Palette fix for the X68000

src/x68000/hal.c

@@ -84,6 +84,22 @@
 #define X68K_GFX_PALETTE     ((volatile uint16_t *)0xE82000L)
 #define X68K_PALETTE_ENTRIES (SURFACE_PALETTE_COUNT * SURFACE_COLORS_PER_PALETTE)
 
+// Video Controller register 2 ($E82600) low byte = per-plane display enable (MAME x68k_v.cpp): bits 0-3
+// graphic layers, bit 4 graphic, bit 5 (0x20) TEXT plane, bit 6 sprite.  _iocs_crtmod leaves the text
+// plane ON, so Human68k's desktop (Drv0-3, the kana/romaji status column) bleeds through the graphics;
+// clearing bit 5 hides it while keeping the graphic layers we draw into.
+#define X68K_VIDCTRL2        ((volatile uint16_t *)0xE82600L)
+#define X68K_VIDCTRL2_TEXT   0x0020u
+
+// Video Controller register 0 ($E82400) low 2 bits select the graphic colour depth (MAME x68k_v.cpp
+// switch(reg[0] & 3)): 0 = 16-colour, 1 = 256-colour palette-indexed, 3 = 65536-colour DIRECT.
+// _iocs_crtmod(13) sets the 512x512 CRTC but leaves this at 3 (direct), whereas this port draws 8-bit
+// PALETTE INDICES into GVRAM and uploads a 256-entry palette at $E82000 -- so the mode MUST be forced to
+// 256-colour or every index is interpreted as a near-black direct colour (the "invisible/dim" bug).
+#define X68K_VIDCTRL0        ((volatile uint16_t *)0xE82400L)
+#define X68K_VIDCTRL0_DEPTH  0x0003u
+#define X68K_VIDCTRL0_256    0x0001u
+
 
 // ----- Millisecond clock -----------------------------------------------------
 //
@@ -161,6 +177,15 @@ bool jlpInit(const jlConfigT *config) {
     gPrevCrtMode = _iocs_crtmod(-1);        // -1 queries without changing
     _iocs_crtmod(X68K_CRTMOD_512_256);
     _iocs_g_clr_on();                       // clear graphics + enable the plane
+    // crtmod 13 leaves the video controller in 65536-colour DIRECT mode (reg[0] & 3 == 3).  This port
+    // draws 8-bit palette indices, so force 256-colour palette-indexed mode or every colour renders
+    // near-black.  Root-caused + proven live on MAME (reg0 0x0003 -> 0x0001 turned a black frame into a
+    // correct red/yellow/blue test pattern).
+    X68K_VIDCTRL0[0] = (uint16_t)((X68K_VIDCTRL0[0] & (uint16_t)~X68K_VIDCTRL0_DEPTH) | X68K_VIDCTRL0_256);
+    // jlpPresent draws into the GRAPHIC plane (GVRAM $C00000), NOT the text plane -- so Human68k's text
+    // plane (the Drv0-3 + kana/romaji desktop that _iocs_crtmod leaves on) bleeds over our frame.  A
+    // reg[2] &= ~0x20 write to hide it did NOT take on MAME (the desktop stayed visible), so that cosmetic
+    // bleed is left as a follow-up; it does not affect the graphic layers we draw into.
     // NOTE: installing vdispHandler via _iocs_vdispst HANGS the machine --
     // tested, no serial output at all, so it wedges before main() gets going.
     // IOCS does NOT wrap the handler: _VDISPST writes the pointer straight into

tools/xdftool.py

@@ -200,6 +200,57 @@ class Xdf:
         struct.pack_into("<I", entry, 28, len(payload))
         self.data[slot:slot + DIR_ENTRY_SIZE] = entry
 
+    def _dir_entry(self, name11, attr, cluster, size):
+        entry = bytearray(DIR_ENTRY_SIZE)
+        entry[0:11] = name11
+        entry[11] = attr
+        struct.pack_into("<H", entry, 22, (12 << 11))                          # 12:00:00
+        struct.pack_into("<H", entry, 24, ((2026 - 1980) << 9) | (1 << 5) | 1)  # 2026-01-01
+        struct.pack_into("<H", entry, 26, cluster)
+        struct.pack_into("<I", entry, 28, size)
+        return entry
+
+    def add_file_in_subdir(self, dirname, name, payload):
+        # Create a one-cluster subdirectory in root (with . and .. entries) and write `name` into it, so a
+        # guest that reads e.g. SAVES/RN.CFG finds it.  Fresh-template semantics: the subdir must not exist
+        # yet (the callers copy a clean image per run).  Human68k FAT12 is otherwise ordinary FAT12.
+        dstem = dirname.upper()
+        if len(dstem) > 8:
+            raise ValueError(f"subdir '{dirname}' does not fit 8.3")
+        cb = self.cluster_bytes
+        need = max(1, (len(payload) + cb - 1) // cb)
+        free = self.free_clusters()
+        if len(free) < need + 1:
+            raise OSError(f"{self.path}: need {need + 1} clusters, {len(free)} free")
+        dir_cluster = free[0]
+        data_chain = free[1:1 + need]
+        # File data clusters.
+        for idx, cluster in enumerate(data_chain):
+            off = self.cluster_offset(cluster)
+            chunk = payload[idx * cb:(idx + 1) * cb]
+            self.data[off:off + len(chunk)] = chunk
+            if len(chunk) < cb:
+                self.data[off + len(chunk):off + cb] = bytes(cb - len(chunk))
+            self.fat_set(cluster, 0xFFF if idx == need - 1 else data_chain[idx + 1])
+        # The subdirectory's own cluster: '.', '..', then the file entry, rest free.
+        doff = self.cluster_offset(dir_cluster)
+        self.data[doff:doff + cb] = bytes(cb)
+        self.data[doff:doff + 32] = self._dir_entry(b".          ", ATTR_DIR, dir_cluster, 0)
+        self.data[doff + 32:doff + 64] = self._dir_entry(b"..         ", ATTR_DIR, 0, 0)
+        self.data[doff + 64:doff + 96] = self._dir_entry(
+            self.encode_name(name), ATTR_ARCHIVE, data_chain[0], len(payload))
+        self.fat_set(dir_cluster, 0xFFF)
+        # Root entry pointing at the subdirectory.
+        slot = None
+        for _, off, e in self._entries():
+            if e[0] in (FREE_MARKER, DELETED_MARKER):
+                slot = off
+                break
+        if slot is None:
+            raise OSError(f"{self.path}: root directory full")
+        self.data[slot:slot + DIR_ENTRY_SIZE] = self._dir_entry(
+            dstem.ljust(8).encode("ascii") + b"   ", ATTR_DIR, dir_cluster, 0)
+
     def flush(self):
         if not self.writable:
             raise PermissionError("opened read-only")
@@ -235,7 +286,12 @@ def main(argv):
         name = argv[4] if len(argv) > 4 else os.path.basename(host)
         img = Xdf(image, writable=True)
         with open(host, "rb") as fp:
-            img.add_file(name, fp.read())
+            payload = fp.read()
+        if "/" in name:                          # SAVES/RN.CFG -> a one-cluster subdirectory + the file
+            sub, _, leaf = name.partition("/")
+            img.add_file_in_subdir(sub, leaf, payload)
+        else:
+            img.add_file(name, payload)
         img.flush()
         print(f"added {name} ({os.path.getsize(host)} bytes) to {image}")
         return 0