Formatting System

Overview

The Formatting System handles text formatting, colors, alignment, and structured output. It uses kernel I/O primitives to display formatted text on the VGA screen.

VGA Color Attributes

VGA colors use the format 0xBF where B = background and F = foreground:

Value	Constant	Color
`0x00`	`COLOR_BLACK`	Black
`0x01`	`COLOR_BLUE`	Blue
`0x02`	`COLOR_GREEN`	Green
`0x03`	`COLOR_CYAN`	Cyan
`0x04`	`COLOR_RED`	Red
`0x05`	`COLOR_MAGENTA`	Magenta
`0x06`	`COLOR_BROWN`	Brown
`0x07`	`COLOR_LIGHT_GRAY`	Light Gray
`0x08`	`COLOR_DARK_GRAY`	Dark Gray
`0x09`	`COLOR_LIGHT_BLUE`	Light Blue
`0x0A`	`COLOR_LIGHT_GREEN`	Light Green
`0x0B`	`COLOR_LIGHT_CYAN`	Light Cyan
`0x0C`	`COLOR_LIGHT_RED`	Light Red
`0x0D`	`COLOR_LIGHT_MAGENTA`	Light Magenta
`0x0E`	`COLOR_YELLOW`	Yellow
`0x0F`	`COLOR_WHITE`	White

Default Colors

Constant	Value	Usage
`COLOR_DEFAULT`	`0x0F`	White on black (default text)
`COLOR_PROMPT`	`0x0F`	White on black (shell prompt)
`COLOR_ERROR`	`0x0C`	Light red on black (error messages)
`COLOR_SUCCESS`	`0x0A`	Light green on black (success messages)
`COLOR_INFO`	`0x0B`	Light cyan on black (info messages)
`COLOR_WARNING`	`0x0E`	Yellow on black (warning messages)
`COLOR_COMMAND`	`0x0E`	Yellow on black (command names)

VGA Screen Constants

Constant	Value	Description
`VGA_WIDTH`	`80`	Characters per line
`VGA_HEIGHT`	`25`	Lines per screen
`VGA_BUFFER`	`0xb8000`	VGA text buffer address
`VGA_BYTES_PER_LINE`	`160`	80 chars * 2 bytes (char + attribute)

API Reference

format_set_color

Sets the current color for subsequent output.

; Set color
mov al, COLOR_LIGHT_GREEN
call format_set_color

format_print_colored

Prints a string with a specific color.

; Print colored string
mov rsi, message_string
mov rcx, message_length
mov al, COLOR_ERROR
call format_print_colored

format_scroll_screen

Scrolls the VGA screen up by one line.

; Scroll screen
call format_scroll_screen

format_clear_screen

Clears the entire VGA screen.

; Clear screen
call format_clear_screen

File Locations

64-bit Implementation: system/shell/formatting_64.asm