Add 64-bit atomics

Author: kjbracey

UNITTESTS/stubs/mbed_critical_stub.c

@@ -103,6 +103,31 @@ uint32_t core_util_atomic_decr_u32(volatile uint32_t *valuePtr, uint32_t delta)
 }
 
 
+uint64_t core_util_atomic_load_u64(const volatile uint64_t *valuePtr)
+{
+    return 0;
+}
+
+void core_util_atomic_store_u64(volatile uint64_t *valuePtr, uint64_t desiredValue)
+{
+}
+
+bool core_util_atomic_cas_u64(volatile uint64_t *ptr, uint64_t *expectedCurrentValue, uint64_t desiredValue)
+{
+    return false;
+}
+
+uint64_t core_util_atomic_incr_u64(volatile uint64_t *valuePtr, uint64_t delta)
+{
+    return 0;
+}
+
+uint64_t core_util_atomic_decr_u64(volatile uint64_t *valuePtr, uint64_t delta)
+{
+    return 0;
+}
+
+
 bool core_util_atomic_cas_ptr(void *volatile *ptr, void **expectedCurrentValue, void *desiredValue)
 {
     return false;

platform/mbed_critical.c

@@ -358,6 +358,58 @@ uint32_t core_util_atomic_decr_u32(volatile uint32_t *valuePtr, uint32_t delta)
 
 #endif
 
+/* No architecture we support has LDREXD/STREXD, so must always disable IRQs for 64-bit operations */
+uint64_t core_util_atomic_load_u64(const volatile uint64_t *valuePtr)
+{
+    core_util_critical_section_enter();
+    uint64_t currentValue = *valuePtr;
+    core_util_critical_section_exit();
+    return currentValue;
+}
+
+void core_util_atomic_store_u64(volatile uint64_t *valuePtr, uint64_t desiredValue)
+{
+    core_util_critical_section_enter();
+    *valuePtr = desiredValue;
+    core_util_critical_section_exit();
+}
+
+bool core_util_atomic_cas_u64(volatile uint64_t *ptr, uint64_t *expectedCurrentValue, uint64_t desiredValue)
+{
+    bool success;
+    uint64_t currentValue;
+    core_util_critical_section_enter();
+    currentValue = *ptr;
+    if (currentValue == *expectedCurrentValue) {
+        *ptr = desiredValue;
+        success = true;
+    } else {
+        *expectedCurrentValue = currentValue;
+        success = false;
+    }
+    core_util_critical_section_exit();
+    return success;
+}
+
+uint64_t core_util_atomic_incr_u64(volatile uint64_t *valuePtr, uint64_t delta)
+{
+    uint64_t newValue;
+    core_util_critical_section_enter();
+    newValue = *valuePtr + delta;
+    *valuePtr = newValue;
+    core_util_critical_section_exit();
+    return newValue;
+}
+
+uint64_t core_util_atomic_decr_u64(volatile uint64_t *valuePtr, uint64_t delta)
+{
+    uint64_t newValue;
+    core_util_critical_section_enter();
+    newValue = *valuePtr - delta;
+    *valuePtr = newValue;
+    core_util_critical_section_exit();
+    return newValue;
+}
 
 bool core_util_atomic_cas_ptr(void *volatile *ptr, void **expectedCurrentValue, void *desiredValue)
 {

platform/mbed_critical.h

@@ -202,175 +202,16 @@ MBED_FORCEINLINE void core_util_atomic_flag_clear(volatile core_util_atomic_flag
  */
 bool core_util_atomic_cas_u8(volatile uint8_t *ptr, uint8_t *expectedCurrentValue, uint8_t desiredValue);
 
-/**
- * Atomic compare and set. It compares the contents of a memory location to a
- * given value and, only if they are the same, modifies the contents of that
- * memory location to a given new value. This is done as a single atomic
- * operation. The atomicity guarantees that the new value is calculated based on
- * up-to-date information; if the value had been updated by another thread in
- * the meantime, the write would fail due to a mismatched expectedCurrentValue.
- *
- * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
- * you to the article on compare-and swap].
- *
- * @param  ptr                  The target memory location.
- * @param[in,out] expectedCurrentValue A pointer to some location holding the
- *                              expected current value of the data being set atomically.
- *                              The computed 'desiredValue' should be a function of this current value.
- *                              @note: This is an in-out parameter. In the
- *                              failure case of atomic_cas (where the
- *                              destination isn't set), the pointee of expectedCurrentValue is
- *                              updated with the current value.
- * @param[in] desiredValue      The new value computed based on '*expectedCurrentValue'.
- *
- * @return                      true if the memory location was atomically
- *                              updated with the desired value (after verifying
- *                              that it contained the expectedCurrentValue),
- *                              false otherwise. In the failure case,
- *                              exepctedCurrentValue is updated with the new
- *                              value of the target memory location.
- *
- * pseudocode:
- * function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
- *     if *p != *old {
- *         *old = *p
- *         return false
- *     }
- *     *p = new
- *     return true
- * }
- *
- * @note: In the failure case (where the destination isn't set), the value
- * pointed to by expectedCurrentValue is instead updated with the current value.
- * This property helps writing concise code for the following incr:
- *
- * function incr(p : pointer to int, a : int) returns int {
- *     done = false
- *     value = *p // This fetch operation need not be atomic.
- *     while not done {
- *         done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
- *     }
- *     return value + a
- * }
- *
- * @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it
- * always succeeds if the current value is expected, as per the pseudocode
- * above; it will not spuriously fail as "atomic_compare_exchange_weak" may.
- */
+/** \copydoc core_util_atomic_cas_u8 */
 bool core_util_atomic_cas_u16(volatile uint16_t *ptr, uint16_t *expectedCurrentValue, uint16_t desiredValue);
 
-/**
- * Atomic compare and set. It compares the contents of a memory location to a
- * given value and, only if they are the same, modifies the contents of that
- * memory location to a given new value. This is done as a single atomic
- * operation. The atomicity guarantees that the new value is calculated based on
- * up-to-date information; if the value had been updated by another thread in
- * the meantime, the write would fail due to a mismatched expectedCurrentValue.
- *
- * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
- * you to the article on compare-and swap].
- *
- * @param  ptr                  The target memory location.
- * @param[in,out] expectedCurrentValue A pointer to some location holding the
- *                              expected current value of the data being set atomically.
- *                              The computed 'desiredValue' should be a function of this current value.
- *                              @note: This is an in-out parameter. In the
- *                              failure case of atomic_cas (where the
- *                              destination isn't set), the pointee of expectedCurrentValue is
- *                              updated with the current value.
- * @param[in] desiredValue      The new value computed based on '*expectedCurrentValue'.
- *
- * @return                      true if the memory location was atomically
- *                              updated with the desired value (after verifying
- *                              that it contained the expectedCurrentValue),
- *                              false otherwise. In the failure case,
- *                              exepctedCurrentValue is updated with the new
- *                              value of the target memory location.
- *
- * pseudocode:
- * function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
- *     if *p != *old {
- *         *old = *p
- *         return false
- *     }
- *     *p = new
- *     return true
- * }
- *
- * @note: In the failure case (where the destination isn't set), the value
- * pointed to by expectedCurrentValue is instead updated with the current value.
- * This property helps writing concise code for the following incr:
- *
- * function incr(p : pointer to int, a : int) returns int {
- *     done = false
- *     value = *p // This fetch operation need not be atomic.
- *     while not done {
- *         done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
- *     }
- *     return value + a
- *
- * @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it
- * always succeeds if the current value is expected, as per the pseudocode
- * above; it will not spuriously fail as "atomic_compare_exchange_weak" may.
- * }
- */
+/** \copydoc core_util_atomic_cas_u8 */
 bool core_util_atomic_cas_u32(volatile uint32_t *ptr, uint32_t *expectedCurrentValue, uint32_t desiredValue);
 
-/**
- * Atomic compare and set. It compares the contents of a memory location to a
- * given value and, only if they are the same, modifies the contents of that
- * memory location to a given new value. This is done as a single atomic
- * operation. The atomicity guarantees that the new value is calculated based on
- * up-to-date information; if the value had been updated by another thread in
- * the meantime, the write would fail due to a mismatched expectedCurrentValue.
- *
- * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
- * you to the article on compare-and swap].
- *
- * @param  ptr                  The target memory location.
- * @param[in,out] expectedCurrentValue A pointer to some location holding the
- *                              expected current value of the data being set atomically.
- *                              The computed 'desiredValue' should be a function of this current value.
- *                              @note: This is an in-out parameter. In the
- *                              failure case of atomic_cas (where the
- *                              destination isn't set), the pointee of expectedCurrentValue is
- *                              updated with the current value.
- * @param[in] desiredValue      The new value computed based on '*expectedCurrentValue'.
- *
- * @return                      true if the memory location was atomically
- *                              updated with the desired value (after verifying
- *                              that it contained the expectedCurrentValue),
- *                              false otherwise. In the failure case,
- *                              exepctedCurrentValue is updated with the new
- *                              value of the target memory location.
- *
- * pseudocode:
- * function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
- *     if *p != *old {
- *         *old = *p
- *         return false
- *     }
- *     *p = new
- *     return true
- * }
- *
- * @note: In the failure case (where the destination isn't set), the value
- * pointed to by expectedCurrentValue is instead updated with the current value.
- * This property helps writing concise code for the following incr:
- *
- * function incr(p : pointer to int, a : int) returns int {
- *     done = false
- *     value = *p // This fetch operation need not be atomic.
- *     while not done {
- *         done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
- *     }
- *     return value + a
- * }
- *
- * @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it
- * always succeeds if the current value is expected, as per the pseudocode
- * above; it will not spuriously fail as "atomic_compare_exchange_weak" may.
- */
+/** \copydoc core_util_atomic_cas_u8 */
+bool core_util_atomic_cas_u64(volatile uint64_t *ptr, uint64_t *expectedCurrentValue, uint64_t desiredValue);
+
+/** \copydoc core_util_atomic_cas_u8 */
 bool core_util_atomic_cas_ptr(void *volatile *ptr, void **expectedCurrentValue, void *desiredValue);
 
 /**
@@ -409,6 +250,13 @@ MBED_FORCEINLINE uint32_t core_util_atomic_load_u32(const volatile uint32_t *val
     return value;
 }
 
+/**
+ * Atomic load.
+ * @param  valuePtr Target memory location.
+ * @return          The loaded value.
+ */
+uint64_t core_util_atomic_load_u64(const volatile uint64_t *valuePtr);
+
 /**
  * Atomic load.
  * @param  valuePtr Target memory location.
@@ -457,6 +305,13 @@ MBED_FORCEINLINE void core_util_atomic_store_u32(volatile uint32_t *valuePtr, ui
     MBED_BARRIER();
 }
 
+/**
+ * Atomic store.
+ * @param  valuePtr     Target memory location.
+ * @param  desiredValue The value to store.
+ */
+void core_util_atomic_store_u64(volatile uint64_t *valuePtr, uint64_t desiredValue);
+
 /**
  * Atomic store.
  * @param  valuePtr     Target memory location.
@@ -493,6 +348,14 @@ uint16_t core_util_atomic_incr_u16(volatile uint16_t *valuePtr, uint16_t delta);
  */
 uint32_t core_util_atomic_incr_u32(volatile uint32_t *valuePtr, uint32_t delta);
 
+/**
+ * Atomic increment.
+ * @param  valuePtr Target memory location being incremented.
+ * @param  delta    The amount being incremented.
+ * @return          The new incremented value.
+ */
+uint64_t core_util_atomic_incr_u64(volatile uint64_t *valuePtr, uint64_t delta);
+
 /**
  * Atomic increment.
  * @param  valuePtr Target memory location being incremented.
@@ -528,6 +391,14 @@ uint16_t core_util_atomic_decr_u16(volatile uint16_t *valuePtr, uint16_t delta);
  */
 uint32_t core_util_atomic_decr_u32(volatile uint32_t *valuePtr, uint32_t delta);
 
+/**
+ * Atomic decrement.
+ * @param  valuePtr Target memory location being decremented.
+ * @param  delta    The amount being decremented.
+ * @return          The new decremented value.
+ */
+uint64_t core_util_atomic_decr_u64(volatile uint64_t *valuePtr, uint64_t delta);
+
 /**
  * Atomic decrement.
  * @param  valuePtr Target memory location being decremented.