current_col: AtomicU16,

current_row: AtomicU16,

text_buffer: AtomicPtr<GlyphAttr>,

current_attr: AtomicU8,

/// Create a TextConsole.

///

/// Has no buffer associated with it

pub const fn new() -> TextConsole {

TextConsole {

current_row: AtomicU16::new(0),

current_col: AtomicU16::new(0),

text_buffer: AtomicPtr::new(core::ptr::null_mut()),

// White on Black, with the default palette

current_attr: AtomicU8::new(

Attr::new(

TextForegroundColour::White,

TextBackgroundColour::Black,

false,

)

.0,

),

}

}

/// Update the text buffer we are using.

///

/// Will reset the cursor. The screen is not cleared.

pub unsafe fn set_text_buffer(&self, text_buffer: *mut GlyphAttr) {

self.text_buffer.store(text_buffer, Ordering::Relaxed)

}

/// Place a single Code Page 850 encoded 8-bit character on the screen.

///

/// Adjusts the current row and column automatically. Also understands

/// Carriage Return and New Line bytes.

pub fn write_font_glyph(&self, glyph: Glyph) {

// Load from global state

let mut row = self.current_row.load(Ordering::Relaxed);

let mut col = self.current_col.load(Ordering::Relaxed);

self.write_at(glyph, &mut row, &mut col);

// Push back to global state

self.current_row.store(row, Ordering::Relaxed);

self.current_col.store(col, Ordering::Relaxed);

}

/// Moves the text cursor to the specified row and column.

///

/// If a value is out of bounds, the cursor is not moved in that axis.

pub fn move_to(&self, row: u16, col: u16) {

let info = crate::vga::VIDEO_MODE.get_mode();

let num_rows = info.mode.text_height().unwrap_or(0);

let num_cols = info.mode.text_width().unwrap_or(0);

if row < num_rows {

self.current_row.store(row, Ordering::Relaxed);

}

if col < num_cols {

self.current_col.store(col, Ordering::Relaxed);

}

}

/// Convert a Unicode Scalar Value to a font glyph.

///

/// Zero-width and modifier Unicode Scalar Values (e.g. `U+0301 COMBINING,

/// ACCENT`) are not supported. Normalise your Unicode before calling

/// this function.

fn map_char_to_glyph(input: char) -> Glyph {

// This fixed table only works for the default font. When we support

// changing font, we will need to plug-in a different table for each font.

let index = match input {

'\u{0000}'..='\u{007F}' => input as u8,

'\u{00A0}' => 255, // NBSP

'\u{00A1}' => 173, // ¡

'\u{00A2}' => 189, // ¢

'\u{00A3}' => 156, // £

'\u{00A4}' => 207, // ¤

'\u{00A5}' => 190, // ¥

'\u{00A6}' => 221, // ¦

'\u{00A7}' => 245, // §

'\u{00A8}' => 249, // ¨

'\u{00A9}' => 184, // ©

'\u{00AA}' => 166, // ª

'\u{00AB}' => 174, // «

'\u{00AC}' => 170, // ¬

'\u{00AD}' => 240, // SHY

'\u{00AE}' => 169, // ®

'\u{00AF}' => 238, // ¯

'\u{00B0}' => 248, // °

'\u{00B1}' => 241, // ±

'\u{00B2}' => 253, // ²

'\u{00B3}' => 252, // ³

'\u{00B4}' => 239, // ´

'\u{00B5}' => 230, // µ

'\u{00B6}' => 244, // ¶

'\u{00B7}' => 250, // ·

'\u{00B8}' => 247, // ¸

'\u{00B9}' => 251, // ¹

'\u{00BA}' => 167, // º

'\u{00BB}' => 175, // »

'\u{00BC}' => 172, // ¼

'\u{00BD}' => 171, // ½

'\u{00BE}' => 243, // ¾

'\u{00BF}' => 168, // ¿

'\u{00C0}' => 183, // À

'\u{00C1}' => 181, // Á

'\u{00C2}' => 182, // Â

'\u{00C3}' => 199, // Ã

'\u{00C4}' => 142, // Ä

'\u{00C5}' => 143, // Å

'\u{00C6}' => 146, // Æ

'\u{00C7}' => 128, // Ç

'\u{00C8}' => 212, // È

'\u{00C9}' => 144, // É

'\u{00CA}' => 210, // Ê

'\u{00CB}' => 211, // Ë

'\u{00CC}' => 222, // Ì

'\u{00CD}' => 214, // Í

'\u{00CE}' => 215, // Î

'\u{00CF}' => 216, // Ï

'\u{00D0}' => 209, // Ð

'\u{00D1}' => 165, // Ñ

'\u{00D2}' => 227, // Ò

'\u{00D3}' => 224, // Ó

'\u{00D4}' => 226, // Ô

'\u{00D5}' => 229, // Õ

'\u{00D6}' => 153, // Ö

'\u{00D7}' => 158, // ×

'\u{00D8}' => 157, // Ø

'\u{00D9}' => 235, // Ù

'\u{00DA}' => 233, // Ú

'\u{00DB}' => 234, // Û

'\u{00DC}' => 154, // Ü

'\u{00DD}' => 237, // Ý

'\u{00DE}' => 232, // Þ

'\u{00DF}' => 225, // ß

'\u{00E0}' => 133, // à

'\u{00E1}' => 160, // á

'\u{00E2}' => 131, // â

'\u{00E3}' => 198, // ã

'\u{00E4}' => 132, // ä

'\u{00E5}' => 134, // å

'\u{00E6}' => 145, // æ

'\u{00E7}' => 135, // ç

'\u{00E8}' => 138, // è

'\u{00E9}' => 130, // é

'\u{00EA}' => 136, // ê

'\u{00EB}' => 137, // ë

'\u{00EC}' => 141, // ì

'\u{00ED}' => 161, // í

'\u{00EE}' => 140, // î

'\u{00EF}' => 139, // ï

'\u{00F0}' => 208, // ð

'\u{00F1}' => 164, // ñ

'\u{00F2}' => 149, // ò

'\u{00F3}' => 162, // ó

'\u{00F4}' => 147, // ô

'\u{00F5}' => 228, // õ

'\u{00F6}' => 148, // ö

'\u{00F7}' => 246, // ÷

'\u{00F8}' => 155, // ø

'\u{00F9}' => 151, // ù

'\u{00FA}' => 163, // ú

'\u{00FB}' => 150, // û

'\u{00FC}' => 129, // ü

'\u{00FD}' => 236, // ý

'\u{00FE}' => 231, // þ

'\u{00FF}' => 152, // ÿ

'\u{0131}' => 213, // ı

'\u{0192}' => 159, // ƒ

'\u{2017}' => 242, // ‗

'\u{2500}' => 196, // ─

'\u{2502}' => 179, // │

'\u{250C}' => 218, // ┌

'\u{2510}' => 191, // ┐

'\u{2514}' => 192, // └

'\u{2518}' => 217, // ┘

'\u{251C}' => 195, // ├

'\u{2524}' => 180, // ┤

'\u{252C}' => 194, // ┬

'\u{2534}' => 193, // ┴

'\u{253C}' => 197, // ┼

'\u{2550}' => 205, // ═

'\u{2551}' => 186, // ║

'\u{2554}' => 201, // ╔

'\u{2557}' => 187, // ╗

'\u{255A}' => 200, // ╚

'\u{255D}' => 188, // ╝

'\u{2560}' => 204, // ╠

'\u{2563}' => 185, // ╣

'\u{2566}' => 203, // ╦

'\u{2569}' => 202, // ╩

'\u{256C}' => 206, // ╬

'\u{2580}' => 223, // ▀

'\u{2584}' => 220, // ▄

'\u{2588}' => 219, // █

'\u{2591}' => 176, // ░

'\u{2592}' => 177, // ▒

'\u{2593}' => 178, // ▓

'\u{25A0}' => 254, // ■

_ => b'?',

};

Glyph(index)

}

/// Put a single character at a specified point on screen.

///

/// The character is relative to the current font, but newline and carriage

/// return will be interpreted appropriately. The given `row` and `col` are

/// updated.

fn write_at(&self, glyph: Glyph, row: &mut u16, col: &mut u16) {

let info = crate::vga::VIDEO_MODE.get_mode();

let buffer = info.ptr as *mut GlyphAttr;

let num_rows = info.mode.text_height().unwrap_or(0) as usize;

let num_cols = info.mode.text_width().unwrap_or(0) as usize;

let attr = Attr(self.current_attr.load(Ordering::Relaxed));

if glyph.0 == b'\r' {

*col = 0;

} else if glyph.0 == b'\n' {

*col = 0;

*row += 1;

} else {

let offset = (*col as usize) + (num_cols * (*row as usize));

// Note (safety): This is safe as we bound `col` and `row`

unsafe {

buffer

.add(offset)

.write_volatile(GlyphAttr::new(glyph, attr))

};

*col += 1;

}

if *col == (num_cols as u16) {

*col = 0;

*row += 1;

}

if *row == (num_rows as u16) {

// Stay on last line

*row = (num_rows - 1) as u16;

unsafe { core::ptr::copy(buffer.add(num_cols), buffer, num_cols * (num_rows - 1)) };

for blank_col in 0..num_cols {

let offset = blank_col + (num_cols * (*row as usize));

unsafe {

buffer

.add(offset)

.write_volatile(GlyphAttr::new(Glyph(b' '), attr))

};

}

}

}

/// Store a new attribute to be used for subsequent characters.

pub fn change_attr(&self, attr: Attr) {

let value = attr.0;

self.current_attr.store(value, Ordering::Relaxed);

}

fn default() -> Self {

Self::new()

}

// Load from global state

let mut row = self.current_row.load(Ordering::Relaxed);

let mut col = self.current_col.load(Ordering::Relaxed);

for ch in s.chars() {

let b = TextConsole::map_char_to_glyph(ch);

self.write_at(b, &mut row, &mut col);

}

// Push back to global state

self.current_row.store(row, Ordering::Relaxed);

self.current_col.store(col, Ordering::Relaxed);

Ok(())