Data Types

Given the multi-platform nature of AIC, no details on precise number formats and dimensions are given here, but some statements are made about the compatibility of implementations on different platforms. In any case, all types used by AIC in this version of the AIC standard are to be abstracted by using the typedef names as described in this Chapter.

Within a single implementation, the representation of the underlying types will be consistent, and hence present no problems. The defined behavior of AIC when two versions are interacting between different platforms is as follows:

The receiving AIC component must check that the encoded transmitted type will fit into an equivalent local variable without causing overflow.
If there will be an overflow, the return value of the highest level API call will indicate the overflow condition with the return code AIC_VALUE_OVERFLOW.

Character Strings

The character string data type is called AIC_String.

The AIC_String is a variable length string, which in a C implementation is interchangeable with a character array or a character pointer. If an AIC_String is passed into an AIC function needs to be retained within AIC for whatever reason (for example, it is the new value for an AICBusVarChar object), a copy of the original parameter will be made. The programmer is then free to re-use or dispose of the AIC_String parameter.

AIC must handle the internal resizing of AIC_Strings with no memory leaks. The length of an AICBusVarChar is unlimited within the memory size of the machine, although there are instances where a user is asked to specify the size of an AIC_String buffer for a return value. The code page or character set in use locally is implementation specific. This subject is covered in more detail in Version Compatibility.

Fixed-Point Binary Numbers

The fixed-point binary number is called AIC_Long. This is expected to be 32 bits in length at a minimum. It should also be signed – although how precisely this is done is not specified here. The underlying implementation must handle the correct transmission between AIC implementations on different platforms and this includes byte and bit ordering.

Floating-Point Numbers

Floating-point numbers are called AIC_Double. an AIC_Double must be able to represent positive and negative values at least in the range 1.00E-99 to 1.00E+99 (and -1.00E-99 to -1.00E+99), although specific implementations may offer better precision than this. Again the most important point is that when AIC_Doubles are passed between a source and recipient machine, the recipient should handle the case where the received value is too large for the internal data type supported.

Note:: No formal IEEE reference is intended.

Date/Time Values

The date/time value is a composite called AIC_DateAndTime. There is a small set of utility API calls for manipulating the date/time values. These must be supported as part of the AIC standard, and completely encapsulate the date/time value. Obviously, this type and the functions defined for manipulating it must handle leap years and be able to perform arithmetic across centuries, years and months. The calendar used by AIC is defined to be the Gregorian calendar.

The AIC_DateAndTime is required to hold dates from 1900 up to the year 9998, in the form


 

<day-month-year hours:minutes:seconds>

The ranges of these components are defined in Date and Time Values, below.

Component Range
Day 1 - 31
Month 1 - 12
Year 1900 - 9998
Hours 0 - 23
Minutes 0 - 59
Seconds 0 - 59

Component	Range
Day	1 - 31
Month	1 - 12
Year	1900 - 9998
Hours	0 - 23
Minutes	0 - 59
Seconds	0 - 59

Table: Date and Time Values

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