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)
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