samples/static_lib: Linking with a static library

This sample shows how to integrate a static libray into a Zephyr
application. A hello_world application and a small library are
included.

Origin: Original

Jira: ZEP-366
Change-Id: Idab38402b47042c3f9369b3a8e433d07d5fa4535
Signed-off-by: Flavio Santes <flavio.santes@intel.com>

samples/static_lib/Makefile

@@ -0,0 +1,38 @@
+#
+# Copyright (c) 2016 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+MYLIB = mylib/lib/libmylib.a
+
+all:
+	make clean
+	make mylib
+	make hello_world
+
+hello_world: $(MYLIB)
+	make -C hello_world
+
+$(MYLIB):
+	make -C mylib
+
+run:
+	make -C hello_world qemu
+
+pristine:
+	make -C mylib clean
+	make -C hello_world pristine
+
+clean:
+	make pristine

samples/static_lib/README

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+Linking with a static library
+#############################
+
+This sample shows how to link a static library to a Zephyr application.
+A sample library is also included.
+
+Read mylib/Makefile to discover how to use the Zephyr's toolchain
+to build a static library.
+
+If the library's source code is available, perhaps it could be more
+easier to integrate that source code to your application than creating
+the static library.
+
+
+Build instructions
+==================
+
+1. It is assumed that ZEPHYR_GCC_VARIANT and ZEPHYR_SDK_INSTALL_DIR
+variables are already set. See:
+
+https://www.zephyrproject.org/doc/getting_started/getting_started.html
+
+2. source $ZEPHYR/zephyr-env.sh
+
+   Where $ZEPHYR points to the directory that contains the zephyr
+   repository.
+
+3. make
+
+4. make run

samples/static_lib/hello_world/Kbuild

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+subdir-ccflags-y += -I$(SOURCE_DIR)/../mylib/include
+
+obj-y += src/

samples/static_lib/hello_world/Makefile

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+#
+# Copyright (c) 2016 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+KERNEL_TYPE = nano
+BOARD = qemu_x86
+CONF_FILE = prj.conf
+
+export SOURCE_DIR = $(ZEPHYR_BASE)/samples/static_lib/hello_world
+export LDFLAGS_zephyr += -L$(CURDIR)/../mylib/lib
+export ALL_LIBS += mylib
+
+include ${ZEPHYR_BASE}/Makefile.inc

samples/static_lib/hello_world/prj.conf

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+CONFIG_STDOUT_CONSOLE=y

samples/static_lib/hello_world/src/Makefile

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+#
+# Copyright (c) 2016 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+obj-y += main.o

samples/static_lib/hello_world/src/main.c

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+/* hello world example: calling functions from a static library */
+
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <zephyr.h>
+#include <stdio.h>
+
+#include <mylib.h>
+
+void main(void)
+{
+	printf("Hello World!\n");
+	mylib_hello_world();
+}
+

samples/static_lib/mylib/Makefile

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+#
+# Copyright (c) 2016 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+include $(ZEPHYR_BASE)/scripts/Makefile.toolchain.$(ZEPHYR_GCC_VARIANT)
+
+# This Makefile is like a replacement of the $(ZEPHYR_BASE)/Makefile
+# for libraries. So, we need to define ARCH here.
+ARCH ?= x86
+
+CROSS_COMPILE = $(CROSS_COMPILE_$(ARCH))
+TOOLCHAIN_CFLAGS = $(TOOLCHAIN_CFLAGS_$(ARCH))
+
+CC = $(CROSS_COMPILE)gcc
+AR = $(CROSS_COMPILE)ar
+
+all:
+	mkdir -p obj lib
+	$(CC) -c $(TOOLCHAIN_CFLAGS) -Iinclude src/mylib.c -o obj/mylib.o
+	$(AR) -rcs lib/libmylib.a obj/mylib.o
+
+clean:
+	rm -rf obj lib
+

samples/static_lib/mylib/include/mylib.h

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+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _MYLIB_H_
+#define _MYLIB_H_
+
+int mylib_hello_world(void);
+
+#endif

samples/static_lib/mylib/src/mylib.c

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+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "mylib.h"
+#include <stdio.h>
+
+int mylib_hello_world(void)
+{
+	printf("mylib says: Hello World!");
+	return 0;
+}