1=pod 2 3=head1 NAME 4 5BN_CTX_start, BN_CTX_get, BN_CTX_end - use temporary BIGNUM variables 6 7=head1 SYNOPSIS 8 9 #include <openssl/bn.h> 10 11 void BN_CTX_start(BN_CTX *ctx); 12 13 BIGNUM *BN_CTX_get(BN_CTX *ctx); 14 15 void BN_CTX_end(BN_CTX *ctx); 16 17=head1 DESCRIPTION 18 19These functions are used to obtain temporary B<BIGNUM> variables from 20a B<BN_CTX> (which can been created by using L<BN_CTX_new(3)>) 21in order to save the overhead of repeatedly creating and 22freeing B<BIGNUM>s in functions that are called from inside a loop. 23 24A function must call BN_CTX_start() first. Then, BN_CTX_get() may be 25called repeatedly to obtain temporary B<BIGNUM>s. All BN_CTX_get() 26calls must be made before calling any other functions that use the 27B<ctx> as an argument. 28 29Finally, BN_CTX_end() must be called before returning from the function. 30If B<ctx> is NULL, nothing is done. 31When BN_CTX_end() is called, the B<BIGNUM> pointers obtained from 32BN_CTX_get() become invalid. 33 34=head1 RETURN VALUES 35 36BN_CTX_start() and BN_CTX_end() return no values. 37 38BN_CTX_get() returns a pointer to the B<BIGNUM>, or B<NULL> on error. 39Once BN_CTX_get() has failed, the subsequent calls will return B<NULL> 40as well, so it is sufficient to check the return value of the last 41BN_CTX_get() call. In case of an error, an error code is set, which 42can be obtained by L<ERR_get_error(3)>. 43 44 45=head1 SEE ALSO 46 47L<BN_CTX_new(3)> 48 49=head1 COPYRIGHT 50 51Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. 52 53Licensed under the Apache License 2.0 (the "License"). You may not use 54this file except in compliance with the License. You can obtain a copy 55in the file LICENSE in the source distribution or at 56L<https://www.openssl.org/source/license.html>. 57 58=cut 59