-- wall_hist.lua -- where does the run END UP, and does it keep changing?
--
-- Samples the PC once per emulated frame but only counts the window
-- [W_START, W_END], so the early boot/test phases do not pollute the histogram
-- of the final state.  Prints a few timestamped PC snapshots so "stuck" is
-- supported by an across-time comparison, not one sample.
--
--   W_START=<frame>   default 5000
--   W_END=<frame>     default 20000
--   W_SNAP=<n>        snapshot stride (default 2000)
--   W_OUT=<file>      printable summary copy
--
--   <mame> vt1200 ... -debug -debugger none -debuglog \
--       VT1200_LOG_UNMAPPED=... VT1200_BOARD_LOG=... VT1200_DUARTLOG=... \
--       -autoboot_script harness/mame/wall_hist.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

local wstart = tonumber(os.getenv("W_START") or "5000")
local wend   = tonumber(os.getenv("W_END") or "20000")
local snap   = tonumber(os.getenv("W_SNAP") or "2000")

local frames = 0
local hist, first, last = {}, {}, {}

emu.register_frame_done(function()
	frames = frames + 1
	local v = cpu.state['PC'].value
	if frames >= wstart then
		hist[v] = (hist[v] or 0) + 1
		if not first[v] then first[v] = frames end
		last[v] = frames
	end
	if frames % snap == 0 then
		print(string.format("frame %6d  PC=%08X", frames, v))
	end
	if frames >= wend then
		local n = 0
		for _ in pairs(hist) do n = n + 1 end
		print(string.format("--- window [%d,%d]: distinct PCs=%d", wstart, wend, n))
		print("--- hottest PCs ---")
		local list = {}
		for k, c in pairs(hist) do list[#list + 1] = {k, c} end
		table.sort(list, function(a, b) return a[2] > b[2] end)
		for i = 1, math.min(25, #list) do
			print(string.format("  PC=%08X  samples=%d  first=%d  last=%d",
				list[i][1], list[i][2], first[list[i][1]], last[list[i][1]]))
		end
		machine:exit()
	end
end, "vt1200-wall")

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