tree 4b557a6168e0764fbd68211e5e5e351f93bfd707
parent e9c0b5d76918acd90e51e44d9d1b67dbfdb77419
author Jerome Forissier <jerome@forissier.org> 1579251937 +0100
committer Jérôme Forissier <jerome@forissier.org> 1579270597 +0100

core: ltc: acipher_helpers.h: add macro mp_to_unsigned_bin2()

Writing a bignum to a fixed size integer buffer in big endian order is
slightly cumbersome, because one has to take into account the actual
size of the bignum in order to have the zero padding on the left.
Let's say I am working with 256-bit numbers:

 unsigned char buf[32] = { };
 void *n = compute_some_bignum(...);

 mp_to_unsigned_bin(n, buf + sizeof(buf) - mp_unsigned_bin_size(n));

This commit introduces mp_to_unsigned_bin2() which can be used like so:

 unsigned char buf[32] = { };
 void *n = compute_some_bignum(...);

 mp_to_unsigned_bin2(n, buf, sizeof(buf));

Signed-off-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>