strspn.c

Go to the documentation of this file.

#include <stdint.h>
#include <string.h>

#define BITOP(a, b, op) \
    ((a)[(size_t)(b) / (8 * sizeof *(a))] op(size_t) 1 << ((size_t)(b) % (8 * sizeof *(a))))

size_t strspn(const char* s, const char* c)
{
    const char* a = s;
    size_t byteset[32 / sizeof(size_t)] = {0};

    if(!c[0])
    {
        return 0;
    }

    if(!c[1])
    {
        for(; *s == *c; s++)
        {
            {
                ;
            }
        }
        return (uintptr_t)s - (uintptr_t)a;
    }

    for(; *c && BITOP(byteset, *(const unsigned char*)c, |=); c++)
    {
        {
            ;
        }
    }
    for(; *s && BITOP(byteset, *(const unsigned char*)s, &); s++)
    {
        {
            ;
        }
    }

    return (uintptr_t)s - (uintptr_t)a;
}