I/O operations

To use the functions described in this page, the file <hal.h> should be included.

Output to the screen

JSLK currently only supports outputting to the screen in text mode, through a 24x80 map. A line is not considered because of the menu bar. The console is started by the kernel entrypoint, in x86 this is done through the startConsole() function defined in vga.c.

`int kprintf(string c, ...)`

Used to print a formatted string to the console.

Arguments

string c: The string to be printed. Use special characters in string to interpolate values.

Optional arguments: The values to be interpolated (in the order specified in the string).

Special characters

%i: Decimal number.

%s: String.

%h: Hexadecimal number.

Return value

Returns 0 if successful.

`void setConsoleColor(uint8_t color)`

Used to change the console color. clear_console() must be called to apply changes to the whole console.

Arguments

uint8_t color: The color of the text to be printed. A color value can be obtained through the getColor() function.

Return value

This function has no return value.

`uint8_t getColor(vga_color text, vga_color background)`

Used to get a console compatible color.

Special Types

vga_color: One of the sixteen possible VGA colors.

vga.h

// ...
enum vga_color_t
{
    vga_black = 0,
    vga_blue = 1,
    vga_green = 2,
    vga_cyan = 3,
    vga_red = 4,
    vga_magenta = 5,
    vga_brown = 6,
    vga_light_grey = 7,
    vga_grey = 8,
    vga_light_blue = 9,
    vga_light_green = 10,
    vga_light_cyan = 11,
    vga_light_red = 12,
    vga_light_magenta = 13,
    vga_light_brown = 14,
    vga_white = 15,
};
// ...

Arguments

vga_color text: Text color in the console (foreground).

vga_color background: Console's background color.

Optional arguments: The values to be interpolated (in the order specified in the string).

Return value

Returns a console compatible color value in a uint8_t.

Sample usage

sample.c

uint8_t color = getColor(vga_grey, vga_black); // Get a color value to use later
setConsoleColor(color);  // Example of how you could use the obtained value

Input from the keyboard

Although there is a keyboard driver provided, there is currently no way of interfacing with it without the need to write auxiliary code. Currently, all input from the keyboard is printed to the screen, and there is one function that will indicate if the enter key was pressed (read_key()), although it was just written for testing purposes and will be removed in the future. If you are in need to use the keyboard, feel free to write your own interface until one is added in a future release.

File I/O

The VFS

I/O with other hardware

The following functions can be used to interface with ports.

`void outb(uint16_t port, uint8_t value)`

Used to send a byte to a specific port.

Arguments

uint16_t port: The port to send the byte to.

uint8_t value: The value to be sent.

Return value

This function has no return value.

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I/O operations

Output to the screen

`int kprintf(string c, ...)`

Return value

`int cprintf(string c, uint8_t color, ...)`

Return value

`void kputc(char c)`

Return value

`void consolePutChar(char c, uint8_t color, size_t x, size_t y);`

Return value

`void clear_console()`

Return value

`void setConsoleColor(uint8_t color)`

Return value

`uint8_t getColor(vga_color text, vga_color background)`

Sample usage

`void setMenubarText(string text)`

`void debugPrint(string msg)`

Input from the keyboard

File I/O

I/O with other hardware

`void outb(uint16_t port, uint8_t value)`

Return value

`uint8_t inb(uint16_t port)`

Return value

`uint16_t inw(uint16_t port)`

Return value

hashtagOutput to the screen

hashtagint kprintf(string c, ...)

hashtagReturn value

hashtagint cprintf(string c, uint8_t color, ...)

hashtagReturn value

hashtagvoid kputc(char c)

hashtagReturn value

hashtagvoid consolePutChar(char c, uint8_t color, size_t x, size_t y);

hashtagReturn value

hashtagvoid clear_console()

hashtagReturn value

hashtagvoid setConsoleColor(uint8_t color)

hashtagReturn value

hashtaguint8_t getColor(vga_color text, vga_color background)

hashtagSample usage

hashtagvoid setMenubarText(string text)

hashtagvoid debugPrint(string msg)

hashtagInput from the keyboard

hashtagFile I/O

hashtagI/O with other hardware

hashtagvoid outb(uint16_t port, uint8_t value)

hashtagReturn value

hashtaguint8_t inb(uint16_t port)

hashtagReturn value

hashtaguint16_t inw(uint16_t port)

hashtagReturn value

Output to the screen

`int kprintf(string c, ...)`

Return value

`int cprintf(string c, uint8_t color, ...)`

Return value

`void kputc(char c)`

Return value

`void consolePutChar(char c, uint8_t color, size_t x, size_t y);`

Return value

`void clear_console()`

Return value

`void setConsoleColor(uint8_t color)`

Return value

`uint8_t getColor(vga_color text, vga_color background)`

Sample usage

`void setMenubarText(string text)`

`void debugPrint(string msg)`

Input from the keyboard

File I/O

I/O with other hardware

`void outb(uint16_t port, uint8_t value)`

Return value

`uint8_t inb(uint16_t port)`

Return value

`uint16_t inw(uint16_t port)`

Return value