[SCSI] Merge up to linux-2.6 head

[pandora-kernel.git] / include / linux / log2.h

diff --git a/include/linux/log2.h b/include/linux/log2.h
index d02e1a5..1b8a2c1 100644 (file)
--- a/include/linux/log2.h
+++ b/include/linux/log2.h
@@ -43,6 +43,17 @@ int __ilog2_u64(u64 n)
 }
 #endif
 
+/*
+ *  Determine whether some value is a power of two, where zero is
+ * *not* considered a power of two.
+ */
+
+static inline __attribute__((const))
+bool is_power_of_2(unsigned long n)
+{
+       return (n != 0 && ((n & (n - 1)) == 0));
+}
+
 /*
  * round up to nearest power of two
  */
@@ -141,14 +152,14 @@ unsigned long __roundup_pow_of_two(unsigned long n)
  * roundup_pow_of_two - round the given value up to nearest power of two
  * @n - parameter
  *
- * round the given balue up to the nearest power of two
+ * round the given value up to the nearest power of two
  * - the result is undefined when n == 0
  * - this can be used to initialise global variables from constant data
  */
 #define roundup_pow_of_two(n)                  \
 (                                              \
        __builtin_constant_p(n) ? (             \
-               (n == 1) ? 0 :                  \
+               (n == 1) ? 1 :                  \
                (1UL << (ilog2((n) - 1) + 1))   \
                                   ) :          \
        __roundup_pow_of_two(n)                 \