Fix fencepost bugs in binary radix writing.

[u/mdw/catacomb] / mptext.c

diff --git a/mptext.c b/mptext.c
index 565322d..40e1764 100644 (file)
--- a/mptext.c
+++ b/mptext.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mptext.c,v 1.14 2002/10/09 00:33:44 mdw Exp $
+ * $Id: mptext.c,v 1.15 2002/10/15 19:18:15 mdw Exp $
  *
  * Textual representation of multiprecision numbers
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mptext.c,v $
+ * Revision 1.15  2002/10/15 19:18:15  mdw
+ * Fix fencepost bugs in binary radix writing.
+ *
  * Revision 1.14  2002/10/09 00:33:44  mdw
  * Allow `0o' and `0b' prefixes for octal and binary (from Haskell)
  *
@@ -629,11 +632,12 @@ static int binary(mp *m, int bit, int radix, const mptext_ops *ops, void *p)
   /* --- Work out where to start --- */
 
   n = mp_bits(m);
-  n += bit - (n % bit);
+  if (n % bit)
+    n += bit - (n % bit);
   b = n % MPW_BITS;
   n /= MPW_BITS;
-  
-  if (n > MP_LEN(m)) {
+
+  if (n >= MP_LEN(m)) {
     n--;
     b += MPW_BITS;
   }
@@ -704,6 +708,9 @@ int mp_write(mp *m, int radix, const mptext_ops *ops, void *p)
 {
   int rc;
 
+  if (MP_EQ(m, MP_ZERO))
+    return (ops->put("0", 1, p));
+
   /* --- Set various things up --- */
 
   m = MP_COPY(m);