The first one is pretty easy. See (tye)Re: 64 bit Integer anyone? for my version. It even detects if the number didn't quite fit in the 52 bits.
- tye (but my friends call me "Tye")
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That's terrific, thanks.
That uses the first idea: unpack as two L's.
It seems your design goal was portability, since you automatically detect the endian.
I see that you try to unpack "Q" first (in the signed form, you should be using "q"). I like that idea, but I think I'll swap out the whole sub so it only tries once when it decides it can't do that. In yours, you'll confuse a valid 0 integer with failure.
I noticed you wrote 1+~0 for 0x100000000, and my first impression was that this was also for portability. But, I think it's nonportable now, and that's just clearer than writing it out in decimal (the hex form overflows Perl's parser and is not allowed). But, unpack "L" is specifically 32-bit fields and not necessarily the native size, and nowhere does it say what size bit operators operate on, but I think this is the definition of "native size".
So, you are assuming that the native size is 32 bits if quadword support is disabled. I think I'll use 2**32 for clarity, and trust the optomizer to fold the constant arithmetic down.
—John
update: I didn't notice the extra ;1; at the end of the eval block. Cute. But easy to miss.
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The author of the Spreadsheet::WriteExcel module
appears to have had a similar problem.
Spreadsheet::WriteExcel will work on the majority of Windows, UNIX and Macintosh platforms. Specifically, the module will work on any system where perl packs floats in the 64 bit IEEE format. The float must also be in little-endian format but it will be reversed if necessary. Thus:
print join(" ", map { sprintf "%#02x", $_ }
unpack("C*", pack "d", 1.2345)), "\n";
should give (or in reverse order):
0x8d 0x97 0x6e 0x12 0x83 0xc0 0xf3 0x3f
So, as I read it, if you aren't concerned about portability, the following should work:
my $dfloat=unpack("d",reverse($yourbigendian));
(remove the reverse bit if your box is big-endian.
I'm assuming it's not, since you mentioned ActiveState..)
Update: Seems I was a bit confused about what
format he did have the numbers in. ( In my defense,
I'm still not clear :) Perhaps a pointer to the IEEE
double format would make this node somewhat useful ?
See This page from Sun | [reply]
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