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sd: convert sd_normal_command() ffs(3) call to ctz32()

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ffs() cannot be replaced with ctz32() when the argument might be zero,
because ffs(0) returns 0 while ctz32(0) returns 32.

The ffs(3) call in sd_normal_command() is a special case though.  It can
be converted to ctz32() + 1 because the argument is never zero:

  if (!(req.arg >> 8) || (req.arg >> (ctz32(req.arg & ~0xff) + 1))) {
      ~~~~~~~~~~~~~~~
            ^--------------- req.arg cannot be zero

Cc: Markus Armbruster <armbru@redhat.com>
Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427124571-28598-7-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2015-03-23 15:29:28 +00:00 committed by Kevin Wolf
parent bd2a88840e
commit c9d9331851
1 changed files with 2 additions and 1 deletions
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3
hw/sd/sd.c
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@ -796,8 +796,9 @@ static sd_rsp_type_t sd_normal_command(SDState *sd,
sd->vhs = 0;
/* No response if not exactly one VHS bit is set. */
if (!(req.arg >> 8) || (req.arg >> ffs(req.arg & ~0xff)))
if (!(req.arg >> 8) || (req.arg >> (ctz32(req.arg & ~0xff) + 1))) {
return sd->spi ? sd_r7 : sd_r0;
}
/* Accept. */
sd->vhs = req.arg;