Perl module idea for making bitfields

Background

I've been doing a lot of hardware IO work lately, which involves lots of talking to hardware devices, where there are byte-wide registers that store little bitfields, sometimes of individual and unrelated bits packed together. To make this easier I tend to write myself lots of pairs of functions to pack/unpack the fields in one of these bytes; for instance:

use constant {
      MASK_RX_RD      => 1<<6,
      MASK_TX_DS      => 1<<5,
      MASK_MAX_RT     => 1<<4,
      EN_CRC          => 1<<3,
      CRCO            => 1<<2,
      PWR_UP          => 1<<1,
      PRIM_RX         => 1<<0,
};

sub unpack_CONFIG
{
   my ( $config ) = @_;
   return
      MASK_RX_RD  => !!( $config & MASK_RX_RD ),
      MASK_TX_DS  => !!( $config & MASK_TX_DS ),
      MASK_MAX_RT => !!( $config & MASK_MAX_RT ),
      EN_CRC      => !!( $config & EN_CRC ),
      CRCO        => $CRCOs[!!( $config & CRCO )],
      PWR_UP      => !!( $config & PWR_UP ),
      PRIM_RX     => !!( $config & PRIM_RX );
}

sub pack_CONFIG
{
   my %config = @_;
   return
      ( $config{MASK_RX_RD}  ? MASK_RX_RD  : 0 ) |
      ( $config{MASK_TX_DS}  ? MASK_TX_DS  : 0 ) |
      ( $config{MASK_MAX_RT} ? MASK_MAX_RT : 0 ) |
      ( $config{EN_CRC}      ? EN_CRC      : 0 ) |
      ( ( _idx_of $config{CRCO}, @CRCOs )
         // croak "Unsupported 'CRCO'" ) * CRCO |
      ( $config{PWR_UP}      ? PWR_UP      : 0 ) |
      ( $config{PRIM_RX}     ? PRIM_RX     : 0 ) );
}

This convenient pair of functions bidirectionally converts bytes into key/value lists. As well as containing 6 simple boolean values, there's also an enumerated field, represented by the values in the array @CRCOs. These functions convert those too.

I'm getting tired of writing these pairs of functions. Hey, this is Perl right? :) I should get Perl to write them for me.

TL;DR - I propose the following

I'd like instead to write something like:

use bitfield;

bitfield CONFIG =>
   MASK_RX_DS  => boolfield(6),
   MASK_TX_DS  => boolfield(5),
   MASK_MAX_RT => boolfield(4),
   EN_CRC      => boolfield(3),
   CRCO        => enumfield(2, qw( values here )),
   PWR_UP      => boolfield(1),
   PRIM_RX     => boolfield(0);

The operation here is that 'bitfield' is automatically exporting a function called bitfield, along with the various *field() functions that create field definitions. boolfield() declares a single true/false boolean bit position, enumfield() declares a range of bits that give an enumeration. I guess also would be required intfield() to use a range of bits as an integer, and finally most likely customfield() taking a pair of conversion CODE refs or somesuch.

What does anyone think to that?