On 2/20/25 09:12, Peter Maydell wrote:
That suggests that we are correctly implementing the x87
required behaviour in QEMU, and so that the TODO comment
I add in this patch isn't right. But then I'm a bit confused
about what the code is actually doing. Why do we need to look
at fmt->m68k_denormal in the input (canonicalize) code (i.e.
to have different behaviour here for x86 and m68k), if
both x86 and m68k accept these pseudodenormals as input?
Is the difference that for x86 we accept but canonicalize
into the equivalent normal number immediately on input,
whereas for m68k we accept and leave the pseudodenormal
as a pseudodenormal (well, m68k calls these a kind of
normal number) ?
The difference is in interpretation: x86 ignores the explicit integer bit of the
pseudo-denormal, m68k considers it part of the input value. This gives m68k one extra bit
of range in their denormal, which allows representation of smaller numbers.
r~
