Makefile.syms

# Utility makefile to generate a helper object 'syms.o'
# who may be linked with CEXP to force the linker adding
# more stuff from the system libraries than needed
# by CEXP itself.
#
# There are two ways of using this.
#  1) you may add object files to OBJLIST. The objects
#     in that list are 'modules' intended to be loaded
#     by the CEXP application later. The set of all 
#     undefined symbols referenced by objects in OBJLIST
#     is added to 'syms.o'
#  2) you may add system libraries to LIBLIST to add
#     all symbols exported by the given libraries to 'syms.o'
#
# The resulting 'syms.o' file must be linked with the
# final CEXP application (e.g. the 'cexp' demo utility)
#
# You may use OBJLIST and LIBLIST at the same time or leave
# either of them empty.
#
# NOTE: in some cases, 'syms.o' may enforce adding parts
#       of libraries who reference symbols that are defined
#       NOWHERE. This may happen when the respective
#       library parts are normally never used but are added
#       as a side effect of 'syms.o'.
#       In this case, you may have to manually tune the intermediate
#       file 'symlist' and remove offending symbols by commenting
#       (C-style /**/ comments) them out.
#
# Author: Till Straumann <strauman@slac.stanford.edu>, 2003/1
# 
# CAVEATS: you may need GNU versions of AWK, NM and LD
#
AWK=awk
NM=nm

# add objects searched for undefined symbols
OBJLIST=

# add libraries searched for exported symbols
LIBLIST=

all: syms.o

objsyms: $(OBJLIST)
	$(RM) -f $@
ifeq "$(OBJLIST)xxx" "xxx"
	touch $@
else
	$(NM) -u $(OBJLIST) > $@
endif

libsyms: $(LIBLIST)
	$(RM) -f $@
ifeq "$(LIBLIST)xxx" "xxx"
	touch $@
else
	$(NM) --defined-only -g $(LIBLIST) > $@
endif

symlist: objsyms libsyms
	$(RM) -f $@
	$(AWK) '/^[^:]+$$/{printf("EXTERN(%s)\n",$$NF);}' $^ | sort | uniq > $@

empty.c:
	touch $@

empty.o: empty.c
	$(CC) -c -o $@ $<

syms.o: empty.o symlist
	$(LD) -T symlist empty.o -o $@

clean::
	$(RM) symlist objsyms libsyms empty.c empty.o symlist