lib/mpi: Extend the MPI library

Expand the mpi library based on libgcrypt, and the ECC algorithm of
mpi based on libgcrypt requires these functions.
Some other algorithms will be developed based on mpi ecc, such as SM2.

Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Tested-by: Xufeng Zhang <yunbo.xufeng@linux.alibaba.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 36 insertions, 10 deletions

diff --git a/lib/mpi/mpi-cmp.c b/lib/mpi/mpi-cmp.c
index d25e9e96c310..c4cfa3ff0581 100644
--- a/lib/mpi/mpi-cmp.c
+++ b/lib/mpi/mpi-cmp.c
@@ -41,28 +41,54 @@ int mpi_cmp_ui(MPI u, unsigned long v)
 }
 EXPORT_SYMBOL_GPL(mpi_cmp_ui);
 
-int mpi_cmp(MPI u, MPI v)
+static int do_mpi_cmp(MPI u, MPI v, int absmode)
 {
-	mpi_size_t usize, vsize;
+	mpi_size_t usize;
+	mpi_size_t vsize;
+	int usign;
+	int vsign;
 	int cmp;
 
 	mpi_normalize(u);
 	mpi_normalize(v);
+
 	usize = u->nlimbs;
 	vsize = v->nlimbs;
-	if (!u->sign && v->sign)
+	usign = absmode ? 0 : u->sign;
+	vsign = absmode ? 0 : v->sign;
+
+	/* Compare sign bits.  */
+
+	if (!usign && vsign)
 		return 1;
-	if (u->sign && !v->sign)
+	if (usign && !vsign)
 		return -1;
-	if (usize != vsize && !u->sign && !v->sign)
+
+	/* U and V are either both positive or both negative.  */
+
+	if (usize != vsize && !usign && !vsign)
 		return usize - vsize;
-	if (usize != vsize && u->sign && v->sign)
-		return vsize - usize;
+	if (usize != vsize && usign && vsign)
+		return vsize + usize;
 	if (!usize)
 		return 0;
 	cmp = mpihelp_cmp(u->d, v->d, usize);
-	if (u->sign)
-		return -cmp;
-	return cmp;
+	if (!cmp)
+		return 0;
+	if ((cmp < 0?1:0) == (usign?1:0))
+		return 1;
+
+	return -1;
+}
+
+int mpi_cmp(MPI u, MPI v)
+{
+	return do_mpi_cmp(u, v, 0);
 }
 EXPORT_SYMBOL_GPL(mpi_cmp);
+
+int mpi_cmpabs(MPI u, MPI v)
+{
+	return do_mpi_cmp(u, v, 1);
+}
+EXPORT_SYMBOL_GPL(mpi_cmpabs);