From c442cbcc2322dac3f237965c3cae99e8788c7466 Mon Sep 17 00:00:00 2001
From: Kaspar Schleiser <kaspar@schleiser.de>
Date: Wed, 22 Mar 2017 11:04:41 +0100
Subject: [PATCH 1/3] make: Makefile.base: don't collect wildcard sources if
 NO_AUTO_SRC is nonempty

---
 Makefile.base | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Makefile.base b/Makefile.base
index 8bbe3e39ad..06f4563251 100644
--- a/Makefile.base
+++ b/Makefile.base
@@ -22,16 +22,16 @@ ${DIRS:%=ALL--%}:
 ${DIRS:%=CLEAN--%}:
 	$(QQ)"$(MAKE)" -C ${@:CLEAN--%=%} clean
 
-ifeq ($(strip $(SRC)),)
+ifeq ($(strip $(SRC))$(NO_AUTO_SRC),)
     SRC := $(filter-out $(SRC_NOLTO), $(wildcard *.c))
 endif
-ifeq ($(strip $(SRCXX)),)
+ifeq ($(strip $(SRCXX))$(NO_AUTO_SRC),)
     SRCXX := $(wildcard *.cpp)
 endif
-ifeq ($(strip $(ASMSRC)),)
+ifeq ($(strip $(ASMSRC))$(NO_AUTO_SRC),)
     ASMSRC := $(wildcard *.s)
 endif
-ifeq ($(strip $(ASSMSRC)),)
+ifeq ($(strip $(ASSMSRC))$(NO_AUTO_SRC),)
     ASSMSRC := $(wildcard *.S)
 endif
 

From 933a7a3efe9f33493a1e04a83626bd4d3b037341 Mon Sep 17 00:00:00 2001
From: Kaspar Schleiser <kaspar@schleiser.de>
Date: Wed, 22 Mar 2017 15:51:36 +0100
Subject: [PATCH 2/3] make: add submodule support

---
 Makefile.base | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Makefile.base b/Makefile.base
index 06f4563251..533e1e7017 100644
--- a/Makefile.base
+++ b/Makefile.base
@@ -22,6 +22,23 @@ ${DIRS:%=ALL--%}:
 ${DIRS:%=CLEAN--%}:
 	$(QQ)"$(MAKE)" -C ${@:CLEAN--%=%} clean
 
+## submodules
+ifeq (1, $(SUBMODULES))
+    # don't use *.c as SRC if SRC is empty (e.g., no module selected)
+    NO_AUTO_SRC := 1
+
+    # allow different submodule basename (e.g., MODULE=cpu_periph_common, but match just periph_%)
+    BASE_MODULE ?= $(MODULE)
+
+    # for each $(BASE_MODULE)_<name> in USEMODULE, add <name>.c to SRC
+    SRC += $(patsubst $(BASE_MODULE)_%,%.c,$(filter $(BASE_MODULE)_%,$(USEMODULE)))
+
+    # don't fail if a selected *.c file does not exist
+    ifeq (1, $(SUBMODULES_NOFORCE))
+        SRC := $(filter $(SRC), $(wildcard *.c))
+    endif
+endif
+
 ifeq ($(strip $(SRC))$(NO_AUTO_SRC),)
     SRC := $(filter-out $(SRC_NOLTO), $(wildcard *.c))
 endif

From 0b10dccf6443a8c6c5720ea2b12badd352b4eed3 Mon Sep 17 00:00:00 2001
From: Kaspar Schleiser <kaspar@schleiser.de>
Date: Wed, 22 Mar 2017 15:01:45 +0100
Subject: [PATCH 3/3] core: adapt to Makefile.submodule

---
 Makefile.pseudomodules | 4 +---
 core/Makefile          | 6 ++++++
 core/mbox.c            | 4 ----
 core/msg.c             | 4 ----
 core/thread_flags.c    | 2 --
 5 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/Makefile.pseudomodules b/Makefile.pseudomodules
index a91c8c63ea..2602805b4b 100644
--- a/Makefile.pseudomodules
+++ b/Makefile.pseudomodules
@@ -3,9 +3,7 @@ PSEUDOMODULES += conn
 PSEUDOMODULES += conn_ip
 PSEUDOMODULES += conn_tcp
 PSEUDOMODULES += conn_udp
-PSEUDOMODULES += core_msg
-PSEUDOMODULES += core_mbox
-PSEUDOMODULES += core_thread_flags
+PSEUDOMODULES += core_%
 PSEUDOMODULES += emb6_router
 PSEUDOMODULES += gnrc_ipv6_default
 PSEUDOMODULES += gnrc_ipv6_router
diff --git a/core/Makefile b/core/Makefile
index 48422e909a..4f12366947 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1 +1,7 @@
+# exclude submodule sources from *.c wildcard source selection
+SRC := $(filter-out mbox.c msg.c thread_flags.c,$(wildcard *.c))
+
+# enable submodules
+SUBMODULES := 1
+
 include $(RIOTBASE)/Makefile.base
diff --git a/core/mbox.c b/core/mbox.c
index 7c14f35147..bd5e32415a 100644
--- a/core/mbox.c
+++ b/core/mbox.c
@@ -28,8 +28,6 @@
 #define ENABLE_DEBUG (0)
 #include "debug.h"
 
-#ifdef MODULE_CORE_MBOX
-
 static void _wake_waiter(thread_t *thread, unsigned irqstate)
 {
     sched_set_status(thread, STATUS_PENDING);
@@ -122,5 +120,3 @@ int _mbox_get(mbox_t *mbox, msg_t *msg, int blocking)
         return 0;
     }
 }
-
-#endif /* MODULE_CORE_MBOX */
diff --git a/core/msg.c b/core/msg.c
index 4ab2061411..190244cca8 100644
--- a/core/msg.c
+++ b/core/msg.c
@@ -34,8 +34,6 @@
 #include "debug.h"
 #include "thread.h"
 
-#ifdef MODULE_CORE_MSG
-
 static int _msg_receive(msg_t *m, int block);
 static int _msg_send(msg_t *m, kernel_pid_t target_pid, bool block, unsigned state);
 
@@ -409,5 +407,3 @@ void msg_queue_print(void)
 
     irq_restore(state);
 }
-
-#endif /* MODULE_CORE_MSG */
diff --git a/core/thread_flags.c b/core/thread_flags.c
index 9396c31e30..281a592306 100644
--- a/core/thread_flags.c
+++ b/core/thread_flags.c
@@ -26,7 +26,6 @@
 #define ENABLE_DEBUG (0)
 #include "debug.h"
 
-#ifdef MODULE_CORE_THREAD_FLAGS
 static thread_flags_t _thread_flags_clear_atomic(thread_t *thread, thread_flags_t mask)
 {
     unsigned state = irq_disable();
@@ -133,4 +132,3 @@ void thread_flags_set(thread_t *thread, thread_flags_t mask)
         irq_restore(state);
     }
 }
-#endif /* MODULE_CORE_THREAD_FLAGS */