Re: [freenet-devl] Re: Yet another GCJ update. (a/k/a PR 1615 followup)

[Per Bothner <per at bothner dot com>]

"Mark J. Roberts" <mjr@statesmean.com> writes:

> This patch breaks BigInteger.divide:

So it does.  It seems like I need to merge in more code ...
Could you try this patch instead?

Index: java/math/BigInteger.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/math/BigInteger.java,v
retrieving revision 1.10
diff -u -r1.10 BigInteger.java
--- BigInteger.java	2001/01/17 04:13:17	1.10
+++ BigInteger.java	2001/02/25 00:38:42
@@ -794,13 +794,7 @@
 	  xwords[xlen++] = 0;
 	MPN.divide(xwords, xlen, ywords, ylen);
 	rlen = ylen;
-	if (remainder != null || rounding_mode != TRUNCATE)
-	  {
-	    if (nshift == 0)
-	      System.arraycopy(xwords, 0, ywords, 0, rlen);
-	    else
-	      MPN.rshift(ywords, xwords, 0, rlen, nshift);
-	  }
+	MPN.rshift0 (ywords, xwords, 0, rlen, nshift);
 
 	qlen = xlen + 1 - ylen;
 	if (quotient != null)
@@ -810,6 +804,12 @@
 	  }
       }
 
+    if (ywords[rlen-1] < 0)
+      {
+        ywords[rlen] = 0;
+        rlen++;
+      }
+
     // Now the quotient is in xwords, and the remainder is in ywords.
 
     boolean add_one = false;
@@ -1399,15 +1399,10 @@
 	  {
 	    if (words == null || words.length < d_len)
 	      realloc(d_len);
-	    if (count == 0)
-	      System.arraycopy(x.words, word_count, words, 0, d_len);
-            else
-	      {
-		MPN.rshift(words, x.words, word_count, d_len, count);
-        	if (neg)
-        	  words[d_len-1] |= -1 << (32 - count);
-              }
+	    MPN.rshift0 (words, x.words, word_count, d_len, count);
 	    ival = d_len;
+	    if (neg)
+	      words[d_len-1] |= -1 << (32 - count);
 	  }
       }
   }
Index: gnu/gcj/math/MPN.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/gnu/gcj/math/MPN.java,v
retrieving revision 1.3
diff -u -r1.3 MPN.java
--- MPN.java	2000/03/07 19:55:24	1.3
+++ MPN.java	2001/02/25 00:38:43
@@ -481,7 +481,7 @@
     return xlen > ylen ? 1 : xlen < ylen ? -1 : cmp (x, y, xlen);
   }
 
-  /* Shift x[x_start:x_start+len-1]count bits to the "right"
+  /* Shift x[x_start:x_start+len-1] count bits to the "right"
    * (i.e. divide by 2**count).
    * Store the len least significant words of the result at dest.
    * The bits shifted out to the right are returned.
@@ -506,6 +506,23 @@
     return retval;
   }
 
+  /* Shift x[x_start:x_start+len-1] count bits to the "right"
+   * (i.e. divide by 2**count).
+   * Store the len least significant words of the result at dest.
+   * OK if dest==x.
+   * Assumes: 0 <= count < 32
+   * Same as rshift, but handles count==0 (and has no return value).
+   */
+  public static void rshift0 (int[] dest, int[] x, int x_start,
+			      int len, int count)
+  {
+    if (count > 0)
+      rshift(dest, x, x_start, len, count);
+    else
+      for (int i = 0;  i < len;  i++)
+	dest[i] = x[i + x_start];
+  }
+
   /** Return the long-truncated value of right shifting.
   * @param x a two's-complement "bignum"
   * @param len the number of significant words in x
@@ -530,20 +547,6 @@
     return ((long)w1 << 32) | ((long)w0 & 0xffffffffL);
   }
 
-  /* Shift x[0:len-1]count bits to the "right" (i.e. divide by 2**count).
-   * Store the len least significant words of the result at dest.
-   * OK if dest==x.
-   * OK if count > 32 (but must be >= 0).
-   */
-  public static void rshift (int[] dest, int[] x, int len, int count)
-  {
-    int word_count = count >> 5;
-    count &= 31;
-    rshift (dest, x, word_count, len, count);
-    while (word_count < len)
-      dest[word_count++] = 0;
-  }
-
   /* Shift x[0:len-1] left by count bits, and store the len least
    * significant words of the result in dest[d_offset:d_offset+len-1].
    * Return the bits shifted out from the most significant digit.
@@ -624,8 +627,8 @@
 
     // Temporarily devide both x and y by 2**sh.
     len -= initShiftWords;
-    MPN.rshift (x, x, initShiftWords, len, initShiftBits);
-    MPN.rshift (y, y, initShiftWords, len, initShiftBits);
+    MPN.rshift0 (x, x, initShiftWords, len, initShiftBits);
+    MPN.rshift0 (y, y, initShiftWords, len, initShiftBits);
 
     int[] odd_arg; /* One of x or y which is odd. */
     int[] other_arg; /* The other one can be even or odd. */
@@ -704,7 +707,7 @@
   }
 
   /** Calcaulte the Common Lisp "integer-length" function.
-   * Assumes input is canonicalized:  len==IntNum.wordsNeeded(words,len) */
+   * Assumes input is canonicalized:  len==BigInteger.wordsNeeded(words,len) */
   public static int intLength (int[] words, int len)
   {
     len--;
@@ -712,7 +715,7 @@
   }
 
   /* DEBUGGING:
-  public static void dprint (IntNum x)
+  public static void dprint (BigInteger x)
   {
     if (x.words == null)
       System.err.print(Long.toString((long) x.ival & 0xffffffffL, 16));


-- 
	--Per Bothner
per@bothner.com   http://www.bothner.com/~per/