soc_desc: add default constructors to most structures

After being caught by several bugs of the type "let's forgot to initialize
a field to default value", I'm finally fixing this.

Change-Id: I01c33e0611d4f697f767db66465e4fb30858cdab

utils/regtools/include/soc_desc.hpp

@@ -39,6 +39,9 @@ typedef uint32_t soc_addr_t;
 typedef uint32_t soc_word_t;
 typedef int soc_id_t;
 
+/** Default value for IDs */
+const soc_id_t DEFAULT_ID = 0xcafebabe;
+
 /** Error class */
 class error_t
 {
@@ -81,6 +84,9 @@ struct enum_t
     std::string name; /** Name (must be unique among field enums) */
     std::string desc; /** Optional description of the meaning of this value */
     soc_word_t value; /** Value of the field */
+
+    /** Default constructor: default ID and value is 0 */
+    enum_t():id(DEFAULT_ID), value(0) {}
 };
 
 /** Register field information */
@@ -93,6 +99,9 @@ struct field_t
     size_t width; /** Width of the field in bits  */
     std::vector< enum_t > enum_; /** List of special values */
 
+    /** Default constructor: default ID, position is 0, width is 1 */
+    field_t():id(DEFAULT_ID), pos(0), width(1) {}
+
     /** Returns the bit mask of the field within the register */
     soc_word_t bitmask() const
     {
@@ -140,6 +149,9 @@ struct variant_t
     soc_id_t id; /** ID (must be unique among register variants) */
     std::string type; /** type of the variant */
     soc_addr_t offset; /** offset of the variant */
+
+    /** Default constructor: default ID, offset is 0 */
+    variant_t():id(DEFAULT_ID), offset(0) {}
 };
 
 /** Register information */
@@ -149,6 +161,9 @@ struct register_t
     std::string desc; /** Optional description of the register */
     std::vector< field_t > field; /** List of fields */
     std::vector< variant_t > variant; /** List of variants */
+
+    /** Default constructor: width is 32 */
+    register_t():width(32) {}
 };
 
 /** Node address range information */
@@ -170,6 +185,9 @@ struct range_t
     std::string variable; /** Formula variable name (for FORMULA) */
     std::vector< soc_word_t > list; /** Address list (for LIST) */
 
+    /** Default constructor: empty stride */
+    range_t():type(STRIDE), first(0), count(0), base(0), stride(0) {}
+
     /** Return the number of indexes (based on count or list) */
     size_t size()
     {
@@ -193,6 +211,9 @@ struct instance_t
     type_t type; /** Instance type */
     soc_word_t addr; /** Address (for SINGLE) */
     range_t range; /** Range (for RANGE) */
+
+    /** Default constructor: single instance at 0 */
+    instance_t():id(DEFAULT_ID), type(SINGLE), addr(0) {}
 };
 
 /** Node information */
@@ -205,6 +226,9 @@ struct node_t
     std::vector< register_t> register_; /** Optional register */
     std::vector< instance_t> instance; /** List of instances */
     std::vector< node_t > node; /** List of sub-nodes */
+
+    /** Default constructor: default ID */
+    node_t():id(DEFAULT_ID) {}
 };
 
 /** System-on-chip information */