Define the header of compressed module data

particle-iot · May 15, 2020 · 7a2bd4e · 7a2bd4e
1 parent 06b32a0
commit 7a2bd4e
Showing 1 changed file with 31 additions and 1 deletion.
diff --git a/dynalib/inc/module_info.h b/dynalib/inc/module_info.h
@@ -61,7 +61,7 @@ typedef struct module_info_t {
     uint8_t  module_index;              /* distinguish modules of the same type */
     module_dependency_t dependency;
     module_dependency_t dependency2;
-} module_info_t;
+} __attribute__((__packed__)) module_info_t;
 
 #define STATIC_ASSERT_MODULE_INFO_OFFSET(field, expected) PARTICLE_STATIC_ASSERT( module_info_##field, offsetof(module_info_t, field)==expected || sizeof(void*)!=4)
 
@@ -169,6 +169,36 @@ module_scheme_t module_scheme(const module_info_t* mi);
  */
 uint8_t module_info_matches_platform(const module_info_t* mi);
 
+/**
+ * Compressed module header.
+ *
+ * In a compressed module, this header immediately follows the module info header (`module_info_t`) and
+ * precedes the compressed data.
+ */
+typedef struct compressed_module_header {
+    /**
+     * Header size.
+     */
+    uint16_t size;
+    /**
+     * Compression method.
+     *
+     * As of now, the only supported method is raw Deflate (0).
+     */
+    uint8_t method;
+    /**
+     * Base two logarithm of the window size used when compressing this module.
+     *
+     * For raw Deflate the valid range is [8, 15]. The value of 0 corresponds to the default window
+     * size of 15 bits.
+     */
+    uint8_t window_bits;
+    /**
+     * Size of the uncompressed data.
+     */
+    uint32_t original_size;
+} __attribute__((__packed__)) compressed_module_header;
+
 /*
  * The structure is a suffix to the module, placed before the end symbol
  */