source: bootcd/isolinux/syslinux-6.03/com32/lib/strcasecmp.c

/*
 * strcasecmp.c
 */

#include <string.h>
#include <ctype.h>

int strcasecmp(const char *s1, const char *s2)
{
    const unsigned char *c1 = (const unsigned char *)s1;
    const unsigned char *c2 = (const unsigned char *)s2;
    unsigned char ch;
    int d = 0;

    while (1) {
        /* toupper() expects an unsigned char (implicitly cast to int)
           as input, and returns an int, which is exactly what we want. */
        d = toupper(ch = *c1++) - toupper(*c2++);
        if (d || !ch)
            break;
    }

    return d;
}