sortix--sortix/libmaxsi/hsrc/sortix-vga.h

/******************************************************************************

	COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.

	This file is part of LibMaxsi.

	LibMaxsi is free software: you can redistribute it and/or modify it under
	the terms of the GNU Lesser General Public License as published by the Free
	Software Foundation, either version 3 of the License, or (at your option)
	any later version.

	LibMaxsi is distributed in the hope that it will be useful, but WITHOUT ANY
	WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
	FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
	more details.

	You should have received a copy of the GNU Lesser General Public License
	along with LibMaxsi. If not, see <http://www.gnu.org/licenses/>.

	sortix-vga.h
	Provides access to the VGA framebuffer under Sortix. This is highly
	unportable and is very likely to be removed or changed radically.

******************************************************************************/

#ifndef LIBMAXSI_SORTIX_VGA_H
#define LIBMAXSI_SORTIX_VGA_H

namespace System
{
	namespace VGA
	{
		// This is the contents of a VGA framebuffer used in text mode. The
		// lower 8 lower bits correspond to an ASCII character, the next 4 bits
		// is the text color, and the upper 4 bits are the background color.
		struct Frame
		{
		public:
			// The width of each line in characters.
			const static size_t width = 80;

			// The number of lines.
			const static size_t height = 25;

			// The data containing the frame.
			uint16_t text[width * height];

			// An opaque file descriptor that defines this frame. Used to change
			// the current frame or deleting frames.
			int fd;

			// Beware: The kernel may or may keep more hidden data here. You may
			// not depend on the usage of this area.

		private:
			// Only the kernel may create an instance of this structure.
			Frame() { }

		};

		// Allocates a framebuffer able to store VGA data. This buffer is not
		// relocatable and must remain at this position.
		Frame* CreateFrame();

		// Sets the process' current VGA frame. If the process currently have
		// focus, then this is the frame shown on the screen. Any edits done
		// on this frame while it is active will be shown instantly on the
		// screen if the process have focus.
		int ChangeFrame(int fd);

		// Deletes a frame. This is equivalent to IO::Close(fd).
		int DeleteFrame(int fd);
	}
}

#endif