Planes flying one-way with crew or cargo spread plague from their old
base to their new base. Planes dropping cargo spread plague from
their base to the drop's target sector.
Why upgrade? I'm not a lawyer, but here's my take on the differences
to version 2:
* Software patents: better protection against abuse of patents to
prevent users from exercising the rights under the GPL. I doubt
we'll get hit with a patent suit, but it's a good move just on
general principles.
* License compatibility: compatible with more free licenses, i.e. can
"steal" more free software for use in Empire. I don't expect to steal
much, but it's nice to have the option.
* Definition of "source code": modernization of some details for today's
networked world, to make it easier to distribute the software. Not
really relevant to us now, as we normally distribute full source code.
* Tivoization: this is about putting GPL-licensed software in hardware,
then make the hardware refuse to run modified software. "Neat" trick
to effectively deny its users their rights under the GPL. Abuse was
"pioneered" by TiVo (popular digital video recorders). GPLv3 forbids
it. Unlikely to become a problem for us.
* Internationalization: more careful wording, to harden the license
outside the US. The lawyers tell us it better be done that way.
* License violations: friendlier way to deal with license violations.
This has come out of past experience enforcing the GPL.
* Additional permissions: Probably not relevant to us.
Also include myself in the list of principal authors.
Oops when a stale copy is written back, i.e. the processor was yielded
since the copy was made. Such bugs are difficult to spot. Sequence
numbers catch them when they do actual harm (they also catch different
bugs). Generation numbers catch them even when they don't.
New ef_generation to count generations. Call new ef_make_stale() to
increment it whenever the processor may be yielded.
New struct emptypedstr member generation. To conserve space, make it
a bit-field of twelve bits, i.e. generations are only recorded modulo
2^12. Make sure all members of unit empobj_storage share it. It is
only used in copies; its value on disk and in the cache is
meaningless. Copies with generation other than ef_generation are
stale. Stale copies that are a multiple of 2^12 generations old can't
be detected, but that is sufficiently improbable.
Set generation to ef_generation by calling new ef_mark_fresh() when
making copies in ef_read() and ef_blank(). nav_ship() and
fltp_to_list() make copies without going through ef_read(), and
therefore need to call ef_mark_fresh() as well. Also call it in
obj_changed() to make check_sect_ok() & friends freshen their argument
when it is unchanged.
New must_be_fresh() oopses when its argument is stale. Call it in
ef_write() to catch write back of stale copies.
Store them and ef_type in bit-fields.
Allocate eight bits for ef_type. Values range from 0 to EF_GAME
(currently 16), so this is plenty.
Allocate twelve bits for sequence numbers. Sequence number mismatches
are now missed when the numbers are equal modulo 2^12. Still
sufficiently improbable.
Common machines store the bit-fields in a 32 bit word. There are
twelve bits left in that word for future use. Total savings 16 bits,
which is exactly what the previous commit spent on wider uids on
common machines.
Before, they were stored as short. Wider uids use more space, but the
next commit will recover it by narrowing other members.
The use of short has always limited the number of ships, planes, land
units and nukes to SHRT_MAX (commonly 32768). Only the most extreme
games ever came close.
Commit 49780e2c (v4.3.12) added struct sctstr member sct_uid to make
struct empobj member uid work for sectors. This made the limit apply
to sectors as well. We've had games with more than 32768 sectors.
These were leftovers from Chainsaw, and their only remaining effect
was a flak bonus.
The got replaced except for flak by plane selector stealth under
Chainsaw option STEALTHV, which became mandatory in Empire 2. It is
unclear why STEALTHV didn't cover flak. No planes with these
capabilities have existed in the stock game since Empire 2.
The ancients designed interception dead simple: when you overfly a
sector, you get intercepted by the sector owner. Fine print
interception rules govern which planes intercept.
Then complexity got piled on top of it.
Chainsaw 2 added an extra interception by surface ship owners, in the
target sector only.
Chainsaw 3 added an extra interception by land unit owners, in the
target sector only (Empire 4 later merged this extra land unit
interception with the extra surface ship interception).
Chainsaw 3 added an entirely separate kind of interception: air
defense missions. When you enter a sector in some air defense op
area, you get intercepted. Fine print air defense rules govern which
planes intercept. These rules differ significantly from the
interception fine print.
Additional complexity comes from these facts:
* Air defense mission interception happens in addition to non-mission
interception. You can boost your total interception by setting up
air defense. Which means you must set it up, or forgo an advantage.
* Air defense planes are not available for non-mission interception
duty. You need to decide on a split.
* In contrast to non-mission interception, interceptors flying air
defense get intercepted.
Moreover, the air defense code breaks one of the plane code's design
assumptions, namely that just one plane sortie is active at a time.
The air defense sortie runs while the sortie it intercepts is in
progress. This leads to two interceptions being active at the same
time: the one intercepting the original sortie, and the one
intercepting the air defense sortie. The same plane can fly in both
interceptions, and damage received in the interception of the air
defense sortie is wiped out, triggering a seqno mismatch oops.
The previous commit already simplified non-mission interception: you
get intercepted by anyone who owns the sector, or a surface ship or a
land unit there, whether it's the target sector or not.
Now simplify mission interception, by merging air defense back into
ordinary interception: when you overfly a sector, you get intercepted
by anyone who owns the sector, or a surface ship or land unit there,
or has an air defense mission covering the sector. That's all. No
multiple interceptions, no separate air defense rules.
Remove air_defense(). Simplify ac_encounter() and sam_intercept()
accordingly; both lose their last parameter.
Change sam_intercept() and ac_intercept() to intercept in mission op
areas. New parameter only_mission to suppress non-mission
interception. Pass zero when the intercepting country owns the sector
or a surface ship or land unit in the sector.
ac_encounter() can't efficiently predict whether a country intercepts,
so it needs to call ac_intercept() unconditionally. This kills the
optimization to collect interceptors only when needed; simplify
accordingly, replacing getilist() by getilists().
pln_nuktype is redundant; it can be computed from the nuke's
nuk_plane.
Make plane selector nuketype virtual and NSC_EXTRA. It should have
been NSC_EXTRA all along. This changes xdump plane.
Don't set it in arm(), disarm(), build_plane(), pln_damage() and
nuk_fixup(). The latter no longer does anything, remove it.
Deprecate edit key 'n' in doplane(), and don't show it in pr_plane().
The key never made much sense.
eff_bomb(), comm_bomb(), ship_bomb(), plane_bomb(), land_bomb(),
strat_bomb(), mission_pln_equip(), air_damage(), msl_hit(),
pln_equip() tested pln_nuketype to check whether a plane carries a
nuke. Test nuk_on_plane() instead.
pdump(), plan(), trade_desc() print whether and what kind of nuke a
plane carries. Adapt that to use nuk_on_plane().
Persistent game state encodes "who carries what" by storing the
carrier uid in the cargo. Cargo lists augment that: they store lists
of cargo for each carrier. They are not persistent.
New unit_cargo_init() to compute the cargo lists from game state.
Call it in ef_init_srv() and at the end of update_main().
New unit_onresize() to resize the cargo list data structure.
Installed as units' struct empfile callback onresize to make them
resize automatically with the unit files.
New unit_carrier_change() to update cargo lists when carriers change
in game state. Convenience wrappers pln_carrier_change(),
lnd_carrier_change() and nuk_carrier_change(). Call them from
prewrite callbacks to keep cargo lists in sync with game state.
To make that work, unused units must not point to a carrier. Add new
pln_oninit(), lnd_oninit() and nuk_oninit() take care of newly created
units. Change lnd_prewrite() and nuk_prewrite() to take dead land
units and nukes off their carrier. pln_prewrite() did that already.
New unit_cargo_first(), unit_cargo_next() to traverse cargo lists.
Convenience wrappers lnd_first_on_ship(), lnd_first_on_land(),
lnd_next_on_unit(), pln_first_on_ship(), pln_first_on_land(),
pln_next_on_unit() and nuk_on_plane(). The latter is disabled for now
because it clashes with an existing function.
This oopses on output dependency violations, e.g. two threads doing a
read-modify-write without synchronization, or the one thread nesting
several read-modify-writes. Such bugs are difficult to spot, and tend
to be abusable. I figure we have quite a few of them.
New struct emptypedstr member seqno. Make sure all members of unit
empobj_storage share it. Initialize it in files: main() and
file_sct_init(). Set it in ef_blank() and new ef_set_uid() by calling
new get_seqno(). Use ef_set_uid() when copying objects: swaps(),
doland(), doship(), doplane(), dounit(), delete_old_news(). Step it
in ef_write() by calling new new_seqno().
Factor do_read() out of fillcache() to make it available for
get_seqno().
Planes normally sit in their base (sector or carrier), where they can
be spied, damaged, captured, loaded, unloaded, upgraded and so forth.
All this must not be possible while they fly. There are two kinds of
flying planes: satellites in orbit, and planes flying a sortie.
Satellites in orbit have always been marked with flag PLN_LAUNCHED.
Works. What didn't work was tracking planes flying a sortie.
If you look at one sortie in isolation, up to three groups of planes
can be flying at any point of time: the primary group, which carries
out the sortie's mission (bomb, transport, ...), their escorts, and a
group of hostile planes flying interception or air defense.
The old code attempted to track these planes by passing those groups
to the places that need to know whether a plane is flying. This was
complex and incomplete, and broke down completely for the pin-bombing
command.
It was complex, because the plane code needs to keep track of all the
call chains that can lead to a place that needs to know whether a
plane flies, and pass the groups down the call chains. This leads to
a rather ugly passing of plane groups all over the place.
It was incomplete, because it generally failed to pass the escorts.
And the whole scheme broke down for the pin-bombing command. That's
because pin-bombing asks the player for targets while his planes are
loitering above the target sector. This yields the processor and lets
other code run. Which does not get the flying planes passed.
The new code marks planes and SAMs (but not other missiles) flying a
sortie with flag PLN_LAUNCHED (the previous commit laid the groundwork
for that), and does away with passing around groups of flying planes.
This fixes the following bugs:
* Many commands could interact with foreign planes flying for a
pin-bombing command as if they were sitting in their base. This
includes spying, damaging, capturing, loading, or upgrading them,
and even getting intercepted by them. Any changes to those planes
were wiped out when they landed. Abusable.
* The bomb command could bomb its own escorts, directly (pin-bomb
planes) or through collateral damage, strategic sector damage,
collapsing bridges or nuke damage. The damage to the escorts was
wiped out when they landed.
* If you asked for a plane to fly both in the primary group and the
escort group, you got charged fuel for two sorties instead of one.
* pln_put1() and pln_put() now recognize planes that didn't take off,
and refrain from making them land. Intercept (since commit
c64e2149) and air defense can do that. Making them land had no
ill-effects, but it was still wrong.
There's one new problem: if PLN_LAUNCHED doesn't get reset properly,
due to game crash during flight or some other bug, the plane gets
stuck in the air. Catch and fix that on game start in ef_verify().
Make sure all members of unit empobj_storage share it.
Add matching timestamp member to struct comstr, struct empobj, struct
gamestr, struct lonstr, struct natstr, struct nwsstr, struct trdstr,
struct trtstr. The timestamp isn't yet set for these. To be fixed.
Move the timestamp member to the right place in struct lndstr, struct
loststr, struct realmstr, struct nukstr, struct plnstr, struct sctstr,
struct shpstr.
New pln_att(), pln_def(), pln_acc(), pln_range_max(), pln_load()
replace the struct plnstr members with the same names.
Make plane selectors att and def virtual.
The macros defining unit stat development in tech are somewhat
inconvenient to use. Define more convenient functions, and hide away
the macros near the function definitions.
Make sure all members of unit empobj_storage share uid in addition to
ef_type.
Add matching uid member to struct gamestr, struct natstr and struct
sctstr, and set them.
Swap struct empobj members uid and own to make that easier, and update
struct comstr, struct lndstr, struct lonstr, struct loststr, struct
nwsstr, struct nukstr, struct plnstr, struct realmstr, struct shpstr,
struct trdstr, struct trtstr accordingly.
Note that the uid isn't properly set for struct nwsstr, struct lonstr,
struct trdstr, struct comstr and struct loststr. To be fixed.
(lndstr, plnstr, sctstr, shpstr): Change timestamp members lnd_access,
pln_access, sct_access, shp_access from real time (time_t) to ETUs
within a turn (short).
(land_ca, plane_ca, sect_ca, ship_ca): Update accordingly.
(build_ship, build_land, build_bridge, build_plane, build_tower)
(explore, check_trade, bsanct, takeover, takeover_ship)
(takeover_land): Use game_tick_to_now() instead of time() to update
the timestamp. Change check_trade(), takeover_ship(), takeover_land()
to do that only when MOB_ACCESS is enabled, for consistency.
(lupgr, supgr, pupgr, takeover_ship): Don't touch the timestamp where
mobility isn't touched either.
(sct_do_upd_mob, shp_do_upd_mob, lnd_do_upd_mob, pln_do_upd_mob): Use
game_tick_to_now() instead of increase_mob() to compute ETUs since
the timestamp and update the timestamp. Closes#1012699.
(increase_mob): Remove.
(mob_sect, mob_ship, mob_land, mob_plane): sct_do_upd_mob() & friends
no longer do the right thing at the update. Use game_reset_tick() and
pass its result directly to do_mob_sect() & friends. This is only
correct when argument is etu_per_update, which it always is. Remove
parameter. Callers changed.
(do_mob_sect, do_mob_ship, do_mob_land, do_mob_plane): Oops on
negative argument.
(mob_acc_globals, timestampfil, mobupdate, updating_mob)
(update_all_mob, timestamp_fixing, update_timestamps, mobility_check):
The mobupdate command was important to let deities manually
synchronize mobility updating with updates. That's no longer needed.
The code behind it is somewhat hairy and ugly, and updating it to work
with the Empire clock is just not worth it. Remove. Users changed.
(player_coms): Update accordingly.
(upda): Remove display of mobility updating state.
(mobility_init): No need to fix up mobility on startup, as the Empire
clock runs normally even when the server is down. Remove. Caller
changed.
other. Ensure headers in include/ can be included in any order
(except for econfig-spec.h, which is special). New header types.h to
help avoid inclusion cycles. Sort include directives. Remove some
superflous includes.
oprange, show_mission, nameofitem, build_mission_list_type,
unit_map, xdvisible, trdswitchown, ontradingblock, trad, check_trade,
unit_type_name, start_stop_unit, scut, scra, mission, multifire,
perform_mission, fuel, NSC_GENITEM): Replace struct genitem with
struct empobj. Remove genitem.h and create a new file empobj.h.
Replace multiple instances of unions of ef_type structures with
one standard union empobj_storage which is a superset of the individual
instances.
