d0f7acf9eb
An x86-64 operating system built from xv6, now largely rewritten: SMP, a copy-on-write root filesystem (SchFS), PCI/USB/virtio drivers, a TTF rasteriser, and a Linux-numbered syscall ABI. No history before this point -- the tree was never under version control. This commit exists so the rename that follows has something to undo to.
56 lines
2.2 KiB
C
56 lines
2.2 KiB
C
#pragma once
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// The display class: what a consumer talks to instead of a driver.
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//
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// A compositor should ask for "the display" and get whatever is bound --
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// today the VBE framebuffer, later virtio-gpu. Without this, every consumer
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// names a driver, and adding the second display driver means editing all of
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// them. That is not hypothetical here: the framebuffer's physical address was
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// once hardcoded in three separate places.
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//
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// Found with device_find_class(DEVCLASS_DISPLAY); see include/device.h.
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struct device;
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struct display_mode {
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int width, height;
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int bpp;
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uint32 stride; // bytes per row of the *visible* framebuffer
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};
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struct display_ops {
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void (*mode)(struct device *, struct display_mode *);
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// The buffer to draw into, and its stride. Returns 0 if double buffering is
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// unavailable, in which case the caller should draw directly and accept
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// tearing rather than not drawing at all.
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//
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// Allocated on first call, never at boot: it is around two megabytes at
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// 800x600, and a machine whose compositor never starts should not pay that.
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void *(*acquire)(struct device *, uint32 *stride_out);
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// Copy a rectangle of the back buffer to the display. Coordinates are in
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// pixels; the whole screen is (0, 0, width, height).
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void (*present)(struct device *, int x, int y, int w, int h);
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// Block until the display is between frames. Optional -- a driver that
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// cannot tell leaves this null, and present() then simply tears less than
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// drawing directly would.
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void (*wait_vblank)(struct device *);
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};
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// The bound display, or 0. Convenience over device_find_class().
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struct device *display_get(void);
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// Wrappers that do nothing gracefully when there is no display or the driver
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// left an op null, so callers are not each written around a maybe-null vtable.
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int display_mode(struct display_mode *out);
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void *display_acquire(uint32 *stride_out);
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void display_present(int x, int y, int w, int h);
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void display_wait_vblank(void);
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// Drive the whole path once and draw a test pattern. `echo d > /proc/sysrq`.
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void display_selftest(void);
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// Draw a text specimen through the display class. `echo t > /proc/sysrq`.
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void text_selftest(void);
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