Name

SPVM::Packer - Pack and Unpack Operations

Description

Packer class in SPVM has methods for pack and unpack operations

Usage

            

              
              
use Packer;
my $packer = Packer->new;
{
  my $objects = [(object)1, 2L, 0.5, [1, 2], "abc"];
   
  my $binary = $packer->pack("lqdl2a128");
   
  my $objects_unpack = $packer->unpack($binary);
}
{
  my $objects = [(object)[1, 2, 3]];
   
  my $binary = $packer->pack("l*");
   
  my $objects_unpack = $packer->unpack($binary);
}
            
          

Class Methods

static method new : Packer ();

Creates a new Packer object.

Instance Methods

pack

static method pack : string ($template : string, $objects : object[]);

Converts the objects $objects to a binary data according to the template $template, and returns it.

Template Syntax:

A template is a string. It consist of specifier parts.

            

              
              
TEMPLATE := "SpecifierPart1SpecifierPart2SpecifierPartN"
            
          

A specifier part is consist of a speficier, an endian, and a length. An endian and a length are optional.

            

              
              
SpecifierPart := Specifier[Endian][Length]
            
          

Here is the list of specifiers.

            

              
              
[Specifiers]  [Types]              [An output binary in pack or an input binary in unpack]
a             string               string. It is null padded in pack method.
h             string               A hex string (low nybble first)
H             string               A hex string (high nybble first)
c             Byte or byte[]       Singed 8-bit integers
C             Byte or byte[]       Unsinged 8-bit integers
s             Short or short[]     Singed 16-bit integers
S             Short or short[]     Unsinged 16-bit integers
l             Int or int[]         Singed 32-bit integers
L             Int or int[]         Unsinged 32-bit integers
q             Long or long[]       Singed 64-bit integers
Q             Long or long[]       Unsinged 64-bit integers
f             Float or float[]     32-bit floating point numbers.
d             Double or double[]   64-bit floating point numbers.
            
          

An endian is big-endian > or little-endian >.

If big-endian is specified, the binary data is converted from big-endian to system-endian in "pack" method, or from system-endian to big-endian in "unpack" method.

If little-endian is specified, the binary data is converted from little-endian to system-endian in "pack" method, or from system-endian to little-endian in "unpack" method.

A length must be a positive integer or a wildcard *. If a length or a wildcard is specified, the type(such as Int) becomes a corresponding array type(such as int[]).

Exceptions:

If template syntax is invalid, an exception is thrown.

The template $template must be defined. Otherwise an exception is thrown.

The objects $objects must be defined. Otherwise an exception is thrown.

The length of the specifiers in the template $template must be less than or equal to the lenght of the objects $objects. Otherwise an exception is thrown.

The type of the element in the objects $objects is invalid, an exception is thrown.

unpack

static method unpack : object[] ($template : string, $binary : string);

Converts the binary data $binary to the objects $objects according to the template $template, and returns it.

See "pack" method about templates.

Exceptions:

If template syntax is invalid, an exception is thrown.

The template $template must be defined. Otherwise an exception is thrown.

The binary data $binary must be defined. Otherwise an exception is thrown.

The current offset $binary_offset plus (the size $size * the length $length of the specifier) must be less than the length($binary_length) of the binary data $binary. Otherwise an exception is thrown.

Copyright & License

Copyright (c) 2024 Yuki Kimoto

MIT License

cpanm SPVM

perl -MCPAN -e shell
install SPVM