run.sh: tablet mode (skip + VSXXX-AB absolute pointing); lightgun options in COMMON, verified inert by frame-md5 A/B

harness/mame/run.sh

@@ -8,6 +8,8 @@
 #   ./run.sh headless [N]    no window; dump frame N (default 600) into this directory
 #   ./run.sh stub            faithful, plus an opt-in stand-in for the level-0
 #                            keyboard-port test fixture -> reaches level 1
+#   ./run.sh tablet          skip + VSXXX-AB tablet: interactive GUI with ABSOLUTE
+#                            pointing (the cursor follows the host pointer)
 #   ./run.sh <mode> -- <extra MAME options>
 #
 # Reboot the running machine with Shift+F3 (MAME's UI_RESET_MACHINE; plain F3 is a
@@ -28,6 +30,11 @@
 #         It is NOT a keyboard model: that test checks only the byte *count* and never
 #         compares the content, so the bytes are arbitrary.  It stands in for an
 #         unknown test fixture, and it is opt-in so the default stays honest.
+#   tablet selects the VSXXX-AB tablet instead of the mouse (VT1200_TABLET=1).  It is
+#         ABSOLUTE: the host pointer position maps directly to where the cursor is,
+#         rather than being integrated from deltas, and it does not grab the pointer.
+#         The mouse stays the default device.  Compose it with any mode by setting the
+#         variable yourself, e.g.  VT1200_TABLET=1 ./run.sh skip
 #
 # Modes other than 'headless' open a window at real speed, so you can watch.
 
@@ -53,8 +60,11 @@ if [ $# -gt 0 ]; then shift; fi
 
 usage() { awk 'NR>1 && /^set -euo pipefail/{exit} NR>1{print}' "$0"; }
 
-# common: correct rompath, no sound (the driver has no audio), no licence screen
-COMMON=(-rompath "$ROMPATH" -sound none -skip_gameinfo)
+# common: correct rompath, no sound (the driver has no audio), no licence screen.
+# The lightgun options give MAME an absolute host pointer for the VSXXX-AB tablet
+# (VT1200_TABLET=1); they are harmless when the tablet is not selected, and they do
+# NOT grab the pointer.
+COMMON=(-rompath "$ROMPATH" -sound none -skip_gameinfo -lightgun -lightgun_device mouse)
 
 case "$MODE" in
     faithful|"")
@@ -75,6 +85,16 @@ case "$MODE" in
             "$MAME" vt1200 "${COMMON[@]}" -window "$@"
         ;;
 
+    tablet)
+        # the useful combination: the OS is only reachable through the skip gate, and
+        # the tablet gives absolute pointing, so the cursor follows the host pointer
+        # positionally instead of through relative deltas.  The OS distinguishes tablet
+        # from mouse by the device-code nibble in its "T" self-test reply, and then
+        # frames 5-byte absolute reports (3-byte relative for the mouse).
+        exec env VT1200_SKIP_LEVEL1=1 VT1200_TABLET=1 \
+            "$MAME" vt1200 "${COMMON[@]}" -window "$@"
+        ;;
+
     pie)
         # `-debug -debugger none` is required: l1patch.lua needs the debugger API.
         exec env VT1200_L1PATCH=1 \