Files
pebble/src/fw/util/bitset.c
2025-01-27 11:38:16 -08:00

34 lines
986 B
C

/*
* Copyright 2024 Google LLC
*
* 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.
*/
#include "bitset.h"
#include <stdint.h>
uint8_t count_bits_set(uint8_t *bitset_bytes, int num_bits) {
uint8_t num_bits_set = 0;
int num_bytes = (num_bits + 7) / 8;
if ((num_bits % 8) != 0) {
bitset_bytes[num_bytes] &= ((0x1 << (num_bits)) - 1);
}
for (int i = 0; i < num_bytes; i++) {
num_bits_set += __builtin_popcount(bitset_bytes[i]);
}
return (num_bits_set);
}