From: Andrei Emeltchenko <andrei.emeltchenko@xxxxxxxxx> --- android/cutils/bitops.h | 120 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100644 android/cutils/bitops.h diff --git a/android/cutils/bitops.h b/android/cutils/bitops.h new file mode 100644 index 0000000..045830d --- /dev/null +++ b/android/cutils/bitops.h @@ -0,0 +1,120 @@ +/* + * Copyright (C) 2011 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#ifndef __CUTILS_BITOPS_H +#define __CUTILS_BITOPS_H + +#include <stdbool.h> +#include <string.h> +#include <strings.h> +#include <sys/cdefs.h> + +__BEGIN_DECLS + +/* + * Bitmask Operations + * + * Note this doesn't provide any locking/exclusion, and isn't atomic. + * Additionally no bounds checking is done on the bitmask array. + * + * Example: + * + * int num_resources; + * unsigned int resource_bits[BITS_TO_WORDS(num_resources)]; + * bitmask_init(resource_bits, num_resources); + * ... + * int bit = bitmask_ffz(resource_bits, num_resources); + * bitmask_set(resource_bits, bit); + * ... + * if (bitmask_test(resource_bits, bit)) { ... } + * ... + * bitmask_clear(resource_bits, bit); + * + */ + +#define BITS_PER_WORD (sizeof(unsigned int) * 8) +#define BITS_TO_WORDS(x) (((x) + BITS_PER_WORD - 1) / BITS_PER_WORD) +#define BIT_IN_WORD(x) ((x) % BITS_PER_WORD) +#define BIT_WORD(x) ((x) / BITS_PER_WORD) +#define BIT_MASK(x) (1 << BIT_IN_WORD(x)) + +static inline void bitmask_init(unsigned int *bitmask, int num_bits) +{ + memset(bitmask, 0, BITS_TO_WORDS(num_bits)*sizeof(unsigned int)); +} + +static inline int bitmask_ffz(unsigned int *bitmask, int num_bits) +{ + int bit, result; + size_t i; + + for (i = 0; i < BITS_TO_WORDS(num_bits); i++) { + bit = ffs(~bitmask[i]); + if (bit) { + // ffs is 1-indexed, return 0-indexed result + bit--; + result = BITS_PER_WORD * i + bit; + if (result >= num_bits) + return -1; + return result; + } + } + return -1; +} + +static inline int bitmask_weight(unsigned int *bitmask, int num_bits) +{ + size_t i; + int weight = 0; + + for (i = 0; i < BITS_TO_WORDS(num_bits); i++) + weight += __builtin_popcount(bitmask[i]); + return weight; +} + +static inline void bitmask_set(unsigned int *bitmask, int bit) +{ + bitmask[BIT_WORD(bit)] |= BIT_MASK(bit); +} + +static inline void bitmask_clear(unsigned int *bitmask, int bit) +{ + bitmask[BIT_WORD(bit)] &= ~BIT_MASK(bit); +} + +static inline bool bitmask_test(unsigned int *bitmask, int bit) +{ + return bitmask[BIT_WORD(bit)] & BIT_MASK(bit); +} + +static inline int popcount(unsigned int x) +{ + return __builtin_popcount(x); +} + +static inline int popcountl(unsigned long x) +{ + return __builtin_popcountl(x); +} + +static inline int popcountll(unsigned long long x) +{ + return __builtin_popcountll(x); +} + +__END_DECLS + +#endif /* __CUTILS_BITOPS_H */ -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
