text: /*
   * Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
   * Copyright 2014 Cryptography Research, Inc.
   *
   * Licensed under the OpenSSL license (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   *
   * Originally written by Mike Hamburg
   */
  
  #include "../field.h"
  
  void gf_mul(gf_s * RESTRICT cs, const gf as, const gf bs)
  {
      const uint32_t *a = as->limb, *b = bs->limb;
      uint32_t *c = cs->limb;
      uint64_t accum0 = 0, accum1 = 0, accum2 = 0;
      uint32_t mask = (1 << 28) - 1;
      uint32_t aa[8], bb[8];
      int i, j;
  
      for (i = 0; i < 8; i++) {
          aa[i] = a[i] + a[i + 8];
          bb[i] = b[i] + b[i + 8];
      }
  
      for (j = 0; j < 8; j++) {
          accum2 = 0;
          for (i = 0; i < j + 1; i++) {
              accum2 += widemul(a[j - i], b[i]);
              accum1 += widemul(aa[j - i], bb[i]);
              accum0 += widemul(a[8 + j - i], b[8 + i]);
          }
          accum1 -= accum2;
          accum0 += accum2;
          accum2 = 0;
          for (i = j + 1; i < 8; i++) {
              accum0 -= widemul(a[8 + j - i], b[i]);
              accum2 += widemul(aa[8 + j - i], bb[i]);
              accum1 += widemul(a[16 + j - i], b[8 + i]);
          }
          accum1 += accum2;
          accum0 += accum2;
          c[j] = ((uint32_t)(accum0)) & mask;
          c[j + 8] = ((uint32_t)(accum1)) & mask;
          accum0 >>= 28;
          accum1 >>= 28;
      }
  
      accum0 += accum1;
      accum0 += c[8];
      accum1 += c[0];
      c[8] = ((uint32_t)(accum0)) & mask;
      c[0] = ((uint32_t)(accum1)) & mask;
  
      accum0 >>= 28;
      accum1 >>= 28;
      c[9] += ((uint32_t)(accum0));
      c[1] += ((uint32_t)(accum1));
  }
  
  void gf_mulw_unsigned(gf_s * RESTRICT cs, const gf as, uint32_t b)
  {
      const uint32_t *a = as->limb;
      uint32_t *c = cs->limb;
      uint64_t accum0 = 0, accum8 = 0;
      uint32_t mask = (1 << 28) - 1;
      int i;
  
      assert(b <= mask);
  
      for (i = 0; i < 8; i++) {
          accum0 += widemul(b, a[i]);
          accum8 += widemul(b, a[i + 8]);
          c[i] = accum0 & mask;
          accum0 >>= 28;
          c[i + 8] = accum8 & mask;
          accum8 >>= 28;
      }
  
      accum0 += accum8 + c[8];
      c[8] = ((uint32_t)accum0) & mask;
      c[9] += (uint32_t)(accum0 >> 28);
  
      accum8 += c[0];
      c[0] = ((uint32_t)accum8) & mask;
      c[1] += (uint32_t)(accum8 >> 28);
  }
  
  void gf_sqr(gf_s * RESTRICT cs, const gf as)
  {
      gf_mul(cs, as, as);         /* Performs better with a dedicated square */
  }
  