Document mpi_mul_hlp
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/bignum.c b/library/bignum.c
index 5cd1c3e..a847e50 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1525,8 +1525,21 @@
return( mbedtls_mpi_sub_mpi( X, A, &_B ) );
}
-/*
- * Helper for mbedtls_mpi multiplication
+/** Helper for mbedtls_mpi multiplication.
+ *
+ * Add \p b * \p s to \p d.
+ *
+ * \param i The number of limbs of \p s.
+ * \param[in] s A bignum to multiply, of size \p i.
+ * It may overlap with \p d, but only if
+ * \p d <= \p s.
+ * Its leading limb must not be \c 0.
+ * \param[in,out] d The bignum to add to.
+ * It must be sufficiently large to store the
+ * result of the multiplication. This means
+ * \p i + 1 limbs if \p d[\p i - 1] started as 0 and \p b
+ * is not known a priori.
+ * \param b A scalar to multiply.
*/
static
#if defined(__APPLE__) && defined(__arm__)
@@ -1536,7 +1549,10 @@
*/
__attribute__ ((noinline))
#endif
-void mpi_mul_hlp( size_t i, mbedtls_mpi_uint *s, mbedtls_mpi_uint *d, mbedtls_mpi_uint b )
+void mpi_mul_hlp( size_t i,
+ const mbedtls_mpi_uint *s,
+ mbedtls_mpi_uint *d,
+ mbedtls_mpi_uint b )
{
mbedtls_mpi_uint c = 0, t = 0;