Add a memory arena for the audio pipeline

1 files changed, 75 insertions, 0 deletions

diff --git a/src/memory/arena.cpp b/src/memory/arena.cpp
new file mode 100644
index 00000000..450ac4f2
--- /dev/null
+++ b/src/memory/arena.cpp
@@ -0,0 +1,75 @@
+#include "arena.hpp"
+
+#include <cstdint>
+#include <optional>
+
+#include "esp_heap_caps.h"
+#include "freertos/queue.h"
+#include "span.hpp"
+
+namespace memory {
+
+Arena::Arena(std::size_t block_size,
+             std::size_t num_blocks,
+             uint32_t alloc_flags)
+    : block_size_(block_size) {
+  pool_ = static_cast<std::byte*>(
+      heap_caps_malloc(block_size * num_blocks, alloc_flags));
+  free_blocks_ = xQueueCreate(num_blocks, sizeof(void*));
+  for (int i = 0; i < num_blocks; i++) {
+    std::byte* block = pool_ + (i * block_size);
+    xQueueSend(free_blocks_, &block, 0);
+  }
+}
+
+Arena::~Arena() {
+  // TODO: assert queue is full?
+  vQueueDelete(free_blocks_);
+  free(pool_);
+}
+
+auto Arena::Acquire() -> std::optional<ArenaPtr> {
+  std::byte* block;
+  bool result = xQueueReceive(free_blocks_, &block, 0);
+  if (result) {
+    ArenaPtr ptr{this, block, block_size_, 0};
+    return ptr;
+  } else {
+    return {};
+  }
+}
+
+auto Arena::Return(ArenaPtr ptr) -> void {
+  assert(ptr.owner == this);
+  xQueueSend(free_blocks_, &ptr.start, 0);
+}
+
+auto ArenaRef::Acquire(Arena* a) -> std::optional<ArenaRef> {
+  auto ptr = a->Acquire();
+  if (ptr) {
+    ArenaRef ref{*ptr};
+    return ref;
+  }
+  return {};
+}
+
+ArenaRef::ArenaRef(ArenaPtr p) : ptr(p) {}
+
+ArenaRef::ArenaRef(ArenaRef&& other) : ptr(other.Release()) {}
+
+auto ArenaRef::Release() -> ArenaPtr {
+  auto ret = ptr;
+  ptr.owner = nullptr;
+  ptr.start = nullptr;
+  ptr.size = 0;
+  ptr.used_size = 0;
+  return ret;
+}
+
+ArenaRef::~ArenaRef() {
+  if (ptr.owner != nullptr) {
+    ptr.owner->Return(ptr);
+  }
+}
+
+}  // namespace memory