Date: Thu, 24 Feb 2005 12:40:27 +0100
From: Vincent Lefevre
To: <Torbjorn Granlund>, <Yves Bertot>, <Nicolas Magaud>, <Paul Zimmermann>
Subject: [patch to mpn_dc_sqrtrem]
Content-Disposition: inline

The patch was incorrect. I've added the comment "signed" for c,
and missing parentheses here:

     c -= (int) ((l == h) ? b : mpn_sub_1 (np + 2 * l, np + 2 * l, 1, b));

so that the cast is applied to the result and not to (l == h).

--- sqrtrem.c   2002-04-18 19:20:28.000000000 +0200
+++ sqrtrem.c.new       2005-01-28 17:10:32.785658988 +0100
@@ -170,7 +170,8 @@
 mpn_dc_sqrtrem (mp_ptr sp, mp_ptr np, mp_size_t n)
 {
   mp_limb_t q;                 /* carry out of {sp, n} */
-  int c, b;                    /* carry out of remainder */
+  mp_limb_t b;
+  int c;                       /* carry out of remainder, signed */
   mp_size_t l, h;
 
   ASSERT (np[2 * n - 1] >= GMP_NUMB_HIGHBIT / 2);
@@ -185,21 +186,21 @@
       if (q != 0)
         mpn_sub_n (np + 2 * l, np + 2 * l, sp + l, h);
       q += mpn_divrem (sp, 0, np + l, n, sp + l, h);
-      c = sp[0] & 1;
+      c = (int) (sp[0] & (mp_limb_t) 1);
       mpn_rshift (sp, sp, l, 1);
       sp[l - 1] |= (q << (GMP_NUMB_BITS - 1)) & GMP_NUMB_MASK;
       q >>= 1;
       if (c != 0)
-        c = mpn_add_n (np + l, np + l, sp + l, h);
+        c = (int) mpn_add_n (np + l, np + l, sp + l, h);
       mpn_sqr_n (np + n, sp, l);
       b = q + mpn_sub_n (np, np, np + n, 2 * l);
-      c -= (l == h) ? b : mpn_sub_1 (np + 2 * l, np + 2 * l, 1, b);
+      c -= (int) ((l == h) ? b : mpn_sub_1 (np + 2 * l, np + 2 * l, 1, b));
       q = mpn_add_1 (sp + l, sp + l, h, q);
 
       if (c < 0)
         {
-          c += mpn_addmul_1 (np, sp, n, 2) + 2 * q;
-          c -= mpn_sub_1 (np, np, n, 1);
+          c += (int) (mpn_addmul_1 (np, sp, n, 2) + 2 * q);
+          c -= (int) mpn_sub_1 (np, np, n, 1);
           q -= mpn_sub_1 (sp, sp, n, 1);
         }
     }

-- 
Vincent Lefèvre <vincent@vinc17.org> - Web: <http://www.vinc17.org/>
100% accessible validated (X)HTML - Blog: <http://www.vinc17.org/blog/>
Work: CR INRIA - computer arithmetic / SPACES project at LORIA