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| author | Keith Wansbrough <keith@lochan.org> | 2008-09-22 14:57:17 -0700 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-10-09 08:56:19 +0200 |
| commit | 9e49184c82e9ec3ab4d45f9ea5a17ccaf43869f0 (patch) | |
| tree | 532d70e75854e1f7c070d4818f3b44cefe528d3e /include/linux/fd.h | |
| parent | 061837bc8687edc2739ef02f721b7ae0b8076390 (diff) | |
| download | lwn-9e49184c82e9ec3ab4d45f9ea5a17ccaf43869f0.tar.gz lwn-9e49184c82e9ec3ab4d45f9ea5a17ccaf43869f0.zip | |
floppy: support arbitrary first-sector numbers
The current floppy_struct allows floppies to number sectors starting
from 0 or 1. This patch allows arbitrary first-sector numbers - for
example, 0xC1 for Amstrad CPC disks.
This extends the existing 1-bit field (FD_ZEROBASED, bit 2 of stretch)
to 8 bits (FD_SECTMASK, bits 2 to 9).
Currently 0x00 denotes a first sector number of 1, and 0x01 denotes a
first sector number of 0. We extend this by interpreting FD_SECTMASK
as the first sector number with the LSB flipped.
Signed-off-by: Keith Wansbrough <keith@lochan.org>
Cc: Alain Knaff <alain@linux.lu>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Karel Zak <kzak@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'include/linux/fd.h')
| -rw-r--r-- | include/linux/fd.h | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/include/linux/fd.h b/include/linux/fd.h index b6bd41d2b460..f5d194af07a8 100644 --- a/include/linux/fd.h +++ b/include/linux/fd.h @@ -15,10 +15,16 @@ struct floppy_struct { sect, /* sectors per track */ head, /* nr of heads */ track, /* nr of tracks */ - stretch; /* !=0 means double track steps */ + stretch; /* bit 0 !=0 means double track steps */ + /* bit 1 != 0 means swap sides */ + /* bits 2..9 give the first sector */ + /* number (the LSB is flipped) */ #define FD_STRETCH 1 #define FD_SWAPSIDES 2 #define FD_ZEROBASED 4 +#define FD_SECTBASEMASK 0x3FC +#define FD_MKSECTBASE(s) (((s) ^ 1) << 2) +#define FD_SECTBASE(floppy) ((((floppy)->stretch & FD_SECTBASEMASK) >> 2) ^ 1) unsigned char gap, /* gap1 size */ |