The DosGetSTDA API is a 16 bit API that returns a copy of the system trace buffer (STDA).
Syntax
The following 16 bit C language function prototype can be used to call the DosGetSTDA API:
// 16 bit compiler
extern unsigned far pascal DosGetSTDA( SEL, SHORT, SHORT );
// 32 bit compiler
APIRET16 APIENTRY16 DosGetSTDA( SEL, SHORT, SHORT );
Where: SEL is the selector to the private buffer
SHORT is the offset to the private buffer
SHORT is the size of the buffer
(maximum value = 64KB)
records
Returns: 0 - indicates correct operation, buffer is now filled
with copy of the system trace buffer
ERROR_SYSTEM_TRACE - System trace is not enabled
Linker Considerations
In order to successfully resolve DosGetSTDA function calls in your program, the following lines must be added to the Linker Definition (DEF) file:
IMPORTS DOSGETSTDA=DOSCALL1.119
Remarks
DosGetSTDA returns a buffer that contains a copy of the system trace buffer. The buffer is circular with a header record that contains pointers to the first and last data bytes and a pointer to the next byte that was available for writing (the buffer is a snapshot of the system trace buffer at the time that the API was called). A set of trace records follows the header. Each trace record contains a trace event trailer and optionally a timestamp and/or a data field. A Timestamp record is optional and will only exist if bit 2 of the flag field in the Trace Event Trailer is set to OFF.
The trace event data contains the information describing each individual trace event. The events traced may be from OS/2 system supplied or other user supplied tracepoints. In either case the data is dependent on each individual tracepoint. Descriptions of the data and formatting instructions for the OS/2 system supplied tracepoints can be found in the System Tracepoints Reference chapter.