1#ifndef __ASM_GENERIC_GETORDER_H
 2#define __ASM_GENERIC_GETORDER_H
 3
 4#ifndef __ASSEMBLY__
 5
 6#include <linux/compiler.h>
 
 7
 8/* Pure 2^n version of get_order */
 9static inline __attribute_const__ int get_order(unsigned long size)
 
 
 
10{
11	int order;
12
13	size = (size - 1) >> (PAGE_SHIFT - 1);
14	order = -1;
15	do {
16		size >>= 1;
17		order++;
18	} while (size);
 
19	return order;
20}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
21
22#endif	/* __ASSEMBLY__ */
23
24#endif	/* __ASM_GENERIC_GETORDER_H */

 1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef __ASM_GENERIC_GETORDER_H
 3#define __ASM_GENERIC_GETORDER_H
 4
 5#ifndef __ASSEMBLY__
 6
 7#include <linux/compiler.h>
 8#include <linux/log2.h>
 9
10/*
11 * Runtime evaluation of get_order()
12 */
13static inline __attribute_const__
14int __get_order(unsigned long size)
15{
16	int order;
17
18	size--;
19	size >>= PAGE_SHIFT;
20#if BITS_PER_LONG == 32
21	order = fls(size);
22#else
23	order = fls64(size);
24#endif
25	return order;
26}
27
28/**
29 * get_order - Determine the allocation order of a memory size
30 * @size: The size for which to get the order
31 *
32 * Determine the allocation order of a particular sized block of memory.  This
33 * is on a logarithmic scale, where:
34 *
35 *	0 -> 2^0 * PAGE_SIZE and below
36 *	1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1
37 *	2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1
38 *	3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1
39 *	4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1
40 *	...
41 *
42 * The order returned is used to find the smallest allocation granule required
43 * to hold an object of the specified size.
44 *
45 * The result is undefined if the size is 0.
46 *
47 * This function may be used to initialise variables with compile time
48 * evaluations of constants.
49 */
50#define get_order(n)						\
51(								\
52	__builtin_constant_p(n) ? (				\
53		((n) == 0UL) ? BITS_PER_LONG - PAGE_SHIFT :	\
54		(((n) < (1UL << PAGE_SHIFT)) ? 0 :		\
55		 ilog2((n) - 1) - PAGE_SHIFT + 1)		\
56	) :							\
57	__get_order(n)						\
58)
59
60#endif	/* __ASSEMBLY__ */
61
62#endif	/* __ASM_GENERIC_GETORDER_H */