#ifndef __ASM_GENERIC_GETORDER_H #define __ASM_GENERIC_GETORDER_H #ifndef __ASSEMBLY__ #include #include /* * Runtime evaluation of get_order() */ static inline __attribute_const__ int __get_order(unsigned long size) { int order; size--; size >>= PAGE_SHIFT; #if BITS_PER_LONG == 32 order = fls(size); #else order = fls64(size); #endif return order; } /** * 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. * * This function may be used to initialise variables with compile time * evaluations of constants. */ #define get_order(n) \ ( \ __builtin_constant_p(n) ? ( \ ((n) == 0UL) ? BITS_PER_LONG - PAGE_SHIFT : \ (((n) < (1UL << PAGE_SHIFT)) ? 0 : \ ilog2((n) - 1) - PAGE_SHIFT + 1) \ ) : \ __get_order(n) \ ) #endif /* __ASSEMBLY__ */ #endif /* __ASM_GENERIC_GETORDER_H */ r>

path: root/include/xen/interface/io/protocols.h

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