CPU::Emulator::6502::Op::ADC - Add memory to accumulator with carry


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

Index


Code Index:

NAME

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CPU::Emulator::6502::Op::ADC - Add memory to accumulator with carry

SYNOPSIS

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DESCRIPTION

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METHODS

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adc( $addr )

Adds data at $addr to the accumulator

AUTHOR

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Brian Cassidy <bricas@cpan.org>

COPYRIGHT AND LICENSE

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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::ADC;

use strict;
use warnings;

use constant INSTRUCTIONS => {
    0x69 => {
        addressing => 'immediate',
        cycles => 2,
        code => \&adc,
    },
    0x65 => {
        addressing => 'zero_page',
        cycles => 3,
        code => \&adc,
    },
    0x75 => {
        addressing => 'zero_page_x',
        cycles => 4,
        code => \&adc,
    },
    0x6D => {
        addressing => 'absolute',
        cycles => 4,
        code => \&adc,
    },
    0x7D => {
        addressing => 'absolute_x',
        cycles => 4,
        code => \&adc,
    },
    0x79 => {
        addressing => 'absolute_y',
        cycles => 4,
        code => \&adc,
    },
    0x61 => {
        addressing => 'indirect_x',
        cycles => 6,
        code => \&adc,
    },
    0x71 => {
        addressing => 'indirect_y',
        cycles => 5,
        code => \&adc,
    },
};

sub adc {
    my $self = shift;
    my $mem  = $self->memory;
    my $reg  = $self->registers;

    my $val  = $mem->[ shift ];
    my $temp = $reg->{ acc } + $val;
    $temp += 1 if $reg->status & CPU::Emulator::6502::SET_CARRY;

    $reg->{ status } &= CPU::Emulator::6502::CLEAR_ZOCS;
    $reg->{ status } |= CPU::Emulator::6502::SET_CARRY if $self->temp > 0xFF;

    if( !( ( $reg->{ acc } ^ $val ) & 0x80 ) && ( ( $reg->{ acc } ^ $temp ) & 0x80 ) ) {
        $reg->{ status } |= CPU::Emulator::6502::SET_OVERFLOW;
    }

    $reg->{ acc } = $self->temp & 0xFF;

    $self->set_nz( $reg->{ acc } );
}

1;