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';

=head1 NAME

M6502 - perl bindings for 6502 emulator

=cut

my $debug = 1;

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 dump(@_);
        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 "# read(",dump(@_),") = ",dump( $byte ),"\n" if $debug;
        return $byte;
}

=head2 write

Write into emory

  write( $address, $byte );

=cut

sub write {
        warn "# 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("# 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 ram

Read searies of bytes from memory without passing through MMU

  $emu->ram( $from, $to );

=cut

sub ram {
        my $self = shift;
        my ($from,$to) = @_;
        warn "ram($from,$to)\n";
        if ($from + $to) {
                printf "ram %04x - %04x\n", $from, $to;
                return @mem[$from .. $to - 1];
        }
        printf "ram %04x\n", $from;
        return $mem[$from] if defined($from);
        confess "no from address";
}

=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 "push_R(",dump(@_),")\n";
        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("PC: %04x A:%02x P:%02x X:%02x Y:%02x S:%02x\n", $PC, $A, $P, $X, $Y, $S);
}

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';
10
11	=head1 NAME
12
13	M6502 - perl bindings for 6502 emulator
14
15	=cut
16
17	my $debug = 1;
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 dump(@_);
41	warn "inside init low-level M6502 from $self\n";
42	};
43
44	=head2 read
45
46	Read from memory
47
48	$byte = read( $address );
49
50	=cut
51
52	sub read {
53	my ($addr) = @_;
54	my $byte = $mem[$addr];
55	warn "# read(",dump(@_),") = ",dump( $byte ),"\n" if $debug;
56	return $byte;
57	}
58
59	=head2 write
60
61	Write into emory
62
63	write( $address, $byte );
64
65	=cut
66
67	sub write {
68	warn "# write(",dump(@_),")\n" if $debug;
69	my ($addr,$byte) = @_;
70	$mem[$addr] = $byte;
71	}
72
73	=head2 poke_code
74
75	Write series of bytes into memory passing through MMU (C<read> and C<write>)
76	functions. If you don't want to trigger MMU, use C<write_chunk>.
77
78	$emu->poke_code( 0xbeef, 0xff, 0x00, 0xff, 0x00, 0xaa );
79
80	=cut
81
82	sub poke_code {
83	my $self = shift;
84	my $addr = shift;
85	warn sprintf("# poke_code(%04x,%s)\n", $addr, dump( @_ )) if $self->debug;
86	#$mem[$addr++] = $_ foreach @_;
87	$self->write($addr++, $_) foreach @_;
88	}
89
90	=head2 write_chunk
91
92	Low-level update of memory, overriding user specified MMU functions C<read> and C<write>
93
94	$emu->write_chunk( $address, $chunk_of_data );
95
96	=cut
97
98	sub write_chunk {
99	my ($self, $addr, $chunk) = @_;
100	my $len = length($chunk);
101	splice @mem, $addr, $len, unpack('C*', $chunk);
102	}
103
104	=head2 ram
105
106	Read searies of bytes from memory without passing through MMU
107
108	$emu->ram( $from, $to );
109
110	=cut
111
112	sub ram {
113	my $self = shift;
114	my ($from,$to) = @_;
115	warn "ram($from,$to)\n";
116	if ($from + $to) {
117	printf "ram %04x - %04x\n", $from, $to;
118	return @mem[$from .. $to - 1];
119	}
120	printf "ram %04x\n", $from;
121	return $mem[$from] if defined($from);
122	confess "no from address";
123	}
124
125	=head2 prompt
126
127	Call this after C<< $run_for >> cycles have been run on processor
128
129	=cut
130
131	sub prompt {
132	warn "prompt -- you should override this\n";
133	return 1;
134	}
135
136	=head2 push_R
137
138	called by C<perl.c> to push changes in registars back to perl variables
139
140	=cut
141
142	sub push_R {
143	warn "push_R(",dump(@_),")\n";
144	my ( $a, $p, $x, $y, $s, $pc ) = @_;
145	$PC = $pc;
146	$S=$s; $X=$x; $Y=$y; $P=$p; $A=$a;
147	dump_R();
148	}
149
150	=head2 dump_R
151
152	helper function which dumps registers
153
154	=cut
155
156	sub dump_R {
157	warn sprintf("PC: %04x A:%02x P:%02x X:%02x Y:%02x S:%02x\n", $PC, $A, $P, $X, $Y, $S);
158	}
159
160	1;