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| 5270 | serge | 1 | #ifndef __ASM_GENERIC_GETORDER_H |
| 2 | #define __ASM_GENERIC_GETORDER_H |
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| 3 | |||
| 4 | #ifndef __ASSEMBLY__ |
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| 5 | |||
| 6 | #include |
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| 7 | #include |
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| 8 | |||
| 9 | /* |
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| 10 | * Runtime evaluation of get_order() |
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| 11 | */ |
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| 12 | static inline __attribute_const__ |
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| 13 | int __get_order(unsigned long size) |
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| 14 | { |
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| 15 | int order; |
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| 16 | |||
| 17 | size--; |
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| 18 | size >>= PAGE_SHIFT; |
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| 19 | #if BITS_PER_LONG == 32 |
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| 20 | order = fls(size); |
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| 21 | #else |
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| 22 | order = fls64(size); |
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| 23 | #endif |
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| 24 | return order; |
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| 25 | } |
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| 26 | |||
| 27 | /** |
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| 28 | * get_order - Determine the allocation order of a memory size |
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| 29 | * @size: The size for which to get the order |
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| 30 | * |
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| 31 | * Determine the allocation order of a particular sized block of memory. This |
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| 32 | * is on a logarithmic scale, where: |
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| 33 | * |
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| 34 | * 0 -> 2^0 * PAGE_SIZE and below |
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| 35 | * 1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1 |
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| 36 | * 2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1 |
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| 37 | * 3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1 |
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| 38 | * 4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1 |
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| 39 | * ... |
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| 40 | * |
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| 41 | * The order returned is used to find the smallest allocation granule required |
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| 42 | * to hold an object of the specified size. |
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| 43 | * |
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| 44 | * The result is undefined if the size is 0. |
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| 45 | * |
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| 46 | * This function may be used to initialise variables with compile time |
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| 47 | * evaluations of constants. |
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| 48 | */ |
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| 49 | #define get_order(n) \ |
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| 50 | ( \ |
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| 51 | __builtin_constant_p(n) ? ( \ |
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| 52 | ((n) == 0UL) ? BITS_PER_LONG - PAGE_SHIFT : \ |
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| 53 | (((n) < (1UL << PAGE_SHIFT)) ? 0 : \ |
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| 54 | ilog2((n) - 1) - PAGE_SHIFT + 1) \ |
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| 55 | ) : \ |
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| 56 | __get_order(n) \ |
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| 57 | ) |
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| 58 | |||
| 59 | #endif /* __ASSEMBLY__ */ |
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| 60 | |||
| 61 | #endif /* __ASM_GENERIC_GETORDER_H */ |