Other people have shown you how to pack it. If you have irregular bit margins (shifts of 31, 32, 33), you might want to do the shifts using big integers:

#!/usr/bin/perl
use warnings;
use strict;

use Math::BigInt;
my $num = Math::BigInt->new('0x01');
my $mask1 = Math::BigInt->new('0x0FFFFFFFF')->blsft(32);
my $mask2 = Math::BigInt->new('0x0FFFFFFFF');
print "Number      : ", $num->as_hex(), "\n";
$num->blsft(32);
print "Num shifted : ", $num->as_hex(), "\n";
#
# Split result into something that can be packed.
#
my $highorder = $num->copy()->band($mask1)->brsft(32);
my $loworder  = $num->copy()->band($mask2);

print "High bits   : ", $highorder->numify(), "\n";
print "Low bits    : ", $loworder->numify(), "\n";
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And the output is:

C:\Code>perl bigint_shift.pl
Number      : 0x1
Num shifted : 0x100000000
High bits   : 1
Low bits    : 0
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