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#![no_std]
/// Raw file descriptor.
///
/// Instances of `Fd` can be constructed with [`stdout()`] and [`stderr()`].
pub struct Fd(i32);
impl core::fmt::Write for Fd {
fn write_str(&mut self, s: &str) -> Result<(), core::fmt::Error> {
if sys::write(self.0, s.as_bytes()) != -1 {
Ok(())
} else {
Err(core::fmt::Error)
}
}
}
/// Construct raw file descriptor for `stdout`.
pub fn stdout() -> Fd {
Fd(1)
}
/// Construct raw file descriptor for `stderr`.
pub fn stderr() -> Fd {
Fd(2)
}
/// Write format string to `stdout`, swallowing any errors.
#[macro_export]
macro_rules! println {
() => ({
$crate::println!("")
});
($($arg:tt)*) => ({
use core::fmt::Write;
let _ = writeln!(&mut $crate::stdout(), $($arg)*);
});
}
/// Write format string to `stderr`, swallowing any errors.
#[macro_export]
macro_rules! eprintln {
() => ({
$crate::eprintln!("")
});
($($arg:tt)*) => ({
use core::fmt::Write;
let _ = writeln!(&mut $crate::stderr(), $($arg)*);
});
}
/// Wrapper to invoke `riscv` linux syscalls.
///
/// Syscalls are generated according to the linux [syscall(2)][man-syscall] abi.
///
/// # Invocation
/// ```
/// Arch/ABI Instruction System Ret Ret
/// call # val val2
/// ----------------------------------------
/// riscv ecall a7 a0 a1
/// ```
///
/// # Arguments
/// ```
/// Arch/ABI arg1 arg2 arg3 arg4 arg5 arg6
/// --------------------------------------------
/// riscv a0 a1 a2 a3 a4 a5
/// ```
///
/// [man-syscall]: https://man7.org/linux/man-pages/man2/syscall.2.html
#[cfg(target_arch = "riscv64")]
pub mod sys {
use core::arch::asm;
// Include generated syscall numbers (build.rs).
include!(concat!(env!("OUT_DIR"), "/syscalls.rs"));
#[inline]
pub fn write(fd: i32, buf: &[u8]) -> i32 {
let mut ret;
unsafe {
asm!(
"ecall",
in("a7") SYS_WRITE,
inlateout("a0") fd => ret,
in("a1") buf.as_ptr(),
in("a2") buf.len(),
);
}
ret
}
#[inline]
pub fn exit(status: i32) -> ! {
unsafe {
asm!(
"ecall",
in("a7") SYS_EXIT,
in("a0") status,
options(noreturn),
);
}
}
}
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