Renamed from `rsa-decrypt', since the name was no longer appropriate.

[u/mdw/catacomb] / mpx.c

diff --git a/mpx.c b/mpx.c
index e63750f..327699c 100644 (file)
--- a/mpx.c
+++ b/mpx.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mpx.c,v 1.6 1999/11/20 22:43:44 mdw Exp $
+ * $Id: mpx.c,v 1.9 2000/06/26 07:52:50 mdw Exp $
  *
  * Low-level multiprecision arithmetic
  *
@@ -30,6 +30,15 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mpx.c,v $
+ * Revision 1.9  2000/06/26 07:52:50  mdw
+ * Portability fix for the bug fix.
+ *
+ * Revision 1.8  2000/06/25 12:59:02  mdw
+ * (mpx_udiv): Fix bug in quotient digit estimation.
+ *
+ * Revision 1.7  1999/12/22 15:49:07  mdw
+ * New function for division by a small integer.
+ *
  * Revision 1.6  1999/11/20 22:43:44  mdw
  * Integrate testing for MPX routines.
  *
@@ -821,21 +830,19 @@ void mpx_udiv(mpw *qv, mpw *qvl, mpw *rv, mpw *rvl,
 
       {
        mpd yh = (mpd)d * q;
-       mpd yl = (mpd)dd * q;
+       mpd yy = (mpd)dd * q;
+       mpw yl;
 
-       if (yl > MPW_MAX) {
-         yh += yl >> MPW_BITS;
-         yl &= MPW_MAX;
-       }
+       if (yy > MPW_MAX)
+         yh += yy >> MPW_BITS;
+       yl = MPW(yy);
 
        while (yh > rh || (yh == rh && yl > rrr)) {
          q--;
          yh -= d;
-         if (yl < dd) {
-           yh++;
-           yl += MPW_MAX;
-         }
-         yl -= dd;
+         if (yl < dd)
+           yh--;
+         yl = MPW(yl - dd);
        }
       }
 
@@ -900,6 +907,35 @@ void mpx_udiv(mpw *qv, mpw *qvl, mpw *rv, mpw *rvl,
   mpx_lsr(rv, rvl, rv, rvl, norm);
 }
 
+/* --- @mpx_udivn@ --- *
+ *
+ * Arguments:  @mpw *qv, *qvl@ = storage for the quotient (may overlap
+ *                     dividend)
+ *             @const mpw *rv, *rvl@ = dividend
+ *             @mpw d@ = single-precision divisor
+ *
+ * Returns:    Remainder after divison.
+ *
+ * Use:                Performs a single-precision division operation.
+ */
+
+mpw mpx_udivn(mpw *qv, mpw *qvl, const mpw *rv, const mpw *rvl, mpw d)
+{
+  size_t i;
+  size_t ql = qvl - qv;
+  mpd r = 0;
+
+  i = rvl - rv;
+  while (i > 0) {
+    i--;
+    r = (r << MPW_BITS) | rv[i];
+    if (i < ql)
+      qv[i] = r / d;
+    r %= d;
+  }
+  return (MPW(r));
+}
+
 /*----- Test rig ----------------------------------------------------------*/
 
 #ifdef TEST_RIG