word2char
word2char(x3, d);
word2char(x4, d + 4);
word2char(x1, d + 8);
word2char(x2, d + 12);
word2char(x3, d);
word2char(x4, d + 4);
word2char(x1, d + 8);
word2char(x2, d + 12);
word2char((I)[0], (C)); \
word2char((I)[1], (C + 4)); \
word2char((I)[2], (C + 8)); \
word2char((I)[3], (C + 12))