qxl: refactor rounding up to a nearest power of 2

We already have pow2floor, mirror it and use instead of a function with
similar results (same in used domain), to clarify our intent.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/util/cutils.c b/util/cutils.c
index dbe7412..c2250d1 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -483,6 +483,20 @@ int64_t pow2floor(int64_t value)
     return value;
 }
 
+/* round up to the nearest power of 2 (0 if overflow) */
+uint64_t pow2ceil(uint64_t value)
+{
+    uint8_t nlz = clz64(value);
+
+    if (is_power_of_2(value)) {
+        return value;
+    }
+    if (!nlz) {
+        return 0;
+    }
+    return 1ULL << (64 - nlz);
+}
+
 /*
  * Implementation of  ULEB128 (http://en.wikipedia.org/wiki/LEB128)
  * Input is limited to 14-bit numbers