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diff --git a/README.Watcom b/README.Watcom new file mode 100644 index 0000000..2974928 --- /dev/null +++ b/README.Watcom @@ -0,0 +1,62 @@ +Watcom compiler notes +===================== + +Status +------ +Not yet usable. Although the library builds under Watcom it +substantially fails the test suite. + +There is a working Wmakefile for wmake for the library build. + +invoke as any of: +wmake -f Wmakefile clean WC +wmake -f Wmakefile clean WC-inlined +wmake -f Wmakefile clean WCE +wmake -f Wmakefile clean WCE-inlined + +These build pthreadWC.dll and pthreadWCE.dll. + +There is a working Wmakefile for wmake for the test suite. + +invoke as any of: +wmake -f Wmakefile clean WC +wmake -f Wmakefile clean WCX +wmake -f Wmakefile clean WCE +wmake -f Wmakefile clean WC-bench +wmake -f Wmakefile clean WCX-bench +wmake -f Wmakefile clean WCE-bench + + +Current known problems +---------------------- + +Library build: +The Watcom compiler uses a different default call convention to MS C or GNU C and so +applications are not compatible with pthreadVC.dll etc using pre 2003-10-14 versions +of pthread.h, sched.h, or semaphore.h. The cdecl attribute can be used on exposed +function prototypes to force compatibility with MS C built DLLs. + +However, there appear to be other incompatibilities. Errno.h, for example, defines +different values for the standard C and POSIX errors to those defined by the MS C +errno.h. It may be that references to Watcom's threads compatible 'errno' do set +and return translated numbers consistently, but I have not verified this. + +Watcom defines errno as a dereferenced pointer returned by the function +_get_errno_ptr(). This is similar to both the MS and GNU C environments for +multithreaded use. However, the Watcom version appears to have a number of problems: + +- different threads return the same pointer value. Compare with the MS and GNU C +versions which correctly return different values (since each thread must maintain +a thread specific errno value). + +- an errno value set within the DLL appears as zero in the application even though +both share the same thread. + +Therefore applications built using the Watcom compiler may need to use +a Watcom built version of the library (pthreadWC.dll). If this is the case, then +the cdecl function attribute should not be required. + +Application builds: +The test suite fails with the Watcom compiler. + +Test semaphore1.c fails for pthreadWC.dll because errno returns 0 instead of EAGAIN. |