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	dpavlin	24	package M6502;
2
3			use strict;
4			use warnings;
5
6	dpavlin	27	use Data::Dump qw/dump/;
7	dpavlin	29	use Carp qw/confess/;
8	dpavlin	34	use Exporter 'import';
9	dpavlin	50	our @EXPORT = qw'@mem $PC $A $P $X $Y $S $IPeriod $run_for $debug';
10	dpavlin	27
11	dpavlin	29	=head1 NAME
12	dpavlin	24
13	dpavlin	29	M6502 - perl bindings for 6502 emulator
14
15			=cut
16
17	dpavlin	50	my $debug = 0;
18	dpavlin	24
19	dpavlin	29	our $VERSION = qw(0.0.1);
20	dpavlin	27
21	dpavlin	29	our @mem = (0xff) x 0x10000; # 64M
22
23	dpavlin	25	# program counter
24	dpavlin	34	our $PC = 0xbeef;
25	dpavlin	25	# CPU registars
26	dpavlin	36	our ( $A, $P, $X, $Y, $S ) = (0) x 5;
27	dpavlin	25	# Set IPeriod to number of CPU cycles between calls to Loop6502
28	dpavlin	27	our $IPeriod = 1;
29	dpavlin	40	# Exec6502 cycles
30	dpavlin	42	our $run_for = 0;
31	dpavlin	24
32	dpavlin	26	=head1 init
33
34			Called before C<Run6502>
35
36			=cut
37
38			sub init {
39	dpavlin	33	my $self = shift;
40			warn "inside init low-level M6502 from $self\n";
41	dpavlin	26	};
42	dpavlin	27
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	dpavlin	50	warn "## M6502::read(",dump(@_),") = ",dump( $byte ),"\n" if $debug;
55	dpavlin	27	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	dpavlin	50	warn "## M6502::write(",dump(@_),")\n" if $debug;
68	dpavlin	27	my ($addr,$byte) = @_;
69			$mem[$addr] = $byte;
70			}
71	dpavlin	29
72			=head2 poke_code
73
74	dpavlin	42	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	dpavlin	29
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	dpavlin	50	warn sprintf("## M6502::poke_code(%04x,%s)\n", $addr, dump( @_ )) if $self->debug;
85	dpavlin	42	#$mem[$addr++] = $_ foreach @_;
86			$self->write($addr++, $_) foreach @_;
87	dpavlin	29	}
88
89	dpavlin	31	=head2 write_chunk
90
91	dpavlin	42	Low-level update of memory, overriding user specified MMU functions C<read> and C<write>
92
93	dpavlin	31	$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	dpavlin	42	=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	dpavlin	38	=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	dpavlin	50	warn "## M6502::push_R(",dump(@_),")\n" if $debug;
122	dpavlin	38	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	dpavlin	50	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	dpavlin	38	}
137
138	dpavlin	24	1;