bignum_core: Extracted mbedtls_mpi_shift_l from prototype
Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/library/bignum_core.c b/library/bignum_core.c
index c6d92fb..26aff15 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -353,6 +353,54 @@
}
}
+int mbedtls_mpi_shift_l( mbedtls_mpi *X, size_t count )
+{
+ int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+ size_t i, v0, t1;
+ mbedtls_mpi_uint r0 = 0, r1;
+ MPI_VALIDATE_RET( X != NULL );
+
+ v0 = count / (biL );
+ t1 = count & (biL - 1);
+
+ i = mbedtls_mpi_bitlen( X ) + count;
+
+ if( X->n * biL < i )
+ MBEDTLS_MPI_CHK( mbedtls_mpi_grow( X, BITS_TO_LIMBS( i ) ) );
+
+ ret = 0;
+
+ /*
+ * shift by count / limb_size
+ */
+ if( v0 > 0 )
+ {
+ for( i = X->n; i > v0; i-- )
+ X->p[i - 1] = X->p[i - v0 - 1];
+
+ for( ; i > 0; i-- )
+ X->p[i - 1] = 0;
+ }
+
+ /*
+ * shift by count % limb_size
+ */
+ if( t1 > 0 )
+ {
+ for( i = v0; i < X->n; i++ )
+ {
+ r1 = X->p[i] >> (biL - t1);
+ X->p[i] <<= t1;
+ X->p[i] |= r0;
+ r0 = r1;
+ }
+ }
+
+cleanup:
+
+ return( ret );
+}
+
mbedtls_mpi_uint mbedtls_mpi_core_add(mbedtls_mpi_uint *X,
const mbedtls_mpi_uint *A,
const mbedtls_mpi_uint *B,
diff --git a/library/bignum_core.h b/library/bignum_core.h
index b3d05a3..25e7e1a 100644
--- a/library/bignum_core.h
+++ b/library/bignum_core.h
@@ -294,6 +294,18 @@
size_t count);
/**
+ * \brief Perform a left-shift on an MPI: X <<= count
+ *
+ * \param X The MPI to shift. This must point to an initialized MPI.
+ * \param count The number of bits to shift by.
+ *
+ * \return \c 0 if successful.
+ * \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if a memory allocation failed.
+ * \return Another negative error code on different kinds of failure.
+ */
+int mbedtls_mpi_shift_l( mbedtls_mpi *X, size_t count );
+
+/**
* \brief Add two fixed-size large unsigned integers, returning the carry.
*
* Calculates `A + B` where `A` and `B` have the same size.