void falling_edge(Core* core) {
    sample_interrupts(core);

    auto code = core.internal.code;
    auto time = core.internal.time;

    actions[code][time][1](core);
}

void sample_interrupts(Core* core) {
    if (core.internal.nmi_latch < core.external.nmi) {
        core.internal.nmi = 1;
    }

    core.internal.nmi_latch = core.external.nmi;
    core.internal.irq = core.external.irq & !core.internal.p.i;
    core.internal.res = core.external.res;

    core.internal.interrupt = ( core.internal.irq | core.internal.res | core.internal.nmi );
}

void resp_code(Core* core) {
    core.internal.code = core.external.data;
    core.internal.time = 0;

    if (core.internal.interrupt) {
        core.internal.code = 0; // mask instruction register to $00 (BRK)
    }
}