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 <arm...@redhat.com>
Cc: Peter Crosthwaite <peter.crosthwa...@xilinx.com>
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
hw/sd/sd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/hw/sd/sd.c b/hw/sd/sd.c
index f955265..8abf0c9 100644
--- a/hw/sd/sd.c
+++ b/hw/sd/sd.c
@@ -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;
--
2.1.0
