bitset.c

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#include "util.h"
#include <lely/libc/strings.h>
#include <lely/util/bitset.h>
#include <lely/util/errnum.h>
 
#include <assert.h>
#include <stdlib.h>
 
#undef INT_BIT
#define INT_BIT (sizeof(int) * CHAR_BIT)
 
int
bitset_init(struct bitset *set, int size)
{
        assert(set);
 
        size = MAX(0, (size + INT_BIT - 1) / INT_BIT);
 
        unsigned int *bits = malloc(size * sizeof(unsigned int));
        if (!bits && size) {
                set_errc(errno2c(errno));
                return -1;
        }
 
        set->size = size;
        set->bits = bits;
 
        return 0;
}
 
void
bitset_fini(struct bitset *set)
{
        assert(set);
 
        set->size = 0;
        free(set->bits);
        set->bits = NULL;
}
 
int
bitset_size(const struct bitset *set)
{
        return set->size * INT_BIT;
}
 
int
bitset_resize(struct bitset *set, int size)
{
        assert(set);
        assert(set->size >= 0);
 
        size = MAX(0, (size + INT_BIT - 1) / INT_BIT);
 
        unsigned int *bits = realloc(set->bits, size * sizeof(unsigned int));
        if (!bits && size) {
                set_errc(errno2c(errno));
                return 0;
        }
 
        // If the size increased, clear the new bits.
        for (int i = set->size; i < size; i++)
                bits[i] = 0;
 
        set->size = size;
        set->bits = bits;
 
        return bitset_size(set);
}
 
int
bitset_get_size(const struct bitset *set)
{
        return set->size * INT_BIT;
}
 
int
bitset_test(const struct bitset *set, int n)
{
        if (n < 0 || n >= bitset_size(set))
                return 0;
        return (set->bits[n / INT_BIT] >> (n & (INT_BIT - 1))) & 1u;
}
 
void
bitset_set(struct bitset *set, int n)
{
        if (n < 0 || n >= bitset_size(set))
                return;
        set->bits[n / INT_BIT] |= 1u << (n & (INT_BIT - 1));
}
 
void
bitset_set_all(struct bitset *set)
{
        for (int i = 0; i < set->size; i++)
                set->bits[i] = ~0u;
}
 
void
bitset_clr(struct bitset *set, int n)
{
        if (n < 0 || n >= bitset_size(set))
                return;
        set->bits[n / INT_BIT] &= ~(1u << (n & (INT_BIT - 1)));
}
 
void
bitset_clr_all(struct bitset *set)
{
        for (int i = 0; i < set->size; i++)
                set->bits[i] = 0;
}
 
void
bitset_compl(struct bitset *set)
{
        for (int i = 0; i < set->size; i++)
                set->bits[i] = ~set->bits[i];
}
 
int
bitset_ffs(const struct bitset *set)
{
        const unsigned int *bits = set->bits;
        int offset = 0;
        for (int i = 0; i < set->size; i++) {
                unsigned int x = *bits++;
                if (x)
                        return offset + ffs(x);
                offset += INT_BIT;
        }
        return 0;
}
 
int
bitset_ffz(const struct bitset *set)
{
        const unsigned int *bits = set->bits;
        int offset = 0;
        for (int i = 0; i < set->size; i++) {
                unsigned int x = *bits++;
                if (~x)
                        return offset + ffs(~x);
                offset += INT_BIT;
        }
        return 0;
}
 
int
bitset_fns(const struct bitset *set, int n)
{
        if (n < 0)
                n = 0;
        if (n >= bitset_size(set))
                return 0;
 
        int size = set->size - n / INT_BIT;
        const unsigned int *bits = set->bits + n / INT_BIT;
        int offset = n & ~(INT_BIT - 1);
        n -= offset;
        while (size) {
                unsigned int x = *bits++;
                if (n) {
                        // Clear the bits smaller than n.
                        x &= ~0u << n;
                        n = 0;
                }
                if (x)
                        return offset + ffs(x);
                size--;
                offset += INT_BIT;
        }
        return 0;
}
 
int
bitset_fnz(const struct bitset *set, int n)
{
        if (n < 0)
                n = 0;
        if (n >= bitset_size(set))
                return 0;
 
        int size = set->size - n / INT_BIT;
        const unsigned int *bits = set->bits + n / INT_BIT;
        int offset = n & ~(INT_BIT - 1);
        n -= offset;
        while (size) {
                unsigned int x = *bits++;
                if (n) {
                        // Set the bits smaller than n.
                        x |= ~0u >> (INT_BIT - n);
                        n = 0;
                }
                if (~x)
                        return offset + ffs(~x);
                size--;
                offset += INT_BIT;
        }
        return 0;
}