X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/f94b972d1c0389e4e9203cc9919ceaadbe655b61..025c5f4aa5ffbf8948482a4233318db81c2df5d2:/f-niceprime.c

diff --git a/f-niceprime.c b/f-niceprime.c
index a6191da..4c9deea 100644
--- a/f-niceprime.c
+++ b/f-niceprime.c
@@ -99,20 +99,20 @@ static mp *fsqrt(field *ff, mp *d, mp *x) {
 
 static mp *fdbl(field *ff, mp *d, mp *x) {
   fctx_niceprime *f = (fctx_niceprime *)ff; d = mp_lsl(d, x, 1);
-  if (MP_CMP(d, >, f->r.p)) d = mp_sub(d, d, f->r.p);
+  if (MP_CMP(d, >=, f->r.p)) d = mp_sub(d, d, f->r.p);
   return (d);
 }
 
 static mp *ftpl(field *ff, mp *d, mp *x) {
   fctx_niceprime *f = (fctx_niceprime *)ff; MP_DEST(d, MP_LEN(x) + 1, x->f);
-  MPX_UMULN(d->v, d->vl, x->v, x->vl, 3);
-  while (MP_CMP(d, >, f->r.p)) d = mp_sub(d, d, f->r.p);
+  MPX_UMULN(d->v, d->vl, x->v, x->vl, 3); d->f &= ~MP_UNDEF;
+  while (MP_CMP(d, >=, f->r.p)) d = mp_sub(d, d, f->r.p);
   return (d);
 }
 
 static mp *fqdl(field *ff, mp *d, mp *x) {
   fctx_niceprime *f = (fctx_niceprime *)ff; d = mp_lsl(d, x, 2);
-  while (MP_CMP(d, >, f->r.p)) d = mp_sub(d, d, f->r.p);
+  while (MP_CMP(d, >=, f->r.p)) d = mp_sub(d, d, f->r.p);
   return (d);
 }
 
@@ -138,7 +138,7 @@ static const field_ops fops = {
  *
  * Arguments:	@mp *p@ = the characteristic of the field
  *
- * Returns:	A pointer to the field.
+ * Returns:	A pointer to the field, or null.
  *
  * Use:		Creates a field structure for a prime field of size %$p$%,
  *		using efficient reduction for nice primes.
@@ -152,8 +152,12 @@ field *field_niceprime(mp *p)
   f->f.one = MP_ONE;
   f->f.nbits = mp_bits(p);
   f->f.noctets = (f->f.nbits + 7) >> 3;
-  mpreduce_create(&f->r, p);
+  if (mpreduce_create(&f->r, p)) {
+    DESTROY(f);
+    return (0);
+  }
   f->f.m = f->r.p;
+  f->f.q = f->r.p;
   return (&f->f);
 }