unsigned search_cocos_fixed (char *s, unsigned len)
{
    if (len<5)
        return len;  // not found
    unsigned seen=0;
    for (unsigned i=0; i<len; i++)
    {
        char ch=s[i]; // this is single read operation
        if (seen==0 && ch=='c')
            seen=1;
        else if (seen==1 && ch=='o')
            seen=2;
        else if (seen==1 && ch!='o')
        {
            // we can be here if the input is 'ccocos'
            if (ch=='c')
                seen=1;
            else
                seen=0;
        }
        else if (seen==2 && ch=='c')
            seen=3;
        else if (seen==3 && ch=='o')
            seen=4;
        else if (seen==3 && ch!='o')
        {
            // if input='coccocos'
            if (ch=='c')
                seen=1;
            else
                seen=0; // reset
        }
        else if (seen==4 && ch=='s')
            return i-4;  // found
        else if (seen==4 && ch!='s')
        {
            // the input string is 'cocoX' where X is not 's'
            // (current state of ch='X')
            // but 'X' could be 'c' if the input string is 'cococos'
            if (ch=='c')
            {
                // if the string is 'cococos',
                // we can say that we have already seen the 'coc' part of it:
                seen=3;
            }
            else
            {
                // 'X' is not 'c', so reset
                seen=0;
            };
        }
        else
            seen=0;      // reset
    }
    return len;  // not found
};