From 2e1f88062c7ec6cd12688ce7522e802bbf09bba1 Mon Sep 17 00:00:00 2001
From: Paul Selkirk <paul@psgd.org>
Date: Wed, 24 May 2017 18:03:19 -0400
Subject: Add task_yield_maybe

---
 task.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

(limited to 'task.c')

diff --git a/task.c b/task.c
index e156940..d8af217 100644
--- a/task.c
+++ b/task.c
@@ -83,12 +83,16 @@ static tcb_t *cur_task = NULL;
 
 #ifdef TASK_METRICS
 static uint32_t tick_start = 0;
-static uint32_t tick_prev  = 0;
 static uint32_t tick_idle  = 0;
 static uint32_t tick_max   = 0;
 static uint32_t nyield     = 0;
 #endif
 
+static uint32_t tick_prev  = 0;
+#ifndef TASK_YIELD_THRESHOLD
+#define TASK_YIELD_THRESHOLD 100
+#endif
+
 /* Add a task.
  */
 tcb_t *task_add(char *name, funcp_t func, void *cookie, void *stack, size_t stack_len)
@@ -221,6 +225,8 @@ void task_yield(void)
     }
     tick_prev = tick;
     ++nyield;
+#else
+    tick_prev = HAL_GetTick();
 #endif
 
     /* If there are no other runnable tasks (and cur_task is runnable),
@@ -256,6 +262,14 @@ void task_yield(void)
     }
 }
 
+/* Yield if it's been "too long" since the last yield.
+ */
+void task_yield_maybe(void)
+{
+    if (HAL_GetTick() - tick_prev >= TASK_YIELD_THRESHOLD)
+        task_yield();
+}
+
 /* Put the current task to sleep (make it non-runnable).
  */
 void task_sleep(void)
-- 
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