Package nom.tam.util

Class ByteFormatter

java.lang.Object
nom.tam.util.ByteFormatter
@Deprecated public final class ByteFormatter extends Object
Deprecated.
This class should not be exposed in the public API and is intended for internal use only in ASCII tables. Also, it may have overlapping functionality with other classes, which should probably be eliminated for simplicity's sake (and thus less chance of nasty bugs).
This class provides mechanisms for efficiently formatting numbers and Strings. Data is appended to existing byte arrays. Note that the formatting of real or double values may differ slightly (in the last bit) from the standard Java packages since this routines are optimized for speed rather than accuracy.

The methods in this class create no objects.

If a number cannot fit into the requested space the truncateOnOverlow flag controls whether the formatter will attempt to append it using the available length in the output (a la C or Perl style formats). If this flag is set, or if the number cannot fit into space left in the buffer it is 'truncated' and the requested space is filled with a truncation fill character. A TruncationException may be thrown if the truncationThrow flag is set.

This class does not explicitly support separate methods for formatting reals in exponential notation. Real numbers near one are by default formatted in decimal notation while numbers with large (or very negative) exponents are formatted in exponential notation. By setting the limits at which these transitions take place the user can force either exponential or decimal notation.

See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final String
    INFINITY
    Deprecated.
    String representation of (positive) infinity values
    static final String
    NEGATIVE_INFINITY
    Deprecated.
    String representation of (negative) infinity values
    static final String
    NOT_A_NUMBER
    Deprecated.
    String representation of NaN values

  • Constructor Summary

    Constructors
    Constructor
    Description
    ByteFormatter()
    Deprecated.
     

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    format(boolean val, byte[] array)
    Deprecated.
    Format a boolean into an existing array.
    int
    format(boolean val, byte[] array, int off, int len)
    Deprecated.
    Format a boolean into an existing array
    int
    format(double val, byte[] array)
    Deprecated.
    Format a double into an array.
    int
    format(double val, byte[] buf, int off, int len)
    Deprecated.
    Format a double into an existing character array.
    int
    format(float val, byte[] array)
    Deprecated.
    Format a float into an array.
    int
    format(float val, byte[] buf, int off, int len)
    Deprecated.
    Format a float into an existing byteacter array.
    int
    format(int val, byte[] array)
    Deprecated.
    Format an int into an array.
    int
    format(int val, byte[] buf, int off, int len)
    Deprecated.
    Format an int into an existing array.
    int
    format(long val, byte[] array)
    Deprecated.
    Format a long into an array.
    int
    format(long val, byte[] buf, int off, int len)
    Deprecated.
    Format a long into an existing array.
    int
    format(String val, byte[] array)
    Deprecated.
    Insert a string at the beginning of an array. * @return Offset of next available character in buffer.
    int
    format(String val, byte[] array, int off, int len)
    Deprecated.
    Insert a String into an existing character array.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • NOT_A_NUMBER

      public static final String NOT_A_NUMBER
      Deprecated.
      String representation of NaN values
      See Also:

    • INFINITY

      public static final String INFINITY
      Deprecated.
      String representation of (positive) infinity values
      See Also:

    • NEGATIVE_INFINITY

      public static final String NEGATIVE_INFINITY
      Deprecated.
      String representation of (negative) infinity values
      See Also:

  • Constructor Details

    • ByteFormatter

      public ByteFormatter()
      Deprecated.

  • Method Details

    • format

      public int format(boolean val, byte[] array)
      Deprecated.
      Format a boolean into an existing array.
      Parameters:
      val - value to write
      array - the array to fill
      Returns:
      Offset of next available character in buffer.

    • format

      public int format(boolean val, byte[] array, int off, int len)
      Deprecated.
      Format a boolean into an existing array
      Parameters:
      val - The boolean to be formatted
      array - The buffer in which to format the data.
      off - The starting offset within the buffer.
      len - The maximum number of characters to use use in formatting the number.
      Returns:
      Offset of next available character in buffer.

    • format

      public int format(double val, byte[] array)
      Deprecated.
      Format a double into an array.
      Parameters:
      val - The double to be formatted.
      array - The array in which to place the result.
      Returns:
      The number of characters used. @ * if the value was truncated

    • format

      public int format(double val, byte[] buf, int off, int len)
      Deprecated.
      Format a double into an existing character array.

      This is hard to do exactly right... The JDK code does stuff with rational arithmetic and so forth. We use a much simpler algorithm which may give an answer off in the lowest order bit. Since this is pure Java, it should still be consistent from machine to machine.

      Recall that the binary representation of the double is of the form d = 0.bbbbbbbb x 2n where there are up to 53 binary digits in the binary fraction (including the assumed leading 1 bit for normalized numbers). We find a value m such that 10m d is between 253 and 263. This product will be exactly convertible to a long with no loss of precision. Getting the decimal representation for that is trivial (see formatLong). This is a decimal mantissa and we have an exponent (-m). All we have to do is manipulate the decimal point to where we want to see it. Errors can arise due to roundoff in the scaling multiplication, but should be no more than a single bit.

      Parameters:
      val - Double to be formatted
      buf - Buffer in which result is to be stored
      off - Offset within buffer
      len - Maximum length of integer
      Returns:
      offset of next unused character in input buffer.

    • format

      public int format(float val, byte[] array)
      Deprecated.
      Format a float into an array.
      Parameters:
      val - The float to be formatted.
      array - The array in which to place the result.
      Returns:
      The number of characters used. @ * if the value was truncated

    • format

      public int format(float val, byte[] buf, int off, int len)
      Deprecated.
      Format a float into an existing byteacter array.

      This is hard to do exactly right... The JDK code does stuff with rational arithmetic and so forth. We use a much simpler algorithm which may give an answer off in the lowest order bit. Since this is pure Java, it should still be consistent from machine to machine.

      Recall that the binary representation of the float is of the form d = 0.bbbbbbbb x 2n where there are up to 24 binary digits in the binary fraction (including the assumed leading 1 bit for normalized numbers). We find a value m such that 10m d is between 224 and 232. This product will be exactly convertible to an int with no loss of precision. Getting the decimal representation for that is trivial (see formatInteger). This is a decimal mantissa and we have an exponent ( -m). All we have to do is manipulate the decimal point to where we want to see it. Errors can arise due to roundoff in the scaling multiplication, but should be very small.

      Parameters:
      val - Float to be formatted
      buf - Buffer in which result is to be stored
      off - Offset within buffer
      len - Maximum length of field
      Returns:
      Offset of next character in buffer. @ * if the value was truncated

    • format

      public int format(int val, byte[] array)
      Deprecated.
      Format an int into an array.
      Parameters:
      val - The int to be formatted.
      array - The array in which to place the result.
      Returns:
      The number of characters used. @ * if the value was truncated

    • format

      public int format(int val, byte[] buf, int off, int len)
      Deprecated.
      Format an int into an existing array.
      Parameters:
      val - Integer to be formatted
      buf - Buffer in which result is to be stored
      off - Offset within buffer
      len - Maximum length of integer
      Returns:
      offset of next unused character in input buffer.

    • format

      public int format(long val, byte[] array)
      Deprecated.
      Format a long into an array.
      Parameters:
      val - The long to be formatted.
      array - The array in which to place the result.
      Returns:
      The number of characters used. @ * if the value was truncated

    • format

      public int format(long val, byte[] buf, int off, int len)
      Deprecated.
      Format a long into an existing array.
      Parameters:
      val - Long to be formatted
      buf - Buffer in which result is to be stored
      off - Offset within buffer
      len - Maximum length of integer
      Returns:
      offset of next unused character in input buffer. @ * if the value was truncated

    • format

      public int format(String val, byte[] array)
      Deprecated.
      Insert a string at the beginning of an array. * @return Offset of next available character in buffer.
      Parameters:
      val - The string to be inserted. A null string will insert len spaces.
      array - The buffer in which to insert the string.
      Returns:
      Offset of next available character in buffer.

    • format

      public int format(String val, byte[] array, int off, int len)
      Deprecated.
      Insert a String into an existing character array. If the String is longer than len, then only the the initial len characters will be inserted.
      Parameters:
      val - The string to be inserted. A null string will insert len spaces.
      array - The buffer in which to insert the string.
      off - The starting offset to insert the string.
      len - The maximum number of characters to insert.
      Returns:
      Offset of next available character in buffer.