From 3958953ceb56aa81e33fb4f3d19ab7ee4c06d1ba Mon Sep 17 00:00:00 2001
From: pca006132 <john.lck40@gmail.com>
Date: Wed, 5 Aug 2020 15:29:28 +0800
Subject: [PATCH] libcortex_a9/sync_channel: added drop_elements function.

---
 experiments/src/main.rs          |  3 +++
 libcortex_a9/src/sync_channel.rs | 11 +++++++++++
 2 files changed, 14 insertions(+)

diff --git a/experiments/src/main.rs b/experiments/src/main.rs
index d9e13f3..6f5d132 100644
--- a/experiments/src/main.rs
+++ b/experiments/src/main.rs
@@ -200,6 +200,9 @@ pub fn main_core0() {
             println!("{} -> {}", i, j);
         }
     });
+    unsafe {
+        core1_req.drop_elements();
+    }
 
     let eth = zynq::eth::Eth::default(HWADDR.clone());
     println!("Eth on");
diff --git a/libcortex_a9/src/sync_channel.rs b/libcortex_a9/src/sync_channel.rs
index d8ef51f..139c8fb 100644
--- a/libcortex_a9/src/sync_channel.rs
+++ b/libcortex_a9/src/sync_channel.rs
@@ -86,6 +86,17 @@ impl<'a, T> Sender<'a, T> where T: Clone {
         }.await
     }
 
+    /// free all items in the queue. It is the user's responsibility to
+    /// ensure no reader is trying to copy the data.
+    pub unsafe fn drop_elements(&mut self) {
+        for v in self.list.iter() {
+            let original = v.swap(core::ptr::null_mut(), Ordering::Relaxed);
+            if !original.is_null() {
+                drop_in_place(original);
+            }
+        }
+    }
+
     /// Reset the `sync_channel`, *forget* all items in the queue. Affects both the sender and
     /// receiver.
     pub unsafe fn reset(&mut self) {