Add section fragments

Fixes #517, and hopefully enables RGBDS as a SDCC back-end

include/asm/section.h

@@ -19,7 +19,7 @@ struct Expression;
 struct Section {
 	char *pzName;
 	enum SectionType nType;
-	bool isUnion;
+	enum SectionModifier modifier;
 	uint32_t size;
 	uint32_t nOrg;
 	uint32_t nBank;
@@ -38,7 +38,8 @@ struct SectionSpec {
 
 struct Section *out_FindSectionByName(const char *pzName);
 void out_NewSection(char const *pzName, uint32_t secttype, uint32_t org,
-		    struct SectionSpec const *attributes, bool isUnion);
+		    struct SectionSpec const *attributes,
+		    enum SectionModifier mod);
 void out_SetLoadSection(char const *name, uint32_t secttype, uint32_t org,
 			struct SectionSpec const *attributes);
 void out_EndLoadSection(void);

include/link/section.h

@@ -42,8 +42,9 @@ struct Section {
 	/* Info contained in the object files */
 	char *name;
 	uint16_t size;
+	uint16_t offset;
 	enum SectionType type;
-	bool isUnion;
+	enum SectionModifier modifier;
 	bool isAddressFixed;
 	uint16_t org;
 	bool isBankFixed;

include/linkdefs.h

@@ -14,7 +14,7 @@
 
 #define RGBDS_OBJECT_VERSION_STRING "RGB%1u"
 #define RGBDS_OBJECT_VERSION_NUMBER 9U
-#define RGBDS_OBJECT_REV 4U
+#define RGBDS_OBJECT_REV 5U
 
 enum AssertionType {
 	ASSERT_WARN,
@@ -73,6 +73,14 @@ enum SectionType {
 	SECTTYPE_INVALID
 };
 
+enum SectionModifier {
+	SECTION_NORMAL,
+	SECTION_UNION,
+	SECTION_FRAGMENT
+};
+
+extern char const * const sectionModNames[];
+
 /**
  * Tells whether a section has data in its object file definition,
  * depending on type.