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.
If we don't do this the prompt *may* appear behind the fullscreened window
and thus cause confusion. This happens both with exclusive fullscreen and
borderless fullscreen (e.g. for OpenGL).
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.
The definition of the function uses the ordering {mod, reg, rm}, which
is correct. Match the prototype to this, so that the parameter list
isn't misleading.
We can just use std::any_of here to collapse the checking code down to a
single assignment as opposed to a loop. This also slightly improves on
the existing code, as this won't continue to iterate through the cluster
metadata if an entry that's non-zero is encountered.
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.
Gets rid of the need to set up memcpy boilerplate to reinterpret between
floating-point and integers.
While we're at it, also do a minor bit of tidying.
Given this is what occurs in both constructors (as one just passes
through to another), we can just initialize the member directly.
While we're at it, amend the struct to follow the general ordering
convention of:
<new types>
<functions>
<variables>
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.
Fairly trivial to resolve, we just initialize the std::array with two
sets of braces (one set to create the array, the other to start and end the
aggregate data that we'll end up returning)
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.
If a NaN of any type is passed as the operand to either of these
instructions, we shouldn't go down the regular code path, as we end up
potentially setting the wrong flags. For example, we wouldn't set the
FPSCR.VXCVI bit properly. We'd also set FPSCR.FI, when in actuality it
should be unset.
If an SNaN is passed as an operand, we also need to set the FPSCR.VXSNAN
bit as well.
The flag setting behavior for these can be found in Appendix C.4.2 in
PowerPC Microprocessor Family: The Programming Environments Manual for
32 and 64-bit Microprocessors.
fctiwz functions in the same manner as fctiw, with the difference being
that fctiwz always assumes the rounding mode being towards zero. Because
of this, we can implement fctiwz in terms of fctiw's code, but modify it
to accept a rounding mode, allowing us to preserve proper behavior for
both instructions.
We also move Helper_UpdateCR1 to a temporary home in
Interpreter_FPUtils.h for the time being. It would be more desirable to
move it to a new common header for all the helpers, so that even JITs
can use them if they so wish, however, this and the following changes
are intended to only touch the interpreter to keep changes minimal for
fixing instruction behavior.
JitCommon already duplicates the Helper_Mask function within
JitBase.cpp/.h, and the ARM JIT includes the Interpreter header in order
to call Helper_Carry. So a follow up is best suited here, as this
touches two other CPU backends.
