TextMode Class Reference

Basic operations in the VGA-compatible text modeThis class provides an interface to access the screen in text mode, with access directly on the hardware level, i.e. the video memory and the I/O ports of the graphics card. More...

#include <machine/textmode.h>

Inheritance diagram for TextMode:

Collaboration diagram for TextMode:

Classes
union	Attribute
	Structure of a character attribute consists of 4 bit fore- and 3 bit background color, and a single blink bit. More...
struct	Attribute.__unnamed__
struct	Cell
	Structure for a cell in text mode. More...

Public Types
enum	Color {   BLACK, BLUE, GREEN, CYAN,   RED, MAGENTA, BROWN, LIGHT_GREY,   DARK_GREY, LIGHT_BLUE, LIGHT_GREEN, LIGHT_CYAN,   LIGHT_RED, LIGHT_MAGENTA, YELLOW, WHITE }
	CGA color palette. More...

Static Public Member Functions
static void	setCursor (unsigned abs_x, unsigned abs_y)
	Set the keyboard hardware cursor to absolute screen position. More...
static void	getCursor (unsigned &abs_x, unsigned &abs_y)
	Retrieve the keyboard hardware cursor position on screen. More...
static void	show (unsigned abs_x, unsigned abs_y, char character, Attribute attrib=Attribute())
	Basic output of a character at a specific position on the screen. More...
static void	show (int abs_x, int abs_y, char character, Attribute attrib=Attribute())
static void	showMouse (unsigned abs_x, unsigned abs_y)
	Show the mouse cursor by switching foreground and background of the cell at cursor position. More...

Static Public Attributes
static const unsigned	ROWS = 25
	Visible rows in text mode.
static const unsigned	COLUMNS = 80
	Visible columns in text mode.

Protected Member Functions
	TextMode ()
	Default constructor.

Static Protected Attributes
static Cell *const	TEXT_BUFFER_BASE = reinterpret_cast<TextMode::Cell *>(0xb8000)
	Base address for linear text buffer in video memory.
static unsigned	mouse_x = 0
	Last reported column of mouse cursor.
static unsigned	mouse_y = 0
	Last reported row of mouse cursor.
static Attribute	mouse_attrib
	(Previous) attributes of cell at mouse cursor

Detailed Description

Basic operations in the VGA-compatible text mode

This class provides an interface to access the screen in text mode, with access directly on the hardware level, i.e. the video memory and the I/O ports of the graphics card.

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Class Documentation

TextMode::Attribute.__unnamed__

struct TextMode::Attribute.__unnamed__

Class Members
uint8_t	foreground: 4	.... XXXX Foreground color
uint8_t	background: 3	.XXX .... Background color
uint8_t	blink: 1	X... .... Blink

Member Enumeration Documentation

Color

enum TextMode::Color

CGA color palette.

Colors for the attribute byte. All 16 colors can be used for the foreground while the background colors are limited to the first eight (fromBLACK to LIGHT_GREY)

Enumerator
BLACK	Black (fore- and background)
BLUE	Blue (fore- and background)
GREEN	Green (fore- and background)
CYAN	Cyan (fore- and background)
RED	Red (fore- and background)
MAGENTA	Magenta (fore- and background)
BROWN	Brown (fore- and background)
LIGHT_GREY	Light grey (fore- and background)
DARK_GREY	Dark grey (foreground only)
LIGHT_BLUE	Light blue (foreground only)
LIGHT_GREEN	Light green (foreground only)
LIGHT_CYAN	Light cyan (foreground only)
LIGHT_RED	Light red (foreground only)
LIGHT_MAGENTA	Light magenta (foreground only)
YELLOW	Yellow (foreground only)
WHITE	White (foreground only)

Member Function Documentation

setCursor()

void TextMode::setCursor ( unsigned  abs_x, unsigned  abs_y  )

static

Set the keyboard hardware cursor to absolute screen position.

Parameters

abs_x	absolute column of the keyboard hardware cursor
abs_y	absolute row of the keyboard hardware cursor

getCursor()

void TextMode::getCursor ( unsigned &  abs_x, unsigned &  abs_y  )

static

Retrieve the keyboard hardware cursor position on screen.

Parameters

abs_x	absolute column of the keyboard hardware cursor
abs_y	absolute row of the keyboard hardware cursor

show()

void TextMode::show ( unsigned  abs_x, unsigned  abs_y, char  character, Attribute  attrib = Attribute()  )

static

Basic output of a character at a specific position on the screen.

This method outputs the given character at the absolute screen position (x, y) with the specified color attribute.

The position (0,0) indicates the upper left corner of the screen. The attribute defines characteristics such as background color, foreground color and blinking.

Parameters

abs_x	Column (abs_x < COLUMNS) in which the character should be displayed
abs_y	Row (abs_y < ROWS) in which the character should be displayed
character	Character to be displayed
attrib	Attribute with color settings

Optional:

Extend this method to deal with the mouse cursor

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

This method outputs the given character at the absolute screen position (x, y) with the specified color attribute. Negative coordinates are interpreted relative to the right (x) and bottom (y) border.

Parameters

abs_x	Column (-COLUMNS ≤ abs_x < COLUMNS) in which the character should be displayed – using the right border (COLUMNS) as reference for negative values.
abs_y	Row (-ROWS ≤ abs_y < ROWS) in which the character should be displayed – using the bottom border (ROWS) as reference for negative values.
character	Character to be displayed
attrib	Attribute with color settings

showMouse()

void TextMode::showMouse ( unsigned  abs_x, unsigned  abs_y  )

static

Show the mouse cursor by switching foreground and background of the cell at cursor position.

Parameters

abs_x	Column (abs_x < COLUMNS) of mouse cursor
abs_y	Row (abs_y < ROWS) of mouse cursor

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The documentation for this class was generated from the following files:

• machine/textmode.h
• machine/textmode.cc