hexdump

void hexdump(char *buf, size_t length)
{
    int star = 0;
    for (size_t i = 0; i < length; i += 16, buf += 16) {
        if (i && !memcmp(buf, buf - 16, 16)) {
            if (!star)
                puts("*");
            star = 1;
            continue;
        }
        star = 0;
        printf("%08zx  ", i);
        for (size_t j = 0; j < 16; j++) {
            printf("%02x ", buf[j] & 0xff);
            if ((j & 7) == 7)
                putchar(' ');
        }
        putchar('|');
        for (size_t j = 0; j < 16; j++) {
            int c = buf[j];
            putchar(c >= ' ' && c <= '~' ? c : '.');
        }
        puts("|");
    }
}