Add macros to return pre-defined MPIs.

* src/gcrypt.h.in (GCRYMPI_CONST_ONE, GCRYMPI_CONST_TWO)
(GCRYMPI_CONST_THREE, GCRYMPI_CONST_FOUR, GCRYMPI_CONST_EIGHT): New.
(_gcry_mpi_get_const): New private function.
* src/visibility.c (_gcry_mpi_get_const): New.
* src/visibility.h: Mark it visible.

Signed-off-by: Werner Koch <wk@gnupg.org>

5 files changed, 32 insertions, 0 deletions

diff --git a/src/gcrypt.h.in b/src/gcrypt.h.in
index 85213ea4..f472b02b 100644
--- a/src/gcrypt.h.in
+++ b/src/gcrypt.h.in
@@ -467,6 +467,13 @@ enum gcry_mpi_flag
   };
 
 
+/* Macros to return pre-defined MPI constants.  */
+#define GCRYMPI_CONST_ONE   (_gcry_mpi_get_const (1))
+#define GCRYMPI_CONST_TWO   (_gcry_mpi_get_const (2))
+#define GCRYMPI_CONST_THREE (_gcry_mpi_get_const (3))
+#define GCRYMPI_CONST_FOUR  (_gcry_mpi_get_const (4))
+#define GCRYMPI_CONST_EIGHT (_gcry_mpi_get_const (8))
+
 /* Allocate a new big integer object, initialize it with 0 and
    initially allocate memory for a number of at least NBITS. */
 gcry_mpi_t gcry_mpi_new (unsigned int nbits);
@@ -692,6 +699,9 @@ void gcry_mpi_clear_flag (gcry_mpi_t a, enum gcry_mpi_flag flag);
 /* Return true when the FLAG is set for A. */
 int gcry_mpi_get_flag (gcry_mpi_t a, enum gcry_mpi_flag flag);
 
+/* Private function - do not use.  */
+gcry_mpi_t _gcry_mpi_get_const (int no);
+
 /* Unless the GCRYPT_NO_MPI_MACROS is used, provide a couple of
    convenience macros for the big integer functions. */
 #ifndef GCRYPT_NO_MPI_MACROS
diff --git a/src/libgcrypt.def b/src/libgcrypt.def
index 4da46232..9eaf8a7a 100644
--- a/src/libgcrypt.def
+++ b/src/libgcrypt.def
@@ -234,3 +234,5 @@ EXPORTS
       gcry_mpi_ec_mul           @211
 
       gcry_pubkey_get_sexp      @212
+
+      _gcry_mpi_get_const       @213
diff --git a/src/libgcrypt.vers b/src/libgcrypt.vers
index 29e46dbe..6aaf0f13 100644
--- a/src/libgcrypt.vers
+++ b/src/libgcrypt.vers
@@ -98,6 +98,8 @@ GCRYPT_1.6 {
     gcry_mpi_ec_get_affine;
     gcry_mpi_ec_dup; gcry_mpi_ec_add; gcry_mpi_ec_mul;
 
+    _gcry_mpi_get_const;
+
     gcry_ctx_release;
 
   local:
diff --git a/src/visibility.c b/src/visibility.c
index b503be66..c86d31b2 100644
--- a/src/visibility.c
+++ b/src/visibility.c
@@ -601,6 +601,20 @@ gcry_mpi_get_flag (gcry_mpi_t a, enum gcry_mpi_flag flag)
   return _gcry_mpi_get_flag (a, flag);
 }
 
+gcry_mpi_t
+_gcry_mpi_get_const (int no)
+{
+  switch (no)
+    {
+    case 1: return _gcry_mpi_const (MPI_C_ONE);
+    case 2: return _gcry_mpi_const (MPI_C_TWO);
+    case 3: return _gcry_mpi_const (MPI_C_THREE);
+    case 4: return _gcry_mpi_const (MPI_C_FOUR);
+    case 8: return _gcry_mpi_const (MPI_C_EIGHT);
+    default: log_bug("unsupported GCRYMPI_CONST_ macro used\n");
+    }
+}
+
 gcry_error_t
 gcry_cipher_open (gcry_cipher_hd_t *handle,
                   int algo, int mode, unsigned int flags)
diff --git a/src/visibility.h b/src/visibility.h
index 1564e865..6887f37b 100644
--- a/src/visibility.h
+++ b/src/visibility.h
@@ -594,6 +594,10 @@ MARK_VISIBLE (gcry_mpi_test_bit)
 
 MARK_VISIBLE (gcry_ctx_release)
 
+/* Functions used to implement macros.  */
+MARK_VISIBLEX(_gcry_mpi_get_const)
+
+
 
 #undef MARK_VISIBLE
 #endif /*_GCRY_INCLUDED_BY_VISIBILITY_C*/