harness: capture the firmware console; it reports LEVEL1/2 VIDEO MEMORY error 22 and restarts

harness/mame/cap.lua

@@ -0,0 +1,46 @@
+-- Capture the firmware's own console output.
+--
+-- The firmware prints through the routine at bit 0x3FDE00C0.  Every call site
+-- follows the same shape:
+--     movi <message pointer>, a9
+--     move a9, *a14+, 1
+--     calla 0x3fde00c0
+-- so at the ENTRY instruction a9 still holds the message pointer.  Breaking
+-- there and logging a9 gives us the firmware's console transcript -- which is
+-- how we learn which self-test is failing without being able to see the screen.
+--
+--   CAP_OUT=<file> CAP_MAX=<n> <mame> vt1200 ... -autoboot_script harness/mame/cap.lua
+
+local machine = manager.machine
+local cpu = machine.devices[':maincpu']
+local dbg = machine.debugger
+
+if not dbg then
+	print("ERROR: debugger not enabled; pass -debug")
+	machine:exit()
+	return
+end
+
+local out = os.getenv("CAP_OUT") or "/home/arti/code/k-space/vt1200/harness/mame/console.txt"
+local maxframes = tonumber(os.getenv("CAP_MAX") or "900")
+
+-- Pointers are BIT addresses; the image is byte-based at 0x07E40000, so a
+-- pointer P maps to file offset (P >> 3) - 0x07E40000.
+local PROG_BASE_BIT = 0x3F200000
+
+dbg:command('bpset 3fde00c0,,{ printf "PRINT pc=%08X a9=%08X\\n", pc, a9 ; g }')
+print("printer breakpoint armed at 3fde00c0")
+
+-- Also catch the error-report table entries, which are where a failing test
+-- lands.  Log the call target so we see which report fires.
+local n = 0
+emu.register_frame_done(function()
+	n = n + 1
+	if n >= maxframes then
+		print("done (" .. n .. " frames)")
+		machine:exit()
+	end
+end, "vt1200-cap")
+
+dbg.visible_cpu = cpu
+dbg.execution_state = 'run'