Commit c5e56868 authored by Lucas Romero's avatar Lucas Romero Committed by Anas Nashif
Browse files

lib: bitarray: add method to count bits set in region 



This is part one of several changes to add more methods to the bitarray api
so that it can be used for broader usecases, specifically LoRaWAN forward
error correction.

Signed-off-by: default avatarLucas Romero <luqasn@gmail.com>
parent e36caec3

include/zephyr/sys/bitarray.h

+17 −0
Original line number Diff line number Diff line
@@ -168,6 +168,23 @@ int sys_bitarray_test_and_clear_bit(sys_bitarray_t *bitarray, size_t bit, int *p 
int sys_bitarray_alloc(sys_bitarray_t *bitarray, size_t num_bits,

		       size_t *offset);



/**

 * Count bits set in a bit array region

 *

 * This counts the number of bits set (@p count) in a

 * region (@p offset, @p num_bits).

 *

 * @param[in]  bitarray Bitarray struct

 * @param[in]  num_bits Number of bits to check, must be larger than 0

 * @param[in]  offset   Starting bit position

 * @param[out] count    Number of bits set in the region if successful

 *

 * @retval 0       Operation successful

 * @retval -EINVAL Invalid argument (e.g. out-of-bounds access, trying to count 0 bits, etc.)

 */

int sys_bitarray_popcount_region(sys_bitarray_t *bitarray, size_t num_bits, size_t offset,

				 size_t *count);



/**

 * Free bits in a bit array

 *

lib/utils/bitarray.c

+49 −0
Original line number Diff line number Diff line
@@ -210,6 +210,55 @@ static void set_region(sys_bitarray_t *bitarray, size_t offset, 
	}

}



int sys_bitarray_popcount_region(sys_bitarray_t *bitarray, size_t num_bits, size_t offset,

				 size_t *count)

{

	k_spinlock_key_t key;

	size_t idx;

	struct bundle_data bd;

	int ret;



	key = k_spin_lock(&bitarray->lock);



	__ASSERT_NO_MSG(bitarray != NULL);

	__ASSERT_NO_MSG(bitarray->num_bits > 0);



	if (num_bits == 0 || offset + num_bits > bitarray->num_bits) {

		ret = -EINVAL;

		goto out;

	}



	CHECKIF(count == NULL) {

		ret = -EINVAL;

		goto out;

	}



	setup_bundle_data(bitarray, &bd, offset, num_bits);



	if (bd.sidx == bd.eidx) {

		/* Start/end at same bundle */

		*count = POPCOUNT(bitarray->bundles[bd.sidx] & bd.smask);

	} else {

		/* Start/end at different bundle.

		 * So count the bits in start and end bundles

		 * separately with correct mask applied. For in-between bundles,

		 * count all bits.

		 */

		*count = 0;

		*count += POPCOUNT(bitarray->bundles[bd.sidx] & bd.smask);

		*count += POPCOUNT(bitarray->bundles[bd.eidx] & bd.emask);

		for (idx = bd.sidx + 1; idx < bd.eidx; idx++) {

			*count += POPCOUNT(bitarray->bundles[idx]);

		}

	}



	ret = 0;



out:

	k_spin_unlock(&bitarray->lock, key);

	return ret;

}



int sys_bitarray_set_bit(sys_bitarray_t *bitarray, size_t bit)

{

	k_spinlock_key_t key;

tests/kernel/common/src/bitarray.c

+98 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 
 *

 * SPDX-License-Identifier: Apache-2.0

 */

#include <errno.h>



#include <zephyr/kernel.h>

#include <zephyr/ztest.h>
@@ -519,6 +520,103 @@ ZTEST(bitarray, test_bitarray_alloc_free) 
	alloc_and_free_interval();

}



ZTEST(bitarray, test_bitarray_popcount_region)

{

	int ret;

	size_t count;



	/* Bitarrays have embedded spinlocks and can't on the stack. */

	if (IS_ENABLED(CONFIG_KERNEL_COHERENCE)) {

		ztest_test_skip();

	}



	SYS_BITARRAY_DEFINE(ba, 128);



	printk("Testing bit array region popcount spanning single bundle\n");



	/* Pre-populate the bits */

	ba.bundles[0] = 0x00000005;

	ba.bundles[1] = 0x00000000;

	ba.bundles[2] = 0x00000000;

	ba.bundles[3] = 0x00000000;



	ret = sys_bitarray_popcount_region(&ba, 1, 0, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 1, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);



	ret = sys_bitarray_popcount_region(&ba, 1, 1, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 0, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);



	ret = sys_bitarray_popcount_region(&ba, 2, 0, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 1, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);



	ret = sys_bitarray_popcount_region(&ba, 3, 0, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 2, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);



	ret = sys_bitarray_popcount_region(&ba, 3, 1, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 1, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);



	printk("Testing bit array region popcount spanning multiple bundles\n");



	/* Pre-populate the bits.

	 * First and last bit of bitarray are set

	 */

	ba.bundles[0] = 0x00000001;

	ba.bundles[1] = 0x00000000;

	ba.bundles[2] = 0x00000000;

	ba.bundles[3] = 0x80000000;



	ret = sys_bitarray_popcount_region(&ba, 126, 1, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 0, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);



	ret = sys_bitarray_popcount_region(&ba, 126, 0, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 1, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);



	ret = sys_bitarray_popcount_region(&ba, 127, 1, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 1, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);

	ret = sys_bitarray_popcount_region(&ba, 1, 127, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 1, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);



	ret = sys_bitarray_popcount_region(&ba, 128, 0, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);

	zassert_equal(count, 2, "sys_bitarray_popcount_region() returned unexpected count: %d",

		      count);



	printk("Testing edge/error cases\n");

	ret = sys_bitarray_popcount_region(&ba, 0, 0, &count);

	zassert_equal(ret, -EINVAL, "sys_bitarray_popcount_region() returned unexpected value: %d",

		      ret);

	ret = sys_bitarray_popcount_region(&ba, 0, 128, &count);

	zassert_equal(ret, -EINVAL, "sys_bitarray_popcount_region() returned unexpected value: %d",

		      ret);

	ret = sys_bitarray_popcount_region(&ba, 128, 0, &count);

	zassert_equal(ret, 0, "sys_bitarray_popcount_region() returned unexpected value: %d", ret);



	ret = sys_bitarray_popcount_region(&ba, 128, 1, &count);

	zassert_equal(ret, -EINVAL, "sys_bitarray_popcount_region() returned unexpected value: %d",

		      ret);

	ret = sys_bitarray_popcount_region(&ba, 129, 0, &count);

	zassert_equal(ret, -EINVAL, "sys_bitarray_popcount_region() returned unexpected value: %d",

		      ret);

}



ZTEST(bitarray, test_bitarray_region_set_clear)

{

	int ret;

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