1#ifndef __ASM_GENERIC_GETORDER_H
 2#define __ASM_GENERIC_GETORDER_H
 3
 4#ifndef __ASSEMBLY__
 5
 6#include <linux/compiler.h>
 7#include <linux/log2.h>
 8
 9/*
10 * Runtime evaluation of get_order()
11 */
12static inline __attribute_const__
13int __get_order(unsigned long size)
14{
15	int order;
16
17	size--;
18	size >>= PAGE_SHIFT;
19#if BITS_PER_LONG == 32
20	order = fls(size);
21#else
22	order = fls64(size);
23#endif
24	return order;
25}
26
27/**
28 * get_order - Determine the allocation order of a memory size
29 * @size: The size for which to get the order
30 *
31 * Determine the allocation order of a particular sized block of memory.  This
32 * is on a logarithmic scale, where:
33 *
34 *	0 -> 2^0 * PAGE_SIZE and below
35 *	1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1
36 *	2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1
37 *	3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1
38 *	4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1
39 *	...
40 *
41 * The order returned is used to find the smallest allocation granule required
42 * to hold an object of the specified size.
43 *
44 * The result is undefined if the size is 0.
45 *
46 * This function may be used to initialise variables with compile time
47 * evaluations of constants.
48 */
49#define get_order(n)						\
50(								\
51	__builtin_constant_p(n) ? (				\
52		((n) == 0UL) ? BITS_PER_LONG - PAGE_SHIFT :	\
53		(((n) < (1UL << PAGE_SHIFT)) ? 0 :		\
54		 ilog2((n) - 1) - PAGE_SHIFT + 1)		\
55	) :							\
56	__get_order(n)						\
57)
58
59#endif	/* __ASSEMBLY__ */
60
61#endif	/* __ASM_GENERIC_GETORDER_H */