As of revision 9546, I have completed the first pass at a new, more powerful public API for libqsastime. This (new) public API is documented in README.qsastime_API and qsastime.h and largely consists of powerful wrappers for the internal helper functions which are well-tested by qsastime_test and qsastime_testlib. Right now the only transformations available are Gregorian versus Julian and arbitrary linear transformations of the continuous time variable.
Immediate future plans include generalizing configqsas so there is an option to specify the offsets by using broken-down time rather than directly. (Thanks to Andrew Ross for this suggestion.) More distant future plans include putting in the transformation (e.g., leap seconds) between UTC broken-down time and atomic-clock based times such as TT. Eventually, I plan the default transformation to be UTC broken-down-time to a continuous TT time in seconds since the TT epoch, but for now the default transformation (flagged by a zero scale) is Gregorian broken-down time (with leap seconds ignored) to seconds since the Unix epoch of 1970-01-01 (with leap seconds ignored). All the helper functions (some of which are tested by qsastime_test and qsastime_testlib) are now not explicitly visible. That is, if you use the -fvisibility=hidden option for gcc, the helper functions will not be available for linking (which is a good thing since we want to keep them private). An issue for libqsastime at the present time is it is not thread safe because of the global qsasconfig pointer to a QSASConfig struct that contains all the information necessary to configure the corrections and linear transformations made to transform between continuous and broken-down-time (and vice versa). Ideally, libqsastime should be made thread safe since that makes it much more useful to users who I assume will be using it independently of PLplot (which is not thread safe, itself, but that is a separate issue) for threaded applications on their multi-processor boxes in the future. I have read http://publib.boulder.ibm.com/infocenter/systems/topic/com.ibm.aix.genprogc/doc/genprogc/writing_reentrant_thread_safe_code.htm which indicates you have to do something special to make libraries with global data such as global pointers thread-safe, but it doesn't say what. Could somebody help me with this issue, please? I have changed plbox.c to use the new public API for libqsastime in a minimal and rather crude way as a proof of concept. Everything builds without issues on my platform and produces identical example 29 results. Tomorrow I hope to (finally) start (and also finish) implementing a PLplot public time API for the C language which will be much less crude than what currently happens in plbox.c. now. This PLplot API will be based on configqsas, btimeqsas, ctimeqsas, and strfqsas. (closeqsas will just be run automatically whenever we run plend so will not require a PLPlot API to wrap it). The new PLplot time API will eventually be propagated to all our languages, and it will also be used for example 29 so that all the cross-platform issues we had before with the C library time functions, the diverse (and sometimes non-existent) time functions for non-C languages, and the difficulty we had turning off time zone corrections that we didn't want, will all be solved in a uniform way. We have been looking forward to accomplishing that goal for a long time so it is really nice to see it getting so much closer to hand. Alan __________________________ Alan W. Irwin Astronomical research affiliation with Department of Physics and Astronomy, University of Victoria (astrowww.phys.uvic.ca). Programming affiliations with the FreeEOS equation-of-state implementation for stellar interiors (freeeos.sf.net); PLplot scientific plotting software package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project (lbproject.sf.net). __________________________ Linux-powered Science __________________________ ------------------------------------------------------------------------------ Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
