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
We can just memcpy the data instead of pointer-casting data, which is
alignment-safe and doesn't run afoul of aliasing rules.
Previously it also made it seem as if data itself pointed to valid
usable data, but it doesn't, it simply functions as an out parameter
where we push data built up from the GetState() functions into it.
This was added in 4bdb4aa0d1 back in
2009-02-27. The only usage spot of this macro involves the same checks
that were used to define that preprocessor macro, so we can simply
remove the macro
If any operand is a signaling NaN, we need to signify this by setting
the VXSNAN bit.
Fixes NaN flag setting for fmsub, fmsubs, fnmsub, fnmsubs, ps_msub, and
ps_nmsub instructions.
If any operand is a signaling NaN, we need to signify this by setting
the VXSNAN bit.
Fixes NaN flag setting for fmadd, fmadds, fnmadd, fnmadds, ps_madd,
ps_nmadd, ps_madds0, and ps_madds1
If either operand is a signaling NaN, we need to signify this by setting
the VXSNAN bit.
This fixes NaN flag setting for fsub, fsubs, and ps_sub instructions.
If either operand is a signaling NaN, we need to signify that by setting
the VXSNAN bit.
This fixes NaN flag setting for fdiv, fdivs and ps_div instructions.
