Module BCD

This module defines generic binary (octet sequence) types, and arbitrary precision floating-point decimal data types.

For generic coding, the decimal types are a useful alternative to the IDL fixed template types which were introduced by CORBA 2.1 and GIOP 1.1, since the use of template types introduces a distinct type for each combination of precision and scale.

Type Index

• Binary
• Decimal
• Money

Types

• Binary

  A generic octet sequence type.

      typedef sequence < octet > Binary;
  

• Decimal

  A floating-point decimal type.

      struct Decimal
      {
          BCD::Binary value;
      };
      

  The Binary representation of floating-point values is designed to support easy conversion to and from strings, while at the same time minimising the size of the binary representation for GIOP.

  A number is converted to the binary representation using the following algorithm.

  • Convert the number to a decimal string, with a leading '-' if negative, and no leading sign if zero or positive.
  • The string may contain a decimal point. If the number's scale is greater than zero, the decimal point is followed by the number's decimal fraction. The number of digits in the fraction indicates the scale; trailing zeroes should not be truncated as that would reduce the implied scale.
  • Convert the string's characters to an octet sequence where each half-octet represents padding, a decimal digit, negative sign, or decimal point, as follows:
    • If the string length is odd, the initial half-octet value is 12. This is used as padding to ensure an even number of half-octets.
    • '0' to '9' map to half-octet values 0 to 9.
    • '.' maps to half-octet value 10.
    • '-' maps to half-octet value 13.
  • In each octet of the sequence, the most significant half-octet is filled first. Thus the value "-9" would be encoded as octet value 13 * 16 + 9 = 217.

  Any program receiving a binary value which is not formed according to the above specification should raise a CORBA::DATA_CONVERSION system exception.

  Note: a struct is used because it allows overloaded methods to be defined in C++ and Java for decimal manipulation. It also guarantees that a distinct type is generated for the Java IDL language mapping.

• Money

  A floating-point decimal (money) type. Uses the same representation as Decimal but may be used where a semantic distinction is required.

      struct Money
      {
          BCD::Binary value;
      };
      

  Note: a struct is used because it allows overloaded methods to be defined in C++ and Java for money manipulation. It also guarantees that a distinct type is generated for the Java IDL language mapping.