X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/f46efa79cd2bb9adc81541f1218965f85a6b2eef..8404fd750e8d1a635ccb3895e4f0e155e5f5e3cf:/mpx.c

diff --git a/mpx.c b/mpx.c
index f1cbbd9..ef93e3e 100644
--- a/mpx.c
+++ b/mpx.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mpx.c,v 1.17 2004/03/27 00:04:46 mdw Exp $
+ * $Id: mpx.c,v 1.19 2004/04/03 03:29:40 mdw Exp $
  *
  * Low-level multiprecision arithmetic
  *
@@ -30,6 +30,16 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mpx.c,v $
+ * Revision 1.19  2004/04/03 03:29:40  mdw
+ * Fix overrun in @mpx_lsr@.
+ *
+ * Revision 1.18  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 1.17  2004/03/27 00:04:46  mdw
  * Implement efficient reduction for pleasant-looking primes.
  *
@@ -653,7 +663,7 @@ void mpx_lsr(mpw *dv, mpw *dvl, const mpw *av, const mpw *avl, size_t n)
   /* --- Single bit shifting --- */
 
   else if (n == 1) {
-    mpw w = *av++ >> 1;
+    mpw w = av < avl ? *av++ >> 1 : 0;
     while (av < avl) {
       mpw t;
       if (dv >= dvl)
@@ -1179,7 +1189,7 @@ void mpx_udiv(mpw *qv, mpw *qvl, mpw *rv, mpw *rvl,
 
     d = dvl[-1];
     for (b = MPW_BITS / 2; b; b >>= 1) {
-      if (d < (MPW_MAX >> b)) {
+      if (d <= (MPW_MAX >> b)) {
 	d <<= b;
 	norm += b;
       }