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[Qemu-devel] [PATCH v3 6/9] sd: convert sd_normal_command() ffs(3) call
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v3 6/9] sd: convert sd_normal_command() ffs(3) call to ctz32() |
Date: |
Mon, 23 Mar 2015 15:29:28 +0000 |
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 <address@hidden>
Cc: Peter Crosthwaite <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
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
- [Qemu-devel] [PATCH v3 0/9] Convert ffs(3) to ctz32(), Stefan Hajnoczi, 2015/03/23
- [Qemu-devel] [PATCH v3 1/9] bt-sdp: fix broken uuids power-of-2 calculation, Stefan Hajnoczi, 2015/03/23
- [Qemu-devel] [PATCH v3 3/9] uninorth: convert ffs(3) to ctz32(), Stefan Hajnoczi, 2015/03/23
- [Qemu-devel] [PATCH v3 2/9] hw/arm/nseries: convert ffs(3) to ctz32(), Stefan Hajnoczi, 2015/03/23
- [Qemu-devel] [PATCH v3 7/9] omap_intc: convert ffs(3) to ctz32() in omap_inth_sir_update(), Stefan Hajnoczi, 2015/03/23
- [Qemu-devel] [PATCH v3 6/9] sd: convert sd_normal_command() ffs(3) call to ctz32(),
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v3 9/9] checkpatch: complain about ffs(3) calls, Stefan Hajnoczi, 2015/03/23
- [Qemu-devel] [PATCH v3 4/9] Convert (ffs(val) - 1) to ctz32(val), Stefan Hajnoczi, 2015/03/23
- [Qemu-devel] [PATCH v3 5/9] Convert ffs() != 0 callers to ctz32(), Stefan Hajnoczi, 2015/03/23
- [Qemu-devel] [PATCH v3 8/9] os-win32: drop ffs(3) prototype, Stefan Hajnoczi, 2015/03/23
- Re: [Qemu-devel] [PATCH v3 0/9] Convert ffs(3) to ctz32(), Stefan Hajnoczi, 2015/03/25