From 76103215711d268b4b02f62e900f2be3032cf295 Mon Sep 17 00:00:00 2001
From: salmonik <salmonik@tuta.io>
Date: Fri, 31 Jul 2026 02:18:30 +0200
Subject: Initial commit: raisernics toy kernel

- Bare-metal x86_64 UEFI kernel (PE32+, no libc)
- GOP framebuffer + 8x16 bitmap font
- PS/2 keyboard (polling, scancode set 1)
- UART 16550 serial driver (COM1, 115200 8N1)
- Bump allocator as #[global_allocator] (alloc::String, Vec, format!)
- UEFI memory map capture (static buffer, ADR 0001)
- Shell with 7 commands (help, echo, clear, hello, info, mem, halt)
- Dual output: GOP framebuffer + serial console
- Makefile: run, run-gui, debug, release, image targets
- tools/: qemu.sh, boot-image.sh, debug-kernel.py
---
 build.rs | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 build.rs

(limited to 'build.rs')

diff --git a/build.rs b/build.rs
new file mode 100644
index 0000000..44e6344
--- /dev/null
+++ b/build.rs
@@ -0,0 +1,70 @@
+/// Build script — extracts glyph data from a PSF2 font file.
+/// Uses zcat (system gzip) to decompress — zero dependencies.
+use std::env;
+use std::fs;
+use std::path::Path;
+use std::process::{Command, Output};
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let font_path = "/usr/share/kbd/consolefonts/lat1-16.psfu.gz";
+    println!("cargo::rerun-if-changed={}", font_path);
+
+    // Decompress via zcat (available on any Linux system)
+    let Output { stdout, status, .. } = Command::new("zcat").arg(font_path).output()?;
+    if !status.success() {
+        return Err(format!("zcat exited with {status:?}").into());
+    }
+    let raw = stdout;
+
+    if raw.len() < 32 {
+        return Err("PSF font too small".into());
+    }
+
+    // PSF2 magic: 0x864ab572 (little-endian)
+    let magic = u32::from_le_bytes(raw[..4].try_into()?);
+    if magic != 0x864ab572 {
+        return Err("not a PSF2 font".into());
+    }
+
+    let hdr_size =     u32::from_le_bytes(raw[8..12].try_into()?) as usize;
+    let num_glyphs =   u32::from_le_bytes(raw[16..20].try_into()?) as usize;
+    let bytes_per_glyph = u32::from_le_bytes(raw[20..24].try_into()?) as usize;
+
+    if num_glyphs != 256 {
+        return Err(format!("expected 256 glyphs, got {num_glyphs}").into());
+    }
+    if bytes_per_glyph != 16 {
+        return Err(format!("expected 16 bytes/glyph, got {bytes_per_glyph}").into());
+    }
+
+    let glyph_data = &raw[hdr_size..hdr_size + num_glyphs * bytes_per_glyph];
+
+    // Write generated Rust source into OUT_DIR
+    let out_dir = env::var("OUT_DIR")?;
+    let dest = Path::new(&out_dir).join("font_data.rs");
+
+    let mut code = String::from(
+        "/// 8×16 bitmap font glyph data (256 glyphs, 16 bytes each).
+#[rustfmt::skip]
+#[allow(clippy::unreadable_literal)]
+pub const GLYPH_8X16: [[u8; 16]; 256] = [",
+    );
+
+    for g in 0..256 {
+        let offset = g * 16;
+        code.push_str("\n    [");
+        for row in 0..16 {
+            if row % 4 == 0 {
+                code.push('\n');
+            }
+            let byte = glyph_data[offset + row];
+            code.push_str(&format!(" 0x{byte:02X},"));
+        }
+        code.push_str("\n    ],");
+    }
+
+    code.push_str("\n];\n");
+
+    fs::write(&dest, code)?;
+    Ok(())
+}
-- 
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