path: root/rsnix/src/gop.rs

/// GOP framebuffer driver — renders text via a bitmap font.
///
/// Text surface (cursor, scrolling, colours) lives in `crate::vt`; this
/// module is the low-level rasteriser: glyph blits and pixel shifts on the
/// linear framebuffer.
use crate::font;
use crate::uefi::{GraphicsOutputProtocol, PIXEL_BGR, PIXEL_RGB};
use core::fmt;
use core::ptr;

/// Framebuffer state captured before ExitBootServices.
pub struct Framebuffer {
    base: *mut u8,
    #[allow(dead_code)]
    width: usize,
    height: usize,
    pitch: usize, // bytes per scan line
    bytes_per_pixel: usize,
    bg: u32, // packed BGRA or RGBA background colour
    bgr: bool,
}

static mut FB: Option<Framebuffer> = None;

/// Initialise the framebuffer from GOP. Call *before* ExitBootServices.
pub fn init(gop: &mut GraphicsOutputProtocol) {
    let mode = unsafe { &*gop.mode };
    let info = unsafe { &*mode.info };
    let base = mode.framebuffer_base as *mut u8;
    let width = info.horizontal_resolution as usize;
    let height = info.vertical_resolution as usize;
    let pitch = info.pixels_per_scan_line as usize * 4; // 32-bit pixel
    let bpp = 4;

    // Pick colours based on pixel format
    let (fg, bg) = match info.pixel_format {
        PIXEL_BGR => (0x00_FF_FF_FFu32, 0x00_00_00_00u32), // white fg, black bg
        PIXEL_RGB => (0x00_FF_FF_FFu32, 0x00_00_00_00u32),
        _ => (0x00_FF_FF_FFu32, 0x00_00_00_00u32),
    };
    let bgr = info.pixel_format == PIXEL_BGR;
    let _ = fg;

    let fb = Framebuffer {
        base,
        width,
        height,
        pitch,
        bytes_per_pixel: bpp,
        bg,
        bgr,
    };

    fb.clear();

    unsafe {
        FB = Some(fb);
    }
}

// ---------------------------------------------------------------------------
// Public text API — the text surface now lives in `crate::vt`; these wrappers
// keep callers (shell, macros) unchanged.
// ---------------------------------------------------------------------------

/// Draw a character at the current terminal cursor position and advance.
pub fn put_char(c: char) {
    let b = if (c as u32) < 0x100 { c as u8 } else { b'?' };
    crate::vt::put_char(b);
}

/// Write a string to the terminal.
pub fn write_str(s: &str) {
    crate::vt::write_str(s);
}

/// Clear the terminal and home the cursor.
pub fn clear_screen() {
    crate::vt::clear_all();
}

/// (cols, rows) of the text surface, from the current framebuffer mode.
pub fn dims() -> (usize, usize) {
    unsafe {
        match FB.as_ref() {
            Some(f) => (f.width / 8, f.height / 16),
            None => (0, 0),
        }
    }
}

/// Pack an (r, g, b) colour for the framebuffer's pixel format.
pub fn rgb(r: u8, g: u8, b: u8) -> u32 {
    unsafe {
        match FB.as_ref() {
            Some(f) if f.bgr => ((r as u32) << 16) | ((g as u32) << 8) | b as u32,
            _ => ((b as u32) << 16) | ((g as u32) << 8) | r as u32,
        }
    }
}

// ---------------------------------------------------------------------------
// Framebuffer implementation
// ---------------------------------------------------------------------------
impl Framebuffer {
    fn clear(&self) {
        let size = self.pitch * self.height;
        // Fill with background colour (32-bit writes)
        let mut p = self.base;
        let end = unsafe { p.add(size) };
        unsafe {
            while p < end {
                ptr::write_volatile(p as *mut u32, self.bg);
                p = p.add(4);
            }
        }
    }

    /// Shift the whole framebuffer up one row (16 pixels) and clear the
    /// exposed bottom row.  Called by `vt::scroll_up`; the vt then re-blits
    /// only the new bottom row.
    pub(crate) fn shift_up(&self) {
        // Move everything up one row (16 pixels)
        let row_bytes = self.pitch * 16;
        let total = self.pitch * self.height;
        unsafe {
            ptr::copy(self.base.add(row_bytes), self.base, total - row_bytes);
            // Clear last row
            let last_row = self.base.add(total - row_bytes);
            for i in 0..(self.pitch * 16 / 4) {
                ptr::write_volatile(last_row.add(i * 4) as *mut u32, self.bg);
            }
        }
    }
}

/// Blit one glyph cell at (col, row) with explicit fg/bg colours.
/// Procedurally-rendered bitmaps for Unicode glyphs missing from the
/// 256-glyph Latin-1 font: box-drawing (U+2500–U+257F), arrows
/// (U+2190–U+2193) and the em dash (U+2014).  Box drawing is pure
/// geometry, so these are computed, not stored.  Same format as the font:
/// one byte per row, bit 7 = leftmost column.
fn unicode_glyph_bits(ch: u16) -> Option<[u8; 16]> {
    let mut g = [0u8; 16];
    match ch {
        // ─ light horizontal, ━ heavy horizontal
        0x2500 => {
            g[7] = 0xFF;
            g[8] = 0xFF;
        }
        0x2501 => {
            g[7] = 0xFF;
            g[8] = 0xFF;
            g[9] = 0xFF;
        }
        // │ light vertical, ┃ heavy vertical
        0x2502 => {
            for y in 0..16 {
                g[y] = 0x18;
            }
        }
        0x2503 => {
            for y in 0..16 {
                g[y] = 0x3C;
            }
        }
        // corners ┌ ┐ └ ┘
        0x250C => {
            g[7] = 0xF0;
            g[8] = 0xF8;
            for y in 9..16 {
                g[y] = 0x18;
            }
        }
        0x2510 => {
            g[7] = 0x0F;
            g[8] = 0x1F;
            for y in 9..16 {
                g[y] = 0x18;
            }
        }
        0x2514 => {
            for y in 0..7 {
                g[y] = 0x18;
            }
            g[7] = 0xF8;
            g[8] = 0xF0;
        }
        0x2518 => {
            for y in 0..7 {
                g[y] = 0x18;
            }
            g[7] = 0x1F;
            g[8] = 0x0F;
        }
        // T junctions ├ ┤ ┬ ┴ and cross ┼
        0x251C => {
            for y in 0..16 {
                g[y] = 0x18;
            }
            g[7] = 0xF8;
            g[8] = 0xF8;
        }
        0x2524 => {
            for y in 0..16 {
                g[y] = 0x18;
            }
            g[7] = 0x1F;
            g[8] = 0x1F;
        }
        0x252C => {
            g[7] = 0xFF;
            g[8] = 0xFF;
            for y in 9..16 {
                g[y] = 0x18;
            }
        }
        0x2534 => {
            for y in 0..7 {
                g[y] = 0x18;
            }
            g[7] = 0xFF;
            g[8] = 0xFF;
        }
        0x253C => {
            for y in 0..16 {
                g[y] = 0x18;
            }
            g[7] = 0xFF;
            g[8] = 0xFF;
        }
        // ═ double horizontal, ║ double vertical
        0x2550 => {
            g[6] = 0xFF;
            g[9] = 0xFF;
        }
        0x2551 => {
            for y in 0..16 {
                g[y] = 0x24;
            }
        }
        // — em dash
        0x2014 => {
            g[7] = 0xFF;
            g[8] = 0xFF;
        }
        // ← → ↑ ↓
        0x2190 => {
            g[8] = 0xFF;
            g[6] = 0xC0;
            g[7] = 0xC0;
            g[9] = 0xC0;
            g[10] = 0xC0;
        }
        0x2192 => {
            g[8] = 0xFF;
            g[6] = 0x03;
            g[7] = 0x03;
            g[9] = 0x03;
            g[10] = 0x03;
        }
        0x2191 => {
            g[0] = 0x18;
            g[1] = 0x3C;
            g[2] = 0x7E;
            for y in 3..16 {
                g[y] = 0x18;
            }
        }
        0x2193 => {
            for y in 0..13 {
                g[y] = 0x18;
            }
            g[13] = 0x7E;
            g[14] = 0x3C;
            g[15] = 0x18;
        }
        _ => return None,
    }
    Some(g)
}

pub(crate) fn blit_glyph(col: usize, row: usize, ch: u16, fg: (u8, u8, u8), bg: (u8, u8, u8)) {
    if let Some(fb) = unsafe { FB.as_ref() } {
        let glyph = font::GLYPH_8X16;
        let data = if ch < 256 {
            match glyph.get(ch as usize) {
                Some(d) => *d,
                None => return,
            }
        } else if let Some(bits) = unicode_glyph_bits(ch) {
            bits
        } else {
            match glyph.get(32) {
                Some(d) => *d,
                None => return,
            }
        };

        let fg = rgb(fg.0, fg.1, fg.2);
        let bg = rgb(bg.0, bg.1, bg.2);
        let x = col * 8;
        let y = row * 16;

        for cy in 0..16 {
            let row_bits = data[cy];
            for cx in 0..8 {
                let offset = (y + cy) * fb.pitch + (x + cx) * fb.bytes_per_pixel;
                unsafe {
                    let px = if row_bits & (0x80 >> cx) != 0 { fg } else { bg };
                    ptr::write_volatile(fb.base.add(offset) as *mut u32, px);
                }
            }
        }
    }
}

/// Shift the framebuffer up one row and clear the bottom row.
pub(crate) fn shift_up() {
    if let Some(fb) = unsafe { FB.as_ref() } {
        fb.shift_up();
    }
}

// ---------------------------------------------------------------------------
// fmt::Write wrapper
// ---------------------------------------------------------------------------
pub struct GopWriter;

impl fmt::Write for GopWriter {
    fn write_str(&mut self, s: &str) -> fmt::Result {
        write_str(s);
        Ok(())
    }
}

/// Write a formatted string to the framebuffer.
#[macro_export]
macro_rules! gop_print {
    ($($arg:tt)*) => {{
        use core::fmt::Write;
        let _ = write!(&mut $crate::gop::GopWriter, $($arg)*);
    }};
}

#[macro_export]
macro_rules! gop_println {
    () => { $crate::gop::write_str("\n"); };
    ($($arg:tt)*) => {{
        $crate::gop_print!($($arg)*);
        $crate::gop::write_str("\n");
    }};
}