Table 1–2 (Cont.) Parameter Data Types
Data Type
Description
longword
32-bit unsigned integer
ptr
Longword pointer to data buffer
short
Synonym for short int
short int
16-bit signed integer
unsigned long int
32-bit unsigned integer
void *
Pointer to object of unknown type
1.3.2 Access
Access describes the way in which the called routine accesses the data specified
by the parameter. The access methods are described in Table 1–3.
Table 1–3 Called Routine Access Methods
Access Method
Description
Read
Data needed by the called routine to perform its operation is read
but not returned.
Write
Data that the called routine returns to the calling routine is written
into a location accessible to the calling routine.
Modify
Data is both read and returned by the called routine; input data
specified by the parameter is overwritten.
1.3.3 Mechanism
The parameter-passing mechanism is the way in which a parameter specifies
the data to be used by the called routine. The passing mechanisms are
described in Table 1–4.
Service Format 1–3
