Hmmm, Number::Binary doesn't seem to be taken, at least according to meta::cpan.
What about $enc = Number::Binary->encoder("name"); $dec = Number::Binary->decoder("name");? You could also make it easy to get inverse functions by accepting an object; e.g. $dec = Number::Binary->decoder($enc); e.g. $e80 = Number::Binary->encoder("intel80")->encode(2.71828) printf( "%s: %s\n", Number::Binary->name("intel80"), Number::Binary->decoder("intel80")->decode($e))' >> Intel extended floating point: 2.71828 Supporting BigXXX for the native value seems important, not only for the large floats, but some ints. E.g. Double precision integers (128 bit, or 64 bit on a 32-bit platform - or 72 bit on a 36-bit platform) You're the expert; whether the encoders figure out whether bignum was used in the caller, or the decoder constructors take a "use_big" option, or the result of decode is specified as a possibly overloaded object that can do math, or ... I leave to you. Besides finessing bignums, making the output of decode an object allows for a path to info methods - besides name, sizes common to all, maybe things like "smallest number of bits that are needed for this value" (e.g. would this fit in a smaller format without loss of precision?) Not sure what the right list would be, but once there's one, it will probably grow. Yes, small can get interesting too - e.g. saturating 8-bit bytes packed in something bigger... Sounds like fun. Hope this helps. Good luck. On 03-Jun-21 08:52, Peter John Acklam wrote: > Thanks for the feedback! > > I see your point regarding the Math:: namespace and agree that it > isn't the best. Alas, Number::Encode is already taken. I suggested > Number::Pack and Number::Unpack because they aren't taken and because > of the module's similar functionality to pack() and unpack(). > > I agree that there should be a simple wrapper and that the format > should not be a part of the module name specified by the user. I also > agree about not assuming floating point. Actually, one of the use > cases is encoding/decoding unsigned 24 bit integers, which are used by > ImageMagic when reading/writing PAM (portable anymap) images. > > There is also Data::IEEE754, but I think the Data:: namespace is too > general. I will only be dealing with numbers. > > Peter > > tor. 3. jun. 2021 kl. 13:22 skrev Timothe Litt <tlhack...@cpan.org>: >> I'd be a bit careful about assuming floating point - will someone want to >> pack/unpack BCD? Or PDP-10 Gfloat (well, OK that's a floating format)? Or... >> >> I don't like Math:: - it implies that it does arithmetic (or calculus, or >> statistics, or - more than a conversion). >> >> And I'd rather not have a format name encoded in the module that the user >> calls. >> >> How about Number::Encode->new("name") & Number::Decode->new("name")? >> >> Let "name" get to a subclass, so other formats can be supported just by >> adding a module - e.g. "Number:Encode::BCD" could be require'd if >> *->new('bcd') called. Obviously, you'd implement IEEE754, Intel80, and >> whatever else... >> >> Define the API for the subclasses - encode(),decode(), perhaps some info >> functions (e.g. a printable name, perhaps exponent and fraction range/#bits, >> ...) >> >> Then someone who wants Number::Decode::VAX_DFLOAT just calls >> Number::Decode->new('vax_dfloat') - after writing it. >> >> Some of these can get interesting if you want to decode and actually do math >> - presumably you'll support Math::BigXxx / bignum? (binary128, VAX >> H_Floating are, IIRC about 36 decimal digits) >> >> And some program that reads archived data can have a description language >> that is simply "name" "format" "byte offset" "length", and not worry about >> what module handles what format. In fact, such a program might appreciate >> the trivial modules Number::Encode::INTEGER32 (and perhaps the less obvious >> Number::Encode::INTEGER32_ONESCOMPLEMENT)... >> >> I suspect there are better names for the format, but the idea is to export a >> simple wrapper so the next format can be added by anyone, and the callers >> don't have to know too much. >> >> FWIW. >> >> >> On 03-Jun-21 06:23, Peter John Acklam wrote: >> >> I also plan to implement the 80 bit "extended precision" format, which >> is not IEEE 754 compatible. Perhaps the best and simplest is >> Number::Pack and Number::Unpack? >> >> Peter >> >> tor. 3. jun. 2021 kl. 11:43 skrev Peter John Acklam <pjack...@gmail.com>: >> >> Hi >> >> I am working on two modules for encoding and decoding numbers as per >> IEEE754. The pack() function can encode and decode the formats binary32 >> (single precision) and binary64 (double precision). My module can also >> handle binary128 (quad precision), binary16 (half precision), bfloat16 (not >> an IEEE754 format, but it follows the IEEE754 pattern), and a few other >> formats. >> >> My question is about the namespace. Is Math::IEEE754::Encoder (and >> ...::Decoder) OK? Or is Number::IEEE754::Encoder better? Or any other? >> >> Here is an example showing how I use it: >> >> my $encoder = Math::IEEE754::Encoder -> new("binary16"); >> my $bytes = $encoder -> (3.14159265358979); # = "\x42\x48" >> >> my $decoder = Math::IEEE754::Decoder -> new("binary16"); >> my $number = $decoder -> ($bytes); # = 3.140625 >> >> The reason for returning an anonymous function rather than implementing the >> function directly, is speed. There are some constants involved, and I don't >> want to compute them for each function call. >> >> Cheers, >> Peter John Acklam (PJACKLAM)
Description: OpenPGP digital signature