diff --git a/bluetooth/hci/hci_packetizer.cc b/bluetooth/hci/hci_packetizer.cc
new file mode 100644
index 0000000..5b6c443
--- /dev/null
+++ b/bluetooth/hci/hci_packetizer.cc
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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 "hci_packetizer.h"
+
+#define LOG_TAG "android.hardware.bluetooth.hci-packetizer"
+#include "log/log.h"
+
+namespace android::hardware::bluetooth::hci {
+
+namespace {
+
+const size_t header_size_for_type[] = {0,
+                                       kCommandHeaderSize,
+                                       kAclHeaderSize,
+                                       kScoHeaderSize,
+                                       kEventHeaderSize,
+                                       kIsoHeaderSize};
+const size_t packet_length_offset_for_type[] = {0,
+                                                kCommandLengthOffset,
+                                                kAclLengthOffset,
+                                                kScoLengthOffset,
+                                                kEventLengthOffset,
+                                                kIsoLengthOffset};
+
+size_t HciGetPacketLengthForType(PacketType type,
+                                 const std::vector<uint8_t>& header) {
+  size_t offset = packet_length_offset_for_type[static_cast<uint8_t>(type)];
+  if (type != PacketType::ACL_DATA && type != PacketType::ISO_DATA) {
+    return header[offset];
+  }
+  return (((header[offset + 1]) << 8) | header[offset]);
+}
+
+}  // namespace
+
+const std::vector<uint8_t>& HciPacketizer::GetPacket() const { return packet_; }
+
+bool HciPacketizer::OnDataReady(PacketType packet_type,
+                                const std::vector<uint8_t>& buffer,
+                                size_t offset) {
+  bool packet_completed = false;
+  size_t bytes_available = buffer.size() - offset;
+  switch (state_) {
+    case HCI_HEADER: {
+      size_t header_size =
+          header_size_for_type[static_cast<size_t>(packet_type)];
+      if (bytes_remaining_ == 0) {
+        bytes_remaining_ = header_size;
+        packet_.clear();
+      }
+      size_t bytes_to_copy = std::min(bytes_remaining_, bytes_available);
+      packet_.insert(packet_.end(), buffer.begin() + offset,
+                     buffer.begin() + offset + bytes_to_copy);
+      bytes_remaining_ -= bytes_to_copy;
+      bytes_available -= bytes_to_copy;
+      if (bytes_remaining_ == 0) {
+        bytes_remaining_ = HciGetPacketLengthForType(packet_type, packet_);
+        if (bytes_remaining_ > 0) {
+          state_ = HCI_PAYLOAD;
+          if (bytes_available > 0) {
+            packet_completed =
+                OnDataReady(packet_type, buffer, offset + bytes_to_copy);
+          }
+        } else {
+          packet_completed = true;
+        }
+      }
+      break;
+    }
+
+    case HCI_PAYLOAD: {
+      size_t bytes_to_copy = std::min(bytes_remaining_, bytes_available);
+      packet_.insert(packet_.end(), buffer.begin() + offset,
+                     buffer.begin() + offset + bytes_to_copy);
+      bytes_remaining_ -= bytes_to_copy;
+      if (bytes_remaining_ == 0) {
+        state_ = HCI_HEADER;
+        packet_completed = true;
+      }
+      break;
+    }
+  }
+  return packet_completed;
+}
+
+}  // namespace android::hardware::bluetooth::hci