test: add lora frame and chunk reassembly logic suite

lib/dd3_transport_logic/src/batch_reassembly_logic.cpp

@@ -0,0 +1,75 @@
+#include "batch_reassembly_logic.h"
+
+#include <string.h>
+
+void batch_reassembly_reset(BatchReassemblyState &state) {
+  state.active = false;
+  state.batch_id = 0;
+  state.next_index = 0;
+  state.expected_chunks = 0;
+  state.total_len = 0;
+  state.received_len = 0;
+  state.last_rx_ms = 0;
+  state.timeout_ms = 0;
+}
+
+BatchReassemblyStatus batch_reassembly_push(BatchReassemblyState &state, uint16_t batch_id, uint8_t chunk_index,
+                                            uint8_t chunk_count, uint16_t total_len, const uint8_t *chunk_data,
+                                            size_t chunk_len, uint32_t now_ms, uint32_t timeout_ms_for_new_batch,
+                                            uint16_t max_total_len, uint8_t *buffer, size_t buffer_cap,
+                                            uint16_t &out_complete_len) {
+  out_complete_len = 0;
+  if (!buffer || !chunk_data) {
+    batch_reassembly_reset(state);
+    return BatchReassemblyStatus::ErrorReset;
+  }
+  if (chunk_len > 0 && total_len == 0) {
+    batch_reassembly_reset(state);
+    return BatchReassemblyStatus::ErrorReset;
+  }
+
+  bool expired = state.timeout_ms > 0 && (now_ms - state.last_rx_ms > state.timeout_ms);
+  if (!state.active || batch_id != state.batch_id || expired) {
+    if (chunk_index != 0) {
+      batch_reassembly_reset(state);
+      return BatchReassemblyStatus::ErrorReset;
+    }
+    if (total_len == 0 || total_len > max_total_len || chunk_count == 0) {
+      batch_reassembly_reset(state);
+      return BatchReassemblyStatus::ErrorReset;
+    }
+    state.active = true;
+    state.batch_id = batch_id;
+    state.expected_chunks = chunk_count;
+    state.total_len = total_len;
+    state.received_len = 0;
+    state.next_index = 0;
+    state.last_rx_ms = now_ms;
+    state.timeout_ms = timeout_ms_for_new_batch;
+  }
+
+  if (!state.active || chunk_index != state.next_index || chunk_count != state.expected_chunks) {
+    batch_reassembly_reset(state);
+    return BatchReassemblyStatus::ErrorReset;
+  }
+
+  if (state.received_len + chunk_len > state.total_len ||
+      state.received_len + chunk_len > max_total_len ||
+      state.received_len + chunk_len > buffer_cap) {
+    batch_reassembly_reset(state);
+    return BatchReassemblyStatus::ErrorReset;
+  }
+
+  memcpy(&buffer[state.received_len], chunk_data, chunk_len);
+  state.received_len += static_cast<uint16_t>(chunk_len);
+  state.next_index++;
+  state.last_rx_ms = now_ms;
+
+  if (state.next_index == state.expected_chunks && state.received_len == state.total_len) {
+    out_complete_len = state.received_len;
+    batch_reassembly_reset(state);
+    return BatchReassemblyStatus::Complete;
+  }
+
+  return BatchReassemblyStatus::InProgress;
+}