reg32_t was a transitive solution, before reg_t's were
adapted to use 32-bit addresses internally, and before
support for SCI3 was added. It was introduced as another
way to handle large script offsets in SCI3, and was only
used for the program counter (PC). It's no longer
needed, as we now support SCI3 script offsets using
reg_t's, so we can use make_reg32 in all cases where
we need to access offsets over 64KB
These objects should have been initialized only during the first
pass. Double-initialization does not cause any visible problem
problem during normal operation (mostly it just causes memory
waste by making Object::_baseVars/_baseMethod double up their
data), but could have silently allowed games to receive bogus data
for an out-of-bounds property or method index, instead of raising
an error.
1. In SCI0/1, selectors and offsets in the method block are
stored contiguously (all selectors, then all offsets), with a
null separator between the two runs. All the later versions of
SCI instead interleave selectors & offsets. Since these values
are already being copied into a new array anyway, code for
reading method selectors/offsets is now simplified by
interleaving this data when it is written into _baseMethod
for SCI0/1, so the same equation for retrieving method
selectors/offsets can be used across all SCI versions.
2. In SCI1.1-2.1 branch, the method count was being copied into
the first entry of the array, which meant that SCI1.1-2.1 had
extra code for dealing with the fact that the first entry was
not an entry. This has been fixed, and the extra code removed.
3. Data was being overread into _baseMethod in all games SCI0-2.1.
(SCI0/1 had an extra magic value of 2, and SCI1.1-2.1 had an
extra magic value of 3). Reviewing history, it's not clear why
this happened, other than that it appears to have been
introduced at 7b0760f1bc. My best
guess is that this was a confusion between byte count and record
count, where the intent was to read an extra 2 bytes for the
null separator in SCI0/1, but it actually read 2 records
instead. (I do not have a guess on why SCI1.1 ended up with a
3.) This overreading has been removed.
This groundwork enables an object to look up its static name
separately from the normal process that is used to populate
Object::_variables when an object is first constructed.
(The static name property needs to be able to be retrieved from
objects inside of earlier save games whose name properties may
have already been modified at runtime, so the code cannot simply
pluck the value out of Object::_variables when they are first
initialised and then persisted into the save game, as nice and
easy as that would have been.)
This commit also helps to clarify the situation with relocation
tables in SCI1 games that start with a zero entry.
Refs Trac#9780.
While extremely rare (only Rama script 64948 seems to have this
profile), it *is* possible for an object to have zero properties
(and thus, zero property offsets).
At least some versions of Island of Dr Brain have a bMessager
instance in script 0 with a var count greater than that of its
class. This probably should never happen since it means the
object has a variable with no corresponding selector.
The next commit adds some extra sanity checking code to object
initialization, to warn on any other games where this happens.
In SCI2/2.1, variable indexes are used along with a range encoded
in the interpreter executable to determine whether an object
variable is a view-related variable. Operands to aTop, sTop, ipToa,
dpToa, ipTos, and dpTos are byte offsets into an object, which
are divided by two to get the varindex to check against the
interpreter range.
In SCI3, objects in game scripts contain groups of 32 selectors,
and each group has a flag that says whether or not the selectors
in that group are view-related. Operands to aTop, sTop, ipToa,
dpToa, ipTos, and dpTos are selectors.
The variable count returned by Object::getVarCount is populated
by variable 1 in SCI1.1, so specially reading the variable
explicitly for that engine version is not necessary.
In SCI3, index-to-selector tables no longer exist in compiled
object data (instead, the SCI3 VM uses selectors directly and
object data contains a bit map of valid selectors). In ScummVM,
the table is generated by Object::initSelectorsSci3 for
compatibility with the design of the ScummVM SCI VM. For
consistency, _baseVars is converted to use a standard container,
which works for all SCI versions.
The table for SCI3 property offsets is also changed to use a
standard container instead of manually managing the memory with
malloc/free.
- Detection works via signatures (couldn't find a better way)
- new kString subcalls were introduced SCI2.1 LATE
- kString now has signatures and is split via subcall table
- kString fix, so that KQ7 doesn't crash, when starting a chapter
- Sci2StringFunctionType removed, because no longer needed
This is because objects may be loaded before their base objects,
which causes initBaseObject to fail for SCI0.
Script::initializeObjectsSci0 already did this, but
SegManager::saveLoadWithSerializer did not when calling
initBaseObject after loading a savegame.
No functionality change has been made with this commit. This avoids
setting and getting the reg_t members directly, and is the basis of any
future work on large SCI3 scripts (larger than 64KB)
This tries to make our code a bit more compliant with our code formatting
conventions. For future use, this is the command I used:
git ls-files "*.cpp" "*.h" | xargs sed -i -e 's/[ \t]*$//'
If an object defines more variables than its base class, some method
selectors may be hidden. This code tries to enumerate the affected
selectors. It may be useful for mass-scanning objects using
'find_callk Dummy'.
It's disabled by default currently since it does things to partially
uninitialized objects that I can't guarantee are 100% safe at this
point.
The cause for this bug turns out to be a corrupt object that as
a side effect accidentally bypasses its own corruption. See the
added comments for details.
Also add a warning that points out similarly corrupted objects.
sluicebox
Eugene Sandulenko
Filippos Karapetis
Colin Snover
Lars Skovlund
Martin Kiewitz
Johannes Schickel
Willem Jan Palenstijn
Filippos Karapetis
Max Horn
strangerke
Matthew Hoops
Lars Skovlund