Add documentation
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/ecp_internal.h b/library/ecp_internal.h
index 07bf386..b028225 100644
--- a/library/ecp_internal.h
+++ b/library/ecp_internal.h
@@ -28,6 +28,18 @@
#include "mbedtls/bignum.h"
#include "bignum_mod.h"
+/** Convert an MPI to its canonical representative.
+ *
+ * \note Currently handles the case when `N->int_rep` is
+ * MBEDTLS_MPI_MOD_REP_MONTGOMERY.
+ *
+ * \param[in,out] X The address of the MPI to be converted. Must have the
+ * same number of limbs as \p N.
+ * \param[in] N The address of the modulus.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p N is invalid.
+ */
int mbedtls_ecp_quasi_reduction(mbedtls_mpi_uint *X,
const mbedtls_mpi_mod_modulus *N);