Cmake和Catkin_make

嵌入式Linux开发

本次技术分享是个人在准备智能车竞赛时候的Linux嵌入式开发所学，也算是对自己的一个勉励，智能车也是本人目前比较感兴趣的一个方向，首先我想跟大家分享的就是最基础的编译部分。

前言：

在传统的linux工程管理用Makefile的比较多（Uboot里面也是大量使用Makefile来进行管理工程）；在新型领域，比如物联网开发（特别是一些开源项目等），用Cmake的比较多。

1.安装

嵌入式Linux一般用ubuntu进行开发，这里打开terminal直接用apt安装即可

apt install cmake

2.例子

简单代码例子

main.c如下

#include <stdio.h>

int main(void)
{
    printf("hello,world\n");
		return 0;

}

比如说当前的目录是 /home/dev

那我们需要创建一个CMakeLists.txt，在终端中输入

touch CMakeLists.txt

这时候我们ls一下，当前目录下应该有

CMakeLists.txt main.c

这两个文件

CMakeLists.txt内容如下

cmake_minimum_required (VERSION 3.0)

project (test)

add_executable(main main.c)

1.表示最低需要cmake版本是3.0

2.表示当前项目名字是test

3.表示源文件是main.c 最终的elf文件是main

3.使用

在当前目录下，在终端中输入cmake .就可以生成makefile等文件，此时再输入make，即可生成elf可执行文件

makefile内容如下：

# CMAKE generated file: DO NOT EDIT!
# Generated by "Unix Makefiles" Generator, CMake Version 3.10

# Default target executed when no arguments are given to make.
default_target: all

.PHONY : default_target

# Allow only one "make -f Makefile2" at a time, but pass parallelism.
.NOTPARALLEL:

#=============================================================================
# Special targets provided by cmake.

# Disable implicit rules so canonical targets will work.
.SUFFIXES:

# Remove some rules from gmake that .SUFFIXES does not remove.
SUFFIXES =

.SUFFIXES: .hpux_make_needs_suffix_list

# Suppress display of executed commands.
$(VERBOSE).SILENT:

# A target that is always out of date.
cmake_force:

.PHONY : cmake_force

#=============================================================================
# Set environment variables for the build.

# The shell in which to execute make rules.
SHELL = /bin/sh

# The CMake executable.
CMAKE_COMMAND = /usr/bin/cmake

# The command to remove a file.
RM = /usr/bin/cmake -E remove -f

# Escaping for special characters.
EQUALS = =

# The top-level source directory on which CMake was run.
CMAKE_SOURCE_DIR = /home/ucar/test

# The top-level build directory on which CMake was run.
CMAKE_BINARY_DIR = /home/ucar/test

#=============================================================================
# Targets provided globally by CMake.

# Special rule for the target rebuild_cache
rebuild_cache:
	@$(CMAKE_COMMAND) -E cmake_echo_color --switch=$(COLOR) --cyan "Running CMake to regenerate build system..."
	/usr/bin/cmake -H$(CMAKE_SOURCE_DIR) -B$(CMAKE_BINARY_DIR)
.PHONY : rebuild_cache

# Special rule for the target rebuild_cache
rebuild_cache/fast: rebuild_cache

.PHONY : rebuild_cache/fast

# Special rule for the target edit_cache
edit_cache:
	@$(CMAKE_COMMAND) -E cmake_echo_color --switch=$(COLOR) --cyan "Running CMake cache editor..."
	/usr/bin/cmake-gui -H$(CMAKE_SOURCE_DIR) -B$(CMAKE_BINARY_DIR)
.PHONY : edit_cache

# Special rule for the target edit_cache
edit_cache/fast: edit_cache

.PHONY : edit_cache/fast

# The main all target
all: cmake_check_build_system
	$(CMAKE_COMMAND) -E cmake_progress_start /home/ucar/test/CMakeFiles /home/ucar/test/CMakeFiles/progress.marks
	$(MAKE) -f CMakeFiles/Makefile2 all
	$(CMAKE_COMMAND) -E cmake_progress_start /home/ucar/test/CMakeFiles 0
.PHONY : all

# The main clean target
clean:
	$(MAKE) -f CMakeFiles/Makefile2 clean
.PHONY : clean

# The main clean target
clean/fast: clean

.PHONY : clean/fast

# Prepare targets for installation.
preinstall: all
	$(MAKE) -f CMakeFiles/Makefile2 preinstall
.PHONY : preinstall

# Prepare targets for installation.
preinstall/fast:
	$(MAKE) -f CMakeFiles/Makefile2 preinstall
.PHONY : preinstall/fast

# clear depends
depend:
	$(CMAKE_COMMAND) -H$(CMAKE_SOURCE_DIR) -B$(CMAKE_BINARY_DIR) --check-build-system CMakeFiles/Makefile.cmake 1
.PHONY : depend

#=============================================================================
# Target rules for targets named main

# Build rule for target.
main: cmake_check_build_system
	$(MAKE) -f CMakeFiles/Makefile2 main
.PHONY : main

# fast build rule for target.
main/fast:
	$(MAKE) -f CMakeFiles/main.dir/build.make CMakeFiles/main.dir/build
.PHONY : main/fast

main.o: main.c.o

.PHONY : main.o

# target to build an object file
main.c.o:
	$(MAKE) -f CMakeFiles/main.dir/build.make CMakeFiles/main.dir/main.c.o
.PHONY : main.c.o

main.i: main.c.i

.PHONY : main.i

# target to preprocess a source file
main.c.i:
	$(MAKE) -f CMakeFiles/main.dir/build.make CMakeFiles/main.dir/main.c.i
.PHONY : main.c.i

main.s: main.c.s

.PHONY : main.s

# target to generate assembly for a file
main.c.s:
	$(MAKE) -f CMakeFiles/main.dir/build.make CMakeFiles/main.dir/main.c.s
.PHONY : main.c.s

# Help Target
help:
	@echo "The following are some of the valid targets for this Makefile:"
	@echo "... all (the default if no target is provided)"
	@echo "... clean"
	@echo "... depend"
	@echo "... rebuild_cache"
	@echo "... main"
	@echo "... edit_cache"
	@echo "... main.o"
	@echo "... main.i"
	@echo "... main.s"
.PHONY : help

#=============================================================================
# Special targets to cleanup operation of make.

# Special rule to run CMake to check the build system integrity.
# No rule that depends on this can have commands that come from listfiles
# because they might be regenerated.
cmake_check_build_system:
	$(CMAKE_COMMAND) -H$(CMAKE_SOURCE_DIR) -B$(CMAKE_BINARY_DIR) --check-build-system CMakeFiles/Makefile.cmake 0
.PHONY : cmake_check_build_system

4.多个源文件

文件目录如下：

|__test1.c

|__test1.h

test1.c内容如下:

#include <stdio.h>
#include "test1.h"

void func(int id)
{
    printf("a=%d\n",id);
}

test1.h内容如下：

#ifndef _TEST1_H
#define _TEST1_H

void func(int id);

#endif /* _TEST1_H */

然后在main.c里面编写如下代码:

#include <stdio.h>
#include "test1.h"
int main(void)
{
    func(6);
    printf("hello,world\n");
    return 0;

}

CMakeLists.txt的内容也要进行更改

cmake_minimum_required (VERSION 3.0)

project (main)

add_executable(main main.c test1.c)

重复cmake. 就可以看到是一样的效果