- Added mpi_get_bit() and mpi_set_bit() individual bit setter/getter functions.
diff --git a/library/bignum.c b/library/bignum.c
index 2e3595c..5635bd2 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -171,6 +171,44 @@
}
/*
+ * Get a specific bit
+ */
+int mpi_get_bit( mpi *X, size_t pos )
+{
+ if( X->n * biL <= pos )
+ return( 0 );
+
+ return ( X->p[pos / biL] >> ( pos % biL ) ) & 0x01;
+}
+
+/*
+ * Set a bit to a specific value of 0 or 1
+ */
+int mpi_set_bit( mpi *X, size_t pos, unsigned char val )
+{
+ int ret = 0;
+ size_t off = pos / biL;
+ size_t idx = pos % biL;
+
+ if( val != 0 && val != 1 )
+ return POLARSSL_ERR_MPI_BAD_INPUT_DATA;
+
+ if( X->n * biL <= pos )
+ {
+ if( val == 0 )
+ return ( 0 );
+
+ MPI_CHK( mpi_grow( X, off + 1 ) );
+ }
+
+ X->p[off] = ( X->p[off] & ~( 0x01 << idx ) ) | ( val << idx );
+
+cleanup:
+
+ return( ret );
+}
+
+/*
* Return the number of least significant bits
*/
size_t mpi_lsb( const mpi *X )
