1#include "fe.h"
2#include "crypto_int64.h"
3#include "crypto_uint64.h"
4
5static crypto_uint64 load_3(const unsigned char *in)
6{
7 crypto_uint64 result;
8 result = (crypto_uint64) in[0];
9 result |= ((crypto_uint64) in[1]) << 8;
10 result |= ((crypto_uint64) in[2]) << 16;
11 return result;
12}
13
14static crypto_uint64 load_4(const unsigned char *in)
15{
16 crypto_uint64 result;
17 result = (crypto_uint64) in[0];
18 result |= ((crypto_uint64) in[1]) << 8;
19 result |= ((crypto_uint64) in[2]) << 16;
20 result |= ((crypto_uint64) in[3]) << 24;
21 return result;
22}
23
24/*
25Ignores top bit of h.
26*/
27
28void fe_frombytes(fe h,const unsigned char *s)
29{
30 crypto_int64 h0 = load_4(s);
31 crypto_int64 h1 = load_3(s + 4) << 6;
32 crypto_int64 h2 = load_3(s + 7) << 5;
33 crypto_int64 h3 = load_3(s + 10) << 3;
34 crypto_int64 h4 = load_3(s + 13) << 2;
35 crypto_int64 h5 = load_4(s + 16);
36 crypto_int64 h6 = load_3(s + 20) << 7;
37 crypto_int64 h7 = load_3(s + 23) << 5;
38 crypto_int64 h8 = load_3(s + 26) << 4;
39 crypto_int64 h9 = (load_3(s + 29) & 8388607) << 2;
40 crypto_int64 carry0;
41 crypto_int64 carry1;
42 crypto_int64 carry2;
43 crypto_int64 carry3;
44 crypto_int64 carry4;
45 crypto_int64 carry5;
46 crypto_int64 carry6;
47 crypto_int64 carry7;
48 crypto_int64 carry8;
49 crypto_int64 carry9;
50
51 carry9 = (h9 + (crypto_int64) (1<<24)) >> 25; h0 += carry9 * 19; h9 -= carry9 << 25;
52 carry1 = (h1 + (crypto_int64) (1<<24)) >> 25; h2 += carry1; h1 -= carry1 << 25;
53 carry3 = (h3 + (crypto_int64) (1<<24)) >> 25; h4 += carry3; h3 -= carry3 << 25;
54 carry5 = (h5 + (crypto_int64) (1<<24)) >> 25; h6 += carry5; h5 -= carry5 << 25;
55 carry7 = (h7 + (crypto_int64) (1<<24)) >> 25; h8 += carry7; h7 -= carry7 << 25;
56
57 carry0 = (h0 + (crypto_int64) (1<<25)) >> 26; h1 += carry0; h0 -= carry0 << 26;
58 carry2 = (h2 + (crypto_int64) (1<<25)) >> 26; h3 += carry2; h2 -= carry2 << 26;
59 carry4 = (h4 + (crypto_int64) (1<<25)) >> 26; h5 += carry4; h4 -= carry4 << 26;
60 carry6 = (h6 + (crypto_int64) (1<<25)) >> 26; h7 += carry6; h6 -= carry6 << 26;
61 carry8 = (h8 + (crypto_int64) (1<<25)) >> 26; h9 += carry8; h8 -= carry8 << 26;
62
63 h[0] = h0;
64 h[1] = h1;
65 h[2] = h2;
66 h[3] = h3;
67 h[4] = h4;
68 h[5] = h5;
69 h[6] = h6;
70 h[7] = h7;
71 h[8] = h8;
72 h[9] = h9;
73}
74