libCom: epicsVersion.h changes

Make version numbers easier to compare.

documentation/RELEASE_NOTES.html

@@ -15,6 +15,26 @@ EPICS Base 3.15.0.x releases are not intended for use in production systems.</p>
 <h2 align="center">Changes between 3.14.x and 3.15.0.x</h2>
 <!-- Insert new items immediately below here ... -->
 
+<h3>
+Changes to epicsVersion.h</h3>
+
+<p>
+The two macros <tt>EPICS_UPDATE_LEVEL</tt> and <tt>EPICS_CVS_SNAPSHOT</tt> have
+been deleted from the epicsVersion.h file; they were deprecated in R3.14 and can
+be replaced with <tt>EPICS_PATCH_LEVEL</tt> and <tt>EPICS_DEV_SNAPSHOT</tt>
+respectively.</p>
+
+<p>
+A new pair of macros has been added to make version number comparisons easier.
+Code that will not work with a version of Base before 3.15.0 can now be
+written like this to prevent it from compiling:</p>
+
+<pre style="margin: 0 2em;">
+#if defined(VERSION_INT) && EPICS_VERSION_INT < VERSION_INT(3,15,0,0)
+#  error EPICS Base R3.15.0 or later is required
+#endif
+</pre>
+
 <h3>
 Added support for iocLogPrefix</h3>
 

src/libCom/misc/RULES

@@ -7,6 +7,7 @@
 
 # This is a Makefile fragment, see src/libCom/Makefile.
 
-$(COMMON_DIR)/epicsVersion.h: $(CONFIG)/CONFIG_BASE_VERSION $(CONFIG)/CONFIG_SITE
+$(COMMON_DIR)/epicsVersion.h: $(CONFIG)/CONFIG_BASE_VERSION \
+	$(CONFIG)/CONFIG_SITE $(LIBCOM)/misc/makeEpicsVersion.pl
 	$(PERL) $(LIBCOM)/misc/makeEpicsVersion.pl $(CONFIG)/CONFIG_BASE_VERSION $(@D) $(EPICS_SITE_VERSION)
 

src/libCom/misc/makeEpicsVersion.pl

@@ -55,6 +55,9 @@ open my $OUT, '>', $epicsVersion
 print $OUT <<"END_OUTPUT";
 /* Generated epicsVersion.h */
 
+#ifndef INC_epicsVersion_H
+#define INC_epicsVersion_H
+
 #define EPICS_VERSION        $ver
 #define EPICS_REVISION       $rev
 #define EPICS_MODIFICATION   $mod
@@ -64,10 +67,14 @@ print $OUT <<"END_OUTPUT";
 #define EPICS_VERSION_STRING "EPICS $ver_str"
 #define epicsReleaseVersion  "EPICS R$ver_str $commit_date"
 
+#define VERSION_INT(V,R,M,P) ( ((V)<<24) | ((R)<<16) | ((M)<<8) | (P))
+#define EPICS_VERSION_INT VERSION_INT($ver, $rev, $mod, $patch)
+
 /* The following names are deprecated, use the equivalent name above */
 #define EPICS_UPDATE_LEVEL   EPICS_PATCH_LEVEL
 #define EPICS_CVS_SNAPSHOT   EPICS_DEV_SNAPSHOT
 
+#endif /* INC_epicsVersion_H */
 END_OUTPUT
 
 close $OUT;