Refactor storage system to support double buffering.

src/main/application/config.c

@@ -24,24 +24,53 @@
 
 /* --------------------------------------------------- CONSTANTS ---------------------------------------------------- */
 
-/**
- * @def     CONFIG_VERSION_CURRENT
- * @brief   The currently active configuration version.
- */
-#define CONFIG_VERSION_CURRENT  ( 1 )
-
 /**
  * @def     MINIMUM_SAVE_PERIOD
  * @brief   Minimum elapsed time between saving config to storage.
  */
 #define MINIMUM_SAVE_PERIOD     ( 5 * TICKS_PER_SEC )
 
+/* ----------------------------------------------------- TYPES ------------------------------------------------------ */
+
+/**
+ * @typedef config_version_t
+ * @brief   Enumeration of the supported configuration versions.
+ * @note    This is to support backwards compatibility with saved configuration when the software changes.
+ */
+typedef uint8_t config_version_t;
+enum
+{
+    CONFIG_VERSION_0,                       /**< Configuration version 0.               */
+
+    CONFIG_VERSION_COUNT,                   /**< Number of valid configuration versions.*/
+
+    CONFIG_VERSION_CURRENT                  /**< Current configuration version.         */
+        = CONFIG_VERSION_0
+};
+
+/**
+ * @typedef config_storage_t
+ * @brief   Struct defining data saved in storage for unit configuration.
+ */
+typedef struct
+{
+    config_version_t version;               /**< Saved version number.                  */
+    union
+    {
+        config_t current;                   /**< Configuration data as current value.   */
+    };
+
+} config_storage_t;
+
 /* ----------------------------------------------------- MACROS ----------------------------------------------------- */
 
 _Static_assert( _CONFIG_DFLT_BUZZER_FREQUENCY >= BUZZER_MINIMUM_FREQUENCY &&
                 _CONFIG_DFLT_BUZZER_FREQUENCY <= BUZZER_MAXIMUM_FREQUENCY,
                 "Invalid default buzzer frequency!" );
 
+_Static_assert( STORAGE_CONFIG_SIZE >= sizeof( config_storage_t ),
+                "Not enough storage allocated for configuration!" );
+
 /* --------------------------------------------------- VARIABLES ---------------------------------------------------- */
 
 static config_t s_config;                   /**< Currently active app configuration.    */
@@ -129,13 +158,17 @@ void config_init( void )
 {
     // Try to get configuration from storage, and restore defaults if that fails.
     // In this case, any existing configuration will be lost the next time config is saved.
-    config_t config;
-    if( ! storage_get_config( CONFIG_VERSION_CURRENT, sizeof( config_t ), & config ) ||
-        ! validate_config( & config ) )
-        config_default( & config );
+    // In the future, this could do migration from previous configuration versions.
+    config_storage_t storage;
+    if( ! storage_get_config( & storage, sizeof( storage ) ) ||
+        storage.version != CONFIG_VERSION_CURRENT ||
+        ! validate_config( & storage.current ) )
+    {
+        config_default( & storage.current );
+    }
 
     // Set local copy
-    s_config = config;
+    s_config = storage.current;
 
 }   /* config_init() */
 
@@ -170,7 +203,11 @@ void config_tick( tick_t tick )
 
 static void flush( tick_t tick )
 {
-    storage_set_config( CONFIG_VERSION_CURRENT, sizeof( config_t ), & s_config );
+    config_storage_t storage;
+    storage.version = CONFIG_VERSION_CURRENT;
+    storage.current = s_config;
+
+    storage_set_config( & storage, sizeof( storage ) );
     s_modified = false;
     s_save_tick = tick;
 

src/main/application/config.h

@@ -24,6 +24,7 @@
 #include "application/keyer.h"
 #include "application/led.h"
 #include "application/wpm.h"
+#include "utility/utility.h"
 
 /* ----------------------------------------------------- TYPES ------------------------------------------------------ */
 
@@ -60,7 +61,7 @@ typedef struct
     /** If set to `true`, the keyer will emit dashes from the left paddle and dots from the right paddle. */
     bool                keyer_paddle_invert;
 
-} __attribute__((packed)) config_t;
+} PACKED_STRUCT config_t;
 
 /**
  * @typedef config_version_t

src/main/application/intf_types.h

@@ -17,6 +17,8 @@
 
 #include <stdint.h>
 
+#include "utility/utility.h"
+
 /* --------------------------------------------------- CONSTANTS ---------------------------------------------------- */
 
 /**
@@ -91,6 +93,6 @@ typedef struct
     uint16_t        size;                   /**< Total size of message payload.         */
     uint16_t        crc;                    /**< 16-bit CRC of message payload.         */
 
-} __attribute__((packed)) intf_header_t;
+} PACKED_STRUCT intf_header_t;
 
 #endif /* !defined( APPLICATION_INTF_TYPES_H ) */