-- hp_trace.lua -- dynamic trace of the level-1 HOST PORT test.
--
-- Polls (per frame, via the address map so device side effects apply):
--   INTENB/INTPEND  (CPU I/O regs)
--   DUART1 ISR  (window 0x06400000 + reg 5 -> program space 0x06400050)
--   DUART1 SRA  (reg 1 -> 0x06400010)
--   DUART1 CRA read? no (write-only-ish); MR1A read ok (reg 0 -> 0x06400000)
-- DO NOT read reg 3 (RHRA) -- it pops the FIFO.
--
-- Also breaks at key PCs and logs registers.
--
--   HP_FRAMES=900 <mame> vt1200 ... -autoboot_script harness/mame/hp_trace.lua

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

if not dbg then print("ERROR: no debugger"); machine:exit(); return end

local rd = function(a) return prog:read_u16(a) end
local maxframes = tonumber(os.getenv("HP_FRAMES") or "900")
local n = 0

-- Frame polling: report changes and every 25 frames a compact snapshot.
local last = {}
local keys = {
  INTENB = 0xc0000110,
  INTPEND = 0xc0000120,
  D1_ISR = 0x06400050,   -- reg 5
  D1_SRA = 0x06400010,   -- reg 1
  D1_MR1 = 0x06400000,   -- reg 0
}
emu.register_frame_done(function()
  n = n + 1
  for name, addr in pairs(keys) do
    local v = rd(addr)
    if last[name] ~= v then
      print(string.format("f%4d %s CHANGED -> %04X", n, name, v))
      last[name] = v
    end
  end
  if n >= maxframes then
    print("done (" .. n .. " frames)")
    machine:exit()
  end
end, "vt1200-hp")

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