From 1c0bbf44044a9a9c3e7a9daa644d02fc8077ba86 Mon Sep 17 00:00:00 2001
From: Yu Chen <yuchen@mail.tsinghua.edu.cn>
Date: Sat, 11 Dec 2021 21:40:04 +0800
Subject: [PATCH] add user app: sync_sem.rs

---
 user/src/bin/sync_sem.rs | 45 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 user/src/bin/sync_sem.rs

diff --git a/user/src/bin/sync_sem.rs b/user/src/bin/sync_sem.rs
new file mode 100644
index 00000000..d72d520d
--- /dev/null
+++ b/user/src/bin/sync_sem.rs
@@ -0,0 +1,45 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+extern crate alloc;
+
+use user_lib::{semaphore_create, semaphore_up, semaphore_down};
+use user_lib::{thread_create, waittid, sleep};
+use user_lib::exit;
+use alloc::vec::Vec;
+
+const SEM_SYNC: usize = 0;
+
+
+unsafe fn first() -> ! {
+    sleep(10);
+    println!("First work and wakeup Second");
+    semaphore_up(SEM_SYNC);
+    exit(0)
+}
+
+unsafe fn second() -> ! {
+    println!("Second want to continue,but need to wait first");
+    semaphore_down(SEM_SYNC);
+    println!("Second can work now");
+    exit(0)
+}
+
+#[no_mangle]
+pub fn main() -> i32 {
+    // create semaphores
+    assert_eq!(semaphore_create(0) as usize, SEM_SYNC);
+    // create threads
+    let mut threads = Vec::new();
+    threads.push(thread_create(first as usize, 0));
+    threads.push(thread_create(second as usize, 0));
+    // wait for all threads to complete
+    for thread in threads.iter() {
+        waittid(*thread as usize);
+    }
+    println!("sync_sem passed!");
+    0
+}