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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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C
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1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253/* SPDX-License-Identifier: GPL-2.0 */#ifndef __ASM_GENERIC_GETORDER_H#define __ASM_GENERIC_GETORDER_H
#ifndef __ASSEMBLER__
#include <linux/compiler.h>#include <linux/log2.h>
/** * get_order - Determine the allocation order of a memory size * @size: The size for which to get the order * * Determine the allocation order of a particular sized block of memory. This * is on a logarithmic scale, where: * * 0 -> 2^0 * PAGE_SIZE and below * 1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1 * 2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1 * 3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1 * 4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1 * ... * * The order returned is used to find the smallest allocation granule required * to hold an object of the specified size. * * The result is undefined if the size is 0. */static __always_inline __attribute_const__ int get_order(unsigned long size){ if (__builtin_constant_p(size)) { if (!size) return BITS_PER_LONG - PAGE_SHIFT;
if (size < (1UL << PAGE_SHIFT)) return 0;
return ilog2((size) - 1) - PAGE_SHIFT + 1; }
size--; size >>= PAGE_SHIFT;#if BITS_PER_LONG == 32 return fls(size);#else return fls64(size);#endif}
#endif /* __ASSEMBLER__ */
#endif /* __ASM_GENERIC_GETORDER_H */