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Changes merged from Kawa's gnu.math.

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* java/math/BigInteger.java
	* gnu/gcj/math/MPN.java (rshift0): New method handles zero shift count.
	(rshift(int[],int[],int,int):  Removed - not needed.
	(gcd):  Use rshift0 rather than rshift.
	* java/math/BigInteger.java (setShiftRight):  Likewise.
	(divide):  Simplify by using rshift0.
	(divide):  Zero-extend results if high-order bit set.

From-SVN: r40177
This commit is contained in:
Per Bothner
2001-03-01 22:55:33 -08:00
committed by Per Bothner
parent d6edb99e92
commit c04278f74f
3 changed files with 44 additions and 35 deletions
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libjava/gnu/gcj/math/MPN.java
+23 -20
View File
@@ -1,4 +1,4 @@
/* Copyright (C) 1999, 2000 Free Software Foundation
/* Copyright (C) 1999, 2000, 2001 Free Software Foundation
This file is part of libgcj.
@@ -481,7 +481,7 @@ public class MPN
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 @@ public class MPN
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 @@ public class MPN
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 @@ public class MPN
// 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 @@ public class MPN
}
/** 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 @@ public class MPN
}
/* 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));