X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/1ba83484ee5bb486da9aa958576de4bc29ef0c1d..34e4f738bcba58e6d8c4cabbb0b3232a65b42a9d:/mpbarrett.c

diff --git a/mpbarrett.c b/mpbarrett.c
index b38aa91..934097d 100644
--- a/mpbarrett.c
+++ b/mpbarrett.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mpbarrett.c,v 1.8 2001/06/16 13:00:20 mdw Exp $
+ * $Id: mpbarrett.c,v 1.9 2004/04/01 12:50:09 mdw Exp $
  *
  * Barrett modular reduction
  *
@@ -30,6 +30,13 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mpbarrett.c,v $
+ * Revision 1.9  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 1.8  2001/06/16 13:00:20  mdw
  * Use the generic exponentiation functions.
  *
@@ -64,7 +71,6 @@
 
 #include "mp.h"
 #include "mpbarrett.h"
-#include "mpbarrett-exp.h"
 
 /*----- Main code ---------------------------------------------------------*/
 
@@ -193,33 +199,6 @@ mp *mpbarrett_reduce(mpbarrett *mb, mp *d, mp *m)
   return (d);
 }
 
-/* --- @mpbarrett_exp@ --- *
- *
- * Arguments:	@mpbarrett *mb@ = pointer to Barrett reduction context
- *              @mp *d@ = fake destination
- *              @mp *a@ = base
- *              @mp *e@ = exponent
- *
- * Returns:     Result, %$a^e \bmod m$%.
- */
-
-mp *mpbarrett_exp(mpbarrett *mb, mp *d, mp *a, mp *e)
-{
-  mp *x = MP_ONE;
-  mp *spare = (e->f & MP_BURN) ? MP_NEWSEC : MP_NEW;
-
-  MP_SHRINK(e);
-  if (!MP_LEN(e))
-    ;
-  else if (MP_LEN(e) < EXP_THRESH)
-    EXP_SIMPLE(x, a, e);
-  else
-    EXP_WINDOW(x, a, e);
-  mp_drop(d);
-  mp_drop(spare);
-  return (x);
-}
-
 /*----- Test rig ----------------------------------------------------------*/
 
 #ifdef TEST_RIG
@@ -254,44 +233,8 @@ static int vmod(dstr *v)
   return (ok);
 }
 
-static int vexp(dstr *v)
-{
-  mp *m = *(mp **)v[0].buf;
-  mp *a = *(mp **)v[1].buf;
-  mp *b = *(mp **)v[2].buf;
-  mp *r = *(mp **)v[3].buf;
-  mp *mr;
-  int ok = 1;
-
-  mpbarrett mb;
-  mpbarrett_create(&mb, m);
-
-  mr = mpbarrett_exp(&mb, MP_NEW, a, b);
-
-  if (!MP_EQ(mr, r)) {
-    fputs("\n*** barrett modexp failed", stderr);
-    fputs("\n m = ", stderr); mp_writefile(m, stderr, 10);
-    fputs("\n a = ", stderr); mp_writefile(a, stderr, 10);
-    fputs("\n e = ", stderr); mp_writefile(b, stderr, 10);
-    fputs("\n r = ", stderr); mp_writefile(r, stderr, 10);
-    fputs("\nmr = ", stderr); mp_writefile(mr, stderr, 10);
-    fputc('\n', stderr);
-    ok = 0;
-  }
-
-  mp_drop(m);
-  mp_drop(a);
-  mp_drop(b);
-  mp_drop(r);
-  mp_drop(mr);
-  mpbarrett_destroy(&mb);
-  assert(mparena_count(MPARENA_GLOBAL) == 0);
-  return ok;
-}
-
 static test_chunk tests[] = {
   { "mpbarrett-reduce", vmod, { &type_mp, &type_mp, &type_mp, 0 } },
-  { "mpbarrett-exp", vexp, { &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
   { 0, 0, { 0 } }
 };