53c2d58ff8
Add function which finds contiguous number of bits which are not set in the 32 bit mask. Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>
51 lines
1.0 KiB
C
51 lines
1.0 KiB
C
/*
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* Copyright (c) 2025 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/sys/util.h>
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#include <zephyr/sys/math_extras.h>
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int bitmask_find_gap(uint32_t mask, size_t num_bits, size_t total_bits, bool first_match)
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{
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uint32_t max = UINT32_MAX;
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int max_loc = -1;
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if (total_bits < 32) {
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mask |= ~BIT_MASK(total_bits);
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}
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mask = ~mask;
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while (mask != 0U) {
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uint32_t block_size;
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uint32_t loc;
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int nidx;
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uint32_t idx = 31 - u32_count_leading_zeros(mask);
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uint32_t rmask = ~BIT_MASK(idx);
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rmask |= mask;
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rmask = ~rmask;
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if (rmask != 0U) {
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nidx = 31 - u32_count_leading_zeros(rmask);
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block_size = idx - nidx;
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loc = nidx + 1;
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mask &= BIT_MASK(nidx);
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} else {
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mask = 0;
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block_size = idx + 1;
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loc = 0;
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}
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if ((block_size == num_bits) || (first_match && block_size > num_bits)) {
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max_loc = loc;
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max = block_size;
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break;
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} else if (block_size >= num_bits && block_size < max) {
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max_loc = loc;
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max = block_size;
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}
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}
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return max_loc;
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}
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