1 #include "fe.h"
2 #include "crypto_int64.h"
3 #include "crypto_uint64.h"
4
load_3(const unsigned char * in)5 static 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
load_4(const unsigned char * in)14 static 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 /*
25 Ignores top bit of h.
26 */
27
fe_frombytes(fe h,const unsigned char * s)28 void 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 -= SHL64(carry9,25);
52 carry1 = (h1 + (crypto_int64) (1<<24)) >> 25; h2 += carry1; h1 -= SHL64(carry1,25);
53 carry3 = (h3 + (crypto_int64) (1<<24)) >> 25; h4 += carry3; h3 -= SHL64(carry3,25);
54 carry5 = (h5 + (crypto_int64) (1<<24)) >> 25; h6 += carry5; h5 -= SHL64(carry5,25);
55 carry7 = (h7 + (crypto_int64) (1<<24)) >> 25; h8 += carry7; h7 -= SHL64(carry7,25);
56
57 carry0 = (h0 + (crypto_int64) (1<<25)) >> 26; h1 += carry0; h0 -= SHL64(carry0,26);
58 carry2 = (h2 + (crypto_int64) (1<<25)) >> 26; h3 += carry2; h2 -= SHL64(carry2,26);
59 carry4 = (h4 + (crypto_int64) (1<<25)) >> 26; h5 += carry4; h4 -= SHL64(carry4,26);
60 carry6 = (h6 + (crypto_int64) (1<<25)) >> 26; h7 += carry6; h6 -= SHL64(carry6,26);
61 carry8 = (h8 + (crypto_int64) (1<<25)) >> 26; h9 += carry8; h8 -= SHL64(carry8,26);
62
63 h[0] = (crypto_int32) h0;
64 h[1] = (crypto_int32) h1;
65 h[2] = (crypto_int32) h2;
66 h[3] = (crypto_int32) h3;
67 h[4] = (crypto_int32) h4;
68 h[5] = (crypto_int32) h5;
69 h[6] = (crypto_int32) h6;
70 h[7] = (crypto_int32) h7;
71 h[8] = (crypto_int32) h8;
72 h[9] = (crypto_int32) h9;
73 }
74