-- osprobe.lua -- observe the DUART1-IP3 gate and the OS cold-start.
--
-- Reports:
--   * whether the boot gate at 0x3F2042D0 takes the OS branch (0x3F2043B0)
--     instead of the level-1 runner (0x3F204400),
--   * whether the OS cold-start at 0x3F5788C0 is reached,
--   * a per-frame PC histogram so the parked PC (the first wall) is explicit.
--
--   <mame> vt1200 -rompath roms ... -debug -debugger none -debuglog \
--       -autoboot_script harness/mame/osprobe.lua -autoboot_delay 0
--   OS_FRAMES overrides the frame budget (default 3000).

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

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

-- Empirical: what memory does the driver actually give the CPU?
do
	local shares = machine.memory.shares
	local tags = {}
	for t, _ in pairs(shares) do tags[#tags + 1] = t end
	table.sort(tags)
	for _, t in ipairs(tags) do
		local s = shares[t]
		print(string.format("SHARE %s size=%d bytes bytewidth=%d length=%d",
			tostring(s.tag), s.size, s.bytewidth, s.length))
	end
end

local maxframes = tonumber(os.getenv("OS_FRAMES") or "3000")
local recent = tonumber(os.getenv("OS_RECENT") or "300")
local frames = 0
local hist = {}
local first = {}
local lastpc = 0
local rhist = {}
local rfirst = {}
local gate = { skip = 0, run = 0, os = 0 }

local function bp(addr, body)
	dbg:command('bpset ' .. addr .. ',,{ ' .. body .. ' ; g }')
end
bp("3f2043b0", 'printf "GATE-SKIP-BRANCH\\n"')
bp("3f204400", 'printf "GATE-RUN-LEVEL1\\n"')
bp("3f5788c0", 'printf "OS-COLD-START pc=%08X\\n", pc')
bp("3fdf72d0", 'printf "LEVEL1-RUNNER-ENTER\\n"')

emu.register_frame_done(function()
	frames = frames + 1
	if os.getenv("OS_TRACE") and frames == tonumber(os.getenv("OS_TRACE_AT") or "1") then
		dbg:command('trace ' .. os.getenv("OS_TRACE"))
		print("TRACE-ON " .. os.getenv("OS_TRACE"))
	end
	if os.getenv("OS_TRACE") and frames == (tonumber(os.getenv("OS_TRACE_AT") or "1") + tonumber(os.getenv("OS_TRACE_FRAMES") or "1")) then
		dbg:command('trace off')
		print("TRACE-OFF")
	end
	if os.getenv("OS_GLOBALS_AT") and frames == tonumber(os.getenv("OS_GLOBALS_AT")) then
		local p = cpu.spaces['program']
		for _, g in ipairs({0x23cbf0, 0x23cc50, 0x23cc30, 0x1b3900, 0x1e9420, 0x16f0}) do
			local v = p:read_u32(g)
			print(string.format("GLOBAL @%08X = %08X", g, v))
		end
		-- TMS34010 on-chip INTENB (0xC0000110): which external lines are enabled.
		print(string.format("INTENB = %04X", p:read_u16(0xc0000110)))
		-- DUART1 MR1A (reg0) and CSRA (reg2) are side-effect-free reads.
		print(string.format("DUART1 MR1A=%02X CSRA=%02X", p:read_u16(0x6400000) & 0xff, p:read_u16(0x6400020) & 0xff))
	end
	local v = pc.value
	hist[v] = (hist[v] or 0) + 1
	if not first[v] then first[v] = frames end
	lastpc = v
	if frames > maxframes - recent then
		rhist[v] = (rhist[v] or 0) + 1
		if not rfirst[v] then rfirst[v] = frames end
	end
	if frames >= maxframes then
		local n = 0
		for _ in pairs(hist) do n = n + 1 end
		print(string.format("--- frames=%d distinct_pcs=%d ---", frames, n))
		print("--- hottest PCs (one sample per frame) ---")
		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(20, #list) do
			print(string.format("  PC=%08X  samples=%d  first_frame=%d",
				list[i][1], list[i][2], first[list[i][1]]))
		end
		print(string.format("--- last frame PC=%08X ; last %d frames ---", lastpc, recent))
		local rlist = {}
		for k, c in pairs(rhist) do rlist[#rlist + 1] = { k, c } end
		table.sort(rlist, function(a, b) return a[2] > b[2] end)
		for i = 1, math.min(12, #rlist) do
			print(string.format("  PARK PC=%08X  samples=%d  first_frame=%d",
				rlist[i][1], rlist[i][2], rfirst[rlist[i][1]]))
		end
		machine:exit()
	end
end, "vt1200-osprobe")

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