[src/trunk]: src/sys/dev/scsipi avoid division and remainder operations for d...

[chs <chs%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d4c615b69dfa
branches:  trunk
changeset: 499577:d4c615b69dfa
user:      chs <chs%NetBSD.org@localhost>
date:      Fri Nov 24 00:17:35 2000 +0000

description:
avoid division and remainder operations for devices where
the sector size is DEV_BSIZE (ie. practically everything).

diffstat:

 sys/dev/scsipi/sd.c |  20 +++++++++++++++-----
 1 files changed, 15 insertions(+), 5 deletions(-)

diffs (55 lines):

diff -r f2e9337b2f62 -r d4c615b69dfa sys/dev/scsipi/sd.c
--- a/sys/dev/scsipi/sd.c       Thu Nov 23 23:22:58 2000 +0000
+++ b/sys/dev/scsipi/sd.c       Fri Nov 24 00:17:35 2000 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sd.c,v 1.165 2000/11/22 00:32:24 soren Exp $   */
+/*     $NetBSD: sd.c,v 1.166 2000/11/24 00:17:35 chs Exp $     */
 
 /*-
  * Copyright (c) 1998 The NetBSD Foundation, Inc.
@@ -555,6 +555,7 @@
        struct disklabel *lp;
        daddr_t blkno;
        int s;
+       boolean_t sector_aligned;
 
        SC_DEBUG(sd->sc_link, SDEV_DB2, ("sdstrategy "));
        SC_DEBUG(sd->sc_link, SDEV_DB1,
@@ -577,8 +578,12 @@
         * The transfer must be a whole number of blocks, offset must not be
         * negative.
         */
-       if ((bp->b_bcount % lp->d_secsize) != 0 ||
-           bp->b_blkno < 0) {
+       if (lp->d_secsize == DEV_BSIZE) {
+               sector_aligned = (bp->b_bcount & (DEV_BSIZE - 1)) == 0;
+       } else {
+               sector_aligned = (bp->b_bcount % lp->d_secsize) == 0;
+       }
+       if (!sector_aligned || bp->b_blkno < 0) {
                bp->b_error = EINVAL;
                goto bad;
        }
@@ -601,7 +606,9 @@
         * Now convert the block number to absolute and put it in
         * terms of the device's logical block size.
         */
-       if (lp->d_secsize >= DEV_BSIZE)
+       if (lp->d_secsize == DEV_BSIZE)
+               blkno = bp->b_blkno;
+       else if (lp->d_secsize > DEV_BSIZE)
                blkno = bp->b_blkno / (lp->d_secsize / DEV_BSIZE);
        else
                blkno = bp->b_blkno * (DEV_BSIZE / lp->d_secsize);
@@ -708,7 +715,10 @@
                 * We have a buf, now we should make a command.
                 */
 
-               nblks = howmany(bp->b_bcount, lp->d_secsize);
+               if (lp->d_secsize == DEV_BSIZE)
+                       nblks = bp->b_bcount >> DEV_BSHIFT;
+               else
+                       nblks = howmany(bp->b_bcount, lp->d_secsize);
 
 #if NSD_SCSIBUS > 0
                /*