factorial: Fix usage message to fit in with conventions.

[u/mdw/catacomb] / gfshare.h

diff --git a/gfshare.h b/gfshare.h
index fe09d8a..87c71a6 100644 (file)
--- a/gfshare.h
+++ b/gfshare.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: gfshare.h,v 1.6 2000/12/06 20:30:10 mdw Exp $
+ * $Id$
  *
  * Secret sharing over %$\gf{2^8}$%
  *
@@ -27,31 +27,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: gfshare.h,v $
- * Revision 1.6  2000/12/06 20:30:10  mdw
- * Change secret sharing interface: present the secret at share
- * construction time.
- *
- * Revision 1.5  2000/06/24 19:11:47  mdw
- * Fix daft error in the comment for @gfshare_get@.
- *
- * Revision 1.4  2000/06/24 18:29:05  mdw
- * Interface change: allow shares to be extracted from a context on demand,
- * rather than building them all up-front.
- *
- * Revision 1.3  2000/06/18 23:12:15  mdw
- * Change typesetting of Galois Field names.
- *
- * Revision 1.2  2000/06/17 11:05:27  mdw
- * Add a commentary on the system.
- *
- * Revision 1.1  2000/06/17 10:56:30  mdw
- * Fast but nonstandard secret sharing system.
- *
- */
-
 /*----- Notes on the system -----------------------------------------------*
  *
  * This uses a variant of Shamir's secret sharing system.  Shamir's original
@@ -97,6 +72,8 @@ typedef struct gfshare {
 
 #define GFSHARE_INIT(t, sz) { t, 0, sz, 0 }
 
+#define GFSHARE_INDEX(s, i) ((s)->v[(i) * ((s)->sz + 1)])
+
 /*----- Functions provided ------------------------------------------------*/
 
 /* --- @gfshare_create@ --- *
@@ -158,6 +135,17 @@ extern void gfshare_mkshares(gfshare */*s*/, grand */*r*/,
 
 extern void gfshare_get(gfshare */*s*/, unsigned /*x*/, void */*buf*/);
 
+/* --- @gfshare_addedp@ --- *
+ *
+ * Arguments:  @gfshare *s@ = pointer to sharing context
+ *             @unsigned x@ = which share number to check
+ *
+ * Returns:    Nonzero if share @x@ has been added already, zero if it
+ *             hasn't.
+ */
+
+extern int gfshare_addedp(gfshare */*s*/, unsigned /*x*/);
+
 /* --- @gfshare_add@ --- *
  *
  * Arguments:  @gfshare *s@ = pointer to sharing context