Add two's complement support. Fix a bug in MPX_UMLAN.

[u/mdw/catacomb] / mpx.h

diff --git a/mpx.h b/mpx.h
index 9429e91..88f547c 100644 (file)
--- a/mpx.h
+++ b/mpx.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mpx.h,v 1.3 1999/11/13 01:51:29 mdw Exp $
+ * $Id: mpx.h,v 1.4 1999/11/17 18:04:43 mdw Exp $
  *
  * Low level multiprecision arithmetic
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mpx.h,v $
+ * Revision 1.4  1999/11/17 18:04:43  mdw
+ * Add two's complement support.  Fix a bug in MPX_UMLAN.
+ *
  * Revision 1.3  1999/11/13 01:51:29  mdw
  * Minor interface changes.  Should be stable now.
  *
@@ -282,6 +285,19 @@ extern void mpx_lsr(mpw */*dv*/, mpw */*dvl*/,
 
 /*----- Unsigned arithmetic -----------------------------------------------*/
 
+/* --- @mpx_2c@ --- *
+ *
+ * Arguments:  @mpw *dv, *dvl@ = destination vector
+ *             @const mpw *v, *vl@ = source vector
+ *
+ * Returns:    ---
+ *
+ * Use:                Calculates the two's complement of @v@.
+ */
+
+extern void mpx_2c(mpw */*dv*/, mpw */*dvl*/,
+                  const mpw */*v*/, const mpw */*vl*/);
+
 /* --- @mpx_ucmp@ --- *
  *
  * Arguments:  @const mpw *av, *avl@ = first argument vector base and limit
@@ -444,18 +460,18 @@ extern void mpx_umul(mpw */*dv*/, mpw */*dvl*/,
 #define MPX_UMLAN(dv, dvl, av, avl, m) do {                            \
   mpw *_dv = (dv), *_dvl = (dvl);                                      \
   const mpw *_av = (av), *_avl = (avl);                                        \
-  mpw _c = 0;                                                          \
+  mpw _cc = 0;                                                         \
   mpd _m = (m);                                                                \
                                                                        \
   while (_av < _avl) {                                                 \
     mpd _x;                                                            \
     if (_dv >= _dvl)                                                   \
       break;                                                           \
-    _x = (mpd)*_dv + (mpd)_m * (mpd)*_av++ + _c;                       \
+    _x = (mpd)*_dv + (mpd)_m * (mpd)*_av++ + _cc;                      \
     *_dv++ = MPW(_x);                                                  \
-    _c = _x >> MPW_BITS;                                               \
+    _cc = _x >> MPW_BITS;                                              \
   }                                                                    \
-  MPX_UADDN(_dv, _dvl, _c);                                            \
+  MPX_UADDN(_dv, _dvl, _cc);                                           \
 } while (0)
 
 /* --- @mpx_usqr@ --- *
@@ -488,8 +504,7 @@ extern void mpx_usqr(mpw */*dv*/, mpw */*dvl*/,
  *             requiring the dividend to be in the result position but it
  *             does make some sense really.  The remainder must have
  *             headroom for at least two extra words.  The scratch space
- *             must be at least two words larger than twice the size of the
- *             divisor.
+ *             must be at least one word larger than the divisor.
  */
 
 extern void mpx_udiv(mpw */*qv*/, mpw */*qvl*/, mpw */*rv*/, mpw */*rvl*/,