Fix of sync lock emulation for cortex-m0

diff --git a/include/core/lpc_core_cm0.h b/include/core/lpc_core_cm0.h
index 0b4ea41..623f333 100644 (file)
--- a/include/core/lpc_core_cm0.h
+++ b/include/core/lpc_core_cm0.h
@@ -341,17 +341,19 @@ static inline void NVIC_SystemReset(void)
 /*******************************************************************************/
 /*            Sync lock                                                        */
 /*******************************************************************************/
-/* There is no syncro instructions on Cortex-M0 */
+/* There is no syncro instructions on Cortex-M0
+ * Returns the old value if the new value has been set (lock acquired)
+ */
 static inline uint32_t sync_lock_test_and_set(volatile uint32_t *addr, uint32_t value)
 {
+       uint32_t oldval;
        lpc_disable_irq();
     dsb();
-       if (*addr == value)
-               return 0;
+       oldval = *addr;
        *addr = value;
     dsb();
        lpc_enable_irq();
-       return value;
+       return oldval;
 }
 /* Remove the lock */
 static inline void sync_lock_release(volatile uint32_t *addr)