Add versioned persistent configuration protocol

configuration_transaction.h

@@ -0,0 +1,57 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "configuration_storage.h"
+
+enum class ConfigurationTransactionStatus : uint8_t {
+    kIdle = 0,
+    kReceiving = 1,
+    kPending = 2,
+    kCommitted = 3,
+    kUnchanged = 4,
+    kMalformed = 5,
+    kUnsupportedSchema = 6,
+    kTooLarge = 7,
+    kOutOfOrder = 8,
+    kBadCrc = 9,
+    kBusy = 10,
+    kStorageError = 11,
+};
+
+struct ConfigurationTransactionSnapshot {
+    uint32_t transaction_id = 0;
+    uint16_t received_size = 0;
+    uint16_t expected_size = 0;
+    uint32_t expected_crc = 0;
+    uint32_t stored_generation = 0;
+    uint32_t stored_crc = 0;
+    ConfigurationTransactionStatus status =
+        ConfigurationTransactionStatus::kIdle;
+};
+
+class ConfigurationTransaction {
+public:
+    ConfigurationTransactionStatus begin(uint32_t transaction_id,
+                                         uint16_t schema_version,
+                                         size_t payload_size,
+                                         uint32_t payload_crc);
+    ConfigurationTransactionStatus append(uint32_t transaction_id,
+                                          size_t offset,
+                                          const uint8_t* data,
+                                          size_t size);
+    ConfigurationTransactionStatus finish(uint32_t transaction_id);
+    void set_result(ConfigurationTransactionStatus status,
+                    uint32_t stored_generation, uint32_t stored_crc);
+    void clear();
+
+    const ConfigurationTransactionSnapshot& snapshot() const;
+    uint16_t schema_version() const;
+    const uint8_t* payload() const;
+
+private:
+    ConfigurationTransactionSnapshot snapshot_{};
+    uint16_t schema_version_ = 0;
+    uint8_t payload_[CONFIGURATION_STORAGE_MAX_PAYLOAD_SIZE]{};
+};