Re: [Qemu-devel] [PATCH v2 3/5] ide/atapi: Use table instead of switch for commands

[Blue Swirl <blauwirbel@gmail.com>]

On Wed, Apr 20, 2011 at 2:30 PM, Kevin Wolf <kwolf@redhat.com> wrote:
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  hw/ide/atapi.c |  115 +++++++++++++++++++++++--------------------------------
>  1 files changed, 48 insertions(+), 67 deletions(-)
>
> diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
> index d161bf7..d0bf7fd 100644
> --- a/hw/ide/atapi.c
> +++ b/hw/ide/atapi.c
> @@ -533,10 +533,11 @@ static unsigned int event_status_media(IDEState *s,
>     return 8; /* We wrote to 4 extra bytes from the header */
>  }
>
> -static void handle_get_event_status_notification(IDEState *s,
> -                                                 uint8_t *buf,
> -                                                 const uint8_t *packet)
> +static void cmd_get_event_status_notification(IDEState *s,
> +                                              uint8_t *buf)
>  {
> +    const uint8_t *packet = buf;
> +
>     struct {
>         uint8_t opcode;
>         uint8_t polled;        /* lsb bit is polled; others are reserved */
> @@ -1064,6 +1065,38 @@ static void cmd_set_speed(IDEState *s, uint8_t* buf)
>     ide_atapi_cmd_ok(s);
>  }
>
> +enum {
> +    /*
> +     * Only commands flagged as ALLOW_UA are allowed to run under a
> +     * unit attention condition. (See MMC-5, section 4.1.6.1)
> +     */
> +    ALLOW_UA = 0x01,
> +};
> +
> +struct {
> +    void (*handler)(IDEState *s, uint8_t *buf);
> +    int flags;
> +} atapi_cmd_table[0x100] = {
> +    [ 0x00 ] = { cmd_test_unit_ready,               0 },

How about using symbols here, like
    [ GPCMD_TEST_UNIT_READY ] = { cmd_test_unit_ready, 0 },
?

The table can probably be static const.

> +    [ 0x03 ] = { cmd_request_sense,                 ALLOW_UA },
> +    [ 0x12 ] = { cmd_inquiry,                       ALLOW_UA },
> +    [ 0x1a ] = { cmd_mode_sense, /* (6) */          0 },
> +    [ 0x1b ] = { cmd_start_stop_unit,               0 },
> +    [ 0x1e ] = { cmd_prevent_allow_medium_removal,  0 },
> +    [ 0x25 ] = { cmd_read_cdvd_capacity,            0 },
> +    [ 0x28 ] = { cmd_read, /* (10) */               0 },
> +    [ 0x2b ] = { cmd_seek,                          0 },
> +    [ 0x43 ] = { cmd_read_toc_pma_atip,             0 },
> +    [ 0x46 ] = { cmd_get_configuration,             ALLOW_UA },
> +    [ 0x4a ] = { cmd_get_event_status_notification, ALLOW_UA },
> +    [ 0x5a ] = { cmd_mode_sense, /* (10) */         0 },
> +    [ 0xa8 ] = { cmd_read, /* (12) */               0 },
> +    [ 0xad ] = { cmd_read_dvd_structure,            0 },
> +    [ 0xbb ] = { cmd_set_speed,                     0 },
> +    [ 0xbd ] = { cmd_mechanism_status,              0 },
> +    [ 0xbe ] = { cmd_read_cd,                       0 },
> +};
> +
>  void ide_atapi_cmd(IDEState *s)
>  {
>     const uint8_t *packet;
> @@ -1082,21 +1115,17 @@ void ide_atapi_cmd(IDEState *s)
>     }
>  #endif
>     /*
> -     * If there's a UNIT_ATTENTION condition pending, only
> -     * REQUEST_SENSE, INQUIRY, GET_CONFIGURATION and
> -     * GET_EVENT_STATUS_NOTIFICATION commands are allowed to complete.
> -     * MMC-5, section 4.1.6.1 lists only these commands being allowed
> -     * to complete, with other commands getting a CHECK condition
> -     * response unless a higher priority status, defined by the drive
> +     * If there's a UNIT_ATTENTION condition pending, only command flagged with
> +     * ALLOW_UA are allowed to complete. with other commands getting a CHECK
> +     * condition response unless a higher priority status, defined by the drive
>      * here, is pending.
>      */
>     if (s->sense_key == SENSE_UNIT_ATTENTION &&
> -        s->io_buffer[0] != GPCMD_REQUEST_SENSE &&
> -        s->io_buffer[0] != GPCMD_INQUIRY &&
> -        s->io_buffer[0] != GPCMD_GET_EVENT_STATUS_NOTIFICATION) {
> +        !(atapi_cmd_table[s->io_buffer[0]].flags & ALLOW_UA)) {
>         ide_atapi_cmd_check_status(s);
>         return;
>     }
> +
>     if (bdrv_is_inserted(s->bs) && s->cdrom_changed) {
>         ide_atapi_cmd_error(s, SENSE_NOT_READY, ASC_MEDIUM_NOT_PRESENT);
>
> @@ -1105,60 +1134,12 @@ void ide_atapi_cmd(IDEState *s)
>         s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
>         return;
>     }
> -    switch(s->io_buffer[0]) {
> -    case GPCMD_TEST_UNIT_READY:
> -        cmd_test_unit_ready(s, buf);
> -        break;
> -    case GPCMD_MODE_SENSE_6:
> -    case GPCMD_MODE_SENSE_10:
> -        cmd_mode_sense(s, buf);
> -        break;
> -    case GPCMD_REQUEST_SENSE:
> -        cmd_request_sense(s, buf);
> -        break;
> -    case GPCMD_PREVENT_ALLOW_MEDIUM_REMOVAL:
> -        cmd_prevent_allow_medium_removal(s, buf);
> -        break;
> -    case GPCMD_READ_10:
> -    case GPCMD_READ_12:
> -        cmd_read(s, buf);
> -        break;
> -    case GPCMD_READ_CD:
> -        cmd_read_cd(s, buf);
> -        break;
> -    case GPCMD_SEEK:
> -        cmd_seek(s, buf);
> -        break;
> -    case GPCMD_START_STOP_UNIT:
> -        cmd_start_stop_unit(s, buf);
> -        break;
> -    case GPCMD_MECHANISM_STATUS:
> -        cmd_mechanism_status(s, buf);
> -        break;
> -    case GPCMD_READ_TOC_PMA_ATIP:
> -        cmd_read_toc_pma_atip(s, buf);
> -        break;
> -    case GPCMD_READ_CDVD_CAPACITY:
> -        cmd_read_cdvd_capacity(s, buf);
> -        break;
> -    case GPCMD_READ_DVD_STRUCTURE:
> -        cmd_read_dvd_structure(s, buf);
> -        break;
> -    case GPCMD_SET_SPEED:
> -        cmd_set_speed(s, buf);
> -        break;
> -    case GPCMD_INQUIRY:
> -        cmd_inquiry(s, buf);
> -        break;
> -    case GPCMD_GET_CONFIGURATION:
> -        cmd_get_configuration(s, buf);
> -        break;
> -    case GPCMD_GET_EVENT_STATUS_NOTIFICATION:
> -        handle_get_event_status_notification(s, buf, packet);
> -        break;
> -    default:
> -        ide_atapi_cmd_error(s, SENSE_ILLEGAL_REQUEST,
> -                            ASC_ILLEGAL_OPCODE);
> -        break;
> +
> +    /* Execute the command */
> +    if (atapi_cmd_table[s->io_buffer[0]].handler) {
> +        atapi_cmd_table[s->io_buffer[0]].handler(s, buf);
> +        return;
>     }
> +
> +    ide_atapi_cmd_error(s, SENSE_ILLEGAL_REQUEST, ASC_ILLEGAL_OPCODE);
>  }
> --
> 1.7.2.3
>
>
>