Integer Types

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XSD defines several integer types including integer, byte, unsignedByte, positiveInteger, etc.. Each of these types is mapped to a C type depending on the following factors:

• The name of the type (for example, unsignedByte is mapped to a different type - OSUINT8 - than integer - OSINT32,
• Value range facets (minInclusive, maxInclusive, minExclusive, maxExclusive) that are applied to the type.

By default, an xsd:integer with no constraints results in the generation of an "OSINT32" type which is a standard C signed 32-bit integer type. The general mapping is as follows:

XSD type:	<xsd:simpleType name="TypeName"> <restriction base="xsd:integer"/> </xsd:simpleType>
Generated C code:	typedef OSINT32 TypeName;
Generated C++ code:	class TypeName : public OSBaseType { OSINT32 value; ... } ;

Value range facets will alter the C type used to represent a given integer value. The smallest integer type that can hold the constrained value will always be used. For example, the following declaration declares an integer to hold a value between 2 and 10 (inclusive):

 
<xsd:simpleType name="Int_2_to_10">
 
        <xsd:restriction base="xsd:integer">
 
           <xsd:minInclusive value="2"/>
 
           <xsd:maxInclusive value="10"/>
 
        </xsd:restriction>
 
     </xsd:simpleType>
 

 

In this case, a byte type (unsigned char) could be used to hold the value because it must be between 2 and 10 (a signed byte could also be used but an unsigned value is always used whenever negative numbers are not required). Other value ranges would cause different integer types to be used that provide the most efficient amount of storage.

The following table shows the types that would be used for the different range values:

Min Lower Bound	Max Upper Bound	C Type (rtx)	C Type (base)
-128	127	OSINT8	char (signed 8-bit int)
0	255	OSUINT8	unsigned char (unsigned 8-bit number)
-32768	32767	OSINT16	short (signed 16-bit int)
0	65535	OSUINT16	unsigned short (unsigned 16-bit int)
-2147483648	2147483647	OSINT32	int (signed 32-bit integer)
0	4294967295	OSUINT32	unsigned int (unsigned 32-bit integer)