X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/b817bfc642225b8c3c0b6a7e42d1fb949b61a606..bccb92dd7abb72205fb3835f746145d271d2b998:/gf-arith.c

diff --git a/gf-arith.c b/gf-arith.c
index c23aa19..eabbff8 100644
--- a/gf-arith.c
+++ b/gf-arith.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: gf-arith.c,v 1.4 2004/04/08 01:36:15 mdw Exp $
+ * $Id$
  *
  * Basic arithmetic on binary polynomials
  *
@@ -179,11 +179,17 @@ void gf_div(mp **qq, mp **rr, mp *a, mp *b)
 
 int gf_irreduciblep(mp *f)
 {
-  unsigned long m = mp_bits(f) - 1;
+  unsigned long m;
   mp *u = MP_TWO;
   mp *v = MP_NEW;
 
-  m /= 2;
+  if (MP_ZEROP(f))
+    return (0);
+  else if (MP_LEN(f) == 1) {
+    if (f->v[0] < 2) return (0);
+    if (f->v[0] < 4) return (1);
+  }
+  m = (mp_bits(f) - 1)/2;
   while (m) {
     u = gf_sqr(u, u);
     gf_div(0, &u, u, f);
@@ -230,6 +236,7 @@ static int verify(const char *op, mp *expect, mp *result, mp *a, mp *b)
 
 RIG(add, gf_add)
 RIG(mul, gf_mul)
+RIG(exp, gf_exp)
 
 #undef RIG
 
@@ -285,6 +292,7 @@ static test_chunk tests[] = {
   { "mul", tmul, { &type_mp, &type_mp, &type_mp, 0 } },
   { "sqr", tsqr, { &type_mp, &type_mp, 0 } },
   { "div", tdiv, { &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
+  { "exp", texp, { &type_mp, &type_mp, &type_mp, 0 } },
   { "irred", tirred, { &type_mp, &type_int, 0 } },
   { 0, 0, { 0 } },
 };