Stephen Rothwell | fd4fd5a | 2005-09-03 15:54:30 -0700 | [diff] [blame] | 1 | #ifndef _ASM_GENERIC_PAGE_H |
| 2 | #define _ASM_GENERIC_PAGE_H |
| 3 | |
| 4 | #ifdef __KERNEL__ |
| 5 | #ifndef __ASSEMBLY__ |
| 6 | |
David Howells | 39d61db | 2006-12-08 02:37:52 -0800 | [diff] [blame] | 7 | #include <linux/log2.h> |
Stephen Rothwell | fd4fd5a | 2005-09-03 15:54:30 -0700 | [diff] [blame] | 8 | |
David Howells | 39d61db | 2006-12-08 02:37:52 -0800 | [diff] [blame] | 9 | /* |
| 10 | * non-const pure 2^n version of get_order |
| 11 | * - the arch may override these in asm/bitops.h if they can be implemented |
| 12 | * more efficiently than using the arch log2 routines |
| 13 | * - we use the non-const log2() instead if the arch has defined one suitable |
| 14 | */ |
| 15 | #ifndef ARCH_HAS_GET_ORDER |
| 16 | static inline __attribute__((const)) |
| 17 | int __get_order(unsigned long size, int page_shift) |
Stephen Rothwell | fd4fd5a | 2005-09-03 15:54:30 -0700 | [diff] [blame] | 18 | { |
David Howells | 39d61db | 2006-12-08 02:37:52 -0800 | [diff] [blame] | 19 | #if BITS_PER_LONG == 32 && defined(ARCH_HAS_ILOG2_U32) |
| 20 | int order = __ilog2_u32(size) - page_shift; |
| 21 | return order >= 0 ? order : 0; |
| 22 | #elif BITS_PER_LONG == 64 && defined(ARCH_HAS_ILOG2_U64) |
| 23 | int order = __ilog2_u64(size) - page_shift; |
| 24 | return order >= 0 ? order : 0; |
| 25 | #else |
Stephen Rothwell | fd4fd5a | 2005-09-03 15:54:30 -0700 | [diff] [blame] | 26 | int order; |
| 27 | |
David Howells | 39d61db | 2006-12-08 02:37:52 -0800 | [diff] [blame] | 28 | size = (size - 1) >> (page_shift - 1); |
Stephen Rothwell | fd4fd5a | 2005-09-03 15:54:30 -0700 | [diff] [blame] | 29 | order = -1; |
| 30 | do { |
| 31 | size >>= 1; |
| 32 | order++; |
| 33 | } while (size); |
| 34 | return order; |
David Howells | 39d61db | 2006-12-08 02:37:52 -0800 | [diff] [blame] | 35 | #endif |
Stephen Rothwell | fd4fd5a | 2005-09-03 15:54:30 -0700 | [diff] [blame] | 36 | } |
David Howells | 39d61db | 2006-12-08 02:37:52 -0800 | [diff] [blame] | 37 | #endif |
| 38 | |
| 39 | /** |
| 40 | * get_order - calculate log2(pages) to hold a block of the specified size |
| 41 | * @n - size |
| 42 | * |
| 43 | * calculate allocation order based on the current page size |
| 44 | * - this can be used to initialise global variables from constant data |
| 45 | */ |
| 46 | #define get_order(n) \ |
| 47 | ( \ |
| 48 | __builtin_constant_p(n) ? \ |
| 49 | ((n < (1UL << PAGE_SHIFT)) ? 0 : ilog2(n) - PAGE_SHIFT) : \ |
| 50 | __get_order(n, PAGE_SHIFT) \ |
| 51 | ) |
Stephen Rothwell | fd4fd5a | 2005-09-03 15:54:30 -0700 | [diff] [blame] | 52 | |
| 53 | #endif /* __ASSEMBLY__ */ |
| 54 | #endif /* __KERNEL__ */ |
| 55 | |
| 56 | #endif /* _ASM_GENERIC_PAGE_H */ |