| /* |
| * Copyright (c) 2016 Nordic Semiconductor ASA |
| * Copyright (c) 2016 Vinayak Kariappa Chettimada |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| #include <zephyr/types.h> |
| #include "util.h" |
| |
| /** |
| * @brief Population count: Count the number of bits set to 1 |
| * @details |
| * TODO: Faster methods available at [1]. |
| * [1] http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel |
| * |
| * @param octets Data to count over |
| * @param octets_len Must not be bigger than 255/8 = 31 bytes |
| * |
| * @return popcnt of 'octets' |
| */ |
| u8_t util_ones_count_get(u8_t *octets, u8_t octets_len) |
| { |
| u8_t one_count = 0U; |
| |
| while (octets_len--) { |
| u8_t bite; |
| |
| bite = *octets; |
| while (bite) { |
| bite &= (bite - 1); |
| one_count++; |
| } |
| octets++; |
| } |
| |
| return one_count; |
| } |
