Starting with PR 7411, the rest of Dolphin reads the game ID from
PARTITION_NONE, but SetRunningGameMetadata was still reading from
the game partition. https://bugs.dolphin-emu.org/issues/11422
This avoids out-of-bounds warnings when replaying FIFO captures.
The value of XF_REGS_SIZE is written into the DFF header and we only
read the min of XF_REGS_SIZE and the header value, so this change is
backward compatible and doesn't break forward compatibility for old
Dolphin versions either.
Switch to using additional overloads of sf::Packet, so we can eliminate
some of the messy code and just use the normal syntax for
BigEndianValue.
We can't avoid helper functions with u64 due to SFML's non-standard way
of defining 64-bit integer types.
Fixes a critical regression from 8bb08d1ca6.
In that commit, I replaced a 1024 byte buffer with a SHCIEventCommand.
However, it looks like some Bluetooth adapters actually require such
a large buffer, so this change needs to be reverted.
Dolphin has traditionally treated the SI IO buffer (128 bytes) as a set of
32 little endian u32s. This works out fine if you only ever read/write
using aligned 32bit accesses. Different sized accesses or misaligned reads
will mess it up. Byte swapping reads/writes will fix this up, but all the
SI devices that use the SI IO buffer need to be adjusted.
Several functions (and one variable) were being given external linkage.
Instead, relocate them all to anonymous namespaces to make them
internally linked.
Puts the comment in the header where it's more likely to be seen
initially. We can also remove the TODO, given doing nothing or returning
an error is what is generally done for the JIT interface if the JIT
instance isn't valid.
With 7aa305ea35 merged, all that remains
within Profiler.cpp is an unused function that just forwards to the
equivalent function within JitInterface. Given that, we can just remove
the source file.
This global belongs in the JitOptions structure, as it's a conditional
setting (A.K.A. option) that changes the behavior of what the JIT does.
Plus it keeps the scope of the variable constrained to the general area
it's intended to be used and nothing further.
swap32() has a const u8* overload that swaps the data being pointed to as
if it were a 32-bit word. We can just use that instead. It gets rid of
undefined behavior, as we're not type punning a pointer and dereferencing it,
and gets rid of the need to cast entirely.
In both cases of the x64 and AArch64 JITs, these would have const casted
away from them, followed by them being placed within an emitter and
having breakpoint instructions written in them.
In this case, we shouldn't be using const period if we're writing to the
emitted data.
Similar in nature to e28d063539 in which
this same change was applied to the x64 emitter.
There's no real requirement to make this const, and this should also
be decided by the calling code, considering we had places that would
simply cast away the const and carry on
Currently, each player buffers their own inputs and sends them to the
host. The host then relays those inputs to everyone else. Every player
waits on inputs from all players to be buffered before continuing. What
this means is all clients run in lockstep, and the total latency of
inputs cannot be lower than the sum of the 2 highest client ping times
in the game (in 3+ player sessions with people across the world, the
latency can be very high).
Host input authority mode changes it so players no longer buffer their
own inputs, and only send them to the host. The host stores only the
most recent input received from a player. The host then sends inputs
for all pads at the SI poll interval, similar to the existing code. If
a player sends inputs to slowly, their last received input is simply
sent again. If they send too quickly, inputs are dropped. This means
that the host has full control over what inputs are actually read by
the game, hence the name of the mode. Also, because the rate at which
inputs are received by SI is decoupled from the rate at which players
are sending inputs, clients are no longer dependent on each other. They
only care what the host is doing. This means that they can set their
buffer individually based on their latency to the host, rather than the
highest latency between any 2 players, allowing someone with lower ping
to the host to have less latency than someone else.
This is a catch to this: as a necessity of how the host's input sending
works, the host has 0 latency. There isn't a good way to fix this, as
input delay is now solely dependent on the real latency to the host's
server. Having differing latency between players would be considered
unfair for competitive play, but for casual play we don't really care.
For this reason though, combined with the potential for a few inputs to
be dropped on a bad connection, the old mode will remain and this new
mode is entirely optional.
Added an option in General config to enable/disable usage statistics. Added a popup on first open if
the user would like to engage in reporting. Clicking cancel or out of the box opts out. Only
clicking 'Ok' will enable reporting. Also added a new android specific values to report.
At some point SetCRFieldBit was modified to operate on RSCRATCH, but the
function was only partially changed. As such, setting SO, GT or LT would
write the right bit to cr_field, but then cr_field would just get
overwritten with RSCRATCH, undoing the work.
also did these things
fixed crash from joining user that isn't hosting via a direct connection
current game stat can now pass to override the current game in config
uses ip endpoint from dolphin.org
Behaviorally, this belongs within the netplay client. The server will
always transmit a known RTC value, so it doesn't even need a global for
this. Given the client receives the packet containing said RTC value, we can
store it as a member variable and provide an accessor for reading that
value.
This removes another global variable within the netplay code.
The idea of this code was to not unroll loops, but it was completely broken.
So we've unrolled all loops, but only up to the second iteration.
Honestly, a better check would test if we branch to code which is already in the compiling block. But this is out of scope for now.
But testing shows that this unrolling actually improve the performance. So instead of fixing this bug, this check can be dropped.
Most settings which affect determinism will now be synced on NetPlay.
Additionally, there's a strict sync mode which will sync various
enhancements to prevent desync in games that use EFB reads.
This also adds a check for all players having the IPL.bin file, and
doesn't load it for anyone if someone is missing it. This prevents
desyncs caused by mismatched system fonts.
Additionally, the NetPlay window was getting too wide with checkboxes,
so FlowLayout has been introduced to make the checkboxes take up
multiple rows dynamically. However, there's some minor vertical
centering issues I haven't been able to solve, but it's better than a
ridiculously wide window.
This is accomplished by having SConfig::GetDirectoryForRegion no longer
return nullptr, as doing that was kind silly, considering we never
check for nullptr.
Basically everything here was race conditions in Qt callbacks, so I changed the client/server instances to std::shared_ptr and added null checks. It checks that the object exists in the callback, and the shared_ptr ensures it doesn't get destroyed until we're done with it.
MD5 check would also cause a segfault if you quit without cancelling it first, which was pretty silly.
This option completely disabled the DCBZ instruction. Users are toggling
this option in dolphin forks and using that same problematic config when
launching dolphin. Removing the option from dolphin will let the config be
ignored.
This adds the functionality of sending the host's save data (raw memory
cards, as well as GCI files and Wii saves with a matching GameID) to
all other clients. The data is compressed using LZO1X to greatly reduce
its size while keeping compression/decompression fast. Save
synchronization is enabled by default, and toggleable with a checkbox
in the NetPlay dialog.
On clicking start, if the option is enabled, game boot will be delayed
until all players have received the save data sent by the host. If any
player fails to receive it properly, boot will be cancelled to prevent
desyncs.
We don't want to write this setting to disk, as SConfig has problems
with leaking settings changed by GameINI into the base configs. The
result of this is that if someone plays an N64 VC game (or other game
where we disable this setting) the branch following option can get
unintentionally disabled globally, which will reduce performance in
many games and cause NetPlay to desync with users who still have it
enabled.
Lessens the amount of files that have to be recompiled if
ConfigManager.h is modified. This also removes an indirect inclusion
within DolphinQt/Main.cpp.
Makes it less error-prone to get state data from analog sticks (no need
to pass any locals), and also allows direct assignment, letting the
retrieved data be const.
Makes it less error-prone to get state data from tilt controls (no need
to pass any pointers to locals), and also allows direct assignment,
letting the retrieved data be const.
Makes it less error-prone to get state data from sliders (no need
to pass any locals), and also allows direct assignment, letting the
retrieved data be const.
Makes it less error-prone to get state data from cursors (no need
to pass any pointers to locals), and also allows direct assignment,
letting the retrieved data be const.
Makes it less error-prone to get state data from analog sticks (no need
to pass any locals), and also allows direct assignment, letting the
retrieved data be const.
Ensures they match their naming within the definition of the function.
In EmulateSwing's case, one parameter was erroneously named tilt_group,
when it's actually supposed to be swing_group.
These aren't necessary in the prototype, however they do apply in the
definition of the function. This just cuts down on line noise within the
prototypes.
This is only ever read from externally, so we can expose a getter that ensures that
immutability, while making the actual instance internal. Given the
filling out of these settings depends on packets received by the client
instance, it makes more sense to make it a part of the client itself.
This trims off one lingering global.
This stops clients randomly deadlocking when a spectator leaves, as the mappings construct is not thread-safe and should not be written while the game is running.
This packet is only used by the host to detect desyncs, and we don't really need to know the exact frame we desynced on (unless you're debugging, but you can just recompile for that), so it's perfectly fine to just send it less often. This makes it so the timebase packet is sent only every 60 frames, rather than every frame, which further cuts back on unnecessary bandwidth consumption.
PowerPCState's cr_val member is an array of u64s, so we can just use the
correct printf macro specifier within cinttypes. This also avoids
truncation on operating systems that use an LLP64 data model (like
Windows), where long is actually 32 bits in size, not 64-bit, which
could result in wonky values being printed, should Trace ever be used on
it.
define how many frames constitute a high or a low swing/shake when the
button is down. Also configurable is the number of frames to execute
the swing/shake after the button is released.
Previously there was only one function under the NetPlay namespace,
which is kind of silly considering we have all of these other types
and functions existing outside of the namespace.
This moves the rest of them into the namespace.
This gets some general names, like Player, for example, out of the global namespace.
Now the detection heuristic has changed, the old value is no longer
valid.
Some example thresholds for known mipmap effects that should trigger:
SMG's lava has a mimimum difference of ~17.8, SMG2's clouds have a
minimum difference of ~14.8, and Wind Waker's foam has a minimum
difference of ~15
Non-triggering examples were tested and all had a calculated difference
lower than 3.
So a value of 14 should lean towards false-negatives instead of
positives, but this is clearly incomplete testing and may require
further tweaks later.
Normally, SI is polled at a rate defined by the game, and we have to send the pad state to other clients on every poll or else we'll desync. This can result in fairly high bandwidth usage, especially with multiple controllers, mostly due to UDP/IP overhead.
This change introduces an option to reduce the SI poll rate to once per frame, which may introduce up to one frame of additional latency, but will reduce bandwidth usage substantially, which is useful for users on very slow internet connections.
Polling SI less frequently than the game asked for did not seem to cause any problems in my testing, so this should be perfectly safe to do.
Given we now use a base class for the interface, we can make all member
functions, types and constants that aren't directly related to
instructions private.
HID2.LSQE is the Load/store quantize enable bit for non-indexed format
instructions (which are psq_l, psq_lu, psq_st, and psq_stu). If this bit
is not set and any of these instructions are attempted to be executed,
then a program exception is supposed to occur.
This register is defined as "optional reserved" within the aarch64 ABI.
Linux doesn't use it, but we must not modify it on ios or windows.
As we have plenty of registers on aarch64, let's just always skip this one.
This function was duplicated across all the opcode tables: the main info
tables, the interpreter tables, and the x86-64 JIT tables. However, we
can just make the type of the std::array parameter a template type and
get rid of this duplication.
const on a parameter being passed by value in a prototype doesn't actually signify
anything, these are only applicable in the definition, where they make
the opcode parameter immutable.
inline has external linkage, which doesn't really make sense here, given
the function is only used within this translation unit. So we can
replace inline with static.
While we're at it, the code within the function can also be compressed
to a single return statement.
Previously these were required to be built into the executable so that
the JIT portion of the DSP code would build properly, as the
x86-64-specifics were tightly coupled to the DSP common code. As this is
no longer the case, this is no longer necessary.
This adds a base class that is used to replace the concrete instance of
the x64 JIT pointer within DSPCore. This fully removes the direct use
(read: non-ifdefed) usage of x86-64-specifics within the main DSP code.
Said base can also be used for creating JITs for other architectures,
such as AArch64, etc.
This is one of the last things that needed to be done in order to
finally separate the x86-64-specific code from the rest of the common
DSP code. This splits the tables up similar to how it's currently done
for the PowerPC CPU tables.
Now, the tables are split up and within their own relevant source files,
so the main table within the common DSP code acts as the "info" table
that provides specifics about a particular instruction, while the other
tables contain the actual instruction.
With this out of the way, all that's left is to make a general base for
the emitters and we can then replace the x64 JIT pointer in DSPCore with
it, getting all x64 out of the common code once and for all.
While shuffling all the code around, the removal of the DSPEmitter
includes in some places uncovered indirect inclusions, so this also
fixes those as well.
Despite both being documented as read-only registers, only one of them
is truly read-only. An mtspr to HID1 will steamroll bits 0-4 with
bits 0-4 of whatever value is currently in the source register, the rest
of the bits are not modified as bits 5-31 are considered reserved, so
these ignore writes to them.
PVR on the other hand, is truly a read-only register. Attempts to write
to it don't modify the value within it, so we model this behavior.
This makes it much more straightforward to access WiimoteDevice
instances and also keeps the implementation details of accessing those
instances in one spot.
Given as all external accesses to the WiimoteDevice instances go through
this function, we can make the other two private.
Using reinterpret_cast (or a C-styled equivalent) to reinterpret
integers as floating-point values and vice-versa invokes undefined
behavior. Instead, use BitCast, which does this in a well-defined
manner.
According to PEM 3.3.6.1, if a division by zero occurs and FPSCR.ZE is
set, then the result of the instruction operation is unchanged (see
table 3-13). Similarly, if an invalid operation occurs and FPSCR.VE is
set, then the destination should also remain unchanged (see table 3-12).
Hardware also matches this behavior.
We were handling this for other relevant instructions, but we weren't
doing so for the arithmetic instructions. This corrects that.
This also alters our NI_* functions to return an FPResult type, which
allows us to see which kind of exception in particular is set in
exceptional cases. This is necessary for cases like the fdiv
instructions, which requires handling both ZE and VE being potentially
set.
Previously the class was intermixing m_ prefixed variables and
non-prefixed ones, which can be misleading. Instead, we make the
prefixing consistent across the board.
Makes the values strongly-typed and gets more identifiers out of the
global namespace.
We are forced to use anything that is not "None" to mean none, because
X11 is garbage in that it has:
\#define None 0L
Because clearly no one else will ever want to use that identifier for
anything in their own code (and is why you should prefix literally
any and all preprocessor macros you expose to library users in public
headers).
Makes the enum values strongly-typed and prevents the identifiers from
polluting the PowerPC namespace. This also cleans up the parameters of
some functions where we were accepting an ambiguous int type and
expecting the correct values to be passed in.
Now those parameters accept a PowerPC::CPUCore type only, making it
immediately obvious which values should be passed in. It also turns out
we were storing these core types into other structures as plain ints,
which have also been corrected.
As this type is used directly with the configuration code, we need to
provide our own overloaded insertion (<<) and extraction (>>) operators
in order to make it compatible with it. These are fairly trivial to
implement, so there's no issue here.
A minor adjustment to TryParse() was required, as our generic function
was doing the following:
N tmp = 0;
which is problematic, as custom types may not be able to have that
assignment performed (e.g. strongly-typed enums), so we change this to:
N tmp;
which is sufficient, as the value is attempted to be initialized
immediately under that statement.
This changes the identifier to represent the x86-64 DSP emitter. If any
other JITs for the DSP are added in the future, they all can't use the
same generic identifier.
In cases where we just want a random value for a primitive arithmetic
type, we can wrap this in a template to allow convenient direct
assignment instead of keeping declaration and initialization separate
(making it more difficult to use values uninitialized). This also allows
the use of Common::Random with functions such as std::generate, making
it more flexible in how random values can be generated.
This is only ever used internally. Also change the std::string name over
to a const char*, so that we don't need to potentially allocate anything
on the heap at immediate runtime.
Previously, a total of 114 std::string instances would need to construct
(allocating on the heap for larger strings that can't be stored with
small string optimizations). We can just use an array of const char*
strings instead, which allows us to avoid this.
Given JitBase shouldn't include platform specifics, we can generalize this
preprocessor define and allow any JIT to use it to indicate that generated code should be logged.
While we're at it, also move these defines beneath the includes with the
rest of the defines.
Rather than introduce this handling in every system instruction that modifies
the FPSCR directly, we can instead just handle it within the data structure
instead, which avoids duplicating mask handling across instructions.
This also allows handling proper masking from the debugger register
windows themselves without duplicating masking behavior there either.
ChunkFile doesn't use any of the file utilities, so we can drop these
headers to avoid pulling in unnecessary dependencies. This also
uncovered a few indirect inclusions.
This only queries internal state, it doesn't modify it. With minor
adjustments to BTEmu, this also allows us to make its usage instance a
constant reference.
UNUSED is quite a generic macro name and has potential to clash with
other libraries, so rename it to DOLPHIN_UNUSED to prevent that, as well
as make its naming consistent with the force inline macro
Instead of globbing things under an ambiguous Common.h header, move
compiler-specifics over to Compiler.h. This gives us a dedicated home
for anything related to compilers that we want to make functional across
all compilers that we support.
This moves us a little closer to eliminating Common.h entirely.
Rather than have a separate independent variable that we need to keep
track of in conjunction with the JIT code buffer size itself, amend the
analyst code to use the code buffer constant in JitBase.
Now if the size ever changes, then the analyst will automatically adjust
to handle it.
Given the code buffer is something truly common to all JIT
implementations, we can centralize it in the base class and avoid
duplicating it all over the place, while still allowing for differently
sized buffers.
Gets rid of an inclusion dependency with the DSP interpreter, as well as
a header-based dependency on the DSP opcode tables. This also uncovered
an indirect inclusion on the logger within DSPSymbols.cpp
As peculiar as this may be, decrementer exceptions by means of setting
the decrementer's zeroth bit from 0 to 1 is valid behavior by software
(and is defined in Programming Environments for 32-bit Microprocessors
in section 2.3.14.1 -- Decrementer operation). Given it's valid behavior,
it doesn't necessarily make sense to use a panic alert and halt, as this
isn't a condition where everything should be considered in a critical
state.
Instead, change it to an info log, so we still make note of it, but
without potentially tearing down state or halting emulation.
This fixes the The Last Story prototype that GerbilSoft was testing,
because the apploader is a bit more lenient with the max size of DOL
sections when it detects that you're using a devkit console.
Deduplicates code, and gets rid of some problems the old code had
(such as: bad performance when calling native functions, only one
disc showing up for multi-disc games, Wii banners being low-res,
unnecessarily much effort being needed for adding more metadata).
By making the jitted function a private static function of DSPEmitter,
we can allow access to data members within the context of the function
without making them public overall.
This finally makes all data members for the x64 DSP emitter private.
This hardware behavior makes sense, as the FI bit is used to signify an
inexact result. An inexact result is a form of value that results during
the rounding phase of denormalization. If any bits of the significand
are lost during said rounding, then the result is considered to be
inexact.
However NaN and infinity are not classed as subnormals and therefore
don't undergo the denormalization step, making loss of precision not
possible (in NaN's case, numerically rounding something that is
literally Not a Number doesn't even make sense).
FR is set to indicate whether or not the last arithmetic or rounding and
conversion instruction that rounded the intermediate result incremented
the fractional portion of the result. Given neither input types would be
affected by this, this should also be unset.
This corrects more of the exceptional case handling for these values to
match hardware.
As suggested here: https://dolp.in/pr7059#pullrequestreview-125401778
More descriptive than having a std::tuple of FS::Mode, and lets us
give names to known triplets of modes (like in ES). Functions that
only forward mode arguments are slightly less verbose now too.
Prevents implicit conversions to types and requires explicitly
specifying them in order to construct instances of them. Given these are
used within emulation code directly, being explicit is always better
than implicit.
As explained within 179d73ac0d, the table
within the Programming Environments Manual for PowerPC lists the FI and
FR bits as cleared for invalid operation cases. So, we amend the
relevant cases here in order to be accurate to hardware.
As explained within commit a08ad82ace, if
an invalid exception occurs and VE is set, then the destination register
should remain unchanged. Ditto for when ZE is set and a zero divide
exception occurs.
This is only used internally, so we don't need to expose it in the
header. This also allows getting rid of inclusion of the byte swapping
utilities in the header as well.
Given they were only made public so that the callback could access class
state, we can simply make the callback a private static function of
CEXIMic, which allows access to members from the callback function
without making all of said members public.
In the PEM manual, within Table 3-12, which lists what should occur for
invalid operation exceptions, the FPSCR.FI and FPSCR.FR bits are listed
as "Cleared" for when FPSCR.VE is unset and set. So we clear these bits
as well to match hardware behavior.
In the PowerPC Microprocessor Family: The Programming Environments
Manual for 32 and 64-bit Microprocessors, in section 3.3.6.1, Table
3-12 lists what should occur if an invalid operation exception occurs in
situations where VE is set and when VE is not set. In the case where VE
is set, it lists the frD as "Unchanged". It also lists the FPRF flags as
"Unchanged".
Further down in Table 3-13, the listings for what should occur when zero
divide exceptions occur is listed, both for when ZE is set, and when it
isn't. When ZE is set, it lists frD as "Unchanged". It also lists the
FPRF flags as "Unchanged" as well.
This also alters the code so that we don't even calculate the result if
we don't need to compute it, making it a little bit less wasteful.
DataBinHeader is not used anywhere in the code other than via Header,
so let's merge them to reduce noise when accessing header fields
(currently we have to do header.hdr which looks silly).
It would make sense for 0x80 and 0xf0c0 to be respectively
sizeof(BkHeader) and sizeof(Header) as Nintendo is signing anything
that comes after the header, including the BkHeader.
The current WiiSave code is extremely messy, as it exposes all kinds of
implementation details in the header (including internal struct
definitions and magic numbers that don't have to be).
The read/write code is intermingled, so it's hard to tell which members
are used, or when/where they are set at all.
It also implicitly relies on some functions being called in a specific
order since it doesn't seek manually every time, which makes the code
even more fragile.
The logic is also hardcoded to only support bin->nand or nand->bin,
even though it would be useful to support nand->nand (for the
Movie save copying code, for example).
This commit attempts to solve these problems by getting rid of the
WiiSave class:
* Read/write code is moved to new Storage classes (NandStorage and
DataBinStorage) with small, clear functions that do one and only
one thing.
* The import/export logic was refactored into a generic Copy function
that takes two storages as parameters.
* The existing import and export functions are now just small wrappers
that call Copy with the appropriate storages.
This makes it easier to generate random numbers or fill a buffer with
random data in a cryptographically secure way.
This also replaces existing usages of RNG functions in the codebase:
* <random> is pretty hard to use correctly, and std::random_device does
not give enough guarantees about its results (it's
implementation-defined, non cryptographically secure and could be
deterministic on some platforms).
Doing things correctly is error prone and verbose.
* rand() is terrible and should not be used especially in crypto code.
Normalizes variable names to conform to our coding conventions.
Previously we were signifying some variables as externally linked
globals, which wasn't the case.
Pretty much all of the source files contain the following:
namespace IOS
{
namespace HLE
{
namespace <name>
{
// actual code here
} // namespace <name>
} // namespace HLE
} // namespace IOS
which is really verbose boilerplate, because most of the files inside
of Core/IOS are for IOS HLE.
This commit replaces that with a more concise `namespace IOS::HLE`
or `namespace IOS::HLE::(name)`.
This is just used as a means of carting around routines. It's not meant
to directly have functionality embedded within it--this is the job of
the inheriting data structure--so we can just make this a basic struct.
Particularly given all the data members were public to begin with.
Switching to blank NAND when emulation is running is an extremely bad
idea. It's akin to opening up a Wii and replacing the NAND chip while
you're playing a game on it.
Except we're not even replacing it with a NAND that has the same
contents. The blank NAND has nothing in it except the save file for
the current game, which is likely to result in the emulated software
getting inconsistent results and possibly even crashing depending on
how it caches title information.
An example of games that check the saves for other games is
Mario Kart Wii -- it checks the filesystem for Super Mario Galaxy saves
to decide whether to unlock characters. With this 'switch NAND
while emulation is active' misfeature, this will likely break.
And that's the main problem: it encourages sloppy emulation and no one
really knows how many things it can break.
Just don't let the user do horrible things like that during emulation.
If they want to use a blank NAND, they can do so by starting input
recording before launching a game. It's likely they will want to do
this if they plan to share their DTM anyway.
Another bit of behavior that we weren't performing correctly is the
unsetting of FPSCR.FI and FPSCR.FR when FPSCR.ZX is supposed to be set.
This is supported in PEM's section 3.3.6.1 where the following is
stated:
"
When a zero divide condition occurs, the following actions are taken:
- Zero divide exception condition bit is set FPSCR[ZX] = 1.
- FPSCR[FR, FI] are cleared.
"
And so, this fixes that behavior.
FPSCR[ZX] is the bit defined to represent the zero divide exception
condition bit, and is defined as (according to PowerPC Microprocessor
Family: The Programming Environments Manual for 32 and 64-bit
Microprocessors, which will be referred to as "PEM" for the rest of this
commit message) at section 3.3.6.1:
"
A zero divide exception condition occurs when a divide instructions is
executed with a zero divisor value and a finite, nonzero dividend value
or when a floating reciprocal estimate single (fres) or a floating
reciprocal square root estimate (frsqrte) instruction is executed with a
zero operand value.
"
Note that it states the divisor must be zero and the dividend must be
nonzero in order for ZX to be set. This means that the interpreter was
performing the wrong behavior for the case where 0/0 (with any sign on
the zeros) is performed. We would incorrectly set the ZX bit when only
the VXZDZ bit should be set.
It's also worth pointing out that N/0 (where N is any finite nonzero
value) and 0/0 are not within the same exception class. N/0 is a zero
divide exception case, while 0/0 is considered an invalid operation
exception case, which is also indicated in the PEM section 3.3.6.1 as
well where it lists the criteria for invalid operation exceptions.
Therefore we should only be setting the VXZDZ bit in the 0/0 case, not
VXZDZ and ZX. This was also verified via hardware tests to ensure that
this behavior indeed holds.
Given this is actually a part of the Host interface, this should be
placed with it.
While we're at it, turn it into an enum class so that we don't dump its
contained values into the surrounding scope. We can also make
Host_Message take the enum type itself directly instead of taking a
general int value.
After this, it'll be trivial to divide out the rest of Common.h and
remove the header from the repository entirely
If invalid operation exceptions are enabled and an invalid operation
occurs, then the destination value remains untouched. This fixes issues
that may arise when using these two instructions where the destination
gets steamrolled by an infinity or NaN value.
Pierre Bourdon