In Windows, export VPI functions from vvp.exe (GitHub issue #395)

This is to support cocotb, who don't use our vpi_user.h and libvpi.a,
instead building their own import library to directly link to vvp.

vvp/Makefile.in

@@ -38,6 +38,7 @@ HOSTCFLAGS = @WARNING_FLAGS@ @WARNING_FLAGS_CC@ @CFLAGS@
 BUILDCC = @CC_FOR_BUILD@
 BUILDEXT = @BUILD_EXEEXT@
 CXX = @CXX@
+DLLTOOL = @DLLTOOL@
 INSTALL = @INSTALL@
 INSTALL_SCRIPT = @INSTALL_SCRIPT@
 INSTALL_PROGRAM = @INSTALL_PROGRAM@
@@ -118,8 +119,22 @@ Makefile: $(srcdir)/Makefile.in
 dep:
 	mkdir dep
 
+ifeq (@WIN32@,yes)
+# To support cocotb, we export the VPI functions directly. This allows
+# cocotb to build VPI modules without using our vpi_user.h and libvpi.a.
+# This requires making the vvp.exe in two steps. The first step makes
+# a vvp.exe that dlltool can use to make an export library, and the
+# second step makes a vvp.exe that really exports those things.
+vvp@EXEEXT@: $O $(srcdir)/vvp.def
+	$(CXX) -o vvp$(suffix)@EXEEXT@ $(LDFLAGS) $O $(dllib) $(LIBS)
+	$(DLLTOOL) --dllname vvp$(suffix)@EXEEXT@ --def $(srcdir)/vvp.def \
+		--output-exp vvp.exp
+	rm -f vvp$(suffix)@EXEEXT@
+	$(CXX) $(LDFLAGS) -o vvp@EXEEXT@ vvp.exp $(LDFLAGS) $O $(dllib) $(LIBS)
+else
 vvp@EXEEXT@: $O
 	$(CXX) $(LDFLAGS) -o vvp@EXEEXT@ $O $(LIBS) $(dllib)
+endif
 
 %.o: %.cc config.h
 	$(CXX) $(CPPFLAGS) -DIVL_SUFFIX='"$(suffix)"' $(MDIR1) $(MDIR2) $(CXXFLAGS) @DEPENDENCY_FLAG@ -c $< -o $*.o

vvp/vpi_modules.cc

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001-2019 Stephen Williams ([email protected])
+ * Copyright (c) 2001-2020 Stephen Williams ([email protected])
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -221,16 +221,13 @@ void vpip_load_module(const char*name)
 
 #if defined(__MINGW32__) || defined (__CYGWIN__)
       void*function = ivl_dlsym(dll, "vpip_set_callback");
-      if (function == 0) {
-	    fprintf(stderr, "%s: no vpip_set_callback()\n", name);
-	    ivl_dlclose(dll);
-	    return;
-      }
-      vpip_set_callback_t set_callback = (vpip_set_callback_t)function;
-      if (!set_callback(&vpi_routines, vpip_routines_version)) {
-	    fprintf(stderr, "Failed to link VPI module %s. Try rebuilding it with iverilog-vpi.\n", name);
-	    ivl_dlclose(dll);
-	    return;
+      if (function) {
+            vpip_set_callback_t set_callback = (vpip_set_callback_t)function;
+            if (!set_callback(&vpi_routines, vpip_routines_version)) {
+	          fprintf(stderr, "Failed to link VPI module %s. Try rebuilding it with iverilog-vpi.\n", name);
+	          ivl_dlclose(dll);
+	          return;
+            }
       }
 #endif
 

vvp/vvp.def

@@ -0,0 +1,45 @@
+EXPORTS
+
+vpi_chk_error
+vpi_compare_objects
+vpi_control
+vpi_flush
+vpi_fopen
+vpi_free_object
+vpi_get
+vpi_get_delays
+vpi_get_file
+vpi_get_str
+vpi_get_systf_info
+vpi_get_time
+vpi_get_userdata
+vpi_get_value
+vpi_get_vlog_info
+vpi_handle
+vpi_handle_by_index
+vpi_handle_by_name
+vpi_iterate
+vpi_mcd_close
+vpi_mcd_flush
+vpi_mcd_name
+vpi_mcd_open
+vpi_mcd_printf
+vpi_mcd_vprintf
+vpi_printf
+vpi_put_delays
+vpi_put_userdata
+vpi_put_value
+vpi_register_cb
+vpi_register_systf
+vpi_remove_cb
+vpi_scan
+vpi_sim_control
+vpi_sim_vcontrol
+vpi_vprintf
+
+vpip_calc_clog2
+vpip_count_drivers
+vpip_format_strength
+vpip_make_systf_system_defined
+vpip_mcd_rawwrite
+vpip_set_return_value