VRac/M6502/M6502.pm

package M6502;

use strict;
use warnings;

use Data::Dump qw/dump/;
use Carp qw/confess/;
use Exporter 'import';
our @EXPORT = qw'@mem $PC $A $P $X $Y $S $IPeriod $run_for $debug';

=head1 NAME

M6502 - perl bindings for 6502 emulator

=cut

my $debug = 0;

our $VERSION = qw(0.0.1);

our @mem = (0xff) x 0x10000;    # 64M

# program counter
our $PC = 0xbeef;
# CPU registars
our ( $A, $P, $X, $Y, $S ) = (0) x 5;
# Set IPeriod to number of CPU cycles between calls to Loop6502
our $IPeriod = 1;
# Exec6502 cycles
our $run_for = 0;

=head1 init

Called before C<Run6502>

=cut

sub init {
        my $self = shift;
        warn "inside init low-level M6502 from $self\n";
};

=head2 read

Read from memory

  $byte = read( $address );

=cut

sub read {
        my ($addr) = @_;
        my $byte = $mem[$addr];
        warn "## M6502::read(",dump(@_),") = ",dump( $byte ),"\n" if $debug;
        return $byte;
}

=head2 write

Write into emory

  write( $address, $byte );

=cut

sub write {
        warn "## M6502::write(",dump(@_),")\n" if $debug;
        my ($addr,$byte) = @_;
        $mem[$addr] = $byte;
}

=head2 poke_code

Write series of bytes into memory passing through MMU (C<read> and C<write>)
functions. If you don't want to trigger MMU, use C<write_chunk>.

  $emu->poke_code( 0xbeef, 0xff, 0x00, 0xff, 0x00, 0xaa );

=cut

sub poke_code {
        my $self = shift;
        my $addr = shift;
        warn sprintf("## M6502::poke_code(%04x,%s)\n", $addr, dump( @_ )) if $self->debug;
        #$mem[$addr++] = $_ foreach @_;
        $self->write($addr++, $_) foreach @_;
}

=head2 write_chunk

Low-level update of memory, overriding user specified MMU functions C<read> and C<write>

  $emu->write_chunk( $address, $chunk_of_data );

=cut

sub write_chunk {
        my ($self, $addr, $chunk) = @_;
        my $len = length($chunk);
        splice @mem, $addr, $len, unpack('C*', $chunk);
}

=head2 prompt

Call this after C<< $run_for >> cycles have been run on processor

=cut

sub prompt {
        warn "prompt -- you should override this\n";
        return 1;
}

=head2 push_R

called by C<perl.c> to push changes in registars back to perl variables

=cut

sub push_R {
        warn "## M6502::push_R(",dump(@_),")\n" if $debug;
        my ( $a, $p, $x, $y, $s, $pc ) = @_;
        $PC = $pc;
        $S=$s; $X=$x; $Y=$y; $P=$p; $A=$a;
        dump_R();
}

=head2 dump_R

helper function which dumps registers

=cut

sub dump_R {
        warn sprintf("## M6502::dump_R PC: %04x A:%02x P:%02x X:%02x Y:%02x S:%02x\n", $PC, $A, $P, $X, $Y, $S) if $debug;
}

1;
1	package M6502;
2
3	use strict;
4	use warnings;
5
6	use Data::Dump qw/dump/;
7	use Carp qw/confess/;
8	use Exporter 'import';
9	our @EXPORT = qw'@mem $PC $A $P $X $Y $S $IPeriod $run_for $debug';
10
11	=head1 NAME
12
13	M6502 - perl bindings for 6502 emulator
14
15	=cut
16
17	my $debug = 0;
18
19	our $VERSION = qw(0.0.1);
20
21	our @mem = (0xff) x 0x10000; # 64M
22
23	# program counter
24	our $PC = 0xbeef;
25	# CPU registars
26	our ( $A, $P, $X, $Y, $S ) = (0) x 5;
27	# Set IPeriod to number of CPU cycles between calls to Loop6502
28	our $IPeriod = 1;
29	# Exec6502 cycles
30	our $run_for = 0;
31
32	=head1 init
33
34	Called before C<Run6502>
35
36	=cut
37
38	sub init {
39	my $self = shift;
40	warn "inside init low-level M6502 from $self\n";
41	};
42
43	=head2 read
44
45	Read from memory
46
47	$byte = read( $address );
48
49	=cut
50
51	sub read {
52	my ($addr) = @_;
53	my $byte = $mem[$addr];
54	warn "## M6502::read(",dump(@_),") = ",dump( $byte ),"\n" if $debug;
55	return $byte;
56	}
57
58	=head2 write
59
60	Write into emory
61
62	write( $address, $byte );
63
64	=cut
65
66	sub write {
67	warn "## M6502::write(",dump(@_),")\n" if $debug;
68	my ($addr,$byte) = @_;
69	$mem[$addr] = $byte;
70	}
71
72	=head2 poke_code
73
74	Write series of bytes into memory passing through MMU (C<read> and C<write>)
75	functions. If you don't want to trigger MMU, use C<write_chunk>.
76
77	$emu->poke_code( 0xbeef, 0xff, 0x00, 0xff, 0x00, 0xaa );
78
79	=cut
80
81	sub poke_code {
82	my $self = shift;
83	my $addr = shift;
84	warn sprintf("## M6502::poke_code(%04x,%s)\n", $addr, dump( @_ )) if $self->debug;
85	#$mem[$addr++] = $_ foreach @_;
86	$self->write($addr++, $_) foreach @_;
87	}
88
89	=head2 write_chunk
90
91	Low-level update of memory, overriding user specified MMU functions C<read> and C<write>
92
93	$emu->write_chunk( $address, $chunk_of_data );
94
95	=cut
96
97	sub write_chunk {
98	my ($self, $addr, $chunk) = @_;
99	my $len = length($chunk);
100	splice @mem, $addr, $len, unpack('C*', $chunk);
101	}
102
103	=head2 prompt
104
105	Call this after C<< $run_for >> cycles have been run on processor
106
107	=cut
108
109	sub prompt {
110	warn "prompt -- you should override this\n";
111	return 1;
112	}
113
114	=head2 push_R
115
116	called by C<perl.c> to push changes in registars back to perl variables
117
118	=cut
119
120	sub push_R {
121	warn "## M6502::push_R(",dump(@_),")\n" if $debug;
122	my ( $a, $p, $x, $y, $s, $pc ) = @_;
123	$PC = $pc;
124	$S=$s; $X=$x; $Y=$y; $P=$p; $A=$a;
125	dump_R();
126	}
127
128	=head2 dump_R
129
130	helper function which dumps registers
131
132	=cut
133
134	sub dump_R {
135	warn sprintf("## M6502::dump_R PC: %04x A:%02x P:%02x X:%02x Y:%02x S:%02x\n", $PC, $A, $P, $X, $Y, $S) if $debug;
136	}
137
138	1;