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d97a073d1b
They all just as the CRT, as all are currently based on the CRT. Which doesn't currently know the total clock rate it would need to in order properly to scale the answer to the question. Further thought coming.
109 lines
3.0 KiB
C++
109 lines
3.0 KiB
C++
//
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// Video.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 03/05/2019.
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// Copyright © 2019 Thomas Harte. All rights reserved.
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//
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#ifndef Video_hpp
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#define Video_hpp
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#include "../../../Outputs/CRT/CRT.hpp"
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#include "../../../ClockReceiver/ClockReceiver.hpp"
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#include "DeferredAudio.hpp"
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#include "DriveSpeedAccumulator.hpp"
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namespace Apple {
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namespace Macintosh {
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constexpr HalfCycles line_length(704);
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constexpr int number_of_lines = 370;
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constexpr HalfCycles frame_length(line_length * HalfCycles(number_of_lines));
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constexpr int sync_start = 36;
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constexpr int sync_end = 38;
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/*!
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Models the 68000-era Macintosh video hardware, producing a 512x348 pixel image,
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within a total scanning area of 370 lines, at 352 cycles per line.
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This class also collects audio and 400kb drive-speed data, forwarding those values.
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*/
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class Video {
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public:
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/*!
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Constructs an instance of @c Video sourcing its pixel data from @c ram and
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providing audio and drive-speed bytes to @c audio and @c drive_speed_accumulator.
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*/
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Video(DeferredAudio &audio, DriveSpeedAccumulator &drive_speed_accumulator);
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/*!
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Sets the target device for video data.
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*/
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void set_scan_target(Outputs::Display::ScanTarget *scan_target);
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/// Gets the current scan status.
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Outputs::Display::ScanStatus get_scan_status() const;
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/*!
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Produces the next @c duration period of pixels.
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*/
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void run_for(HalfCycles duration);
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/*!
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Sets whether the alternate screen and/or audio buffers should be used to source data.
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*/
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void set_use_alternate_buffers(bool use_alternate_screen_buffer, bool use_alternate_audio_buffer);
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/*!
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Provides a base address and a mask indicating which parts of the generated video and audio/drive addresses are
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actually decoded, accessing *word-sized memory*; e.g. for a 128kb Macintosh this should be (1 << 16) - 1 = 0xffff.
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*/
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void set_ram(uint16_t *ram, uint32_t mask);
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/*!
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@returns @c true if the video is currently outputting a vertical sync, @c false otherwise.
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*/
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bool vsync();
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/*
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@returns @c true if in @c offset half cycles from now, the video will be outputting pixels;
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@c false otherwise.
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*/
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bool is_outputting(HalfCycles offset = HalfCycles(0)) {
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const auto offset_position = frame_position_ + offset % frame_length;
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const int column = int((offset_position % line_length).as_integral()) >> 4;
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const int line = int((offset_position / line_length).as_integral());
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return line < 342 && column < 32;
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}
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/*!
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@returns the amount of time until there is next a transition on the
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vsync signal.
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*/
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HalfCycles get_next_sequence_point();
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private:
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DeferredAudio &audio_;
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DriveSpeedAccumulator &drive_speed_accumulator_;
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Outputs::CRT::CRT crt_;
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uint16_t *ram_ = nullptr;
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uint32_t ram_mask_ = 0;
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HalfCycles frame_position_;
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size_t video_address_ = 0;
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size_t audio_address_ = 0;
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uint8_t *pixel_buffer_ = nullptr;
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bool use_alternate_screen_buffer_ = false;
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bool use_alternate_audio_buffer_ = false;
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};
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}
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}
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#endif /* Video_hpp */
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