1 files changed, 55 insertions, 0 deletions
diff --git a/pw_allocator/fallback_allocator.cc b/pw_allocator/fallback_allocator.cc
new file mode 100644
index 000000000..1e3faf666
--- /dev/null
+++ b/pw_allocator/fallback_allocator.cc
@@ -0,0 +1,55 @@
+
+// Copyright 2023 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+
+#include "pw_allocator/fallback_allocator.h"
+
+#include "pw_assert/check.h"
+
+namespace pw::allocator {
+
+void FallbackAllocator::Initialize(Allocator& primary, Allocator& secondary) {
+  primary_ = &primary;
+  secondary_ = &secondary;
+}
+
+Status FallbackAllocator::DoQuery(const void* ptr, Layout layout) const {
+  PW_DCHECK(primary_ != nullptr && secondary_ != nullptr);
+  auto status = primary_->Query(ptr, layout);
+  return status.ok() ? status : secondary_->Query(ptr, layout);
+}
+
+void* FallbackAllocator::DoAllocate(Layout layout) {
+  PW_DCHECK(primary_ != nullptr && secondary_ != nullptr);
+  void* ptr = primary_->Allocate(layout);
+  return ptr != nullptr ? ptr : secondary_->Allocate(layout);
+}
+
+void FallbackAllocator::DoDeallocate(void* ptr, Layout layout) {
+  PW_DCHECK(primary_ != nullptr && secondary_ != nullptr);
+  if (primary_->Query(ptr, layout).ok()) {
+    primary_->Deallocate(ptr, layout);
+  } else {
+    secondary_->Deallocate(ptr, layout);
+  }
+}
+
+bool FallbackAllocator::DoResize(void* ptr, Layout layout, size_t new_size) {
+  PW_DCHECK(primary_ != nullptr && secondary_ != nullptr);
+  return primary_->Query(ptr, layout).ok()
+             ? primary_->Resize(ptr, layout, new_size)
+             : secondary_->Resize(ptr, layout, new_size);
+}
+
+}  // namespace pw::allocator