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static int ata_request_dma_init(struct ata_request* request)
{
    struct ata_device* dev = request->dev;
    struct ata_controller* ctrl = dev->controller;
    uint64_t size = request->block_size * request->block_count;

    *ctrl->prdt_virt = (uint32_t) ctrl->dma_buf_phys;
    // Groesse nicht ueber 64K, 0 == 64K
    *ctrl->prdt_virt |= (size & (ATA_DMA_MAXSIZE - 1)) << 32L;
    // Letzter Eintrag in PRDT
    *ctrl->prdt_virt |= (uint64_t) 1L << 63L;

    // Die laufenden Transfers anhalten
    cdi_outb(ctrl->port_bmr_base + BMR_COMMAND, 0);
    cdi_outb(ctrl->port_bmr_base + BMR_STATUS,
        cdi_inb(ctrl->port_bmr_base + BMR_STATUS) | 0x06);

    // Adresse der PRDT eintragen
    cdi_outl(ctrl->port_bmr_base + BMR_PRDT, (uint32_t) ctrl->prdt_phys);

    if (request->flags.direction != READ) {
        memcpy(ctrl->dma_buf_virt, request->buffer, size);
    }

    return 1;
}


static int ata_protocol_dma(struct ata_request* request)
{
    struct ata_device* dev = request->dev;
    struct ata_controller* ctrl = dev->controller;
    
    // Aktueller Status im Protokol
    enum {
        IRQ_WAIT,
        CHECK_STATUS,
        TRANSFER_DATA
    } state;

    cdi_inb(ctrl->port_bmr_base + BMR_COMMAND);
    cdi_inb(ctrl->port_bmr_base + BMR_STATUS);
    if (request->flags.direction != READ) {
        cdi_outb(ctrl->port_bmr_base + BMR_COMMAND, 1 | (1 << 3));
    } else {
        cdi_outb(ctrl->port_bmr_base + BMR_COMMAND, 1);
    }
    cdi_inb(ctrl->port_bmr_base + BMR_COMMAND);
    cdi_inb(ctrl->port_bmr_base + BMR_STATUS);

    state = IRQ_WAIT;
    while (1) {
        puts("a");
        switch (state) {
            case IRQ_WAIT:
                // Auf IRQ warten
                if (!ata_wait_irq(ctrl, ATA_IRQ_TIMEOUT)) {
                    request->error = IRQ_TIMEOUT;
                    DEBUG("pio_out IRQ-Timeout\n");
                    return 0;
                }

                state = CHECK_STATUS;
                break;

            default:
            case CHECK_STATUS: {
                uint8_t status = ata_reg_inb(ctrl, REG_STATUS);
                printf("\nstat=%x\n", status);

                // Transfer abgeschlossen
                if ((status & (STATUS_BSY | STATUS_DRQ)) == 0) {
                    cdi_inb(ctrl->port_bmr_base + BMR_STATUS);
                    cdi_outb(ctrl->port_bmr_base + BMR_COMMAND, 0);
                    goto out_success;
                }
                break;
            }
        }
    }

out_success:
    if (request->flags.direction == READ) {
        memcpy(request->buffer, ctrl->dma_buf_virt,
            request->block_size * request->block_count);
    }
    return 1;
}