lokinet/crypto/curve25519/sandy2x/fe_frombytes_sandy2x.c
2019-09-03 08:02:35 -05:00

99 lines
1.8 KiB
C

/*
This file is basically ref10/fe_frombytes.h.
*/
#include "fe.h"
#ifdef HAVE_AVX_ASM
static uint64_t
load_3(const unsigned char *in)
{
uint64_t result;
result = (uint64_t)in[0];
result |= ((uint64_t)in[1]) << 8;
result |= ((uint64_t)in[2]) << 16;
return result;
}
static uint64_t
load_4(const unsigned char *in)
{
uint64_t result;
result = (uint64_t)in[0];
result |= ((uint64_t)in[1]) << 8;
result |= ((uint64_t)in[2]) << 16;
result |= ((uint64_t)in[3]) << 24;
return result;
}
void
fe_frombytes(fe h, const unsigned char *s)
{
uint64_t h0 = load_4(s);
uint64_t h1 = load_3(s + 4) << 6;
uint64_t h2 = load_3(s + 7) << 5;
uint64_t h3 = load_3(s + 10) << 3;
uint64_t h4 = load_3(s + 13) << 2;
uint64_t h5 = load_4(s + 16);
uint64_t h6 = load_3(s + 20) << 7;
uint64_t h7 = load_3(s + 23) << 5;
uint64_t h8 = load_3(s + 26) << 4;
uint64_t h9 = (load_3(s + 29) & 8388607) << 2;
uint64_t carry0;
uint64_t carry1;
uint64_t carry2;
uint64_t carry3;
uint64_t carry4;
uint64_t carry5;
uint64_t carry6;
uint64_t carry7;
uint64_t carry8;
uint64_t carry9;
carry9 = h9 >> 25;
h0 += carry9 * 19;
h9 &= 0x1FFFFFF;
carry1 = h1 >> 25;
h2 += carry1;
h1 &= 0x1FFFFFF;
carry3 = h3 >> 25;
h4 += carry3;
h3 &= 0x1FFFFFF;
carry5 = h5 >> 25;
h6 += carry5;
h5 &= 0x1FFFFFF;
carry7 = h7 >> 25;
h8 += carry7;
h7 &= 0x1FFFFFF;
carry0 = h0 >> 26;
h1 += carry0;
h0 &= 0x3FFFFFF;
carry2 = h2 >> 26;
h3 += carry2;
h2 &= 0x3FFFFFF;
carry4 = h4 >> 26;
h5 += carry4;
h4 &= 0x3FFFFFF;
carry6 = h6 >> 26;
h7 += carry6;
h6 &= 0x3FFFFFF;
carry8 = h8 >> 26;
h9 += carry8;
h8 &= 0x3FFFFFF;
h[0] = h0;
h[1] = h1;
h[2] = h2;
h[3] = h3;
h[4] = h4;
h[5] = h5;
h[6] = h6;
h[7] = h7;
h[8] = h8;
h[9] = h9;
}
#endif