text: /*
   * Copyright 2014-2018 The OpenSSL Project Authors. All Rights Reserved.
   *
   * Licensed under the Apache License 2.0 (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
   */
  
  #ifndef HEADER_BN_INT_H
  # define HEADER_BN_INT_H
  
  # include <openssl/bn.h>
  # include <limits.h>
  
  BIGNUM *bn_wexpand(BIGNUM *a, int words);
  BIGNUM *bn_expand2(BIGNUM *a, int words);
  
  void bn_correct_top(BIGNUM *a);
  
  /*
   * Determine the modified width-(w+1) Non-Adjacent Form (wNAF) of 'scalar'.
   * This is an array r[] of values that are either zero or odd with an
   * absolute value less than 2^w satisfying scalar = \sum_j r[j]*2^j where at
   * most one of any w+1 consecutive digits is non-zero with the exception that
   * the most significant digit may be only w-1 zeros away from that next
   * non-zero digit.
   */
  signed char *bn_compute_wNAF(const BIGNUM *scalar, int w, size_t *ret_len);
  
  int bn_get_top(const BIGNUM *a);
  
  int bn_get_dmax(const BIGNUM *a);
  
  /* Set all words to zero */
  void bn_set_all_zero(BIGNUM *a);
  
  /*
   * Copy the internal BIGNUM words into out which holds size elements (and size
   * must be bigger than top)
   */
  int bn_copy_words(BN_ULONG *out, const BIGNUM *in, int size);
  
  BN_ULONG *bn_get_words(const BIGNUM *a);
  
  /*
   * Set the internal data words in a to point to words which contains size
   * elements. The BN_FLG_STATIC_DATA flag is set
   */
  void bn_set_static_words(BIGNUM *a, const BN_ULONG *words, int size);
  
  /*
   * Copy words into the BIGNUM |a|, reallocating space as necessary.
   * The negative flag of |a| is not modified.
   * Returns 1 on success and 0 on failure.
   */
  /*
   * |num_words| is int because bn_expand2 takes an int. This is an internal
   * function so we simply trust callers not to pass negative values.
   */
  int bn_set_words(BIGNUM *a, const BN_ULONG *words, int num_words);
  
  /*
   * Some BIGNUM functions assume most significant limb to be non-zero, which
   * is customarily arranged by bn_correct_top. Output from below functions
   * is not processed with bn_correct_top, and for this reason it may not be
   * returned out of public API. It may only be passed internally into other
   * functions known to support non-minimal or zero-padded BIGNUMs. Even
   * though the goal is to facilitate constant-time-ness, not each subroutine
   * is constant-time by itself. They all have pre-conditions, consult source
   * code...
   */
  int bn_mul_mont_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
                            BN_MONT_CTX *mont, BN_CTX *ctx);
  int bn_to_mont_fixed_top(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont,
                           BN_CTX *ctx);
  int bn_from_mont_fixed_top(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont,
                             BN_CTX *ctx);
  int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
                           const BIGNUM *m);
  int bn_mod_sub_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
                           const BIGNUM *m);
  int bn_mul_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx);
  int bn_sqr_fixed_top(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx);
  int bn_lshift_fixed_top(BIGNUM *r, const BIGNUM *a, int n);
  int bn_rshift_fixed_top(BIGNUM *r, const BIGNUM *a, int n);
  int bn_div_fixed_top(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m,
                       const BIGNUM *d, BN_CTX *ctx);
  
  #endif
  