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[Qemu-devel] [PATCH v3 1/9] bt-sdp: fix broken uuids power-of-2 calculat
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v3 1/9] bt-sdp: fix broken uuids power-of-2 calculation |
Date: |
Mon, 23 Mar 2015 15:29:23 +0000 |
The binary search in sdp_uuid_match() only works when the number of
elements to search is a power of two.
lo = record->uuid;
hi = record->uuids;
while (hi >>= 1)
if (lo[hi] <= val)
lo += hi;
return *lo == val;
I noticed that the record->uuids calculation in
sdp_service_record_build() was suspect:
record->uuids = 1 << ffs(record->uuids - 1);
Unlike most ffs(val) - 1 users, the expression is ffs(val - 1)!
Actually ffs() is the wrong function to use for power-of-2. Use
pow2ceil() to achieve the correct effect. Now the record->uuid[] array
is sized correctly and the binary search in sdp_uuid_match() should
work.
I'm not sure how to run/test this code.
Cc: Andrzej Zaborowski <address@hidden>
Cc: address@hidden
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
hw/bt/sdp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/bt/sdp.c b/hw/bt/sdp.c
index 218e075..c903747 100644
--- a/hw/bt/sdp.c
+++ b/hw/bt/sdp.c
@@ -707,7 +707,7 @@ static void sdp_service_record_build(struct
sdp_service_record_s *record,
len += sdp_attr_max_size(&def->attributes[record->attributes ++].data,
&record->uuids);
}
- record->uuids = 1 << ffs(record->uuids - 1);
+ record->uuids = pow2ceil(record->uuids);
record->attribute_list =
g_malloc0(record->attributes * sizeof(*record->attribute_list));
record->uuid =
--
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 <=
- [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, 2015/03/23
- [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