p = 2 255 − 19 p=2^{255}-19 p=2255−19
1. 2 255 − 19 2^{255}-19 2255−19以FieldElement51表示对应的公式为：
f
=
f
0
+
f
1
2
51
x
+
f
2
2
102
x
2
+
f
3
2
153
x
3
+
f
4
2
204
x
4
f=f_0+f_12^{51}x+f_22^{102}x^2+f_32^{153}x^3+f_42^{204}x^4
f=f0+f1251x+f22102x2+f32153x3+f42204x4 
对应的sage验证为：
sage: 16*(2^255-19)
926336713898529563388567880069503262826159877325124512315660672063305037119184
sage: (2^255-19)
57896044618658097711785492504343953926634992332820282019728792003956564819949
sage: 36028797018963664+36028797018963952*2^51+36028797018963952*2^102+360287970
....: 18963952*2^153+36028797018963952*2^204
926336713898529563388567880069503262826159877325124512315660672063305037119184
f
=
f
0
+
f
1
2
26
x
+
f
2
2
51
x
2
+
f
3
2
77
x
3
+
f
4
2
102
x
4
+
f
5
2
128
x
5
+
f
6
2
153
x
6
+
f
7
2
179
x
7
+
f
8
2
204
x
8
+
f
9
2
230
x
9
f=f_0+f_12^{26}x+f_22^{51}x^2+f_32^{77}x^3+f_42^{102}x^4+f_52^{128}x^5+f_62^{153}x^6+f_72^{179}x^7+f_82^{204}x^8+f_92^{230}x^9
f=f0+f1226x+f2251x2+f3277x3+f42102x4+f52128x5+f62153x6+f72179x7+f82204x8+f92230x9 
博客dalek-Curve25519 avx2并行计算学习笔记中指出：对于4 field elements vector
(
a
,
b
,
c
,
d
)
(a,b,c,d)
(a,b,c,d)可以
[
u
32
×
8
;
5
]
[u32\times8;5]
[u32×8;5]数组（以little-endian形式）来表示：
(
a
0
,
b
0
,
a
1
,
b
1
,
c
0
,
d
0
,
c
1
,
d
1
)
(a_0,b_0,a_1,b_1,c_0,d_0,c_1,d_1)
(a0,b0,a1,b1,c0,d0,c1,d1)
(
a
2
,
b
2
,
a
3
,
b
3
,
c
2
,
d
2
,
c
3
,
d
3
)
(a_2,b_2,a_3,b_3,c_2,d_2,c_3,d_3)
(a2,b2,a3,b3,c2,d2,c3,d3)
(
a
4
,
b
4
,
a
5
,
b
5
,
c
4
,
d
4
,
c
5
,
d
5
)
(a_4,b_4,a_5,b_5,c_4,d_4,c_5,d_5)
(a4,b4,a5,b5,c4,d4,c5,d5)
(
a
6
,
b
6
,
a
7
,
b
7
,
c
6
,
d
6
,
c
7
,
d
7
)
(a_6,b_6,a_7,b_7,c_6,d_6,c_7,d_7)
(a6,b6,a7,b7,c6,d6,c7,d7)
(
a
8
,
b
8
,
a
9
,
b
9
,
c
8
,
d
8
,
c
9
,
d
9
)
(a_8,b_8,a_9,b_9,c_8,d_8,c_9,d_9)
(a8,b8,a9,b9,c8,d8,c9,d9)
( 2 p , 2 p , 2 p , 2 p ) (2p,2p,2p,2p) (2p,2p,2p,2p)对应以 [ u 32 × 8 ; 5 ] [u32\times8;5] [u32×8;5]数组（以little-endian形式）来表示： [P_TIMES_2_LO,P_TIMES_2_HI,P_TIMES_2_HI,P_TIMES_2_HI,P_TIMES_2_HI]
相应的sage脚本验证为：
sage: 67108845+(33554431 *2^26)+(67108863 *2^51)+(33554431 *2^77)+ (67108863 *2
....: ^102)+(33554431 *2^128) +(67108863 *2^153)+(33554431 *2^179)+(67108863 *2^
....: 204)+(33554431 *2^230)
57896044618658097711785492504343953926634992332820282019728792003956564819949
sage: (2^255-19)
57896044618658097711785492504343953926634992332820282019728792003956564819949
在src/backend/vector/avx2/edwards.rs中：
let basepoint_odd_lookup_table = NafLookupTable8::::from(&constants::ED25519_BASEPOINT_POINT);
println!("BASEPOINT_ODD_LOOKUP_TABLE is: {:?}", basepoint_odd_lookup_table);
