g4_inv
g4_inv (wh2,wl2, wh2,wl2); wl3 ^= wl2 ^ 32; wh3 ^= wh2;
g4_inv (wh3,wl3, wh3,wl3); wl4 ^= wl3 ^ 27; wh4 ^= wh3;
wh3 ^= wh4; wl3 ^= wl4 ^ 22; g4_inv (wh4,wl4, wh4,wl4);
wh4 ^= wh1; wl4 ^= wl1 ^ 17; g4_inv (wh1,wl1, wh1,wl1);
g4_inv (wh2,wl2, wh2,wl2); wl3 ^= wl2 ^ 12; wh3 ^= wh2;
wh2 ^= wh3; wl2 ^= wl3 ^ 7; g4_inv (wh3,wl3, wh3,wl3);
wh3 ^= wh4; wl3 ^= wl4 ^ 2; g4_inv (wh4,wl4, wh4,wl4);