Adds a couple of more functions to cortex-M0 atomic operations.

src/freertos_drivers/common/libatomic.c

@@ -55,19 +55,19 @@ uint16_t __atomic_fetch_sub_2(uint16_t *ptr, uint16_t val, int memorder)
     return ret;
 }
 
-uint8_t __atomic_exchange_1(uint8_t *ptr, uint8_t val, int memorder)
+uint8_t __atomic_fetch_or_1(uint8_t *ptr, uint8_t val, int memorder)
 {
     ACQ_LOCK();
     uint8_t ret = *ptr;
-    *ptr = val;
+    *ptr = ret | val;
     REL_LOCK();
     return ret;
 }
 
-uint8_t __atomic_fetch_or_1(uint8_t *ptr, uint8_t val, int memorder)
+uint32_t __atomic_fetch_or_4(uint32_t *ptr, uint32_t val, int memorder)
 {
     ACQ_LOCK();
-    uint8_t ret = *ptr;
+    uint32_t ret = *ptr;
     *ptr = ret | val;
     REL_LOCK();
     return ret;
@@ -82,4 +82,61 @@ uint8_t __atomic_fetch_and_1(uint8_t *ptr, uint8_t val, int memorder)
     return ret;
 }
 
+uint32_t __atomic_fetch_and_4(uint32_t *ptr, uint32_t val, int memorder)
+{
+    ACQ_LOCK();
+    uint32_t ret = *ptr;
+    *ptr = ret & val;
+    REL_LOCK();
+    return ret;
+}
+
+uint8_t __atomic_exchange_1(uint8_t *ptr, uint8_t val, int memorder)
+{
+    ACQ_LOCK();
+    uint8_t ret = *ptr;
+    *ptr = val;
+    REL_LOCK();
+    return ret;
+}
+
+/// This built-in function implements an atomic compare and exchange
+/// operation. This compares the contents of *ptr with the contents of
+/// *exp. If equal, the operation is a read-modify-write operation that
+/// writes desired into *ptr. If they are not equal, the operation is a read
+/// and the current contents of *ptr are written into *expected.
+///
+/// If desired is written into *ptr then true is returned.
+_Bool __atomic_compare_exchange_1(uint8_t *ptr, uint8_t *exp, uint8_t desired,
+    _Bool weak, int success_memorder, int failure_memorder)
+{
+    ACQ_LOCK();
+    uint8_t curr = *ptr;
+    if (curr == *exp)
+    {
+        *ptr = desired;
+        REL_LOCK();
+        return 1;
+    }
+    *exp = curr;
+    REL_LOCK();
+    return 0;
+}
+
+_Bool __atomic_compare_exchange_4(uint32_t *ptr, uint32_t *exp,
+    uint32_t desired, _Bool weak, int success_memorder, int failure_memorder)
+{
+    ACQ_LOCK();
+    uint32_t curr = *ptr;
+    if (curr == *exp)
+    {
+        *ptr = desired;
+        REL_LOCK();
+        return 1;
+    }
+    *exp = curr;
+    REL_LOCK();
+    return 0;
+}
+
 #endif // guard for arduino compilation