Added macros print! and println! (#430)

Author: JonahPlusPlus

uefi-services/src/lib.rs

@@ -26,6 +26,7 @@ extern crate log;
 extern crate uefi;
 
 use core::ffi::c_void;
+use core::fmt::Write;
 use core::ptr::NonNull;
 
 use cfg_if::cfg_if;
@@ -93,6 +94,53 @@ pub fn init(st: &mut SystemTable<Boot>) -> Result {
     }
 }
 
+// Internal function for print macros.
+#[doc(hidden)]
+pub fn _print(args: core::fmt::Arguments) {
+    unsafe {
+        let st = SYSTEM_TABLE
+            .as_mut()
+            .expect("The system table handle is not available");
+
+        st.stdout()
+            .write_fmt(args)
+            .expect("Failed to write to stdout");
+    }
+}
+
+/// Prints to the standard output.
+///
+/// # Panics
+/// Will panic if `SYSTEM_TABLE` is `None` (Before [init()] and after [uefi::prelude::SystemTable::exit_boot_services()]).
+///
+/// # Examples
+/// ```
+/// print!("");
+/// print!("Hello World\n");
+/// print!("Hello {}", "World");
+/// ```
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => ($crate::_print(core::format_args!($($arg)*)));
+}
+
+/// Prints to the standard output, with a newline.
+///
+/// # Panics
+/// Will panic if `SYSTEM_TABLE` is `None` (Before [init()] and after [uefi::prelude::SystemTable::exit_boot_services()]).
+///
+/// # Examples
+/// ```
+/// println!();
+/// println!("Hello World");
+/// println!("Hello {}", "World");
+/// ```
+#[macro_export]
+macro_rules! println {
+    () => ($crate::print!("\n"));
+    ($($arg:tt)*) => ($crate::_print(core::format_args!("{}{}", core::format_args!($($arg)*), "\n")));
+}
+
 /// Set up logging
 ///
 /// This is unsafe because you must arrange for the logger to be reset with

uefi-test-runner/src/main.rs

@@ -11,6 +11,7 @@ use alloc::string::String;
 use uefi::prelude::*;
 use uefi::proto::console::serial::Serial;
 use uefi::table::boot::{OpenProtocolAttributes, OpenProtocolParams};
+use uefi_services::{print, println};
 
 mod boot;
 mod proto;
@@ -28,6 +29,14 @@ fn efi_main(image: Handle, mut st: SystemTable<Boot>) -> Status {
     st.firmware_vendor().as_str_in_buf(&mut buf).unwrap();
     info!("Firmware Vendor: {}", buf.as_str());
 
+    // Test print! and println! macros.
+    let (print, println) = ("print!", "println!"); // necessary for clippy to ignore
+    print!("Testing {} macro with formatting: {:#010b} ", print, 155u8);
+    println!(
+        "Testing {} macro with formatting: {:#010b} ",
+        println, 155u8
+    );
+
     // Reset the console before running all the other tests.
     st.stdout().reset(false).expect("Failed to reset stdout");