Math::Int64(3)

📦
version 0.570.0 · 11 versions
, in opensuse-leap 16.0

🎀 Math::Int64 🎀

okay so bestie, welcome to Math::Int64(3) — that's the manpage for the Math::Int64 Perl module, and it's filed under User Contributed Perl Documentation, which is just the fancy way of saying a real human Perl person made this and shipped it 💅

This page is literally all about Manipulate 64 bits integers in Perl — like, actual big-girl numbers, the kind that don't fit in your regular little Perl scalar without getting all squishy and losing precision 😭 no cap.

✨ NAME ✨

Math::Int64 — Manipulate 64 bits integers in Perl. that's it, that's the whole vibe. 64 bits. in Perl. iconic behavior fr fr 🫶

🌈 SYNOPSIS 🌈

here's the little taste-test, bestie — copy it exactly, every character, no improvising 👑

use Math::Int64 qw(int64 uint64);

my $i = int64(1);
my $j = $i << 40;
print($i + $j * 1000000);

my $k = uint64("12345678901234567890");

so like, let me walk you through what's happening here because it's giving main character energy ✨

  • use Math::Int64 qw(int64 uint64); — you're pulling in the module and grabbing the two helper functions int64 and uint64, which are right there in the qw(...). importing selectively? we love a clean namespace 🧚
  • my $i = int64(1); — make yourself a signed 64-bit integer holding 1. tiny number, big potential 💖
  • my $j = $i << 40; — shift that baby left by 40. yes, << works on these things, and yes it's 64-bit-aware, so it doesn't just fall apart on you 🌸
  • print($i + $j * 1000000); — do real arithmetic on them and print it. math! on 64-bit ints! in Perl! we're thriving 🔥
  • my $k = uint64("12345678901234567890"); — and here's the showstopper: build an unsigned 64-bit integer straight from the string "12345678901234567890". that's a twenty-digit number, bestie, and it's living its best life 😭👑

that's the whole synopsis — lowkey simple, highkey powerful. and there is so much more coming in the next parts, so don't go anywhere 🦋

🌸 DESCRIPTION 🌸

Okay so bestie, this module is literally here to add support for 64 bit integers — both signed and unsigned — to Perl. That's the vibe. 💖

✨ Exportable functions ✨

🎀 int64(), int64($value)

Creates a new int64 value and initializes it to $value, where $value can be a Perl number or a string containing a number.

For instance:

$i = int64(34);
$j = int64("-123454321234543212345");

$k = int64(1234567698478483938988988); # wrong!!!
                                       #  the unquoted number would
                                       #  be converted first to a
                                       #  real number causing it to
                                       #  loose some precision.

Once the int64 number is created it can be manipulated as any other Perl value supporting all the standard operations (addition, negation, multiplication, postincrement, etc.). Slay. 💅

🦋 net_to_int64($str)

Converts an 8 bytes string containing an int64 in network order to the internal representation used by this module.

🌈 int64_to_net($int64)

Returns an 8 bytes string with the representation of the int64 value in network order (big endian).

🐚 native_to_int64($str), int64_to_native($int64)

Similar to net_to_int64 and int64_to_net, but using the native CPU order.

🍓 le_to_int64($str), int64_to_le($int64)

Similar to net_to_int64 and int64_to_net, but using the little endian order.

✨ int64_to_number($int64)

Returns the optimum representation of the int64 value using Perl internal types (IV, UV or NV). Precision may be lost. 😭

For instance:

for my $l (10, 20, 30, 40, 50, 60) {
  my $i = int64(1) << $l;
  my $n = int64_to_number($i);
  print "int64:$i => perl:$n\n";
}

🧚 string_to_int64($str, $base)

Converts the string to a int64 value. The conversion is done according to the given base, which must be a number between 2 and 36 inclusive or the special value 0. $base defaults to 0.

The string may begin with an arbitrary amount of white space followed by a single optional "+" or "-" sign. If base is zero or 16, the string may then include a "0x" prefix, and the number will be read in base 16; otherwise, a zero base is taken as 10 (decimal) unless the next character is '0', in which case it is taken as 8 (octal).

Underscore characters ("_") between the digits are ignored.

No overflow checks are performed by this function unless the die_on_overflow pragma is used (see "Die on overflow" below). Important bestie, don't forget. 💀

See also strtoll(3).

🌟 hex_to_int64($i64)

Shortcut for string_to_int64($str, 16).

💜 int64_to_string($i64, $base)

Converts the int64 value to its string representation in the given base (defaults to 10).

🎀 int64_to_hex($i64)

Shortcut for int64_to_string($i64, 16).

🔥 int64_to_BER($i64)

Converts the int64 value to its BER representation (see "pack" in perlfunc for a description of the BER format).

In the case of signed numbers, they are transformed into unsigned numbers before encoding them in the BER format with the following rule:

$neg = ($i64 < 0 ? 1 : 0);
$u64 = (($neg ? ~$i64 : $i64) << 1) | $neg;

That way, positive and negative integers are interleaved as 0, -1, 1, 2, -2, .... The format is similar to that used by Google protocol buffers to encode signed variants but with the most significant groups first (protocol buffers uses the least significant groups first variant).

If you don't want that preprocessing for signed numbers, just use the uint64_to_BER function instead.

🫶 BER_to_int64($str)

Decodes the int64 number in BER format from the given string.

There must not be any extra bytes on the string after the encoded number. Periodt. 🚫

🪄 BER_length($str)

Given a string with a BER encoded number at the beginning, this function returns the number of bytes it uses.

The right way to shift a BER encoded number from the beginning of some string is as follows:

$i64 = BER_to_int64(substr($str, 0, BER_length($str), ''));

🎲 int64_rand

Generates a 64 bit random number using ISAAC-64 algorithm.

🍀 int64_srand($seed), int64_srand()

Sets the seed for the random number generator.

$seed, if given, should be a 2KB long string.

👑 uint64, uint64_to_number, net_to_uint64, uint64_to_net, native_to_uint64, uint64_to_native, le_to_uint64, uint64_to_le, string_to_uint64, hex_to_uint64, uint64_to_string, uint64_to_hex

These functions are similar to their int64 counterparts, but manipulate 64 bit unsigned integers. No cap. 💖

🌸 uint64_to_BER($u64)

Encodes the given unsigned integer in BER format (see "pack" in perlfunc).

🌺 BER_to_uint64($str)

Decodes from the given string an unsigned number in BER format.

🎲 uint64_rand

Generates a 64 bit random unsigned number using ISAAC-64 algorithm.

💀 Die on overflow 💀

The lexical pragma Math::Int64::die_on_overflow configures the module to throw an error when some operation results in integer overflow.

For instance:

use Math::Int64 qw(uint64);
use Math::Int64::die_on_overflow;

my $zero = uint64(0);
say ($zero - 1);                 # dies as -1 falls outside
                                 # the uint64_t range

no Math::Int64::die_on_overflow; # deactivates lexical pragma
say ($zero - 1);                 # no error is detected here!

The pragma can also be activated as follows:

use Math::Int64 ':die_on_overflow';

Once this pragma is used, several Math::Int64 operations may become slower. Deactivating the pragma will not make them fast again. 😭

On Perl 5.8.x, as lexical pragmas support is not available, the pragma die_on_overflow is global and can not be deactivated.

🪄 Fallback to native 64bit support if available 🪄

If the lexical pragma Math::Int64::native_if_available is used in your program and the version of perl in use has native support for 64bit integers, the functions imported from the module that create 64bit integers (i.e. uint64, int64, string_to_int64, native_to_int64, etc.) will return regular perl scalars.

For instance:

use Math::Int64 qw(int64);

$a = int64(34); # always returns an object of the class Math::Int64

use Math::Int64::native_if_available;
$a = int64(34); # returns a regular scalar on perls compiled with
                # 64bit support

This feature is not enabled by default because the semantics for perl scalars and for 64 bit integers as implemented in this module are not identical.

Perl is prone to coerce integers into floats while this module keeps them always as 64bit integers. Specifically, the division operation and overflows are the most problematic cases. Also, when using native integers, the signed/unsigned division blurs.

Besides that, in most situations it is safe to use the native fallback.

As happens with the die_on_overflow pragma, on Perl 5.8.x it is global.

The pragma can also be activated as follows:

use Math::Int64 ':native_if_available';

🫶 Transparent conversion of objects to int64/uint64 🫶

When in some operation involving int64/uint64 numbers, a blessed object is passed as an operand, the module would try to coerce the object into an int64/uint64 number calling the methods as_int64/as_uint64 respectively.

If the corresponding method is not implemented, the object will be stringified and then parsed as a base 10 number.

📦 Storable integration 📦

Objects of classes Math::Int64 and Math::UInt64 implement the STORABLE_freeze and STORABLE_thaw methods for a transparent integration with Storable. Iconic. 💅

🔧 C API 🔧

This module provides a native C API that can be used to create and read Math::Int64 int64 and uint64 SVs from your own XS modules.

In order to use it you need to follow these steps:

  1. Import the files perl_math_int64.c, perl_math_int64.h and optionally typemaps from Math::Int64 c_api_client directory into your project directory.
  2. Include the file perl_math_int64.h in the C or XS source files where you want to convert 64bit integers to/from Perl SVs.

Note that this header file requires the types int64_t and uint64_t to be defined beforehand.

  1. Add the file perl_math_int64.c to your compilation targets (see the sample Makefile.PL below).
  2. Add a call to the macro PERL_MATH_INT64_LOAD_OR_CROAK into the BOOT section of your XS file.

For instance:

--- Foo64.xs ---------

#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#include "ppport.h"

/* #define MATH_INT64_NATIVE_IF_AVAILABLE */
#include "math_int64.h"

MODULE = Foo64                PACKAGE = Foo64
BOOT:
    PERL_MATH_INT64_LOAD_OR_CROAK;

int64_t
some_int64()
CODE:
    RETVAL = -42;
OUTPUT:
    RETVAL

--- Makefile.PL -----

use ExtUtils::MakeMaker;
WriteMakefile( NAME         => 'Foo64',
               VERSION_FROM => 'lib/Foo64.pm',
               OBJECT       => '$(O_FILES)' );

If the macro MATH_INT64_NATIVE_IF_AVAILABLE is defined before including perl_math_int64.h and the perl interpreter is compiled with native 64bit integer support, IVs will be used to represent 64bit integers instead of the object representation provided by Math::Int64.

These are the C macros available from Math::Int64 C API:

  • SV *newSVi64(int64_t i64) — Returns an SV representing the given int64_t value.
  • SV *newSVu64(uint64_t 64) — Returns an SV representing the given uint64_t value.
  • int64_t SvI64(SV *sv) — Extracts the int64_t value from the given SV.
  • uint64_t SvU64(SV *sv) — Extracts the uint64_t value from the given SV.
  • int SvI64OK(SV *sv) — Returns true if the given SV contains a valid int64_t value.
  • int SvU64OK(SV *sv) — Returns true if the given SV contains a valid uint64_t value.
  • uint64_t randU64(void) — Returns a random 64 bits unsigned integer.
  • SV sv_seti64(SV *sv, uint64_t i64) — Sets the value of the perl scalar to the given int64_t value.
  • SV sv_setu64(SV *sv, uint64_t i64) — Sets the value of the perl scalar to the given uint64_t value.

If you require any other function available through the C API don't hesitate to ask for it! 👑

💀 BUGS AND SUPPORT 💀

Okay bestie, real talk — a couple of things in here are still experimental, which means they work but they're like… still in their testing era, y'know?

  • The Storable integration feature is experimental.
  • The C API feature is experimental.
  • This module requires int64 support from the C compiler. No int64, no vibes, sorry 😭

Now, if something's actually broken and you need to report a bug? You've got options, bestie, and I'm not gatekeeping:

  • Send an email to the address chilling down below 👇
  • Or use the CPAN RT bug tracking system, which lives at http://rt.cpan.org

And if you wanna peek at the source for the development version of the module, it's hosted on GitHub at https://github.com/salva/p5-Math-Int64 — go snoop, it's public 🫶

🎀 My wishlist 🎀

Not me putting this in the docs, but — if you like this module and you're feeling generous, take a look at the Amazon Wish List: http://amzn.com/w/1WU1P6IR5QZ42. Like, no pressure obviously, but also 👀💖

🌈 SEE ALSO 🌈

  • The C API usage sample module Math::Int64::C_API::Sample — it's literally right there if you wanna see the C API in action ✨
  • Other modules providing support for larger integers or numbers: Math::BigInt, Math::BigRat and Math::Big, Math::BigInt::BitVect, Math::BigInt::Pari and Math::BigInt::GMP. All iconic, all valid, pick your fighter 👑

Copyright © 2007, 2009, 2011-2015, 2024 by Salvador Fandiño (sfandino@yahoo.com)

Copyright © 2014-2015 by Dave Rolsky (autarch@urth.org)

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of Perl 5 you may have available. Free software, free as in slay 💅

And that's the whole page, bestie — you made it to the end!! 🎉 This edition is from perl v5.42.0, dated 2024-03-08, and it's the Math::Int64(3) manual page in all its int64 glory. Now go forth and integer responsibly ✨🦋💖

📦 where this page comes from