Class::Bits 0.05

Class::Bits is a Perl module with class wrappers around bit vectors.

SYNOPSIS

package MyClass;
use Class::Bits;

make_bits( a => 4, # 0..15
b => 1, # 0..1
c => 1, # 0..1
d => 2, # 0..3
e => s4 # -8..7
f => s1 # -1..0
);

package;

$o=MyClass->new(a=>12, d=>2);
print "o->b is ", $o->b, "n";

print "bit vector is ", unpack("h*", $$o), "n";

$o2=$o->new();
$o3=MyClass->new($string);

ABSTRACT

Class::Bits creates class wrappers around bit vectors.

Class::Bits defines classes using bit vectors as storage.
Object attributes are stored in bit fields inside the bit vector. Bit field sizes have to be powers of 2 (1, 2, 4, 8, 16 or 32).

There is a class constructor subroutine:

make_bits( field1 => size1, field2 => size2, ...)

exports in the calling package a ctor, accessor methods, some utility methods and some constants:

Sizes can be prefixed by s or u to define signedness of the field. Default is unsigned.

$class->new()

creates a new object with all zeros.

$class->new($bitvector)

creates a new object over $bitvector.

$class->new(%fields)

creates a new object and initializes its fields with the values in %fields.

$obj->new()

clones an object.

$obj->$field()
$obj->$field($value)

gets or sets the value of the bit field $field inside the bit vector.

$class->length
$obj->lenght

returns the size in bits of the bit vector used for storage.

$class->keys
$obj->keys

returns an array with the names of the object attributes

$obj->as_hash

returns a flatten hash with the object attributes, i.e.:
my %values=$obj->as_hash;

%INDEX

hash with offsets as used by vec perl operator (to get an offset in bits, the value has to be multiplied by the corresponding bit field size).

%SIZES

hash with bit field sizes in bits.

%SIGNED

hash with signedness of the fields

Bit fields are packed in the bit vector in the order specified as arguments to make_bits.

Bit fields are padded inside the bit vector, i.e. a class created like

make_bits(A=>1, B=>2, C=>1, D=>4, E=>8, F=>16);

will have the layout

AxBBCxxx DDDDxxxx EEEEEEEE xxxxxxxx FFFFFFFF FFFFFFFF