static void process_ncq_command(AHCIState *s, int port, uint8_t *cmd_fis,

                                int slot)

{

    AHCIDevice *ad = &s->dev[port];

    IDEState *ide_state = &ad->port.ifs[0];

    NCQFrame *ncq_fis = (NCQFrame*)cmd_fis;

    uint8_t tag = ncq_fis->tag >> 3;

    NCQTransferState *ncq_tfs = &ad->ncq_tfs[tag];



    if (ncq_tfs->used) {

        /* error - already in use */

        fprintf(stderr, "%s: tag %d already used\n", __FUNCTION__, tag);

        return;

    }



    ncq_tfs->used = 1;

    ncq_tfs->drive = ad;

    ncq_tfs->slot = slot;

    ncq_tfs->lba = ((uint64_t)ncq_fis->lba5 << 40) |

                   ((uint64_t)ncq_fis->lba4 << 32) |

                   ((uint64_t)ncq_fis->lba3 << 24) |

                   ((uint64_t)ncq_fis->lba2 << 16) |

                   ((uint64_t)ncq_fis->lba1 << 8) |

                   (uint64_t)ncq_fis->lba0;



    /* Note: We calculate the sector count, but don't currently rely on it.

     * The total size of the DMA buffer tells us the transfer size instead. */

    ncq_tfs->sector_count = ((uint16_t)ncq_fis->sector_count_high << 8) |

                                ncq_fis->sector_count_low;



    DPRINTF(port, "NCQ transfer LBA from %"PRId64" to %"PRId64", "

            "drive max %"PRId64"\n",

            ncq_tfs->lba, ncq_tfs->lba + ncq_tfs->sector_count - 2,

            ide_state->nb_sectors - 1);



    ahci_populate_sglist(ad, &ncq_tfs->sglist, 0);

    ncq_tfs->tag = tag;



    switch(ncq_fis->command) {

        case READ_FPDMA_QUEUED:

            DPRINTF(port, "NCQ reading %d sectors from LBA %"PRId64", "

                    "tag %d\n",

                    ncq_tfs->sector_count-1, ncq_tfs->lba, ncq_tfs->tag);



            DPRINTF(port, "tag %d aio read %"PRId64"\n",

                    ncq_tfs->tag, ncq_tfs->lba);



            dma_acct_start(ide_state->blk, &ncq_tfs->acct,

                           &ncq_tfs->sglist, BLOCK_ACCT_READ);

            ncq_tfs->aiocb = dma_blk_read(ide_state->blk,

                                          &ncq_tfs->sglist, ncq_tfs->lba,

                                          ncq_cb, ncq_tfs);

            break;

        case WRITE_FPDMA_QUEUED:

            DPRINTF(port, "NCQ writing %d sectors to LBA %"PRId64", tag %d\n",

                    ncq_tfs->sector_count-1, ncq_tfs->lba, ncq_tfs->tag);



            DPRINTF(port, "tag %d aio write %"PRId64"\n",

                    ncq_tfs->tag, ncq_tfs->lba);



            dma_acct_start(ide_state->blk, &ncq_tfs->acct,

                           &ncq_tfs->sglist, BLOCK_ACCT_WRITE);

            ncq_tfs->aiocb = dma_blk_write(ide_state->blk,

                                           &ncq_tfs->sglist, ncq_tfs->lba,

                                           ncq_cb, ncq_tfs);

            break;

        default:

            if (is_ncq(cmd_fis[2])) {

                DPRINTF(port,

                        "error: unsupported NCQ command (0x%02x) received\n",

                        cmd_fis[2]);

            } else {

                DPRINTF(port,

                        "error: tried to process non-NCQ command as NCQ\n");

            }

            qemu_sglist_destroy(&ncq_tfs->sglist);

    }

}
