-- fonttrace.lua -- step-by-step trace of one TFTP font fetch.
--
-- Prints the control-flow milestones inside the firmware's TFTP client
-- (tftp_read 0x3f5ed230, tftp_open 0x3f5ebc40, tftp_close 0x3f5ec860) with the
-- key registers, so the reason a transfer is abandoned is read off the run
-- rather than inferred from the disassembly.
--
--   FT_FRAMES=<n> budget (default 20000)

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

dbg:command('bpset 3f5ed230,,{ printf "TFTP-ENTRY fr=%d a14=%08X\\n", FRAME, a14 ; g }')
dbg:command('bpset 3f5ed3f0,,{ printf "  EXPECTED->%d fr=%d\\n", a11, FRAME ; g }')
dbg:command('bpset 3f5ed690,,{ printf "  RECV ret=%08X fr=%d\\n", a8, FRAME ; g }')
dbg:command('bpset 3f5edb20,,{ printf "  OPCODE=%04X fr=%d\\n", a11, FRAME ; g }')
dbg:command('bpset 3f5ee3d0,,{ printf "  BLKREAD=%04X fr=%d\\n", a11, FRAME ; g }')
dbg:command('bpset 3f5ee420,,{ printf "  BLKCHK blk=%04X exp=%08X fr=%d\\n", a11, a9, FRAME ; g }')
dbg:command('bpset 3f5ee720,,{ printf "  ->ACK/send path fr=%d\\n", FRAME ; g }')
dbg:command('bpset 3f5eeae0,,{ printf "  SEND-RET a8=%08X a11=%08X fr=%d\\n", a8, a11, FRAME ; g }')
dbg:command('bpset 3f5eecf0,,{ printf "  COPY reclen=%08X fr=%d\\n", a9, FRAME ; g }')
dbg:command('bpset 3f5ef090,,{ printf "  READ-RET a8=%08X fr=%d\\n", a8, FRAME ; g }')
dbg:command('bpset 3f5ec750,,{ printf "OPEN-OK fr=%d\\n", FRAME ; g }')
dbg:command('bpset 3f5ec860,,{ printf "CLOSE fr=%d\\n", FRAME ; g }')
dbg:command('bpset 3f5ecd10,,{ printf "  CLOSE->ERROR3 fr=%d\\n", FRAME ; g }')

local maxframes = tonumber(os.getenv("FT_FRAMES") or "20000")
emu.register_frame_done(function()
	FRAME = FRAME + 1
	if FRAME >= maxframes then
		print("done (" .. FRAME .. " frames)")
		machine:exit()
	end
end, "vt1200-ft")

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