[instance] fix index computation in multi-instances context (#11099)

In multi instances context, the GetIdx function did not return the correct instance index.
zephyrproject-rtos · Jan 9, 2025 · 3ae741f · 3ae741f
1 parent d7a2668
commit 3ae741f
Showing 1 changed file with 1 addition and 3 deletions.
diff --git a/src/core/instance/instance.cpp b/src/core/instance/instance.cpp
@@ -351,9 +351,7 @@ Instance &Instance::Get(uint8_t aIdx)
 
 uint8_t Instance::GetIdx(Instance *aInstance)
 {
-    return static_cast<uint8_t>(
-        (reinterpret_cast<uint8_t *>(aInstance) - reinterpret_cast<uint8_t *>(gMultiInstanceRaw)) /
-        INSTANCE_SIZE_ALIGNED);
+    return static_cast<uint8_t>((reinterpret_cast<uint64_t *>(aInstance) - gMultiInstanceRaw) / INSTANCE_SIZE_ALIGNED);
 }
 
 #endif // #if OPENTHREAD_CONFIG_MULTIPLE_STATIC_INSTANCE_ENABLE