raze/polymer/eduke32/source/lunatic/defs.ilua

-- INTERNAL
-- definitions of BUILD and game types for the Lunatic Interpreter

local require = require
local ffi = require("ffi")
local ffiC = ffi.C

local bit = bit
local string = string
local table = table
local math = math

local assert = assert
local error = error
local ipairs = ipairs
local loadstring = loadstring
local pairs = pairs
local rawget = rawget
local rawset = rawset
local setmetatable = setmetatable
local setfenv = setfenv
local tonumber = tonumber
local tostring = tostring
local type = type

-- The "gv" global will provide access to C global *scalars* and safe functions.
-- NOTE: This exposes C library functions from e.g. the global C namespace, but
-- without their declarations, they will be sitting there like a stone.
local gv_ = {}
-- [key]=<boolean> forbids, [key]=<non-boolean (e.g. table, function)> overrides
local gv_access = {}

-- This is for declarations of arrays or pointers which should not be
-- accessible through the "gv" global. The "defs_common" module will
-- use this function.
--
-- Notes: do not declare multiple scalars on one line (this is bad:
-- "int32_t a, b"). Do not name array arguments (or add a space
-- between the identifier and the '[' instead).
function decl(str, ...)
    -- NOTE that the regexp also catches non-array/non-function identifiers
    -- like "user_defs ud;"
    for varname in string.gmatch(str, "([%a_][%w_]*)[[(;]") do
        if (ffiC._DEBUG_LUNATIC ~= 0) then
            print("FORBID "..varname)
        end
        gv_access[varname] = true
    end

    ffi.cdef(str, ...)
end

-- Load the definitions common to the game's and editor's Lua interface.
local defs_c = require("defs_common")
local cansee = defs_c.cansee
local strip_const = defs_c.strip_const
local setmtonce = defs_c.setmtonce

-- Must be after loading "defs_common" which redefines "print" to use
-- OSD_Printf()
local print = print


---=== EDuke32 game definitions ===---

local INV_NAMES = {
    "STEROIDS",
    "SHIELD",
    "SCUBA",
    "HOLODUKE",
    "JETPACK",
    "DUMMY1",
    "ACCESS",
    "HEATS",
    "DUMMY2",
    "FIRSTAID",
    "BOOTS",
}

local WEAPON_NAMES = {
    "KNEE",
    "PISTOL",
    "SHOTGUN",
    "CHAINGUN",
    "RPG",
    "HANDBOMB",
    "SHRINKER",
    "DEVISTATOR",
    "TRIPBOMB",
    "FREEZE",
    "HANDREMOTE",
    "GROW",
}

---- game structs ----
ffi.cdef([[
enum dukeinv_t {
]].. "GET_"..table.concat(INV_NAMES, ",GET_") ..[[,
    GET_MAX
};

enum dukeweapon_t {
]].. table.concat(WEAPON_NAMES, "_WEAPON,").."_WEAPON," ..[[
    MAX_WEAPONS
};

enum {
    MAXPLAYERS = 16,
};
]])

ffi.cdef[[
struct action {
    int16_t startframe, numframes;
    int16_t viewtype, incval, delay;
};

struct move {
    int16_t hvel, vvel;
};

#pragma pack(push,1)
typedef struct { int32_t id; struct move mv; } con_move_t;
typedef struct { int32_t id; struct action ac; } con_action_t;
#pragma pack(pop)

typedef struct {
    int32_t id;
    con_action_t act;
    con_move_t mov;
    int32_t movflags;
} con_ai_t;
]]

-- Struct template for actor_t. It already has 'const' fields (TODO: might need
-- to make more 'const'), but still has array members exposed, so is unsuited
-- for external exposure.
local ACTOR_STRUCT = [[
__attribute__((packed)) struct {
    const int32_t t_data[10];  // 56b sometimes used to hold offsets to con code
    const struct move mv;
    const struct action ac;
    const int16_t _padding[1];

    int32_t flags; //4b
    vec3_t bpos; //12b
    int32_t floorz,ceilingz,lastvx,lastvy; //16b
    int32_t lasttransport; //4b

    const int16_t picnum;
    int16_t ang, extra;
    const int16_t owner;
    int16_t movflag,tempang,timetosleep; //6b

    int16_t actorstayput;
    const int16_t dispicnum;
    int16_t shootzvel, cgg;

    const int16_t lightId, lightcount, lightmaxrange;
    const union { intptr_t ptr; uint64_t dummy; } _light;
}
]]

local bcarray = require("bcarray")

local bcheck = require("bcheck")
local check_sector_idx, check_tile_idx = bcheck.sector_idx, bcheck.tile_idx
local check_sprite_idx = bcheck.sprite_idx
local check_weapon_idx, check_inventory_idx = bcheck.weapon_idx, bcheck.inventory_idx
local check_sound_idx = bcheck.sound_idx

bcarray.new("int16_t", 64, "loogie", "int16_x_64")  -- TODO: randomize member names
bcarray.new("int16_t", ffiC.MAX_WEAPONS, "weapon", "int16_x_MAX_WEAPONS", WEAPON_NAMES)
bcarray.new("int16_t", ffiC.GET_MAX, "inventory", "int16_x_GET_MAX", INV_NAMES)

-- NOTE: writing e.g. "ps.jetpack_on" in Lua when "ps.jetpack_on~=0" was meant
-- is probably one of the most commonly committed errors, so we make it a bool
-- type instead of uint8_t. The only issue is that if CON coders used these
-- fields to store more than just one bit, we're in trouble.
-- This will need to be documented and frozen for release.
local DUKEPLAYER_STRUCT = [[
__attribute__((packed)) struct {
    vec3_t pos, opos, vel, npos;
    int32_t bobposx, bobposy;
    int32_t truefz, truecz, player_par;
    int32_t randomflamex, exitx, exity;
    int32_t runspeed, max_player_health, max_shield_amount;
    int32_t autostep, autostep_sbw;

    uint32_t interface_toggle_flag;

    int32_t pipebombControl, pipebombLifetime, pipebombLifetimeVar;
    int32_t tripbombControl, tripbombLifetime, tripbombLifetimeVar;

    int32_t zrange;
    int16_t angrange, autoaimang;

    uint16_t max_actors_killed, actors_killed;
    uint16_t gotweapon, zoom;

    int16_x_64 loogiex;
    int16_x_64 loogiey;
    int16_t sbs, sound_pitch;

    int16_t ang, oang, angvel;
    const int16_t cursectnum;
    int16_t look_ang, last_extra, subweapon;
    int16_x_MAX_WEAPONS max_ammo_amount;
    int16_x_MAX_WEAPONS ammo_amount;
    int16_x_GET_MAX inv_amount;
    int16_t wackedbyactor, pyoff, opyoff;

    int16_t horiz, horizoff, ohoriz, ohorizoff;
    const int16_t newowner;
    int16_t jumping_counter, airleft;
    int16_t fta;
    const int16_t ftq, access_wallnum, access_spritenum;
    int16_t got_access, weapon_ang, visibility;
    int16_t somethingonplayer, on_crane;
    const int16_t i;
    const int16_t one_parallax_sectnum;
    int16_t random_club_frame, one_eighty_count;
    const int16_t dummyplayersprite;
    int16_t extra_extra8;
    int16_t actorsqu, timebeforeexit;
    const int16_t customexitsound;
    int16_t last_pissed_time;

    int16_x_MAX_WEAPONS weaprecs;
    int16_t weapon_sway, crack_time, bobcounter;

    int16_t orotscrnang, rotscrnang, dead_flag;   // JBF 20031220: added orotscrnang
    int16_t holoduke_on, pycount;
    int16_t transporter_hold;

    uint8_t max_secret_rooms, secret_rooms;
    uint8_t frag, fraggedself, quick_kick, last_quick_kick;
    uint8_t return_to_center;
    bool reloading;
    const uint8_t weapreccnt;
    uint8_t aim_mode, auto_aim, weaponswitch, movement_lock, team;
    uint8_t tipincs, hbomb_hold_delay, frag_ps, kickback_pic;

    uint8_t gm;
    bool on_warping_sector;
    uint8_t footprintcount, hurt_delay;
    bool hbomb_on, jumping_toggle, rapid_fire_hold, on_ground;
    // NOTE: there's array indexing with inven_icon, but always after a
    // bound check:
    uint8_t inven_icon, buttonpalette;
    bool over_shoulder_on;
    uint8_t show_empty_weapon;

    bool jetpack_on, spritebridge;
    uint8_t lastrandomspot;  // unused
    bool scuba_on;
    uint8_t footprintpal;
    bool heat_on;
    uint8_t invdisptime;

    bool holster_weapon;
    uint8_t falling_counter, footprintshade;
    uint8_t refresh_inventory, last_full_weapon;

    bool toggle_key_flag;
    uint8_t knuckle_incs, knee_incs, access_incs;
    uint8_t walking_snd_toggle, palookup, hard_landing, fist_incs;

    int8_t numloogs, loogcnt, scream_voice;
    int8_t last_weapon, cheat_phase, weapon_pos, wantweaponfire;
    const int8_t curr_weapon;

    uint8_t palette;
    palette_t _pals;

    // NOTE: In C, the struct type has no name. We only have it here to define
    // a metatype later.
    const weaponaccess_t weapon;
    const int8_t _padding;
}
]]

local PROJECTILE_STRUCT = [[
struct {
    int32_t workslike, cstat;
    int32_t hitradius, range, flashcolor;
    const int16_t spawns;
    int16_t sound, isound, vel;
    const int16_t decal, trail;
    int16_t tnum, drop;
    int16_t offset, bounces, bsound;
    int16_t toffset;
    int16_t extra, extra_rand;
    int8_t sxrepeat, syrepeat, txrepeat, tyrepeat;
    int8_t shade, xrepeat, yrepeat, pal;
    int8_t movecnt;
    uint8_t clipdist;
    int8_t filler[6];
}
]]

-- KEEPINSYNC weapondata_mt below.
local WEAPONDATA_STRUCT = "struct {"..table.concat(con_lang.wdata_members, ';').."; }"

local randgen = require("randgen")
local geom = require("geom")

local ma_rand = randgen.new(true)  -- initialize to "random" (time-based) seed
local ma_count = nil

local function ma_replace_array(typestr, neltstr)
    local nelts = tonumber(neltstr)
    if (nelts==nil) then
        nelts = ffiC[neltstr]
        assert(type(nelts)=="number")
    end

    local strtab = { "const ", typestr.." " }
    for i=1,nelts do
        local ch1 = 97 + (ma_rand:getu32() % 25)  -- 'a'..'z'
        strtab[i+2] = string.format("_%c%x%s", ch1, ma_count, (i<nelts) and "," or ";")
        ma_count = ma_count+1
    end

    return table.concat(strtab)
end

-- Converts a template struct definition to an external one, in which arrays
-- have been substituted by randomly named scalar fields.
local function mangle_arrays(structstr)
    ma_count = 0
    -- NOTE: regexp only works for non-nested arrays and for one array per line.
    return (string.gsub(structstr, "const%s+([%w_]+)[^\n]+%[([%w_]+)%];", ma_replace_array))
end

--print(mangle_arrays(ACTOR_STRUCT))

--- default defines etc.
local con_lang = require("con_lang")

ffi.cdef([[
typedef struct { int32_t _p; } weaponaccess_t;

typedef struct {
    uint32_t bits; // 4b
    int16_t fvel, svel; // 4b
    int8_t avel, horz; // 2b
    int8_t extbits, filler; // 2b
} input_t;

typedef
]].. mangle_arrays(ACTOR_STRUCT) ..[[
actor_t;

typedef
]].. mangle_arrays(DUKEPLAYER_STRUCT) ..[[
DukePlayer_t;

typedef __attribute__((packed)) struct {
    DukePlayer_t *ps;
    input_t *sync;

    int32_t netsynctime;
    int16_t ping, filler;
    int32_t pcolor, pteam;
    uint8_t frags[MAXPLAYERS], wchoice[MAX_WEAPONS];

    char vote, gotvote, pingcnt, playerquitflag, ready;
    char user_name[32];
    uint32_t revision;
} playerdata_t;

typedef struct {
    int32_t cur, count;
    int32_t gunposx, lookhalfang;
    int32_t gunposy, lookhoriz;
    int32_t shade;
} hudweapon_t;

typedef
]].. WEAPONDATA_STRUCT ..[[
weapondata_t;

typedef
]].. PROJECTILE_STRUCT ..[[
projectile_t;

typedef struct {
    uint32_t flags;  // XXX: do we want to have this accessible at game time?
    const int32_t _cacherange;
    const projectile_t _defproj;
} tiledata_t;

typedef struct {
    vec3_t pos;
    int32_t dist, clock;
    int16_t ang, horiz;
    int16_t sect;
} camera_t;

enum
{
    MAXMOUSEBUTTONS = 10,
    MAXMOUSEAXES = 2,
    MAXJOYBUTTONS = (32+4),
    MAXJOYAXES = 8,
    NUMGAMEFUNCTIONS = 56,
};

typedef struct {
    int32_t const_visibility,uw_framerate;
    int32_t camera_time,folfvel,folavel,folx,foly,fola;
    int32_t reccnt,crosshairscale;

    int32_t runkey_mode,statusbarscale,mouseaiming,weaponswitch,drawweapon;   // JBF 20031125
    int32_t democams,color,msgdisptime,statusbarmode;
    int32_t m_noexits,noexits,autovote,automsg,idplayers;
    int32_t team, viewbob, weaponsway, althud, weaponscale, textscale;

    int32_t entered_name,screen_tilting,shadows,fta_on,executions,auto_run;
    int32_t coords,tickrate,levelstats,m_coop,coop,screen_size,lockout,crosshair;
    int32_t playerai,angleinterpolation,obituaries;

    int32_t respawn_monsters,respawn_items,respawn_inventory,recstat,monsters_off,brightness;
    int32_t m_respawn_items,m_respawn_monsters,m_respawn_inventory,m_recstat,m_monsters_off,detail;
    int32_t m_ffire,ffire,m_player_skill,m_level_number,m_volume_number,multimode;
    int32_t player_skill,level_number,volume_number,m_marker,marker,mouseflip;

    int32_t configversion;

    int16_t pause_on,from_bonus;
    int16_t camerasprite,last_camsprite;
    int16_t last_level,secretlevel, bgstretch;

    struct {
        int32_t UseJoystick;
        int32_t UseMouse;
        int32_t AutoAim;
        int32_t ShowOpponentWeapons;
        int32_t MouseDeadZone,MouseBias;
        int32_t SmoothInput;

        // JBF 20031211: Store the input settings because
        // (currently) jmact can't regurgitate them
        int32_t MouseFunctions[MAXMOUSEBUTTONS][2];
        int32_t MouseDigitalFunctions[MAXMOUSEAXES][2];
        int32_t MouseAnalogueAxes[MAXMOUSEAXES];
        int32_t MouseAnalogueScale[MAXMOUSEAXES];
        int32_t JoystickFunctions[MAXJOYBUTTONS][2];
        int32_t JoystickDigitalFunctions[MAXJOYAXES][2];
        int32_t JoystickAnalogueAxes[MAXJOYAXES];
        int32_t JoystickAnalogueScale[MAXJOYAXES];
        int32_t JoystickAnalogueDead[MAXJOYAXES];
        int32_t JoystickAnalogueSaturate[MAXJOYAXES];
        uint8_t KeyboardKeys[NUMGAMEFUNCTIONS][2];

        //
        // Sound variables
        //
        int32_t FXDevice;
        int32_t MusicDevice;
        int32_t FXVolume;
        int32_t MusicVolume;
        int32_t SoundToggle;
        int32_t MusicToggle;
        int32_t VoiceToggle;
        int32_t AmbienceToggle;

        int32_t NumVoices;
        int32_t NumChannels;
        int32_t NumBits;
        int32_t MixRate;

        int32_t ReverseStereo;

        //
        // Screen variables
        //

        int32_t ScreenMode;

        int32_t ScreenWidth;
        int32_t ScreenHeight;
        int32_t ScreenBPP;

        int32_t ForceSetup;
        int32_t NoAutoLoad;

        const int32_t scripthandle;
        int32_t setupread;

        int32_t CheckForUpdates;
        int32_t LastUpdateCheck;
        int32_t useprecache;
    } config;

    char overhead_on,last_overhead,showweapons;
    char god,warp_on,cashman,eog,showallmap;
    char show_help,scrollmode,noclip;
    char ridecule[10][40];
    char savegame[10][22];
    char pwlockout[128],rtsname[128];
    char display_bonus_screen;
    char show_level_text;
} user_defs;

typedef struct {
    int32_t partime, designertime;
    char *name, *filename, *musicfn, *alt_musicfn;
    void *savedstate;
} map_t;
]])

-- EXTERNALLY EXPOSED GAME VARIABLES
ffi.cdef[[
const int32_t screenpeek;
hudweapon_t hudweap;
int32_t g_logoFlags;
]]

-- INTERNAL VARIABLES/FUNCTIONS
decl("map_t MapInfo[$*$];", con_lang.MAXVOLUMES+1, con_lang.MAXLEVELS)

decl[[
const char *s_buildRev;
const char *g_sizes_of_what[];
int32_t g_sizes_of[];
int32_t g_elCallDepth;
int32_t g_elEventRETURN;
const char **g_argv;
char g_modDir[];
actor_t actor[MAXSPRITES];
camera_t g_camera;
user_defs ud;
playerdata_t g_player[MAXPLAYERS];
DukePlayer_t *g_player_ps[MAXPLAYERS];
weapondata_t g_playerWeapon[MAXPLAYERS][MAX_WEAPONS];
tiledata_t g_tile[MAXTILES];
projectile_t ProjectileData[MAXTILES];
projectile_t SpriteProjectile[MAXSPRITES];

// Used from lunacon.lua for dynamic tile remapping:
struct
{
    const char *str;
    int32_t *dynvalptr;
    const int16_t staticval;
} g_dynTileList[];

char *ScriptQuotes[];

const int32_t playerswhenstarted;
int32_t lastvisinc;
int16_t g_spriteDeleteQueueSize;
int16_t BlimpSpawnSprites[15];
int32_t g_scriptVersion;
const int32_t g_currentFrameRate;
const int32_t g_currentMenu;
uint16_t g_earthquakeTime;
char CheatKeys[2];

// Must not have functions here that may call events directly or
// indirectly. See lunatic_game.c.

int32_t A_IncurDamage(int32_t sn);  // not bound-checked!
int32_t G_CheckActivatorMotion(int32_t lotag);
int32_t A_Dodge(spritetype *s);
int32_t A_MoveSprite(int32_t spritenum, const vec3_t *change, uint32_t cliptype);
void P_DoQuote(int32_t q, DukePlayer_t *p);
void P_SetGamePalette(DukePlayer_t *player, uint8_t palid, int32_t set);
void G_AddUserQuote(const char *daquote);
void G_ClearCameraView(DukePlayer_t *ps);
void G_DrawTileGeneric(int32_t x, int32_t y, int32_t zoom, int32_t tilenum,
                       int32_t shade, int32_t orientation, int32_t p);
void G_InitTimer(int32_t ticspersec);
void G_GetTimeDate(int32_t *vals);
int32_t G_ToggleWallInterpolation(int32_t w, int32_t doset);
int32_t G_StartTrack(int32_t level);

const char *KB_ScanCodeToString(uint8_t scancode);

int32_t A_CheckAnySoundPlaying(int32_t i);
int32_t S_CheckSoundPlaying(int32_t i, int32_t num);
void S_StopEnvSound(int32_t num, int32_t i);
int32_t FX_StopAllSounds(void);
void S_ChangeSoundPitch(int32_t num, int32_t i, int32_t pitchoffset);

int32_t minitext_(int32_t x,int32_t y,const char *t,int32_t s,int32_t p,int32_t sb);
void G_DrawTXDigiNumZ(int32_t starttile, int32_t x,int32_t y,int32_t n,int32_t s,int32_t pal,
                      int32_t cs,int32_t x1, int32_t y1, int32_t x2, int32_t y2, int32_t z);
int32_t G_PrintGameText(int32_t f,  int32_t tile, int32_t x,  int32_t y,  const char *t,
                        int32_t s,  int32_t p,    int32_t o,
                        int32_t x1, int32_t y1,   int32_t x2, int32_t y2, int32_t z);
]]

decl[[
int32_t kopen4loadfrommod(const char *filename, char searchfirst);
int32_t kfilelength(int32_t handle);
void kclose(int32_t handle);
int32_t kread(int32_t handle, void *buffer, int32_t leng);

char **g_scriptModules;
int32_t g_scriptModulesNum;

const char *G_ConFile(void);
void G_DoGameStartup(const int32_t *params);
int32_t C_DefineSound(int32_t sndidx, const char *fn, int32_t args [5]);
void C_DefineMusic(int32_t vol, int32_t lev, const char *fn);
void C_DefineQuote(int32_t qnum, const char *qstr);
void C_DefineVolumeName(int32_t vol, const char *name);
void C_DefineSkillName(int32_t skill, const char *name);
void C_DefineLevelName(int32_t vol, int32_t lev, const char *fn,
                       int32_t partime, int32_t designertime,
                       const char *levelname);
void C_DefineProjectile(int32_t j, int32_t what, int32_t val);
void C_DefineGameFuncName(int32_t idx, const char *name);
int32_t C_SetDefName(const char *name);

int32_t SCRIPT_GetNumber(int32_t scripthandle, const char *sectionname, const char *entryname, int32_t *number);
void SCRIPT_PutNumber(int32_t scripthandle, const char *sectionname, const char *entryname, int32_t number,
                      int32_t hexadecimal, int32_t defaultvalue);
]]


-- http://lua-users.org/wiki/SandBoxes says "potentially unsafe"
-- as it allows to see implementations of functions.
--local string_dump = string.dump
string.dump = nil


-- sanity-check struct type sizes
local good = true
for i=0,8 do
    local what = ffi.string(ffiC.g_sizes_of_what[i])
    local fsz = ffi.sizeof(what)
    local csz = ffiC.g_sizes_of[i]
    if (ffiC._DEBUG_LUNATIC ~= 0) then
        print(i..": "..what..": C sizeof = "..tostring(csz)..", FFI sizeof = "..tostring(fsz))
    end
    if (fsz ~= csz) then
        good = false;
    end
end

if (not good) then
    error("Some sizes don't match between C and LuaJIT/FFI.")
end


--== "player" global, needed by the "control" module ==--

local player_static_members = {}

player_static_members.INPUT_BITS = defs_c.conststruct
{
    JUMP =                      1,
    CROUCH =                    2,
    FIRE =                      4,
    AIM_UP =                    8,
    AIM_DOWN =                 16,
    RUNNING =                  32,
    LOOK_LEFT =                64,
    LOOK_RIGHT =              128,
    -- weapons...
    STEROIDS =               4096,
    LOOK_UP =                8192,
    LOOK_DOWN =             16384,
    NIGHTVISION =           32768,
    MEDKIT =                65536,
    RESERVED =             131072,
    CENTER_VIEW =          262144,
    HOLSTER_WEAPON =       524288,
    INVENTORY_LEFT =      1048576,
    PAUSE =               2097152,
    QUICK_KICK =          4194304,
    AIM_MODE =            8388608,
    HOLODUKE =           16777216,
    JETPACK =            33554432,
    QUIT =               67108864,
    INVENTORY_RIGHT =   134217728,
    TURN_AROUND =       268435456,
    OPEN =              536870912,
    INVENTORY =        1073741824,
    ESC =              2147483648,
}

player_static_members.INPUT_EXT_BITS = defs_c.conststruct
{
    INPUT_MOVE_FORWARD =  1,
    INPUT_MOVE_BACKWARD = 2,
    INPUT_STRAFE_LEFT =   4,
    INPUT_STRAFE_RIGHT =  8,
    INPUT_TURN_LEFT =    16,
    INPUT_TURN_RIGHT =   32,
}

local tile_static_members = {}
tile_static_members.sizx = defs_c.creategtab(ffiC.tilesizx, ffiC.MAXTILES, "tilesizx[]")
tile_static_members.sizy = defs_c.creategtab(ffiC.tilesizy, ffiC.MAXTILES, "tilesizy[]")

-- XXX: error message will say "g_player_ps"
player = setmtonce({}, defs_c.GenStructMetatable("g_player_ps", "playerswhenstarted", player_static_members))

-- needed by "control"
actor = defs_c.creategtab(ffiC.actor, ffiC.MAXSPRITES, "actor[]")

local projectile = defs_c.creategtab(ffiC.ProjectileData, ffiC.MAXTILES, "projectile[]")
local g_tile = setmtonce({}, defs_c.GenStructMetatable("g_tile", "MAXTILES", tile_static_members))

--== Custom operations for BUILD data structures ==--
-- Among other things, declares struct action and struct move, and their
-- ID-wrapped types con_action_t and con_move_t
local con = require("control")
local MV, AC, AI = con.MV, con.AC, con.AI

-- Add game-side metamethods to "spritetype" and register it with "metatype"
local spr_mt_index_add = {
    isenemy = function(s)
        return con.isenemytile(s.picnum)
    end,
}
defs_c.finish_spritetype(spr_mt_index_add)

-- All-zero action and move
local nullac, nullmv = ffi.new("const struct action"), ffi.new("const struct move")

local function check_literal_am(am, typename)
    if (type(am) ~= "number") then
        error("bad argument: expected number or "..typename, 3)
    end

    if (not (am >= 0 and am <= 32767)) then
        error("bad argument: expected number in [0 .. 32767]", 3)
    end
end

-- An unrestricted actor_t pointer, for internal use:
local actor_ptr_ct = ffi.typeof("$ *", ffi.typeof(strip_const(ACTOR_STRUCT)))
local player_ptr_ct = ffi.typeof("$ *", ffi.typeof(strip_const(DUKEPLAYER_STRUCT)))
local projectile_ptr_ct = ffi.typeof("$ *", ffi.typeof(strip_const(PROJECTILE_STRUCT)))
local weapondata_ptr_ct = ffi.typeof("$ *", ffi.typeof((strip_const(WEAPONDATA_STRUCT):gsub(" _"," "))))
local con_action_ct = ffi.typeof("con_action_t")
local con_move_ct = ffi.typeof("con_move_t")
local con_ai_ct = ffi.typeof("con_ai_t")

local function get_actor_idx(a)
    local i = ffi.cast(actor_ptr_ct, a)-ffi.cast(actor_ptr_ct, ffiC.actor)
    assert(not (i >= ffiC.MAXSPRITES+0ULL))
    return i
end

local actor_mt = {
    __index = {
        -- action
        set_action = function(a, act)
            a = ffi.cast(actor_ptr_ct, a)
            if (type(act)=="string") then
                act = AC[act];
            end
            -- TODO: disallow passing the FFI types altogether, in favor of
            -- strings (also move, ai)?
            if (ffi.istype(con_action_ct, act)) then
                a.t_data[4] = act.id
                a.ac = act.ac
            else
                check_literal_am(act, "action")
                a.t_data[4] = act
                a.ac = nullac
            end

            a.t_data[2] = 0
            a.t_data[3] = 0
        end,

        has_action = function(a, act)
            a = ffi.cast(actor_ptr_ct, a)
            if (type(act)=="string") then
                act = AC[act];
            end
            if (ffi.istype(con_action_ct, act)) then
                return (a.t_data[4]==act.id)
            else
                check_literal_am(act, "action")
                return (a.t_data[4]==act)
            end
        end,

        -- count
        set_count = function(a)
            ffi.cast(actor_ptr_ct, a).t_data[0] = 0
        end,

        get_count = function(a)
            return ffi.cast(actor_ptr_ct, a).t_data[0]
        end,

        -- action count
        reset_acount = function(a)
            ffi.cast(actor_ptr_ct, a).t_data[2] = 0
        end,

        get_acount = function(a)
            return ffi.cast(actor_ptr_ct, a).t_data[2]
        end,

        -- move
        set_move = function(a, mov, movflags)
            a = ffi.cast(actor_ptr_ct, a)
            if (type(mov)=="string") then
                mov = MV[mov];
            end
            if (ffi.istype(con_move_ct, mov)) then
                a.t_data[1] = mov.id
                a.mv = mov.mv
            else
                check_literal_am(mov, "move")
                a.t_data[1] = mov
                a.mv = nullmv
            end

            a.t_data[0] = 0
            local i = get_actor_idx(a)
            ffiC.sprite[i].hitag = movflags or 0

            -- TODO: random angle moveflag
        end,

        has_move = function(a, mov)
            a = ffi.cast(actor_ptr_ct, a)
            if (type(mov)=="string") then
                mov = MV[mov];
            end
            if (ffi.istype(con_move_ct, mov)) then
                return (a.t_data[1]==mov.id)
            else
                check_literal_am(mov, "move")
                return (a.t_data[1]==mov)
            end
        end,

        -- ai
        set_ai = function(a, ai)
            local oa = a
            a = ffi.cast(actor_ptr_ct, a)

            if (type(ai)=="string") then
                ai = AI[ai];
            end
            -- TODO: literal number AIs?
            if (not ffi.istype(con_ai_ct, ai)) then
                error("bad argument: expected ai", 2)
            end

            -- NOTE: compare with gameexec.c
            a.t_data[5] = ai.id

            oa:set_action(ai.act)
            oa:set_move(ai.mov, ai.movflags)

            a.t_data[0] = 0
        end,

        has_ai = function(a, ai)
            a = ffi.cast(actor_ptr_ct, a)

            if (type(ai)=="string") then
                ai = AI[ai];
            end
            if (ffi.istype(con_ai_ct, ai)) then
                return (a.t_data[5]==ai.id)
            else
                check_literal_am(ai, "ai")
                return (a.t_data[5]==ai)
            end
        end,

        -- Getters/setters.
        -- TODO: make a bcarray instead.
        get_t_data = function(a, idx)
            if (idx >= 10ULL) then
                error("Invalid t_data index "..idx, 2)
            end
            return ffi.cast(actor_ptr_ct, a).t_data[idx]
        end,

        _set_t_data = function(a, idx, val)
            if (idx >= 10ULL) then
                error("Invalid t_data index "..idx, 2)
            end
            ffi.cast(actor_ptr_ct, a).t_data[idx] = val
        end,

        set_picnum = function(a, picnum)
            check_tile_idx(picnum)
            ffi.cast(actor_ptr_ct, a).picnum = picnum
        end,

        set_owner = function(a, owner)
            -- XXX: is it permissible to set to -1?
            check_sprite_idx(owner)
            ffi.cast(actor_ptr_ct, a).owner = owner
        end,
    },
}

local function actor_index_index(a, key)
    -- actor[].proj gets an actor's projectile ([gs]etthisprojectile in CON)
    if (key=="proj") then
        return ffiC.SpriteProjectile[get_actor_idx(a)]
    end
end

setmtonce(actor_mt.__index, { __index = actor_index_index })
ffi.metatype("actor_t", actor_mt)


--- PER-PLAYER WEAPON SETTINGS
local weapondata_mt = {
    __newindex = function(wd, member, val)
        if (string.match(member, "sound")) then
            if (val < 0) then
                val = 0  -- Set to 0 if oob (e.g. CrackDown).
            else
                check_sound_idx(val)
            end
        elseif (member=="workslike") then
            check_weapon_idx(val)
        elseif (member=="spawn" or member=="shoots") then
            if (val < 0) then
                -- Set to 0 if oob (e.g. CrackDown). This is a bit problematic
                -- for .shoots because it's used unconditionally except in one
                -- case (see player.c).
                val = 0
            else
                check_tile_idx(val)
            end
        end

        ffi.cast(weapondata_ptr_ct, wd)[member] = val
    end,
}
ffi.metatype("weapondata_t", weapondata_mt)

local weaponaccess_mt = {
    -- Make syntax like "player[0].weapon.KNEE.shoots" possible
    __index = function(wa, key)
        if (type(key)=="number") then
            check_weapon_idx(key)
            return ffiC.g_playerWeapon[wa._p][key]
        end

        return ffiC.g_playerWeapon[wa._p][ffiC[key.."_WEAPON"]]
    end,
}
ffi.metatype("weaponaccess_t", weaponaccess_mt)

local player_mt = {
    __index = {
        --- Getters/setters
        get_ammo_amount = function(p, weap)
            return p.ammo_amount[weap]
        end,

        set_ammo_amount = function(p, weap, amount)
            p.ammo_amount[weap] = amount
        end,

        get_max_ammo_amount = function(p, weap)
            return p.max_ammo_amount[weap]
        end,

        set_max_ammo_amount = function(p, weap, amount)
            p.max_ammo_amount[weap] = amount
        end,

        set_curr_weapon = function(p, weap)
            check_weapon_idx(weap)
            ffi.cast(player_ptr_ct, p).curr_weapon = weap
        end,

        get_inv_amount = function(p, inv)
            return p.inv_amount[inv]
        end,

        set_inv_amount = function(p, inv, amount)
            p.inv_amount[inv] = amount
        end,

        set_ftq = function(p, ftq)
            bcheck.quote_idx(ftq)
            ffi.cast(player_ptr_ct, p).ftq = ftq
        end,

        set_cursectnum = function(p, sectnum)
            check_sector_idx(sectnum)
            ffi.cast(player_ptr_ct, p).cursectnum = sectnum
        end,

        set_customexitsound = function(p, soundnum)
            check_sound_idx(soundnum)
            ffi.cast(player_ptr_ct, p).customexitsound = soundnum
        end,

        -- CON-like addammo/addweapon, but without the non-local control flow
        -- (returns true if weapon's ammo was at the max. instead).
        addammo = con._addammo,
        addweapon = con._addweapon,

        stomp = con._pstomp,

        have_weapon = function(p, weap)
            return (bit.band(p.gotweapon, bit.lshift(1, weap)) ~= 0)
        end,

        give_weapon = function(p, weap)
            p.gotweapon = bit.bor(p.gotweapon, bit.lshift(1, weap))
        end,

        take_weapon = function(p, weap)
            p.gotweapon = bit.band(p.gotweapon, bit.bnot(bit.lshift(1, weap)))
        end,

        -- Give or take weapon, for implementation of CON's .gotweapon access.
        _gt_weapon = function(p, weap, give_p)
            if (give_p ~= 0) then
                p:give_weapon(weap)
            else
                p:take_weapon(weap)
            end
        end,

        -- XXX: is the correct spelling "whack"?
        wack = function(p, no_return_to_center)
            p.horiz = p.horiz + 64
            if (not no_return_to_center) then
                p.return_to_center = 9
            end
            local n = bit.arshift(128-bit.band(ffiC.krand(),255), 1)
            p.rotscrnang = n
            p.look_ang = n
        end,

        --- Not fully specified, off-limits to users.  Might disappear, change
        --- signature, etc...
        -- TODO: need to think about external API: 0-255 based? 0-1 based?
        _palfrom = function(p, f, r,g,b)
            local pals = p._pals
            pals.f = f
            pals.r, pals.g, pals.b = r, g, b
        end,
    },
}

local function player_index_index(p, key)
    if (key=="_input") then
        return ffiC.g_player[p.weapon._p].sync[0]
    end
end

setmtonce(player_mt.__index, { __index = player_index_index })
ffi.metatype("DukePlayer_t", player_mt)

local function GenProjectileSetFunc(Member)
    return function(self, picnum)
        if (picnum >= 0) then
            check_tile_idx(picnum)
        end
        ffi.cast(projectile_ptr_ct, self)[Member] = picnum
    end
end

local projectile_mt = {
    __index = {
        set_spawns = GenProjectileSetFunc "spawns",
        set_decal = GenProjectileSetFunc "decal",
        set_trail = GenProjectileSetFunc "trail",
    },
}
ffi.metatype("projectile_t", projectile_mt)

local user_defs_mt = {
    __index = {
        set_screen_size = function(ud, screen_size)
            -- TODO: modify .statusbarmode accordingly
            ud.screen_size = screen_size
        end,

        set_volume_number = function(ud, volume_number)
            -- XXX: should volume_number==MAXVOLUMES be allowed too?
            if (volume_number >= con_lang.MAXVOLUMES+0ULL) then
                error("invalid volume number "..volume_number, 2)
            end
            ud.volume_number = volume_number
        end,
    },
}
ffi.metatype("user_defs", user_defs_mt)

--- CUSTOM "gv" VARIABLES
local camera_mt = {
    -- TODO: "set position" method, which also updates the sectnum
    __index = ffiC.g_camera,
    __newindex = function(_, key, val)
        if (key=="sect") then
            check_sector_idx(val)
        end
        ffiC.g_camera[key] = val
    end,
}

gv_access.cam = setmtonce({}, camera_mt)
gv_access._ud = ffiC.ud

-- Support for some CON global system gamevars
gv_access._csv = ffi.new "struct { int32_t RETURN, LOTAG, HITAG, TEXTURE; }"

function gv_access._get_yxaspect()
    return ffiC.yxaspect
end

function gv_access._get_viewingrange()
    return ffiC.viewingrange
end

function gv_access._currentFramerate()
    return ffiC.g_currentFrameRate
end

function gv_access._currentMenu()
    return ffiC.g_currentMenu
end

function gv_access._set_guniqhudid(id)
    local MAXUNIQHUDID = 256  -- KEEPINSYNC build.h
    if (id >= MAXUNIQHUDID+0ULL) then
        error("invalid unique HUD ID "..id)
    end
    ffiC.guniqhudid = id
end

function gv_access._RETURN(setval)
    if (setval ~= nil) then
        ffiC.g_elEventRETURN = setval
    else
        return ffiC.g_elEventRETURN
    end
end

-- TODO: make return 1-based index
function gv_access.currentEpisode()
    return ffiC.ud.volume_number
end

function gv_access.currentLevel()
    return ffiC.ud.level_number
end

function gv_access.currentRenderMode()
    -- TODO: USE_OPENGL=0 build
    return ffiC.rendmode
end

function gv_access.doQuake(gametics, snd)
    ffiC.g_earthquakeTime = gametics
    if (snd ~= nil) then
        con._globalsound(ffiC.screenpeek, snd)
    end
end

-- Declare all con_lang.labels constants in the global FFI namespace.
for i=1,#con_lang.labels do
    local strbuf = {"enum {"}

    for label, val in pairs(con_lang.labels[i]) do
        strbuf[#strbuf+1] = string.format("%s = %d,", label, val)
    end
    strbuf[#strbuf+1] = "};"

    ffi.cdef(table.concat(strbuf))
end


---=== Set up restricted global environment ===---

local allowed_modules = {
    coroutine=coroutine, bit=bit, table=table, math=math, string=string,

    os = {
        clock = function() return gv_.gethitickms()*0.001 end,
    },

    randgen = randgen,
    geom = geom,
    stat = require("stat"),
    bitar = require("bitar"),
    xmath = require("xmath"),

    con = con,
}

for modname, themodule in pairs(allowed_modules) do
    local mt = {
        __index = themodule,
        __newindex = function(tab,idx,val)
            error("modifying base module table forbidden", 2)
        end,
    }

    -- Comment out to make base modules not protected:
    allowed_modules[modname] = setmtonce({}, mt)
end

local function check_valid_modname(modname, errlev)
    if (type(modname) ~= "string") then
        error("module name must be a string", errlev+1)
    end

    -- TODO: restrict valid names?
end

local function errorf(level, fmt, ...)
    local errmsg = string.format(fmt, ...)
    error(errmsg, level+1)
end


local package_loaded = {}
local modname_stack = {}
local ERRLEV = 5

local function readintostr(fn)
    -- XXX: this is pretty much the same as the code in L_RunOnce()

    local fd = ffiC.kopen4loadfrommod(fn, 0)  -- TODO: g_loadFromGroupOnly
    if (fd < 0) then
        return nil
    end

    local sz = ffiC.kfilelength(fd)
    if (sz == 0) then
        ffiC.kclose(fd)
        return ""
    end

    if (sz < 0) then
        ffi.kclose(fd)
        error("INTERNAL ERROR: kfilelength() returned negative length", ERRLEV)
    end

    local str = ffi.new("char [?]", sz)
    local readlen = ffiC.kread(fd, str, sz)

    ffiC.kclose(fd); fd=-1

    if (readlen ~= sz) then
        errorf(ERRLEV, "INTERNAL ERROR: couldn't read \"%s\" wholly", fn)
    end

    return ffi.string(str, sz)
end

-- The "require" function accessible to Lunatic code.
-- Base modules in allowed_modules are wrapped so that they cannot be
-- modified, user modules are searched in the EDuke32 search
-- path.  Also, our require
--  * never messes with the global environment, it only returns the module.
--  * allows passing varargs beyond the name to the module.
local function our_require(modname, ...)
    check_valid_modname(modname, 2)

    -- see whether it's a base module name first
    if (allowed_modules[modname] ~= nil) then
        return allowed_modules[modname]
    end

    --- search user modules

    local omod = package_loaded[modname]
    if (omod ~= nil) then
        if (omod==true) then
            error("Loop while loading modules", ERRLEV-1)
        end

        -- already loaded
        return omod
    end

    local modfn = modname .. ".lua"
    local str = readintostr(modfn)
    if (str == nil) then
        errorf(ERRLEV-1, "Couldn't open file \"%s\"", modfn)
    end

    local modfunc, errmsg = loadstring(str)
    if (modfunc == nil) then
        errorf(ERRLEV-1, "Couldn't load \"%s\": %s", modname, errmsg)
    end

    package_loaded[modname] = true
    table.insert(modname_stack, modname)

    -- Run the module code!
    modfunc(modname, ...)  -- TODO: call protected and report errors here later

    table.remove(modname_stack)

    local modtab = package_loaded[modname]

    if (type(modtab) == "table") then
        -- Protect module table if there is one...
        local mt = {
            __index = modtab,
            __newindex = function(tab,idx,val)
                error("modifying module table forbidden", 2)
            end,
        }

        setmetatable(modtab, mt)
    end

    return modtab
end


local module_mt = {
    __index = function (_, n)
        error("attempt to read undeclared variable '"..n.."'", 2)
    end,
}

-- Our 'module' replacement doesn't get the module name from the function args
-- since a malicious user could remove other loaded modules this way.
-- Also, our 'module' has no varargs ("option functions" in Lua).
-- TODO: make transactional?
local function our_module()
    local modname = modname_stack[#modname_stack]
    if (type(modname) ~= "string") then
        error("'module' must be called at the top level of a require'd file", 2)
    end

    local M = setmetatable({}, module_mt)
    package_loaded[modname] = M
    -- change the environment of the function which called us:
    setfenv(2, M)
end

-- overridden 'error' that always passes a string to the base 'error'
local function our_error(errmsg, level)
    if (type(errmsg) ~= "string") then
        error("error using 'error': error message must be a string", 2)
    end

    if (level) then
        if (type(level) ~= "number") then
            error("error using 'error': error level must be a number", 2)
        end

        error(errmsg, level==0 and 0 or level+1)
    end

    error(errmsg, 2)
end


-- _G tweaks -- pull in only 'safe' stuff
local G_ = {}  -- our soon-to-be global environment

G_.assert = assert
G_.error = our_error
G_.ipairs = ipairs
G_.pairs = pairs
G_.pcall = pcall
G_.print = print
G_.module = our_module
G_.next = next
G_.require = our_require
G_.select = select
G_.tostring = tostring
G_.tonumber = tonumber
G_.type = type
G_.unpack = unpack
G_.xpcall = xpcall
G_._VERSION = _VERSION

-- Available through our 'require':
-- bit, coroutine, math, string, table

-- Not available:
-- collectgarbage, debug, dofile, gcinfo (DEPRECATED), getfenv, getmetatable,
-- jit, load, loadfile, loadstring, newproxy (NOT STD?), package, rawequal,
-- rawget, rawset, setfenv, setmetatable

G_._G = G_

local gameactor_internal = gameactor_internal  -- included in lunatic.c
-- gameactor(tilenum [, strength [, act [, mov [, movflags]]]], actor_func)
local function our_gameactor(tilenum, ...)
    bcheck.top_level("gameactor")

    local args = {...}
    if (type(tilenum) ~= "number") then
        error("invalid argument #1 to gameactor: must be a number", 2)
    end
    if (tilenum >= ffiC.MAXTILES+0ULL) then
        error("invalid argument #1 to gameactor: must be a tile number (0 .. MAXTILES-1)", 2)
    end
    if (#args == 0) then
        error("invalid call to gameactor: must have at least two arguments (tilenum, func)", 2)
    end
    if (#args > 5) then
        error("invalid call to gameactor: must have at most six arguments", 2)
    end
    if (type(args[#args]) ~= "function") then
        error("invalid last argument to gameactor: must be a function", 2)
    end

    local strength = (#args >= 2) and args[1] or 0
    if (type(strength) ~= "number") then
        error("invalid 'strength' argument to gameactor: must be a number", 2)
    end

    -- TODO: literal number action other than 0?
    local act = (#args >= 3) and args[2] or "NO"
    if (type(act)=="string") then
        act = AC[act]
    end
    if (not ffi.istype(con_action_ct, act)) then
        error("invalid 'act' argument to gameactor: must be a string or action", 2)
    end

    -- TODO: literal number move other than 0?
    local mov = (#args >= 4) and args[3] or "NO"
    if (type(mov)=="string") then
        mov = MV[mov]
    end
    if (not ffi.istype(con_move_ct, mov)) then
        error("invalid 'mov' argument to gameactor: must be a string or move", 2)
    end

    local movflags = (#args >= 5) and args[4] or 0
    if (type(movflags) ~= "number") then
        error("invalid 'movflags' argument to gameactor: must be a number", 2)
    end

    gameactor_internal(tilenum, strength, act, mov, movflags, args[#args])
end

-- Event functions, saved for event chaining
local event_funcs = {}

local gameevent_internal = gameevent_internal  -- included in lunatic.c
-- gameevent(<event idx or string>, <event function>)
local function our_gameevent(event, func)
    if (ffiC.g_elCallDepth > 0) then
        error("Invalid use of gameevent: must be called from top level", 2)
    end
    if (type(event) == "string") then
        if (event:sub(1,6) ~= "EVENT_") then
            event = "EVENT_"..event
        end
        local eventidx = con_lang.EVENT[event]
        if (eventidx == nil) then
            errorf(2, "gameevent: invalid event label %q", event)
        end
        event = eventidx
    end
    if (type(event) ~= "number") then
        error("invalid argument #1 to gameevent: must be a number", 2)
    end
    if (event >= con_lang.MAXEVENTS+0ULL) then
        error("invalid argument #1 to gameevent: must be an event number (0 .. MAXEVENTS-1)", 2)
    end

    if (type(func) ~= "function") then
        error("invalid argument #2 to gameevent: must be a function", 2)
    end

    local newfunc = func
    local oldfunc = event_funcs[event]
    -- event chaining: events defined later come first
    if (oldfunc ~= nil) then
        newfunc = function(aci, pli, dist)
            func(aci, pli, dist)
            return oldfunc(aci, pli, dist)
        end
    end

    gameevent_internal(event, newfunc)
    event_funcs[event] = newfunc
end

--- non-default data and functions
G_.gameevent = our_gameevent
G_.gameactor = our_gameactor
-- These come from above:
G_.player = player
G_.actor = actor
G_.projectile = projectile
G_.g_tile = g_tile


---=== Lunatic interpreter setup ===---

local concode

--- Compile CONs
do
    read_into_string = readintostr  -- for lunacon
    local lunacon = require("lunacon")

    local confn = { ffi.string(ffiC.G_ConFile()) }

    local nummods = ffiC.g_scriptModulesNum
    if (nummods > 0) then
        assert(ffiC.g_scriptModules ~= nil)

        for i=1,nummods do
            confn[i+1] = ffi.string(ffiC.g_scriptModules[i-1])
        end
    end

    local lineinfo
    concode, lineinfo = lunacon.compile(confn)

    if (concode == nil) then
        error("Failure compiling CON code, exiting.", 0)
    end
    assert(lineinfo)

    -- Translate one Lua line number to a CON file name + line number
    local function transline(lnum)
        return string.format("%s:%d", lineinfo:getfline(tonumber(lnum)))
    end

    -- Register the function that tweaks an error message, looking out for
    -- errors from CON and translating the line numbers.
    local function tweak_traceback_msg(errmsg)
        return errmsg:gsub('%[string "CON"%]:([0-9]+)', transline)
    end

    set_tweak_traceback_internal(tweak_traceback_msg)
end

-- change the environment of this chunk to the table G_
-- NOTE: all references to global variables from this point on
-- (also in functions created after this point) refer to G_ !
setfenv(1, G_)

-- Print keys and values of a table.
local function printkv(label, table)
    print("========== Keys and values of "..label.." ("..tostring(table)..")")
    for k,v in pairs(table) do
        print(k .. ": " .. tostring(v))
    end
    print("----------")
end

--printkv('_G AFTER SETFENV', _G)


---=== Restricted access to C variables from Lunatic ===---

-- error(..., 2) is to blame the caller and get its line numbers

gv = gv_
local tmpmt = {
    __index = function(gv, key)
        if (gv_access[key] == nil) then
            return ffiC[key]
        end
        if (type(gv_access[key])~="boolean") then
            -- overridden...
            return gv_access[key]
        end
        error("access forbidden", 2)
    end,

    __newindex = function(gv, key, val)
        if (key=="g_logoFlags") then
            ffiC[key] = val
        else
            error("write access forbidden", 2)
        end
    end,
}
setmtonce(gv, tmpmt)

-- This will create 'sprite', 'wall', etc. HERE, i.e. in the environment of this chunk
defs_c.create_globals(_G)


---=== Game variables ===---

-- gamevarNames[name] is true if that gamevar was declared
local gamevarNames = {}

-- code for prohibiting initial assignments to create new variables,
-- based on 14.2 of PiL
function gamevar(name, initval)  -- aka 'declare'
    if (type(name) ~= "string") then
        error("First argument to 'gamevar' must be a string", 2)
    end

    if (not string.match(name, "^[%a_][%w_]*$")) then
        error("First argument to 'gamevar' must be a valid identifier", 2)
    end

    if (string.match(name, "^_")) then
        error("Identifier names starting with an underscore are reserved", 2)
    end

    if (gamevarNames[name]) then
        error(string.format("Duplicate declaration of identifier '%s'", name), 2)
    end

    if (rawget(G_, name) ~= nil) then
        error(string.format("Identifier name '%s' is already used in the global environment", name), 2)
    end

    gamevarNames[name] = true
    rawset(G_, name, initval or false)
end


---=== Serialization, from PiL with modifications ===---
local function basicSerialize(o)
    if (type(o) == "number") then
        if (o ~= o) then return "0/0" end  -- nan
        if (o == 1/0) then return "1/0" end  -- inf
        if (o == -1/0) then return "-1/0" end  -- -inf

        return tostring(o)
    elseif (type(o) == "boolean") then
        return tostring(o)
    elseif (type(o) == "string") then
        return string.format("%q", o)
    end
end

-- will contain all gamevar tables as keys (and true as value)
local tmpgvtabs = {}

local function save(name, value, saved, strings)
    saved = saved or {}       -- initial value

    strings[#strings+1] = name .. "="

    local str = basicSerialize(value)

    if (str ~= nil) then
        strings[#strings+1] = str .. "\n"
    elseif (type(value) == "table") then
        if (saved[value]) then    -- value already saved?
            strings[#strings+1] = saved[value] .. "\n"  -- use its previous name
        else
            saved[value] = name   -- save name for next time
            strings[#strings+1] = "{}\n"  -- create a new table

            for k,v in pairs(value) do      -- save its fields
                local keystr = basicSerialize(k)
                if (keystr == nil) then
                    error("cannot save a " .. type(k) .. " as key of a table", 2);
                end
                local fieldname = string.format("%s[%s]", name, keystr)
                if (type(v)=="table" and not tmpgvtabs[v]) then
                    error("cannot save \""..name..
                          "\": gamevar tables may only contain tables that are also gamevars", 2)
                end
                save(fieldname, v, saved, strings)
            end
        end
    else
        error("cannot save \""..name.."\", a " .. type(value), 2)
    end
end

local function serializeGamevars()
    local saved = {}
    local strings = {}

    for gvname,_ in pairs(gamevarNames) do
        if (type(G_[gvname])=="table") then
            tmpgvtabs[G_[gvname]] = true
        end
    end

    -- TODO: catch errors in save()
    for gvname,_ in pairs(gamevarNames) do
        save(gvname, G_[gvname], saved, strings)
    end
    strings[#strings+1] = "\n"

    tmpgvtabs = {}

    return table.concat(strings)
end

local function loadGamevarsString(string)
--[=[
    for gvname,_ in pairs(gamevarNames) do
        G_[gvname] = nil;
    end
    gamevarNames = {};  -- clear gamevars
--]=]

    assert(loadstring(string))()
end


-- REMOVE this for release
DBG_ = {}
DBG_.debug = require("debug")
DBG_.printkv = printkv
DBG_.loadstring = loadstring
DBG_.serializeGamevars = serializeGamevars
DBG_.loadGamevarsString = loadGamevarsString
DBG_.oom = function()
    local s = "1"
    for i=1,math.huge do
        s = s..s
    end
end

-- Test reading from all struct members
function DBG_.testmembread()
    for _1, sac in pairs { con_lang.StructAccessCode, con_lang.StructAccessCode2 } do
        for what, labels in pairs(sac) do
            if (what~="tspr") then
                for _3, membaccode in pairs(labels) do
                    if (type(membaccode)=="table") then
                        membaccode = membaccode[1]
                    end
                    if (membaccode) then
                        local codestr = "do local _bit,_math=require'bit',require'math'; local tmp="..
                            membaccode:gsub("%%s","0").." end"
                        local code = assert(loadstring(codestr))
                        code()
                    end
                end
            end
        end
    end
end


---=== Finishing environment setup ===---

--printkv('_G AFTER DECLS', _G)


-- PiL 14.2 continued
-- We need this at the end because we were previously doing just that!
setmetatable(
    G_, {
        __newindex = function (_1, n, _2)
            error("attempt to write to undeclared variable '"..n.."'", 2)
        end,
        __index = function (_, n)
            error("attempt to read undeclared variable '"..n.."'", 2)
        end,
        })

-- Change the environment of the running Lua thread so that everything
-- what we've set up will be available when this chunk is left.
-- In particular, we need the globals defined after setting this chunk's
-- environment earlier.
setfenv(0, _G)

-- Finally, run the CON code translated into Lua.
if (concode) then
    local confunc, conerrmsg = loadstring(concode, "CON")
    if (confunc == nil) then
        error("Failure loading translated CON code: "..conerrmsg, 0)
    end
    confunc()
end