wolfssl/wolfcrypt/src/fp_mul_comba_4.i

/* fp_mul_comba_4.i
 *
 * Copyright (C) 2006-2022 wolfSSL Inc.
 *
 * This file is part of wolfSSL.
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
 */



#ifdef TFM_MUL4
int fp_mul_comba4(fp_int *A, fp_int *B, fp_int *C)
{
   fp_digit c0, c1, c2;
#ifndef WOLFSSL_SMALL_STACK
   fp_digit at[8];
#else
   fp_digit *at;
#endif

#ifdef WOLFSSL_SMALL_STACK
   at = (fp_digit*)XMALLOC(sizeof(fp_digit) * 8, NULL, DYNAMIC_TYPE_TMP_BUFFER);
   if (at == NULL)
       return FP_MEM;
#endif

   XMEMCPY(at, A->dp, 4 * sizeof(fp_digit));
   XMEMCPY(at+4, B->dp, 4 * sizeof(fp_digit));
   COMBA_START;

   COMBA_CLEAR;
   /* 0 */
   MULADD(at[0], at[4]); 
   COMBA_STORE(C->dp[0]);
   /* 1 */
   COMBA_FORWARD;
   MULADD(at[0], at[5]);    MULADD(at[1], at[4]); 
   COMBA_STORE(C->dp[1]);
   /* 2 */
   COMBA_FORWARD;
   MULADD(at[0], at[6]);    MULADD(at[1], at[5]);    MULADD(at[2], at[4]); 
   COMBA_STORE(C->dp[2]);
   /* 3 */
   COMBA_FORWARD;
   MULADD(at[0], at[7]);    MULADD(at[1], at[6]);    MULADD(at[2], at[5]);    MULADD(at[3], at[4]); 
   COMBA_STORE(C->dp[3]);
   /* 4 */
   COMBA_FORWARD;
   MULADD(at[1], at[7]);    MULADD(at[2], at[6]);    MULADD(at[3], at[5]); 
   COMBA_STORE(C->dp[4]);
   /* 5 */
   COMBA_FORWARD;
   MULADD(at[2], at[7]);    MULADD(at[3], at[6]); 
   COMBA_STORE(C->dp[5]);
   /* 6 */
   COMBA_FORWARD;
   MULADD(at[3], at[7]); 
   COMBA_STORE(C->dp[6]);
   COMBA_STORE2(C->dp[7]);
   C->used = 8;
   C->sign = A->sign ^ B->sign;
   fp_clamp(C);
   COMBA_FINI;

#ifdef WOLFSSL_SMALL_STACK
   XFREE(at, NULL, DYNAMIC_TYPE_TMP_BUFFER);
#endif
   return FP_OKAY;
}
#endif