-- Is the firmware making forward progress, or orbiting a fixed set of addresses?
--
-- Samples the PC once per emulated frame and, every COV_WINDOW frames, reports
-- how many *new* PCs appeared in that window.  A plateau means a loop; a steady
-- trickle means it is still executing new code.
--
--   COV_FRAMES=3000 COV_WINDOW=100 <mame> vt1200 ... \
--       -autoboot_script harness/mame/coverage.lua -autoboot_delay 0

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

local maxframes = tonumber(os.getenv("COV_FRAMES") or "3000")
local window    = tonumber(os.getenv("COV_WINDOW") or "100")

local seen = {}
local frames, winnew, total = 0, 0, 0

emu.register_frame_done(function()
	frames = frames + 1
	local v = pc.value
	if not seen[v] then
		seen[v] = true
		winnew = winnew + 1
		total = total + 1
	end
	if frames % window == 0 then
		print(string.format("frame %5d  new=%4d  total_distinct=%5d  PC=%08X",
			frames, winnew, total, v))
		winnew = 0
	end
	if frames >= maxframes then
		machine:exit()
	end
end, "vt1200-coverage")

dbg.execution_state = 'run'