Examples of ptolemy.math.Precision

ptolemy.math.Precision

This class defines the precision of a signed or unsigned fixed point value. The precision of a fixed point value is represented as internally as three fields: the number of bits (n), the binary exponent (e), and a sign bit (s). The number of bits (n) defines the dynamic range of the format (2ⁿ). The exponent (e) determines the placement of the binary point for all values of this format. This binary point placement is "fixed" and is specified within the precision format rather than within individual Fixed point values. The mantissa bits of all fixed point values using this this precision format are multiplied by 2^m. Note that m can take on a positive, negative, or zero value. This allows the binary point to be placed anywhere necessary and even beyond the bounds of the mantissa (i.e. to the right of the lsb or to the left of the msb). The sign value s is used to indicate whether the fixed point precision value is treated as signed (s = 1) or unsigned (s = 0).

Signed fixed point formats are represented in a 2's complement format. As a consequence, a single bit is used to represent the sign of the number. The value of a multi-bit signed number is:

Signed(B) = 2^m x (- b_{n-1} x 2^{n-1} + \sum_{i=0}^{n-2} b_i x 2^i), where b_i is the value of bit i of the bit vector.

Unsigned fixed formats are represented as unsigned binary values. No bits are used to represent the sign and all values are positive. The actual value of a multi-bit unsigned fixed point number is:

Unsigned(B) = 2^m x (\sum_{i=0}^{n-1} b_i x 2^i)

This class supports several different String formats for specifying and displaying the Precision. These String formats are supported by several classes that extend the {@link PrecisionFormat} class. Several such classeshave been created. Any given precision string format can be represented in any of the valid precision string formats. The four supported Precision String formats are shown in the table below. A static singleton object of each of these formats is provided in this class. Each String Representation column of the table represent equivalent Precision formats:

Format Name	Format Spec	String Representation
{@link IntegerFractionPrecisionFormat}	[integer bits].[fraction bits]	3.2	0.7	-2.12	12.-4	32.0	U1.7
{@link LengthIntegerPrecisionFormat}	[total bits]/[integer bits]	5/3	7/0	10/-2	8/12	32/32	U8/1
{@link VHDLPrecisionFormat}	[MSb position]:[LSb position]	2:-2	-1:-7	-3:-12	11:4	31:0	U0:-7
{@link LengthExponentPrecisionFormat}	[total bits]e[binary point position]	5e-2	7e-7	10e-12	8e4	32e0	U8e-7

An instance of the class is immutable, meaning that its value is set in the constructor and cannot then be modified. @author Bart Kienhuis, Contributor: Mike Wirthlin @version $Id: Precision.java,v 1.73 2007/12/06 21:57:08 cxh Exp $ @since Ptolemy II 0.4 @Pt.ProposedRating Yellow (kienhuis) @Pt.AcceptedRating Red (kienhuis) @see FixPoint

     *  @param numberOfBits The total number of bits.
     *  @param integerBits The number of bits used for the integer part.
     *  @return A fixed point representation of the value.
     */
    public static FixPoint fix(double value, int numberOfBits, int integerBits) {
        Precision precision = new Precision(numberOfBits, integerBits);
        return Quantizer.round(value, precision);
    }

View Full Code Here

     *  @param integerBits The number of bits used for the integer part.
     *  @return a double with value that is quantized.
     */
    public static double quantize(double value, int numberOfBits,
            int integerBits) {
        FixPoint fixValue = Quantizer.round(value, new Precision(numberOfBits,
                integerBits));
        return fixValue.doubleValue();
    }

View Full Code Here

                ptolemy.data.Token length = parseTreeEvaluator
                        .evaluateParseTree(lengthNode, _scope);


                ptolemy.data.Token integerBits = parseTreeEvaluator
                        .evaluateParseTree(integerBitsNode, _scope);
                _setType(node, new FixType(new Precision(((ScalarToken) length)
                        .intValue(), ((ScalarToken) integerBits).intValue())));
                return;
            } catch (Throwable throwable) {
                // Do nothing... rely on the regular method resolution
                // to generate the right type.

View Full Code Here

        if (A.isKnown() && A.hasToken(0)) {
            FixPoint valueA = ((FixToken) A.get(0)).fixValue();
            bitsInResult = valueA.getPrecision().getNumberOfBits();
            BigInteger bigIntA = valueA.getUnscaledValue();
            intResult = bigIntA.not();
            Precision precision = new Precision(1, bitsInResult, 0);
            FixToken result = new FixToken(intResult.doubleValue(), precision);
            sendOutput(output, 0, result);
        } else {
            output.resend(0);
        }

View Full Code Here

            if (trigger.hasToken(i)) {
                trigger.get(i);
            }
        }


        Precision precision = new Precision(
                ((Parameter) getAttribute("outputPrecision")).getExpression());


        Overflow overflow = Overflow
                .getName(((Parameter) getAttribute("outputOverflow"))
                        .getExpression().toLowerCase());

View Full Code Here

            if ((token.getRowCount() != 1) || (token.getColumnCount() != 2)) {
                throw new IllegalActionException(this,
                        "Invalid precision (not a 1 by 2 matrix).");
            }


            Precision precision = new Precision(token.getElementAt(0, 0), token
                    .getElementAt(0, 1));
            output.setTypeEquals(new FixType(precision));
            _quantization = _quantization.setPrecision(precision);
        } else if (attribute == rounding) {
            Rounding r = Rounding.getName(rounding.getExpression());

View Full Code Here

            if ((token.getRowCount() != 1) || (token.getColumnCount() != 2)) {
                throw new IllegalActionException(this,
                        "Invalid precision (not a 1 by 2 matrix).");
            }


            Precision precision = new Precision(token.getElementAt(0, 0), token
                    .getElementAt(0, 1));
            _quantization = _quantization.setPrecision(precision);
            if (_quantization.getOverflow() == Overflow.GROW) {
                output.setTypeEquals(BaseType.UNSIZED_FIX);
            } else {

View Full Code Here

                }
            } catch (NameDuplicationException ex) {
                throw new IllegalActionException(this, ex,
                        "Fail to set the initialValue parameter.");
            }
            Precision precision = new Precision(
                    ((Parameter) getAttribute("outputPrecision"))
                            .getExpression());


            Overflow overflow = Overflow
                    .getName(((Parameter) getAttribute("outputOverflow"))
                            .getExpression().toLowerCase());


            Rounding rounding = Rounding
                    .getName(((Parameter) getAttribute("outputRounding"))
                            .getExpression().toLowerCase());


            FixPoint result = new FixPoint(((ScalarToken) initialValue
                    .getToken()).doubleValue(), new FixPointQuantization(
                    precision, overflow, rounding));
            output.setInitToken(new FixToken(result));
        }
        if (attribute == initialValue) {
            Precision precision = new Precision(
                    ((Parameter) getAttribute("outputPrecision"))
                            .getExpression());


            Overflow overflow = Overflow
                    .getName(((Parameter) getAttribute("outputOverflow"))

View Full Code Here


    /** Initialize the state of the actor.
     *  @exception IllegalActionException If there is no director.
     */
    public void initialize() throws IllegalActionException {
        Precision precision = new Precision(
                ((Parameter) getAttribute("outputPrecision")).getExpression());


        Overflow overflow = Overflow
                .getName(((Parameter) getAttribute("outputOverflow"))
                        .getExpression().toLowerCase());

View Full Code Here

            Arrays.fill(mask, newStartValue, newEndValue, '1');


            BigDecimal value = new BigDecimal(in.fixValue().getUnscaledValue()
                    .and(new BigInteger(new String(mask), 2)).shiftRight(
                            shiftBits));
            Precision precision = new Precision(
                    ((Parameter) getAttribute("outputPrecision"))
                            .getExpression());
            if ((newEndValue - newStartValue) != precision.getNumberOfBits()) {
                throw new IllegalActionException(this, "Bit width of "
                        + (newEndValue - newStartValue)
                        + " is not equal to precision " + precision);
            }

View Full Code Here

0 1 2

TOP

Related Classes of ptolemy.math.Precision

ptolemy.actor.lib.conversions.DoubleToFix

ptolemy.actor.lib.conversions.FixToFix

ptolemy.actor.lib.vhdl.Concat

ptolemy.actor.lib.vhdl.FixComparator

ptolemy.actor.lib.vhdl.FixConst

ptolemy.actor.lib.vhdl.FixSequence

ptolemy.actor.lib.vhdl.FixTransformer

ptolemy.actor.lib.vhdl.LogicalNot

ptolemy.actor.lib.vhdl.LogicFunction

ptolemy.actor.lib.vhdl.Memory

All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.