tbm-mcu/source/bitops.c

#include <stdint.h>

#include <bitops.h>
#include <macros.h>

#define BIT_WORD(n) ((n) / BIT_SIZE(unsigned long))
#define BIT_MASK(n) (1UL << ((n) % BIT_SIZE(unsigned long)))

unsigned ilog2(unsigned n)
{
	unsigned ret = 0;

	while (n >>= 1)
		++ret;

	return ret;
}

int is_bit_set(void *base, size_t n)
{
	unsigned long *word = (unsigned long *)base + BIT_WORD(n);
	unsigned long mask = BIT_MASK(n);

	return (*word & mask) ? 1 : 0;
}

void set_bit(void *base, size_t n)
{
	unsigned long *word = (unsigned long *)base + BIT_WORD(n);
	unsigned long mask = BIT_MASK(n);

	*word |= mask;
}

void clear_bit(void *base, size_t n)
{
	unsigned long *word = (unsigned long *)base + BIT_WORD(n);
	unsigned long mask = BIT_MASK(n);

	*word &= ~mask;
}

size_t next_set_bit(void *base, size_t n)
{
	size_t i;

	for (i = 0; i < n; ++i) {
		if (is_bit_set(base, i))
			return i;
	}

	return SIZE_MAX;
}

size_t next_clear_bit(void *base, size_t n)
{
	size_t i;

	for (i = 0; i < n; ++i) {
		if (!is_bit_set(base, i))
			return i;
	}

	return SIZE_MAX;
}