術語“非平凡旋轉”是什麼意思？

論文“Gimli: a cross-platform permutation”包含以下資訊：

偶爾（在第 24、20、16 等回合之後）Gimli 會在第一行的條目 0 中添加一個不對稱常數。這個常數有很多位設置（它本質上是黃金比例0x9e3779b9，如在 TEA 中使用的那樣），並且不接近它的任何非平凡旋轉（從不小於 12 位不同）

術語“非平凡旋轉”是什麼意思？如何區分“非平凡”輪換和“平凡”輪換？

平凡的旋轉是旋轉的輸入等於輸出的旋轉（因此旋轉等於恆等函式）。旋轉倍數 $ n $ 對所有人來說都是微不足道的旋轉 $ n $ 位值。請注意，對於某些值，可能存在其他微不足道的旋轉。請參閱下面的（右）旋轉值0x9e3779b9（ $ n = 32 $ ) 以及每個不同位的數量：

0:  0x9e3779b9 (0  bits different)
1:  0xcf1bbcdc (14 bits different)
2:  0x678dde6e (22 bits different)
3:  0x33c6ef37 (18 bits different)
4:  0x99e3779b (12 bits different)
5:  0xccf1bbcd (14 bits different)
6:  0xe678dde6 (18 bits different)
7:  0x733c6ef3 (16 bits different)
8:  0xb99e3779 (14 bits different)
9:  0xdccf1bbc (12 bits different)
10: 0x6e678dde (16 bits different)
11: 0x3733c6ef (16 bits different)
12: 0x9b99e377 (16 bits different)
13: 0xcdccf1bb (14 bits different)
14: 0xe6e678dd (12 bits different)
15: 0xf3733c6e (16 bits different)
16: 0x79b99e37 (20 bits different)
17: 0xbcdccf1b (16 bits different)
18: 0xde6e678d (12 bits different)
19: 0xef3733c6 (14 bits different)
20: 0x779b99e3 (16 bits different)
21: 0xbbcdccf1 (16 bits different)
22: 0xdde6e678 (16 bits different)
23: 0x6ef3733c (12 bits different)
24: 0x3779b99e (14 bits different)
25: 0x1bbcdccf (16 bits different)
26: 0x8dde6e67 (18 bits different)
27: 0xc6ef3733 (14 bits different)
28: 0xe3779b99 (12 bits different)
29: 0xf1bbcdcc (18 bits different)
30: 0x78dde6e6 (22 bits different)
31: 0x3c6ef373 (14 bits different)

引用自：https://crypto.stackexchange.com/questions/64191