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package Acme::6502;

use warnings FATAL => 'all';
use strict;
use Carp;

our $VERSION = '0.77';

# CPU flags
use constant {
  N => 0x80,
  V => 0x40,
  R => 0x20,
  B => 0x10,
  D => 0x08,
  I => 0x04,
  Z => 0x02,
  C => 0x01
};

use constant FLAGS => 'NVRBDIZC';

# Other CPU constants
use constant {
  STACK => 0x0100,
  BREAK => 0xFFFE
};

# Opcode to thunk into perlspace
use constant {
  ESCAPE_OP  => 0x0B,
  ESCAPE_SIG => 0xAD
};

BEGIN {
    for my $reg ( qw(a x y s p pc) ) {
        no strict 'refs';
        *{ __PACKAGE__ . "\::get_${reg}" } = sub {
            my $self = shift;
            return $self->{ reg }->{ $reg };
        };
        *{ __PACKAGE__ . "\::set_${reg}" } = sub {
            my ( $self, $v ) = @_;
            $self->{ reg }->{ $reg } = $v;
        };
    }
}

sub new {
    my $class = shift;
    my $self  = bless { }, $class;

    $self->_BUILD( @_ );

    return $self;
}

my @OP_CACHE;

sub _BUILD {
    my( $self, $args ) = @_;

    $args ||= {};

    $self->{ mem } = [ ( 0 ) x 65536 ];
    $self->{ reg } = {
        map { $_ => 0 } qw( a x y s p pc )
    };
    $self->{ os } = [ ];