-- load_mame.lua -- debugger entry for the Bad Apple payload.
--
-- Loads the payload at bit 0x018C0000 and the movie at bit 0x00080000, then
-- enters the payload at the OS idle loop.  This is the development path; the
-- real delivery path is tools/load.sh (rdebug + LANCE).
--
-- Env:
--   BA_MODE=one|play   (one is the only mode implemented here)
--   BA_MOVIE           movie file (default bad-apple/data/test_movie.bin)
--   BA_PAYLOAD         raw payload (default bad-apple/player/build/player.bin)
--   BA_ENV             player.env with ENTRY_PTR (default .../player.env)
--   BA_AT              load frame (default 2500)
--   BA_END             inspection/exit frame (default 2600)

local function hex(v, w)
    return string.format("%0" .. (w or 8) .. "X", v)
end

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

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

local ORIGIN = 0x018C0000
local MOVIE = tonumber(os.getenv("BA_MOVIE_BASE") or "0x01D00000")
local MARK = 0x01810000
local ENTRY_PC = 0x3F579970
local AT = tonumber(os.getenv("BA_AT") or "2500")
local STOP_AT = tonumber(os.getenv("BA_END") or "2600")
local START = tonumber(os.getenv("BA_START") or "0")
local COUNT = tonumber(os.getenv("BA_COUNT") or "0")
local PACE = tonumber(os.getenv("BA_PACE") or "0")
local WAIT = tonumber(os.getenv("BA_WAIT") or "0")
local MOVIE_PATH = os.getenv("BA_MOVIE") or "bad-apple/data/test_movie.bin"
local PAYLOAD_PATH = os.getenv("BA_PAYLOAD") or "bad-apple/player/build/player.bin"
local ENV_PATH = os.getenv("BA_ENV") or "bad-apple/player/build/player.env"

local function read_all(path)
    local f, err = io.open(path, "rb")
    if not f then
        print("BA ERROR: cannot open " .. path .. ": " .. tostring(err))
        machine:exit()
        return nil
    end
    local data = f:read("*a")
    f:close()
    return data
end

local function entry_from_env()
    local explicit = os.getenv("BA_ENTRY")
    if explicit then
        return tonumber(explicit)
    end
    local f = io.open(ENV_PATH, "r")
    if not f then
        return ORIGIN
    end
    for line in f:lines() do
        local value = line:match("ENTRY_PTR=0x(%x+)")
        if value then
            f:close()
            return tonumber(value, 16)
        end
    end
    f:close()
    return ORIGIN
end

local payload = read_all(PAYLOAD_PATH)
local movie = read_all(MOVIE_PATH)
if not payload or not movie then
    return
end
local entry = entry_from_env()
print(string.format("BA: payload %d bytes, movie %d bytes, entry %s",
    #payload, #movie, hex(entry)))

local function write_bytes(data, base)
    local i
    local n = #data
    i = 0
    while i + 4 <= n do
        local b0 = data:byte(i + 1)
        local b1 = data:byte(i + 2)
        local b2 = data:byte(i + 3)
        local b3 = data:byte(i + 4)
        local word = b0 | (b1 << 8) | (b2 << 16) | (b3 << 24)
        prog:write_u32(base + i * 8, word)
        i = i + 4
    end
    while i < n do
        prog:write_u8(base + i * 8, data:byte(i + 1))
        i = i + 1
    end
end

local function verify(data, base)
    local i
    for i = 0, #data - 1 do
        if prog:read_u8(base + i * 8) ~= data:byte(i + 1) then
            return false, i
        end
    end
    return true, 0
end

local loaded = false
local entered = false
local done = false
local movie_sent = false
local frames = 0

local function load_and_enter()
    write_bytes(payload, ORIGIN)
    local ok, bad = verify(payload, ORIGIN)
    if not ok then
        print("BA ERROR: payload readback mismatch at byte " .. bad)
        machine:exit()
        return
    end
    prog:write_u32(MARK + 0x20 * 8, START)
    prog:write_u32(MARK + 0x24 * 8, COUNT)
    prog:write_u32(MARK + 0x28 * 8, PACE)
    prog:write_u32(MARK + 0x2C * 8, MOVIE)
    prog:write_u32(MARK + 0x30 * 8, #movie)
    prog:write_u32(MARK + 0x34 * 8, WAIT)
    prog:write_u32(MARK + 0x38 * 8, 0)
    prog:write_u32(MARK + 0x3C * 8, 0)  -- debugger path, never network
    dbg:command("bpset " .. hex(ENTRY_PC) .. ",,{ pc = " .. hex(entry) .. " ; g }")
    if WAIT == 0 then
        write_bytes(movie, MOVIE)
        ok, bad = verify(movie, MOVIE)
        if not ok then
            print("BA ERROR: movie readback mismatch at byte " .. bad)
            machine:exit()
            return
        end
    end
    print(string.format("BA: loaded; start=%d count=%d pace=%d wait=%d",
        START, COUNT, PACE, WAIT))
end

emu.register_frame_done(function()
    frames = frames + 1
    if frames == AT and not loaded then
        loaded = true
        load_and_enter()
    end
    if loaded and WAIT == 1 and not movie_sent
        and prog:read_u16(MARK + 0x10 * 8) == 0x10 then
        movie_sent = true
        print("BA: takeover seen; sending movie to low RAM")
        write_bytes(movie, MOVIE)
        local ok, bad = verify(movie, MOVIE)
        if not ok then
            print("BA ERROR: movie readback mismatch at byte " .. bad)
            machine:exit()
            return
        end
        prog:write_u32(MARK + 0x38 * 8, 1)
        print("BA: movie ready")
    end
    if loaded and not entered then
        local status = prog:read_u16(MARK + 0x10 * 8)
        if status == 1 or status == 2 then
            entered = true
            done = true
            print(string.format("BA: STATUS=%d at frame %d; FRAME=%d",
                status, frames, prog:read_u16(MARK)))
        end
    end
    if loaded and not done and frames > AT + 10 then
        local err = prog:read_u32(MARK)
        if err >= 0xBAD00000 then
            print(string.format("BA ERROR: marker %s at frame %d",
                hex(err), frames))
            machine:exit()
        end
    end
    if frames >= STOP_AT then
        print(string.format("BA: end at frame %d (loaded=%s done=%s)",
            frames, tostring(loaded), tostring(done)))
        machine:exit()
    end
end, "vt1200-badapple-loader")

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