0xff;
int left_margin_ = 0, right_margin_ = 0;
const uint16_t *alt_ind_palettes[4];
enum class Mode {
Vsync,
Pixel,
Attr,
CH256,
CH128,
CH64,
Unused,
LPixel,
} mode_ = Mode::Vsync;
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;
// The destination for new pixels.
static constexpr int allocation_size = 336;
static_assert((allocation_size % 16) == 0, "Allocation size must be a multiple of 16");
uint16_t *pixel_pointer_ = nullptr, *allocated_pointer_ = nullptr;
// 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]{};
// The first column with pixels on it; will be either 8 or 10 depending
// on whether the colour burst is meaningful to the current display type.
int first_pixel_window_ = 10;
// Specific outputters.
template <int bpp, bool is_lpixel> void output_pixel(uint16_t *target, int columns) const;
template <int bpp, int index_bits> void output_character(uint16_t *target, int columns) const;
template <int bpp> void output_attributed(uint16_t *target, int columns) const;
};
}
#endif /* Nick_hpp */