CPU::Emulator::6502::Op::CPX - Compare the X register

Games-NES-Emulator documentation Contained in the Games-NES-Emulator distribution.

Index

Code Index:

NAME

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CPU::Emulator::6502::Op::CPX - Compare the X register

SYNOPSIS

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DESCRIPTION

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METHODS

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cpx( $addr )

Compares the X register to the data held at $addr.

AUTHOR

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Brian Cassidy <bricas@cpan.org>

COPYRIGHT AND LICENSE

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Copyright 2007 by Brian Cassidy

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

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* CPU::Emulator::6502
Games-NES-Emulator documentation Contained in the Games-NES-Emulator distribution. 
package CPU::Emulator::6502::Op::CPX;

use strict;
use warnings;

use constant INSTRUCTIONS => {
    0xE0 => {
        addressing => 'immediate',
        cycles => 2,
        code => \&cpx
    },
    0xE4 => {
        addressing => 'zero_page',
        cycles => 3,
        code => \&cpx
    },
    0xEC => {
        addressing => 'absolute',
        cycles => 4,
        code => \&cpx
    }
};


sub cpx {
    my $self = shift;
    my $reg = $self->registers;
    
    my $temp = $reg->{ x } - $self->memory->[ shift ];
    $reg->{ status } &= CPU::Emulator::6502::CLEAR_SZC;
    $self->set_nz( $temp );
    $reg->{ status } |= CPU::Emulator::6502::SET_CARRY if $temp < 0x100;
}


1;