X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/21a7c4b1cffbf33a19e4cf421e29420187ed7a89..34e4f738bcba58e6d8c4cabbb0b3232a65b42a9d:/mpbarrett.h

diff --git a/mpbarrett.h b/mpbarrett.h
index d9c02ad..3168205 100644
--- a/mpbarrett.h
+++ b/mpbarrett.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mpbarrett.h,v 1.1 1999/12/10 23:22:00 mdw Exp $
+ * $Id: mpbarrett.h,v 1.4 2004/04/01 12:50:09 mdw Exp $
  *
  * Barrett modular reduction
  *
@@ -30,6 +30,19 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mpbarrett.h,v $
+ * Revision 1.4  2004/04/01 12:50:09  mdw
+ * Add cyclic group abstraction, with test code.  Separate off exponentation
+ * functions for better static linking.  Fix a buttload of bugs on the way.
+ * Generally ensure that negative exponents do inversion correctly.  Add
+ * table of standard prime-field subgroups.  (Binary field subgroups are
+ * currently unimplemented but easy to add if anyone ever finds a good one.)
+ *
+ * Revision 1.3  2001/06/16 12:58:47  mdw
+ * Added simultaneous exponentiation with Barrett reduction.
+ *
+ * Revision 1.2  2000/10/08 12:03:44  mdw
+ * (mpbarrett_reduce): Cope with negative numbers.
+ *
  * Revision 1.1  1999/12/10 23:22:00  mdw
  * Barrett reduction support: works with even moduli.
  *
@@ -109,8 +122,7 @@ extern void mpbarrett_destroy(mpbarrett */*mb*/);
  * Returns:	The residue of @m@ modulo the number in the reduction
  *		context.
  *
- * Use:		Performs an efficient modular reduction.  The argument is
- *		assumed to be positive.
+ * Use:		Performs an efficient modular reduction.
  */
 
 extern mp *mpbarrett_reduce(mpbarrett */*mb*/, mp */*d*/, mp */*m*/);
@@ -127,6 +139,23 @@ extern mp *mpbarrett_reduce(mpbarrett */*mb*/, mp */*d*/, mp */*m*/);
 
 extern mp *mpbarrett_exp(mpbarrett */*mb*/, mp */*d*/, mp */*a*/, mp */*e*/);
 
+/* --- @mpbarrett_mexp@ --- *
+ *
+ * Arguments:	@mpbarrett *mb@ = pointer to Barrett reduction context
+ *		@mp *d@ = fake destination
+ *		@const mp_expfactor *f@ = pointer to array of factors
+ *		@size_t n@ = number of factors supplied
+ *
+ * Returns:	If the bases are %$g_0, g_1, \ldots, g_{n-1}$% and the
+ *		exponents are %$e_0, e_1, \ldots, e_{n-1}$% then the result
+ *		is:
+ *
+ *		%$g_0^{e_0} g_1^{e_1} \ldots g_{n-1}^{e_{n-1}} \bmod m$%
+ */
+
+extern mp *mpbarrett_mexp(mpbarrett */*mb*/, mp */*d*/,
+			  const mp_expfactor */*f*/, size_t /*n*/);
+
 /*----- That's all, folks -------------------------------------------------*/
 
 #ifdef __cplusplus