[Qemu-devel] [PATCH 2/2] vhdx: Simplify vhdx_set_shift_bits()

[Max Reitz <mreitz@redhat.com>]

For values which are powers of two (and we do assume all of these to
be), sizeof(x) * 8 - 1 - clz(x) == ctz(x). Therefore, use ctz().

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/vhdx.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/block/vhdx.c b/block/vhdx.c
index 3955f7f..475f602 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -263,10 +263,10 @@ static void vhdx_region_unregister_all(BDRVVHDXState *s)
 
 static void vhdx_set_shift_bits(BDRVVHDXState *s)
 {
-    s->logical_sector_size_bits = 31 - clz32(s->logical_sector_size);
-    s->sectors_per_block_bits =   31 - clz32(s->sectors_per_block);
-    s->chunk_ratio_bits =         63 - clz64(s->chunk_ratio);
-    s->block_size_bits =          31 - clz32(s->block_size);
+    s->logical_sector_size_bits = ctz32(s->logical_sector_size);
+    s->sectors_per_block_bits =   ctz32(s->sectors_per_block);
+    s->chunk_ratio_bits =         ctz64(s->chunk_ratio);
+    s->block_size_bits =          ctz32(s->block_size);
 }
 
 /*
-- 
2.6.4