mirror of
https://github.com/TomHarte/CLK.git
synced 2024-12-11 15:49:38 +00:00
214 lines
6.5 KiB
C++
214 lines
6.5 KiB
C++
//
|
||
// Video.hpp
|
||
// Clock Signal
|
||
//
|
||
// Created by Thomas Harte on 31/10/2020.
|
||
// Copyright © 2020 Thomas Harte. All rights reserved.
|
||
//
|
||
|
||
#ifndef Apple_IIgs_Video_hpp
|
||
#define Apple_IIgs_Video_hpp
|
||
|
||
#include "../AppleII/VideoSwitches.hpp"
|
||
#include "../../../Outputs/CRT/CRT.hpp"
|
||
#include "../../../ClockReceiver/ClockReceiver.hpp"
|
||
|
||
namespace Apple {
|
||
namespace IIgs {
|
||
namespace Video {
|
||
|
||
/*!
|
||
Provides IIgs video output; assumed clocking here is seven times the usual Apple II clock.
|
||
So it'll produce a single line of video every 456 cycles — 65*7 + 1, allowing for the
|
||
stretched cycle.
|
||
*/
|
||
class Video: public Apple::II::VideoSwitches<Cycles> {
|
||
public:
|
||
Video();
|
||
void set_internal_ram(const uint8_t *);
|
||
|
||
bool get_is_vertical_blank(Cycles offset);
|
||
uint8_t get_horizontal_counter(Cycles offset);
|
||
uint8_t get_vertical_counter(Cycles offset);
|
||
|
||
void set_new_video(uint8_t);
|
||
uint8_t get_new_video();
|
||
|
||
void clear_interrupts(uint8_t);
|
||
uint8_t get_interrupt_register();
|
||
void set_interrupt_register(uint8_t);
|
||
bool get_interrupt_line();
|
||
|
||
void notify_clock_tick();
|
||
|
||
void set_border_colour(uint8_t);
|
||
void set_text_colour(uint8_t);
|
||
uint8_t get_text_colour();
|
||
uint8_t get_border_colour();
|
||
|
||
void set_composite_is_colour(bool);
|
||
bool get_composite_is_colour();
|
||
|
||
/// Sets the scan target.
|
||
void set_scan_target(Outputs::Display::ScanTarget *scan_target);
|
||
|
||
/// Gets the current scan status.
|
||
Outputs::Display::ScanStatus get_scaled_scan_status() const;
|
||
|
||
/// Sets the type of output.
|
||
void set_display_type(Outputs::Display::DisplayType);
|
||
|
||
/// Gets the type of output.
|
||
Outputs::Display::DisplayType get_display_type() const;
|
||
|
||
/// Determines the period until video might autonomously update its interrupt lines.
|
||
Cycles get_next_sequence_point() const;
|
||
|
||
/// Sets the Mega II interrupt enable state — 1/4-second and VBL interrupts are
|
||
/// generated here.
|
||
void set_megaii_interrupts_enabled(uint8_t);
|
||
|
||
uint8_t get_megaii_interrupt_status();
|
||
|
||
void clear_megaii_interrupts();
|
||
|
||
private:
|
||
Outputs::CRT::CRT crt_;
|
||
|
||
// This is coupled to Apple::II::GraphicsMode, but adds detail for the IIgs.
|
||
enum class GraphicsMode {
|
||
Text = 0,
|
||
DoubleText,
|
||
HighRes,
|
||
DoubleHighRes,
|
||
LowRes,
|
||
DoubleLowRes,
|
||
FatLowRes,
|
||
|
||
// Additions:
|
||
DoubleHighResMono,
|
||
SuperHighRes
|
||
};
|
||
constexpr bool is_colour_ntsc(GraphicsMode m) { return m >= GraphicsMode::HighRes && m <= GraphicsMode::FatLowRes; }
|
||
|
||
GraphicsMode graphics_mode(int row) const {
|
||
if(new_video_ & 0x80) {
|
||
return GraphicsMode::SuperHighRes;
|
||
}
|
||
|
||
const auto ii_mode = Apple::II::VideoSwitches<Cycles>::graphics_mode(row);
|
||
switch(ii_mode) {
|
||
// Coupling very much assumed here.
|
||
case Apple::II::GraphicsMode::DoubleHighRes:
|
||
if(new_video_ & 0x20) {
|
||
return GraphicsMode::DoubleHighResMono;
|
||
}
|
||
[[fallthrough]];
|
||
|
||
default: return GraphicsMode(int(ii_mode)); break;
|
||
}
|
||
}
|
||
|
||
enum class PixelBufferFormat {
|
||
Text, DoubleText, NTSC, NTSCMono, SuperHighRes
|
||
};
|
||
constexpr PixelBufferFormat format_for_mode(GraphicsMode m) {
|
||
switch(m) {
|
||
case GraphicsMode::Text: return PixelBufferFormat::Text;
|
||
case GraphicsMode::DoubleText: return PixelBufferFormat::DoubleText;
|
||
default: return PixelBufferFormat::NTSC;
|
||
case GraphicsMode::DoubleHighResMono: return PixelBufferFormat::NTSCMono;
|
||
case GraphicsMode::SuperHighRes: return PixelBufferFormat::SuperHighRes;
|
||
}
|
||
}
|
||
|
||
void advance(Cycles);
|
||
|
||
uint8_t new_video_ = 0x01;
|
||
uint8_t interrupts_ = 0x00;
|
||
void set_interrupts(uint8_t);
|
||
|
||
int cycles_into_frame_ = 0;
|
||
const uint8_t *ram_ = nullptr;
|
||
|
||
// The modal colours.
|
||
uint16_t border_colour_ = 0;
|
||
uint8_t border_colour_entry_ = 0;
|
||
uint8_t text_colour_entry_ = 0xf0;
|
||
uint16_t text_colour_ = 0xffff;
|
||
uint16_t background_colour_ = 0;
|
||
|
||
// Current pixel output buffer and conceptual format.
|
||
PixelBufferFormat pixels_format_;
|
||
uint16_t *pixels_ = nullptr, *next_pixel_ = nullptr;
|
||
int pixels_start_column_;
|
||
|
||
void output_row(int row, int start, int end);
|
||
|
||
uint16_t *output_super_high_res(uint16_t *target, int start, int end, int row) const;
|
||
|
||
uint16_t *output_text(uint16_t *target, int start, int end, int row) const;
|
||
uint16_t *output_double_text(uint16_t *target, int start, int end, int row) const;
|
||
uint16_t *output_char(uint16_t *target, uint8_t source, int row) const;
|
||
|
||
uint16_t *output_low_resolution(uint16_t *target, int start, int end, int row);
|
||
uint16_t *output_fat_low_resolution(uint16_t *target, int start, int end, int row);
|
||
uint16_t *output_double_low_resolution(uint16_t *target, int start, int end, int row);
|
||
|
||
uint16_t *output_high_resolution(uint16_t *target, int start, int end, int row);
|
||
uint16_t *output_double_high_resolution(uint16_t *target, int start, int end, int row);
|
||
uint16_t *output_double_high_resolution_mono(uint16_t *target, int start, int end, int row);
|
||
|
||
// Super high-res per-line state.
|
||
uint8_t line_control_;
|
||
uint16_t palette_[16];
|
||
|
||
// Storage used for fill mode.
|
||
uint16_t *palette_zero_[4] = {nullptr, nullptr, nullptr, nullptr}, palette_throwaway_;
|
||
|
||
// Lookup tables and state to assist in the IIgs' mapping from NTSC to RGB.
|
||
//
|
||
// My understanding of the real-life algorithm is: maintain a four-bit buffer.
|
||
// Fill it in a circular fashion. Ordinarily, output the result of looking
|
||
// up the RGB mapping of those four bits of Apple II output (which outputs four
|
||
// bits per NTSC colour cycle), commuted as per current phase. But if the bit
|
||
// being inserted differs from that currently in its position in the shift
|
||
// register, hold the existing output for three shifts.
|
||
//
|
||
// From there I am using the following:
|
||
|
||
// Maps from:
|
||
//
|
||
// b0 = b0 of the shift register
|
||
// b1 = b4 of the shift register
|
||
// b2– = current delay count
|
||
//
|
||
// to a new delay count.
|
||
uint8_t ntsc_delay_lookup_[20];
|
||
uint32_t ntsc_shift_ = 0; // Assumption here: logical shifts will ensue, rather than arithmetic.
|
||
int ntsc_delay_ = 0;
|
||
|
||
/// Outputs the lowest 14 bits from @c ntsc_shift_, mapping to RGB.
|
||
/// Phase is derived from @c column.
|
||
uint16_t *output_shift(uint16_t *target, int column);
|
||
|
||
// Common getter for the two counters.
|
||
struct Counters {
|
||
Counters(int v, int h) : vertical(v), horizontal(h) {}
|
||
const int vertical, horizontal;
|
||
};
|
||
Counters get_counters(Cycles offset);
|
||
|
||
// Marshalls the Mega II-style interrupt state.
|
||
uint8_t megaii_interrupt_mask_ = 0;
|
||
uint8_t megaii_interrupt_state_ = 0;
|
||
int megaii_frame_counter_ = 0; // To count up to quarter-second interrupts.
|
||
};
|
||
|
||
}
|
||
}
|
||
}
|
||
|
||
#endif /* Video_hpp */
|
||
|