-- fontprobe.lua -- live values for the TFTP font-read capacity check.
--
-- Breaks inside the firmware's tftp_read (0x3f5ed230) at the point where the
-- per-datagram payload (a9) is compared with the buffer capacity (a11), and at
-- the error path.  Prints the frame, PC, a9 (payload), a11 (capacity) and the
-- accumulated total (dword at a13+8) so the "disk full" verdict can be read
-- directly rather than inferred.
--
--   FP_FRAMES=<n> budget (default 20000)
--   <mame> vt1200 ... -debug -debugger none -debuglog \
--       -autoboot_script harness/mame/fontprobe.lua -autoboot_delay 0

local machine = manager.machine
local dbg = machine.debugger
local cpu = machine.devices[':maincpu']

if not dbg then
	print("ERROR: debugger not enabled; pass -debug")
	machine:exit()
	return
end

FRAME = 0

-- tftp_read entry: dump the three arguments from the callee frame (a13-12/-8/-4)
dbg:command('bpset 3f5ed290,,{ printf "TFTP-ARGS fr=%d arg1(len)=%08X arg2(buf)=%08X arg3(sock)=%08X\\n", FRAME, d@(a13-12), d@(a13-8), d@(a13-4) ; g }')
-- capacity check, just after `cmp a11,a9` (a9 = payload, a11 = capacity)
dbg:command('bpset 3f5eed50,,{ printf "CHK fr=%d pc=%08X payload(a9)=%08X capacity(a11)=%08X a13=%08X [%08X %08X %08X | %08X %08X %08X]\\n", FRAME, PC, a9, a11, a13, d@(a13-12), d@(a13-8), d@(a13-4), d@(a13), d@(a13+4), d@(a13+8) ; g }')
-- error path just before the message is formatted (a9 = payload first arg, a11 = capacity second)
dbg:command('bpset 3f5eeda0,,{ printf "BUFSIZE-ERR fr=%d a9=%08X a11=%08X\\n", FRAME, a9, a11 ; g }')
-- ERROR code 3 being sent
dbg:command('bpset 3f5eee50,,{ printf "SEND-ERROR-3 fr=%d\\n", FRAME ; g }')
-- tftp_read entry, count calls
dbg:command('bpset 3f5ed230,,{ printf "TFTP-READ-ENTRY fr=%d a14=%08X\\n", FRAME, a14 ; g }')
-- received an ERROR packet from the peer
dbg:command('bpset 3f5edb30,,{ printf "GOT-ERROR-PKT fr=%d\\n", FRAME ; g }')

local maxframes = tonumber(os.getenv("FP_FRAMES") or "20000")
emu.register_frame_done(function()
	FRAME = FRAME + 1
	if FRAME % 2000 == 0 then
		print(string.format("frame %d PC=%08X", FRAME, cpu.state['PC'].value))
	end
	if FRAME >= maxframes then
		print("done (" .. FRAME .. " frames)")
		machine:exit()
	end
end, "vt1200-fp")

dbg.visible_cpu = cpu
dbg.execution_state = 'run'