enable stdio and fix stdout flushing

Author: max-niederman

library/std/src/sys/pal/vexos/mod.rs

@@ -15,7 +15,6 @@ pub mod os;
 pub mod pipe;
 #[path = "../unsupported/process.rs"]
 pub mod process;
-#[path = "../unsupported/stdio.rs"]
 pub mod stdio;
 #[path = "../unsupported/thread.rs"]
 pub mod thread;
@@ -63,7 +62,9 @@ pub extern "C" fn __rust_abort() -> ! {
 
 pub unsafe fn init(_argc: isize, _argv: *const *const u8, _sigpipe: u8) {}
 
-pub unsafe fn cleanup() {}
+pub unsafe fn cleanup() {
+    stdio::
+}
 
 pub fn unsupported<T>() -> crate::io::Result<T> {
     Err(unsupported_err())

library/std/src/sys/pal/vexos/stdio.rs

@@ -52,7 +52,9 @@ impl io::Write for Stdout {
 
     fn flush(&mut self) -> io::Result<()> {
         unsafe {
-            vex_sdk::vexTasksRun();
+            while (vex_sdk::vexSerialWriteFree(STDIO_CHANNEL) as usize) != STDOUT_BUF_SIZE {
+                vex_sdk::vexTasksRun();
+            }
         }
 
         Ok(())
@@ -75,7 +77,8 @@ impl io::Write for Stderr {
     }
 }
 
-pub const STDIN_BUF_SIZE: usize = 0;
+pub const STDIN_BUF_SIZE: usize = 4096;
+const STDOUT_BUF_SIZE: usize = 2048;
 
 pub fn is_ebadf(_err: &io::Error) -> bool {
     true