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CLK/Machines/Apple/Macintosh/Video.hpp

107 lines
3.0 KiB
C++

//
// Video.hpp
// Clock Signal
//
// Created by Thomas Harte on 03/05/2019.
// Copyright © 2019 Thomas Harte. All rights reserved.
//
#ifndef Video_hpp
#define Video_hpp
#include "../../../Outputs/CRT/CRT.hpp"
#include "../../../ClockReceiver/ClockReceiver.hpp"
#include "DeferredAudio.hpp"
#include "DriveSpeedAccumulator.hpp"
namespace Apple::Macintosh {
constexpr HalfCycles line_length(704);
constexpr int number_of_lines = 370;
constexpr HalfCycles frame_length(line_length * HalfCycles(number_of_lines));
constexpr int sync_start = 36;
constexpr int sync_end = 38;
/*!
Models the 68000-era Macintosh video hardware, producing a 512x348 pixel image,
within a total scanning area of 370 lines, at 352 cycles per line.
This class also collects audio and 400kb drive-speed data, forwarding those values.
*/
class Video {
public:
/*!
Constructs an instance of @c Video sourcing its pixel data from @c ram and
providing audio and drive-speed bytes to @c audio and @c drive_speed_accumulator.
*/
Video(DeferredAudio &audio, DriveSpeedAccumulator &drive_speed_accumulator);
/*!
Sets the target device for video data.
*/
void set_scan_target(Outputs::Display::ScanTarget *scan_target);
/// Gets the current scan status.
Outputs::Display::ScanStatus get_scaled_scan_status() const;
/*!
Produces the next @c duration period of pixels.
*/
void run_for(HalfCycles duration);
/*!
Sets whether the alternate screen and/or audio buffers should be used to source data.
*/
void set_use_alternate_buffers(bool use_alternate_screen_buffer, bool use_alternate_audio_buffer);
/*!
Provides a base address and a mask indicating which parts of the generated video and audio/drive addresses are
actually decoded, accessing *word-sized memory*; e.g. for a 128kb Macintosh this should be (1 << 16) - 1 = 0xffff.
*/
void set_ram(uint16_t *ram, uint32_t mask);
/*!
@returns @c true if the video is currently outputting a vertical sync, @c false otherwise.
*/
bool vsync();
/*
@returns @c true if in @c offset half cycles from now, the video will be outputting pixels;
@c false otherwise.
*/
bool is_outputting(HalfCycles offset = HalfCycles(0)) {
const auto offset_position = frame_position_ + offset % frame_length;
const int column = int((offset_position % line_length).as_integral()) >> 4;
const int line = int((offset_position / line_length).as_integral());
return line < 342 && column < 32;
}
/*!
@returns the amount of time until there is next a transition on the
vsync signal.
*/
HalfCycles next_sequence_point();
private:
DeferredAudio &audio_;
DriveSpeedAccumulator &drive_speed_accumulator_;
Outputs::CRT::CRT crt_;
uint16_t *ram_ = nullptr;
uint32_t ram_mask_ = 0;
HalfCycles frame_position_;
size_t video_address_ = 0;
size_t audio_address_ = 0;
uint64_t *pixel_buffer_ = nullptr;
bool use_alternate_screen_buffer_ = false;
bool use_alternate_audio_buffer_ = false;
};
}
#endif /* Video_hpp */