org.apache.poi.ss.formula.functions.Bin2Dec Maven / Gradle / Ivy
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package org.apache.poi.ss.formula.functions;
import org.apache.poi.ss.formula.OperationEvaluationContext;
import org.apache.poi.ss.formula.eval.ErrorEval;
import org.apache.poi.ss.formula.eval.NumberEval;
import org.apache.poi.ss.formula.eval.OperandResolver;
import org.apache.poi.ss.formula.eval.RefEval;
import org.apache.poi.ss.formula.eval.ValueEval;
/**
* Implementation for Excel Bin2Dec() function.
*
* Syntax:
Bin2Dec (number)
*
* Converts a binary number to decimal.
*
* 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.
*
* 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) {
final String number;
if (numberVE instanceof RefEval) {
RefEval re = (RefEval) numberVE;
number = OperandResolver.coerceValueToString(re.getInnerValueEval(re.getFirstSheetIndex()));
} else {
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;
try {
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
int 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
int sum = getDecimalValue(inverted);
//Add 1 to obtained number
sum++;
value = "-" + sum;
}
} catch (NumberFormatException e) {
return ErrorEval.NUM_ERROR;
}
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]);
}
}