release/src/router/libsodium/src/libsodium/crypto_scalarmult/curve25519/sandy2x/fe_frombytes_sandy2x.c

   1 /*
   2    This file is basically ref10/fe_frombytes.h.
   3 */
   4
   5 #include "fe.h"
   6
   7 #ifdef HAVE_AVX_ASM
   8
   9 static uint64_t load_3(const unsigned char *in)
  10 {
  11   uint64_t result;
  12   result = (uint64_t) in[0];
  13   result |= ((uint64_t) in[1]) << 8;
  14   result |= ((uint64_t) in[2]) << 16;
  15   return result;
  16 }
  17
  18 static uint64_t load_4(const unsigned char *in)
  19 {
  20   uint64_t result;
  21   result = (uint64_t) in[0];
  22   result |= ((uint64_t) in[1]) << 8;
  23   result |= ((uint64_t) in[2]) << 16;
  24   result |= ((uint64_t) in[3]) << 24;
  25   return result;
  26 }
  27
  28 void fe_frombytes(fe h,const unsigned char *s)
  29 {
  30   uint64_t h0 = load_4(s);
  31   uint64_t h1 = load_3(s + 4) << 6;
  32   uint64_t h2 = load_3(s + 7) << 5;
  33   uint64_t h3 = load_3(s + 10) << 3;
  34   uint64_t h4 = load_3(s + 13) << 2;
  35   uint64_t h5 = load_4(s + 16);
  36   uint64_t h6 = load_3(s + 20) << 7;
  37   uint64_t h7 = load_3(s + 23) << 5;
  38   uint64_t h8 = load_3(s + 26) << 4;
  39   uint64_t h9 = (load_3(s + 29) & 8388607) << 2;
  40   uint64_t carry0;
  41   uint64_t carry1;
  42   uint64_t carry2;
  43   uint64_t carry3;
  44   uint64_t carry4;
  45   uint64_t carry5;
  46   uint64_t carry6;
  47   uint64_t carry7;
  48   uint64_t carry8;
  49   uint64_t carry9;
  50
  51   carry9 = h9 >> 25; h0 += carry9 * 19; h9 &= 0x1FFFFFF;
  52   carry1 = h1 >> 25; h2 += carry1; h1 &= 0x1FFFFFF;
  53   carry3 = h3 >> 25; h4 += carry3; h3 &= 0x1FFFFFF;
  54   carry5 = h5 >> 25; h6 += carry5; h5 &= 0x1FFFFFF;
  55   carry7 = h7 >> 25; h8 += carry7; h7 &= 0x1FFFFFF;
  56
  57   carry0 = h0 >> 26; h1 += carry0; h0 &= 0x3FFFFFF;
  58   carry2 = h2 >> 26; h3 += carry2; h2 &= 0x3FFFFFF;
  59   carry4 = h4 >> 26; h5 += carry4; h4 &= 0x3FFFFFF;
  60   carry6 = h6 >> 26; h7 += carry6; h6 &= 0x3FFFFFF;
  61   carry8 = h8 >> 26; h9 += carry8; h8 &= 0x3FFFFFF;
  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
  75 #endif