From f03fa6fa77a68bff80b65ee69765042076a306c2 Mon Sep 17 00:00:00 2001
From: Samuel Perrouault <samuel.perrouault@gmail.com>
Date: Wed, 23 Jul 2025 00:05:12 +0200
Subject: exploring a fully static path

---
 src/main.rs | 130 +++++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 103 insertions(+), 27 deletions(-)

(limited to 'src/main.rs')

diff --git a/src/main.rs b/src/main.rs
index bb0ae71..5f977ba 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,31 +1,107 @@
-use std::{
-    fs::File,
-    io::BufReader,
-    time::{Duration, Instant},
-};
-
-const SECOND: u64 = 1_000_000_000;
-const REFRESH_RATE: u64 = 60;
-const FRAME_DURATION: Duration = Duration::from_nanos(SECOND / REFRESH_RATE);
-
-fn main() -> std::io::Result<()> {
-    if let Some(arg) = std::env::args().nth(1) {
-        let mut chip8 = chip8::Chip8::new();
-        {
-            let file = File::open(arg)?;
-            let buf_reader = BufReader::new(file);
-            chip8.load_rom(buf_reader)?;
+#![no_std]
+#![no_main]
+
+use core::fmt::Write;
+
+#[cfg(target_arch = "x86_64")]
+core::arch::global_asm!(
+    ".text",
+    ".global _start",
+    ".type _start,@function",
+    "_start:",
+    "xor rbp,rbp",
+    "mov rdi, rsp",
+    ".weak _DYNAMIC",
+    ".hidden _DYNAMIC",
+    "lea rsi, [rip + _DYNAMIC]",
+    "and rsp,-16",
+    "call __proxy_main"
+);
+
+struct Printer {
+    buf: [u8; 512],
+    pos: usize,
+}
+
+impl Printer {
+    fn new() -> Self {
+        Self {
+            buf: [0; 512],
+            pos: 0,
         }
-        loop {
-            let start = Instant::now();
-            for _ in 0..8 {
-                chip8.cycle();
-            }
-            chip8.display()?;
-            std::thread::sleep(FRAME_DURATION - start.elapsed());
+    }
+
+    fn bytes(&self) -> &[u8] {
+        &self.buf[..self.pos]
+    }
+}
+
+impl core::fmt::Write for Printer {
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
+        let remaining_buf = &mut self.buf[self.pos..];
+        let raw_s = s.as_bytes();
+        let write_num = raw_s.len().min(remaining_buf.len());
+        remaining_buf[..write_num].copy_from_slice(&raw_s[..write_num]);
+        self.pos += raw_s.len();
+        if write_num < raw_s.len() {
+            Err(core::fmt::Error)
+        } else {
+            Ok(())
         }
-    } else {
-        println!("usage: chip8 rompath")
     }
-    Ok(())
 }
+
+#[panic_handler]
+fn panic(info: &core::panic::PanicInfo) -> ! {
+    let mut p = Printer::new();
+    let _ = write!(&mut p, "Fatal error: {}\n", info);
+    let stderr = unsafe { rustix::stdio::stderr() };
+    let _ = rustix::io::write(stderr, p.bytes());
+    rustix::runtime::exit_group(1)
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn __proxy_main(_stack_ptr: *const u8, _dynv: *const usize) {
+    let code = main();
+    rustix::runtime::exit_group(code);    
+}
+
+fn main() -> i32 {
+    let mut p = Printer::new();
+    write!(&mut p, "Hello {}, you are worth {} tons of gold\n", "Jacques", 10_000).expect("Could not format this");
+    let stdout = unsafe { rustix::stdio::stdout() };
+    let _ = rustix::io::write(stdout, p.bytes());
+    0
+}
+
+// use std::{
+//     fs::File,
+//     io::BufReader,
+//     time::{Duration, Instant},
+// };
+
+// const SECOND: u64 = 1_000_000_000;
+// const REFRESH_RATE: u64 = 60;
+// const FRAME_DURATION: Duration = Duration::from_nanos(SECOND / REFRESH_RATE);
+
+// fn main() -> std::io::Result<()> {
+//     if let Some(arg) = std::env::args().nth(1) {
+//         let mut chip8 = chip8::Chip8::new();
+//         {
+//             let file = File::open(arg)?;
+//             let buf_reader = BufReader::new(file);
+//             chip8.load_rom(buf_reader)?;
+//         }
+//         loop {
+//             let start = Instant::now();
+//             for _ in 0..8 {
+//                 chip8.cycle();
+//             }
+//             chip8.display()?;
+//             std::thread::sleep(FRAME_DURATION - start.elapsed());
+//         }
+//     } else {
+//         println!("usage: chip8 rompath")
+//     }
+//     Ok(())
+// }
-- 
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