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Re: [Qemu-devel] [PATCH v3 02/11] fdc: refactor pick_geometry


From: John Snow
Subject: Re: [Qemu-devel] [PATCH v3 02/11] fdc: refactor pick_geometry
Date: Thu, 17 Dec 2015 12:50:47 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0


On 12/17/2015 02:53 AM, Markus Armbruster wrote:
> John Snow <address@hidden> writes:
> 
>> Modify this function to operate directly on FDrive objects instead of
>> unpacking and passing all of those parameters manually.
>>
>> Helps reduce complexity in each caller, and reduces the number of args.
> 
> For now, there's just one.
> 
> Diffstat suggests it's an overall simplification.
> 
>> Signed-off-by: John Snow <address@hidden>
>> ---
>>  hw/block/fdc.c | 54 +++++++++++++++++++++++-------------------------------
>>  1 file changed, 23 insertions(+), 31 deletions(-)
>>
>> diff --git a/hw/block/fdc.c b/hw/block/fdc.c
>> index 246b631..09bb63d 100644
>> --- a/hw/block/fdc.c
>> +++ b/hw/block/fdc.c
>> @@ -241,11 +241,9 @@ static void fd_recalibrate(FDrive *drv)
>>      fd_seek(drv, 0, 0, 1, 1);
>>  }
>>  
>> -static void pick_geometry(BlockBackend *blk, int *nb_heads,
>> -                          int *max_track, int *last_sect,
>> -                          FDriveType drive_in, FDriveType *drive,
>> -                          FDriveRate *rate)
>> +static void pick_geometry(FDrive *drv)
>>  {
>> +    BlockBackend *blk = drv->blk;
>>      const FDFormat *parse;
>>      uint64_t nb_sectors, size;
>>      int i, first_match, match;
>> @@ -258,8 +256,8 @@ static void pick_geometry(BlockBackend *blk, int 
>> *nb_heads,
>>          if (parse->drive == FDRIVE_DRV_NONE) {
>>              break;
>>          }
>> -        if (drive_in == parse->drive ||
>> -            drive_in == FDRIVE_DRV_NONE) {
>> +        if (drv->drive == parse->drive ||
>> +            drv->drive == FDRIVE_DRV_NONE) {
>>              size = (parse->max_head + 1) * parse->max_track *
>>                  parse->last_sect;
>>              if (nb_sectors == size) {
>> @@ -279,41 +277,35 @@ static void pick_geometry(BlockBackend *blk, int 
>> *nb_heads,
>>          }
>>          parse = &fd_formats[match];
>>      }
>> -    *nb_heads = parse->max_head + 1;
>> -    *max_track = parse->max_track;
>> -    *last_sect = parse->last_sect;
>> -    *drive = parse->drive;
>> -    *rate = parse->rate;
>> +
>> +    if (parse->max_head == 0) {
>> +        drv->flags &= ~FDISK_DBL_SIDES;
>> +    } else {
>> +        drv->flags |= FDISK_DBL_SIDES;
>> +    }
>> +    drv->max_track = parse->max_track;
>> +    drv->last_sect = parse->last_sect;
>> +    drv->drive = parse->drive;
>> +    drv->media_rate = parse->rate;
>> +
>> +    if (drv->media_inserted) {
>> +        FLOPPY_DPRINTF("Floppy disk (%d h %d t %d s) %s\n",
>> +                       parse->max_head + 1,
>> +                       drv->max_track, drv->last_sect,
>> +                       drv->ro ? "ro" : "rw");
>> +    }
> 
> One half of the debug print moved from...
> 
>>  }
>>  
>>  /* Revalidate a disk drive after a disk change */
>>  static void fd_revalidate(FDrive *drv)
>>  {
>> -    int nb_heads, max_track, last_sect, ro;
>> -    FDriveType drive;
>> -    FDriveRate rate;
>> -
>>      FLOPPY_DPRINTF("revalidate\n");
>>      if (drv->blk != NULL) {
>> -        ro = blk_is_read_only(drv->blk);
>> -        pick_geometry(drv->blk, &nb_heads, &max_track,
>> -                      &last_sect, drv->drive, &drive, &rate);
>> +        drv->ro = blk_is_read_only(drv->blk);
>> +        pick_geometry(drv);
>>          if (!drv->media_inserted) {
>>              FLOPPY_DPRINTF("No disk in drive\n");
>> -        } else {
>> -            FLOPPY_DPRINTF("Floppy disk (%d h %d t %d s) %s\n", nb_heads,
>> -                           max_track, last_sect, ro ? "ro" : "rw");
>>          }
> 
> ... here.  Recommend to move both or none.  If you add more callers,
> both might make more sense.
> 

Later in the series, pick_geometry cannot be called if there's no
diskette, so the "no disk!" message stayed outside.

... I'll just wiggle this printf back into fd_revalidate, so it looks sane.

I encourage you to take a few shots of something stiff and press further
into the series. It doesn't get truly wild until patch 9. If you
eyeballed everything except patch 9, I'd be willing to just do a very
early dev window pull and call it a day on this.

--js

>> -        if (nb_heads == 1) {
>> -            drv->flags &= ~FDISK_DBL_SIDES;
>> -        } else {
>> -            drv->flags |= FDISK_DBL_SIDES;
>> -        }
>> -        drv->max_track = max_track;
>> -        drv->last_sect = last_sect;
>> -        drv->ro = ro;
>> -        drv->drive = drive;
>> -        drv->media_rate = rate;
>>      } else {
>>          FLOPPY_DPRINTF("No drive connected\n");
>>          drv->last_sect = 0;





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