1.11.4. Datatypes

1.11.4.1. RTS datatypes

The runtime system defines its own typesystem based on the portable “ANSI stdint” types (see stdint.h datatypes). The types are defined in CmpStd.h and starts always with RTS_, e.g. RTS_UI32.

Rules:

• Use always the predefined RTS_ datatypes in all interfaces!

• Additionally you must use it in all implementations, where a fix size is needed (e.g. L7 service in communication)!

• For all other internal implementations it is recommended, to use this datatypes too. The only exception for using native datatypes is when calling native OS- or Firmware functions.

• For IEC libraries there are the corresponding IEC type definitions in CmpStd.h:

  e.g. RTS_IEC_BOOL for an IEC bool value. The types are exported automatically of the m4-Export Tool in CODESYS out of a library. Use the Systems Hungarian notation! That means the datatype of an identifier is described in as a prefix in the name.

  For example:

  RTS_UI32 ui32NumOfTasks;

  All prefixes are described in the tables below.

• static variables with s_ as prefix, e.g. static char s_cTag;

• static arrays with a as prefix, e.g. static RTS_UI8 s­_aui8Buffer[100];

  Note: Static arrays have the prefix a to avoid confusing a variable with a pointer p!

• Pointers starts with p as prefix, e.g. RTS_UI8 *pui8Buffer;

• Function pointers starts with pf as prefix, e.g. INT_HANDLER *pfHandler;

RTS datatypes:

The standard RTS_ datatypes contains the real size Bits, e.g. RTS_I8 (8 Bits). So the corresponding size is identical on every platform!

Datatype	Prefix	Size in Bits	Usage
RTS_I8	i8	8	Signed values
RTS_UI8	ui8	8	Unsigned values
RTS_I16	i16	16	Signed values
RTS_UI16	ui16	16	Unsigned values
RTS_I32	i32	32	Signed values
RTS_UI32	ui32	32	Unsigned values
RTS_I64	i64	64	Signed values
RTS_UI64	ui64	64	Unsigned values
RTS_REAL32	r32	32	Floating point values
RTS_REAL64	r64	64	Floating point values
RTS_WCHAR	wsz	16	16Bit Unicode character	The wsz and sz prefixes are for pointers to characters or arrays of characters. Examples: RTS_WCHAR * wszName; RTS_CSTRING szName[];
RTS_CSTRING	sz	8	8Bit ASCII character

There are some special datatypes which usage is explained here:

Datatype	Prefix	Size in Bits	Usage
RTS_HANDLE	h	Size to hold always a pointer	For every handle in the runtime system
RTS_RESULT	r	32	For error codes
RTS_UINTPTR	uiptr	Size to hold always the address of a pointer	For pointer arithmetic hold in an unsigned integral type
RTS_INTPTR	iptr	Size to hold always the address of a pointer	For pointer arithmetic hold in a signed integral type
RTS_PTRDIFF	ptrdiff	Size to hold always a pointer difference for a buffer offset	Signed integral type that can hold an array index
RTS_SIZE	si	Size to hold always a buffer offset	Unsigned integral type that can hold a buffer offset
RTS_TIME	t	dependant on the platform (e.g. 32Bit on 32Bit platforms, 64Bit on 64Bit platforms)	Time to hold a UTC value
RTS_INT	i	Variant size, typical the platform specific int size	Data type has no constant size, so be careful, in sharing such data types with IEC!
RTS_BOOL	b	Variant size, typical the platform specific int size	Boolean value (TRUE or FALSE) Data type has no constant size, so be careful, in sharing with IEC!

1.11.4.2. ANSI/ISO C native datatypes

stdint.h datatypes

With the ISO standard C99, a new portable typesystem was introduced by stdint.h. See opengroup stdint.h.

We ported the RTS datatypes to this typesystem to be widely portable.

ANSI-C datatypes

Native ANSI C89/ISO C89 datatypes should be avoided! They are forbidden in newer interfaces, because they are binary portable! See ANSI C Datatypes for the platform specific ANIC-C datatypes.