Bug 55055: patch for missing function Bin2Dec

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1531386 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/ss/formula/atp/AnalysisToolPak.java

@@ -67,7 +67,7 @@ public final class AnalysisToolPak implements UDFFinder {
         r(m, "BESSELJ", null);
         r(m, "BESSELK", null);
         r(m, "BESSELY", null);
-        r(m, "BIN2DEC", null);
+        r(m, "BIN2DEC", Bin2Dec.instance);
         r(m, "BIN2HEX", null);
         r(m, "BIN2OCT", null);
         r(m, "COMPLEX", Complex.instance);

src/java/org/apache/poi/ss/formula/functions/Bin2Dec.java

@@ -0,0 +1,95 @@
+package org.apache.poi.ss.formula.functions;
+
+import org.apache.poi.ss.formula.OperationEvaluationContext;
+import org.apache.poi.ss.formula.eval.*;
+
+/**
+ * Implementation for Excel Bin2Dec() function.<p/>
+ * <p/>
+ * <b>Syntax</b>:<br/> <b>Bin2Dec  </b>(<b>number</b>)<br/>
+ * <p/>
+ * Converts a binary number to decimal.
+ * <p/>
+ * Number is the binary number you want to convert. Number cannot contain more than 10 characters (10 bits).
+ * The most significant bit of number is the sign bit. The remaining 9 bits are magnitude bits.
+ * Negative numbers are represented using two's-complement notation.
+ * <p/>
+ * Remark
+ * If number is not a valid binary number, or if number contains more than 10 characters (10 bits),
+ * BIN2DEC returns the #NUM! error value.
+ *
+ * @author cedric dot walter @ gmail dot com
+ */
+public class Bin2Dec extends Fixed1ArgFunction implements FreeRefFunction {
+
+    public static final FreeRefFunction instance = new Bin2Dec();
+
+    public ValueEval evaluate(int srcRowIndex, int srcColumnIndex, ValueEval numberVE) {
+        String number = OperandResolver.coerceValueToString(numberVE);
+        if (number.length() > 10) {
+            return ErrorEval.NUM_ERROR;
+        }
+
+        String unsigned;
+
+        //If the leftmost bit is 0 -- number is positive.
+        boolean isPositive;
+        if (number.length() < 10) {
+            unsigned = number;
+            isPositive = true;
+        } else {
+            unsigned = number.substring(1);
+            isPositive = number.startsWith("0");
+        }
+
+        String value;
+        int sum;
+        if (isPositive) {
+            //bit9*2^8 + bit8*2^7 + bit7*2^6 + bit6*2^5 + bit5*2^4+ bit3*2^2+ bit2*2^1+ bit1*2^0
+            sum = getDecimalValue(unsigned);
+            value = String.valueOf(sum);
+        } else {
+            //The leftmost bit is 1 -- this is negative number
+            //Inverse bits [1-9]
+            String inverted = toggleBits(unsigned);
+            // Calculate decimal number
+            sum = getDecimalValue(inverted);
+
+            //Add 1 to obtained number
+            sum++;
+
+            value = "-" + String.valueOf(sum);
+        }
+
+        return new NumberEval(Long.parseLong(value));
+    }
+
+    private int getDecimalValue(String unsigned) {
+        int sum = 0;
+        int numBits = unsigned.length();
+        int power = numBits - 1;
+
+        for (int i = 0; i < numBits; i++) {
+            int bit = Integer.parseInt(unsigned.substring(i, i + 1));
+            int term = (int) (bit * Math.pow(2, power));
+            sum += term;
+            power--;
+        }
+        return sum;
+    }
+
+    private static String toggleBits(String s) {
+        long i = Long.parseLong(s, 2);
+        long i2 = i ^ ((1L << s.length()) - 1);
+        String s2 = Long.toBinaryString(i2);
+        while (s2.length() < s.length()) s2 = '0' + s2;
+        return s2;
+    }
+
+    public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
+        if (args.length != 1) {
+            return ErrorEval.VALUE_INVALID;
+        }
+        return evaluate(ec.getRowIndex(), ec.getColumnIndex(), args[0]);
+    }
+}