tmp[Slen + 0] = (i & 0xff000000) >> 24;
tmp[Slen + 1] = (i & 0x00ff0000) >> 16;
tmp[Slen + 2] = (i & 0x0000ff00) >> 8;
tmp[Slen + 3] = (i & 0x000000ff) >> 0;
rc = gc_hmac_sha1 (P, Plen, tmp, tmplen, U);
tmp[Slen + 0] = (i & 0xff000000) >> 24;
tmp[Slen + 1] = (i & 0x00ff0000) >> 16;
tmp[Slen + 2] = (i & 0x0000ff00) >> 8;
tmp[Slen + 3] = (i & 0x000000ff) >> 0;
rc = gc_hmac_sha1 (P, Plen, tmp, tmplen, U);