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106 lines
2.9 KiB
C++
106 lines
2.9 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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static const HalfCycles line_length(704);
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static const int number_of_lines = 370;
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static const HalfCycles frame_length(line_length * HalfCycles(number_of_lines));
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static const int sync_start = 36;
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static const 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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/*!
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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 = (offset_position % line_length).as_int() >> 4;
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const int line = (offset_position / line_length).as_int();
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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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