Add RomTag

Makefile

@@ -237,6 +237,14 @@ AMIGA_ASM_SRCS = platform/amiga/startup.S
 endif
 AMIGA_ASM_OBJS = $(patsubst %.S,$(AMIGA_BUILD)/%.o,$(AMIGA_ASM_SRCS))
 
+# The resident/romtag object is linked directly into the handler right after
+# startup.o, not archived into libodfs.a
+ifeq ($(AMIGA_TARGET),os4)
+AMIGA_RESIDENT_OBJ =
+else
+AMIGA_RESIDENT_OBJ = $(AMIGA_BUILD)/platform/amiga/resident.o
+endif
+
 HOST_LIB_SRCS  = $(CORE_SRCS) $(HOST_SRCS)
 HOST_LIB_OBJS  = $(patsubst %.c,$(HOST_BUILD)/%.o,$(HOST_LIB_SRCS))
 HOST_LIB_DEPS  = $(HOST_LIB_OBJS:.o=.d)
@@ -593,10 +601,10 @@ $(AMIGA_TEST_TOOL): $(AMIGA_TEST_BUILD)/tests/amiga/test_handler.o
 
 # ---- Amiga handler ----
 
-$(HANDLER): $(AMIGA_ASM_OBJS) $(AMIGA_BUILD)/libodfs.a
+$(HANDLER): $(AMIGA_ASM_OBJS) $(AMIGA_RESIDENT_OBJ) $(AMIGA_BUILD)/libodfs.a
 	@mkdir -p $(@D)
 	@echo "  LINK  $@"
-	@$(CC) $(LDFLAGS) $(HANDLER_LDFLAGS) -o $@ $(AMIGA_ASM_OBJS) -L$(AMIGA_BUILD) -lodfs $(HANDLER_LIBS)
+	@$(CC) $(LDFLAGS) $(HANDLER_LDFLAGS) -o $@ $(AMIGA_ASM_OBJS) $(AMIGA_RESIDENT_OBJ) -L$(AMIGA_BUILD) -lodfs $(HANDLER_LIBS)
 	@echo "  STRIP $@"
 	@$(STRIP) $@
 

platform/amiga/handler_main.c

@@ -53,7 +53,7 @@
 #define ODFS_GIT_VERSION "unknown"
 #endif
 
-static const char version_string[] __attribute__((used)) =
+const char version_string[] __attribute__((used)) =
     "$VER: ODFileSystem " ODFS_GIT_VERSION
     " (" ODFS_AMIGA_DATE ")";
 
@@ -83,6 +83,7 @@ static void copy_pure_audio_volume_name(handler_global_t *g);
 #endif
 static int scsi_is_unsupported_command(const uint8_t *sense);
 
+
 /* ------------------------------------------------------------------ */
 /* Amiga media adapter                                                 */
 /* ------------------------------------------------------------------ */

platform/amiga/resident.c

@@ -0,0 +1,94 @@
+/*
+ * resident.c
+ *
+ * Resident (romtag) initialisation for the m68k ODFileSystem handler.
+ *
+ * On coldstart the OS scans the binary for this romtag and calls rt_init,
+ * which registers ODFileSystem with FileSystem.resource by adding a
+ * FileSysEntry for our DosType. This lets DOS mount and (re)load the
+ * filesystem from the resource -- required when the handler lives in a
+ * custom ROM, and harmless when loaded from disk. The entry is only added
+ * if one for the same DosType isn't already present.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ */
+
+#include <proto/exec.h>
+#include <exec/types.h>
+#include <exec/memory.h>
+#include <exec/resident.h>
+#include <exec/nodes.h>
+#include <exec/lists.h>
+#include <resources/filesysres.h>
+
+#define DOSTYPE 0x43443031
+#define MAJOR_VER 0
+#define MINOR_VER 6
+
+extern const char version_string[];
+static const char name_string[] = "ODFileSystem";
+
+void entrypoint(void);
+static int rt_init(BPTR seglist asm("a0"), struct ExecBase *SysBase asm("a6"));
+
+static const struct Resident __attribute__((used,no_reorder)) romtag = {
+    .rt_MatchWord = RTC_MATCHWORD,
+    .rt_MatchTag  = (APTR)&romtag,
+    .rt_EndSkip   = (APTR)(&romtag+1),
+    .rt_Flags     = RTF_COLDSTART,
+    .rt_Version   = MAJOR_VER,
+    .rt_Type      = NT_UNKNOWN,
+    .rt_Pri       = 10,
+    .rt_Name      = (APTR)&name_string,
+    .rt_IdString  = (APTR)&version_string,
+    .rt_Init      = (APTR)rt_init
+};
+
+static int rt_init(BPTR seglist asm("a0"), struct ExecBase *SysBase asm("a6")) {
+    struct FileSysResource *fsr = OpenResource((STRPTR)FSRNAME);
+    struct FileSysEntry *fse = NULL;
+    BOOL found = FALSE;
+
+    if (fsr) {
+        /* Check if there's already a CDFS in FileSystem.resource */
+        Forbid();
+        for (fse = (struct FileSysEntry*)fsr->fsr_FileSysEntries.lh_Head;
+             fse->fse_Node.ln_Succ != NULL;
+             fse = (struct FileSysEntry*)fse->fse_Node.ln_Succ)
+        {
+            if (fse->fse_DosType == DOSTYPE) {
+                /* Already one there, don't bother adding this */
+                found = TRUE;
+                break;
+            }
+        }
+        Permit();
+
+        if (!found) {
+            fse = AllocMem(sizeof(struct FileSysEntry), MEMF_PUBLIC | MEMF_CLEAR);
+            if (fse) {
+                // seglist will be NULL if this was part of a custom ROM
+                // Back up from the entrypoint to fake the seglist
+                if (seglist == NULL) {
+                    seglist = MKBADDR((UBYTE *)entrypoint - 4);
+                }
+                fse->fse_Node.ln_Name = (char *)name_string;
+                fse->fse_DosType      = DOSTYPE;
+                fse->fse_GlobalVec    = -1;
+                fse->fse_PatchFlags   = 0x190;
+                fse->fse_StackSize    = 16384;
+                fse->fse_Version      = MAJOR_VER << 16 | MINOR_VER;
+                fse->fse_SegList      = (BPTR)seglist;
+                fse->fse_Priority     = 10;
+
+                Forbid();
+                AddHead(&fsr->fsr_FileSysEntries,(struct Node *)fse);
+                Permit();
+            }
+        }
+
+    }
+
+    return 0;
+}