# This makefile is freely available from the website of Cygnus Solutions
# at http://www.cygnus.com on the cygwin32 home page. The author is
# Fergus Henderson <fjh@cs.mu.oz.au> http://www.cs.mu.oz.au/~fjh
# Before using this file you should read and understand the documentation
# on the Cygnus website.
# This file comes with a suitable disclaimer; i.e.,
# This is provided AS IS, with absolutely NO WARRANTY EITHER EXPRESSED
# OR IMPLIED.

#-----------------------------------------------------------------------------#

# Makefile.DLLs, version 0.7.

# This Makefile contains rules for creating DLLs on Windows using gnu-win32.

#-----------------------------------------------------------------------------#

# The SYM_PREFIX is used as a prefix for the symbols in the files
# that this makefiles automatically generates.
#
# The default SYM_PREFIX for libfoo.dll is `libfoo'.
# But you can override this by setting `SYM_PREFIX-libfoo = blah'.

SYM_PREFIX = $(firstword $(SYM_PREFIX-$*) $*)

GUARD_MACRO =		$(SYM_PREFIX)_GLOBALS_H
DEFINE_DLL_MACRO =	$(SYM_PREFIX)_DEFINE_DLL
USE_DLL_MACRO =		$(SYM_PREFIX)_USE_DLL
IMP_MACRO =		$(SYM_PREFIX)_IMP
GLOBAL_MACRO =		$(SYM_PREFIX)_GLOBAL
IMPURE_PTR =		$(SYM_PREFIX)_impure_ptr

# This rule creates a `.def' file, which lists the symbols that are exported
# from the DLL.  We use `nm' to get a list of all the exported text (`T')
# symbols and data symbols -- including uninitialized data (`B'),
# initialized data (`D'), read-only data (`R'), and common blocks (`C').
# We also export `_impure_ptr', suitably renamed, so that the
# main program can do the necessary initialization of the DLL's _impure_ptr.
# (Since there can be more than one DLL, we must rename _impure_ptr as
# $(SYM_PREFIX)_impure_ptr to prevent name collisions.)
%.def: %.a
	echo EXPORTS > $@
	echo $(IMPURE_PTR) = _impure_ptr >> $@
	nm $< | sed -n '/^........ [BCDRT] _/s/[^_]*_//p' >> $@

# We need to use macros to access global data:
# the user of the DLL must refer to `bar' as `(*__imp_bar)'.
# This rule creates a pair of files `foo_dll.h' and `foo_globals.h'
# which contains macros for doing this.
#
# The DLL may also contain some references to _impure_ptr
# (e.g. stdin is defined as a macro which expands to _impure_ptr.stdin).
# We need to provide a definition for this (otherwise it will link in
# the definition in libccrt.o, which causes lots of problems,
# eventually leading to undefined symbol `WinMain').
# The DLL's entry function (below) will initialize the _impure_ptr variable
# in the DLL so that they point to the main program's reent_data struct.

%_dll.h:
	echo "/* automatically generated by Makefile.DLLs */"	> $@
	echo "#ifndef $(GUARD_MACRO)"				>> $@
	echo "#define $(GUARD_MACRO)"				>> $@
	echo ""							>> $@
	echo "#if defined(__GNUC__) && defined(__CYGWIN32__)"	>> $@
	echo "  #if defined($(USE_DLL_MACRO))"			>> $@
	echo "    #define $(IMP_MACRO)(name)	__imp_##name" 	>> $@
	echo "    #define $(GLOBAL_MACRO)(name)	(*$(IMP_MACRO)(name))" >> $@
	echo "    #include \"$*_globals.h\""			>> $@
	echo "  #endif /* $(USE_DLL_MACRO) */"			>> $@
	echo "#endif /* __GNUC__ && __CYGWIN32__ */"		>> $@
	echo ""							>> $@
	echo "#endif /* $(GUARD_MACRO) */"			>> $@

%_globals.h: %.a
	echo "/* automatically generated by Makefile.DLLs */"	> $@
	for sym in $(IMPURE_PTR) \
		`nm $< | grep '^........ [BCDR] _' | sed 's/[^_]*_//'`; \
	do \
		echo "#define $$sym	$(GLOBAL_MACRO)($$sym)"	>> $@; \
	done

%_dll.c:
	echo "/* automatically generated by Makefile.DLLs */"	> $@
	echo "void *_impure_ptr;"				>> $@

# This rule creates the export object file (`foo.exp') which contains the
# jump table array; this export object file becomes part of the DLL.
# This rule also creates the import library (`foo_dll.a') which contains small
# stubs for all the functions exported by the DLL which jump to them via the
# jump table.  Executables that will use the DLL must be linked against this
# stub library.
%.exp %_dll.a : %.def
	dlltool $(DLLTOOLFLAGS) $(DLLTOOLFLAGS-$*)		\
		--def $<					\
		--dllname $*.dll				\
		--output-exp $*.exp				\
		--output-lib $*_dll.a

# The `sed' commands below are to convert DOS-style `C:\foo\bar'
# pathnames into Unix-style `//c/foo/bar' pathnames.
CYGWIN32_LIBS = $(shell echo					\
	-L`dirname \`gcc -print-file-name=libgcc.a |		\
	sed -e 's@^\\\\([A-Za-z]\\\\):@//\\\\1@g' -e 's@\\\\\\\\@/@g' \` ` \
	-L`dirname \`gcc -print-file-name=libcygwin.a |	\
	sed -e 's@^\\\\([A-Za-z]\\\\):@//\\\\1@g' -e 's@\\\\\\\\@/@g' \` ` \
	-L`dirname \`gcc -print-file-name=libkernel32.a | \
	sed -e 's@^\\\\([A-Za-z]\\\\):@//\\\\1@g' -e 's@\\\\\\\\@/@g' \` ` \
	-lgcc -lcygwin -lkernel32 -lgcc)

# Making relocatable DLLs doesn't seem to work.
# Not quite sure why.  The --image-base values below
# where chosen at random, they seem to work on my machine.
# DYNRELOC=no is the default
# DLLDFLAGS-libgc +=	--image-base=0x2345000
# DLLDFLAGS-libmer +=	--image-base=0x1234000
# DLLDFLAGS-libmercury +=	--image-base=0x3456000

ifeq "$(strip $(DYNRELOC))" "yes"

# to create relocatable DLLs, we need to do two passes
# (warning: this is untested)
%.dll: %.exp %.a %_dll.o dll_init.o dll_fixup.o
	$(DLLD) $(DLLDFLAGS) $(DLLDFLAGS-$*) --dll -o $*.base			\
		-e _dll_entry@12					\
		$*.exp $*.a $*_dll.o					\
		dll_init.o dll_fixup.o					\
		$(LDLIBS) $(LDLIBS-$*)					\
		$(CYGWIN32_LIBS)
	# untested
	dlltool $(DLLTOOLFLAGS) $(DLLTOOLFLAGS-$*)		\
		--def $*.def					\
		--dllname $*.dll				\
		--base-file $*.base				\
		--output-exp $*.exp
	$(DLLD) $(DLLDFLAGS) $(DLLDFLAGS-$*) --dll -o $*.base			\
		-e _dll_entry@12					\
		$*.exp $*.a $*_dll.o					\
		dll_init.o dll_fixup.o					\
		$(LDLIBS) $(LDLIBS-$*)					\
		$(CYGWIN32_LIBS)
	dlltool $(DLLTOOLFLAGS) $(DLLTOOLFLAGS-$*)		\
		--def $*.def					\
		--dllname $*.dll				\
		--base-file $*.base				\
		--output-exp $*.exp
	# end untested stuff
	$(DLLD) $(DLLDFLAGS) $(DLLDFLAGS-$*) --dll --base-file $*.base -o $@	\
		-e _dll_entry@12 					\
		$*.exp $*.a $*_dll.o 					\
		dll_init.o dll_fixup.o					\
		$(LDLIBS) $(LDLIBS-$*)					\
		$(CYGWIN32_LIBS)
	rm -f $*.base

else

%.dll: %.exp %.a %_dll.o dll_fixup.o dll_init.o
	$(DLLD) $(DLLDFLAGS) $(DLLDFLAGS-$*) --dll -o $@			\
		-e _dll_entry@12 					\
		$*.exp $*.a $*_dll.o 					\
		dll_init.o dll_fixup.o					\
		$(LDLIBS) $(LDLIBS-$*)					\
		$(CYGWIN32_LIBS)

endif

# This black magic piece of assembler needs to be linked in in order to
# properly terminate the list of imported DLLs.
dll_fixup.s:
	echo '.section .idata$$3' 	> dll_fixup.s
	echo '.long 0,0,0,0,0'		>> dll_fixup.s

dll_fixup.o: dll_fixup.s
	$(AS) $(ASFLAGS) -o dll_fixup.o dll_fixup.s

# Windows requires each DLL to have an initialization function
# that is called at certain points (thread/process attach/detach).
# This one just initializes `_impure_ptr'.
dll_init.c:
	echo '#include <stdio.h>' 				> dll_init.c
	echo 'extern struct _reent *_impure_ptr;'		>> dll_init.c
	echo 'extern __declspec(dllimport) struct _reent reent_data;' >> dll_init.c
	echo '__attribute__((stdcall))'				>> dll_init.c
	echo 'int dll_entry(int handle, int reason, void *ptr)'	>> dll_init.c
	echo '{ _impure_ptr = reent_data; return 1; }'	>> dll_init.c

# The following rule is just there to convince gcc
# to keep otherwise unused intermediate targets around.
dont_throw_away: dll_fixup.o dll_init.o