Bring java.math up to JDK 1.2 compliance.

(code still needs to be rigorously tested)

1 files changed, 325 insertions, 0 deletions

diff --git a/java/math/BigDecimal.java b/java/math/BigDecimal.java
new file mode 100644
index 000000000..e947e94f5
--- /dev/null
+++ b/java/math/BigDecimal.java
@@ -0,0 +1,325 @@
+import java.math.BigInteger;
+
+package java.math;
+
+public class BigDecimal extends Number implements Comparable {
+  BigInteger num;
+  int scale;
+
+  private final static BigDecimal ZERO = 
+    new BigDecimal (BigInteger.valueOf (0), 0);
+
+  private final static BigDecimal ONE = 
+    new BigDecimal (BigInteger.valueOf (1), 0);
+
+  public final static int ROUND_UP = 0;
+  public final static int ROUND_DOWN = 1;
+  public final static int ROUND_CEILING = 2;
+  public final static int ROUND_FLOOR = 3;
+  public final static int ROUND_HALF_UP = 4;
+  public final static int ROUND_HALF_DOWN = 5;
+  public final static int ROUND_HALF_EVEN = 6;
+  public final static int ROUND_UNNECESSARY = 7;
+
+  public BigDecimal (BigInteger num) 
+  {
+    this (num, 0);
+  }
+
+  public BigDecimal (BigInteger num, int scale) throws NumberFormatException 
+  {
+    if (scale < 0) 
+      throw new NumberFormatException ("scale of " + scale + " is < 0");
+    this.num = num;
+    this.scale = scale;
+  }
+
+  public BigDecimal (double num) throws NumberFormatException 
+  {
+    this (Double.toString (num));
+  }
+
+  public BigDecimal (String num) throws NumberFormatException 
+  {
+    int point = num.indexOf('.');
+    this.num = new BigInteger (point == -1 ? num :
+			       num.substring (0, point) + 
+			       num.substring (point + 1));
+    scale = num.length() - (point == -1 ? num.length () : point + 1);
+  }
+
+  public static BigDecimal valueOf (long val) 
+  {
+    return valueOf (val, 0);
+  }
+
+  public static BigDecimal valueOf (long val, int scale) 
+    throws NumberFormatException 
+  {
+    if (scale == 0)
+      switch ((int) val)
+	{
+	case 0:
+	  return ZERO;
+	case 1:
+	  return ONE;
+	}
+
+    return new BigDecimal (BigInteger.valueOf (val), scale);
+  }
+
+  public BigDecimal add (BigDecimal val) 
+  {
+    return new BigDecimal (num.add (val.num), Math.max (scale, val.scale));
+  }
+
+  public BigDecimal substract (BigDecimal val) 
+  {
+    return new BigDecimal (num.subtract (val.num), 
+			   Math.max (scale, val.scale));
+  }
+
+  public BigDecimal multiply (BigDecimal val) 
+  {
+    return new BigDecimal (num.multiply (val.num), scale + val.scale);
+  }
+
+  public BigDecimal divide (BigDecimal val, int roundingMode) 
+    throws ArithmeticException, IllegalArgumentException 
+  {
+    return divide (val, scale, roundingMode);
+  }
+
+  public BigDecimal divide(BigDecimal val, int newScale, int roundingMode)
+    throws ArithmeticException, IllegalArgumentException 
+  {
+    if (roundingMode < 0 || roundingMode > 7)
+      throw 
+	new IllegalArgumentException("illegal rounding mode: " + roundingMode);
+
+    if (scale < 0)
+      throw new ArithmeticException ("scale is negative: " + scale);
+
+    if (num.signum () == 0)	// handle special case of 0.0/0.0
+      return ZERO;
+    
+    BigInteger dividend = num.multiply (BigInteger.valueOf (10).pow 
+					(newScale + 1 - (scale - val.scale)));
+    
+    BigInteger parts[] = dividend.divideAndRemainder (val.num);
+//      System.out.println("int: " + parts[0]);
+//      System.out.println("rem: " + parts[1]);
+
+    int roundDigit = parts[0].mod (BigInteger.valueOf (10)).intValue ();
+    BigInteger unrounded = parts[0].divide (BigInteger.valueOf (10));
+
+    if (roundDigit == 0 && parts[1].signum () == 0) // no rounding necessary
+      return new BigDecimal (unrounded, newScale);
+
+    int sign = unrounded.signum ();
+
+    switch (roundingMode)
+      {
+      case ROUND_UNNECESSARY:
+	throw new ArithmeticException ("newScale is not large enough");
+      case ROUND_CEILING:
+	roundingMode = (sign == 1) ? ROUND_UP : ROUND_DOWN;
+	break;
+      case ROUND_FLOOR:
+	roundingMode = (sign == 1) ? ROUND_DOWN : ROUND_UP;
+	break;
+      case ROUND_HALF_UP:
+	roundingMode = (roundDigit >= 5) ? ROUND_UP : ROUND_DOWN;
+	break;
+      case ROUND_HALF_DOWN:
+	roundingMode = (roundDigit > 5) ? ROUND_UP : ROUND_DOWN;
+	break;
+      case ROUND_HALF_EVEN:
+	if (roundDigit < 5)
+	  roundingMode = ROUND_DOWN;
+	else
+	  {
+	    int rightmost = 
+	      unrounded.mod (BigInteger.valueOf (10)).intValue ();
+	    if (rightmost % 2 == 1) // odd, then ROUND_HALF_UP
+	      roundingMode = ROUND_UP;
+	    else // even, then ROUND_HALF_DOWN
+	      roundingMode = (roundDigit > 5) ? ROUND_UP : ROUND_DOWN;
+	  }
+	break;
+      }
+
+    if (roundingMode == ROUND_UP)
+      return new BigDecimal (unrounded.add (BigInteger.valueOf (1)), newScale);
+
+    // roundingMode == ROUND_DOWN
+    return new BigDecimal (unrounded, newScale);
+  }
+    
+  public int compareTo (BigDecimal val) 
+  {
+    if (scale == val.scale)
+      return num.compareTo (val.num);
+
+    BigInteger thisParts[] = 
+      num.divideAndRemainder (BigInteger.valueOf (10).pow (scale));
+    BigInteger valParts[] =
+      val.num.divideAndRemainder (BigInteger.valueOf (10).pow (val.scale));
+    
+    int compare;
+    if ((compare = thisParts[0].compareTo (valParts[0])) != 0)
+      return compare;
+
+    // quotients are the same, so compare remainders
+
+    // remove trailing zeros
+    if (thisParts[1].equals (BigInteger.valueOf (0)) == false)
+      while (thisParts[1].mod (BigInteger.valueOf (10)).equals
+	     (BigInteger.valueOf (0)))
+      thisParts[1] = thisParts[1].divide (BigInteger.valueOf (10));
+    // again...
+    if (valParts[1].equals(BigInteger.valueOf (0)) == false)
+      while (valParts[1].mod (BigInteger.valueOf (10)).equals
+	     (BigInteger.valueOf (0)))
+	valParts[1] = valParts[1].divide (BigInteger.valueOf (10));
+
+    // and compare them
+    return thisParts[1].compareTo (valParts[1]);
+  }
+
+  public boolean equals (Object o) 
+  {
+    return (o instanceof BigDecimal 
+	    && scale == ((BigDecimal) o).scale
+	    && compareTo ((BigDecimal) o) == 0);
+  }
+
+  public int hashCode() 
+  {
+    return intValue() ^ scale;
+  }
+
+  public BigDecimal max (BigDecimal val)
+  {
+    switch (compareTo (val)) 
+      {
+      case 1:
+	return this;
+      default:
+	return val;
+      }
+  }
+
+  public BigDecimal min (BigDecimal val) 
+  {
+    switch (compareTo (val)) 
+      {
+      case -1:
+	return this;
+      default:
+	return val;
+      }
+  }
+
+  public BigDecimal movePointLeft (int n)
+  {
+    return (n < 0) ? movePointRight (-n) : new BigDecimal (num, scale + n);
+  }
+
+  public BigDecimal movePointRight (int n)
+  {
+    if (n < 0)
+      return movePointLeft (-n);
+
+    if (scale >= n)
+      return new BigDecimal (num, scale - n);
+
+    return new BigDecimal (num.multiply 
+			   (BigInteger.valueOf (10).pow (n - scale)), 0);
+  }
+
+  public int signum () 
+  {
+    return num.signum ();
+  }
+
+  public int scale () 
+  {
+    return scale;
+  }
+  
+  public BigDecimal abs () 
+  {
+    return new BigDecimal (num.abs (), scale);
+  }
+
+  public BigDecimal negate () 
+  {
+    return new BigDecimal (num.negate (), scale);
+  }
+
+  public String toString () 
+  {
+    String bigStr = num.toString();
+    if (scale == 0) 
+      return bigStr;
+
+    int point = bigStr.length() - scale;
+    boolean negative = (bigStr.charAt(0) == '-');
+    StringBuffer sb = new StringBuffer(bigStr.length() + 1 + 
+				       (point <= 0 ? -point+1 : 0));
+    if (negative)
+      sb.append('-');
+    while (point <= 0)
+      {
+	sb.append('0');
+	point++;
+      }
+    sb.append(bigStr.substring(negative ? 1 : 0));
+    sb.insert(point, '.');
+    return sb.toString();
+  }
+
+  public BigInteger toBigInteger () 
+  {
+    return scale == 0 ? num : num.divide (BigInteger.valueOf (10).pow (scale));
+  }
+
+
+  public int intValue () 
+  {
+    return toBigInteger ().intValue ();
+  }
+
+  public long longValue ()
+  {
+    return toBigInteger().longValue();
+  }
+
+  public float floatValue() 
+  {
+    return Float.valueOf(toString()).floatValue();
+  }
+
+  public double doubleValue() 
+  {
+    return Double.valueOf(toString()).doubleValue();
+  }
+
+  public static void main(String args[]) {
+    BigDecimal a,b;
+
+//     a = new BigDecimal("1.00");
+//     System.out.println(a.scale());
+
+//     a = a.movePointRight(1);
+//     System.out.println(a);
+//     System.out.println(a.scale());
+    
+//     a = a.movePointRight(4);
+//     System.out.println(a);
+//     System.out.println(a.scale());
+    a = new BigDecimal("1");
+    System.out.println (a.divide(new BigDecimal("3.1"), 5, BigDecimal.ROUND_DOWN));
+  }
+}