Travis Geiselbrecht | 9e60486 | 2009-06-28 12:24:07 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2008 Travis Geiselbrecht |
| 3 | * |
| 4 | * Permission is hereby granted, free of charge, to any person obtaining |
| 5 | * a copy of this software and associated documentation files |
| 6 | * (the "Software"), to deal in the Software without restriction, |
| 7 | * including without limitation the rights to use, copy, modify, merge, |
| 8 | * publish, distribute, sublicense, and/or sell copies of the Software, |
| 9 | * and to permit persons to whom the Software is furnished to do so, |
| 10 | * subject to the following conditions: |
| 11 | * |
| 12 | * The above copyright notice and this permission notice shall be |
| 13 | * included in all copies or substantial portions of the Software. |
| 14 | * |
| 15 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| 16 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| 17 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| 18 | * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| 19 | * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| 20 | * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| 21 | * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| 22 | */ |
| 23 | #ifndef __POW2_H |
| 24 | #define __POW2_H |
| 25 | |
| 26 | #include <sys/types.h> |
| 27 | #include <compiler.h> |
| 28 | |
| 29 | /* routines for dealing with power of 2 values for efficiency */ |
| 30 | static inline __ALWAYS_INLINE bool ispow2(uint val) |
| 31 | { |
| 32 | return ((val - 1) & val) == 0; |
| 33 | } |
| 34 | |
| 35 | static inline __ALWAYS_INLINE uint log2(uint val) |
| 36 | { |
| 37 | if (!ispow2(val)) |
| 38 | return 0; // undefined |
| 39 | |
| 40 | return __builtin_ctz(val); |
| 41 | } |
| 42 | |
| 43 | static inline __ALWAYS_INLINE uint valpow2(uint valp2) |
| 44 | { |
| 45 | return 1 << valp2; |
| 46 | } |
| 47 | |
| 48 | static inline __ALWAYS_INLINE uint divpow2(uint val, uint divp2) |
| 49 | { |
| 50 | return val >> divp2; |
| 51 | } |
| 52 | |
| 53 | static inline __ALWAYS_INLINE uint modpow2(uint val, uint modp2) |
| 54 | { |
| 55 | return val & ((1UL << modp2) - 1); |
| 56 | } |
| 57 | |
| 58 | |
| 59 | #endif |
| 60 | |