11.MariaDB笔记——cmake使用介绍六动态产生代码文件

11.MariaDB笔记——cmake使用介绍六动态产生代码文件

继续学习cmake.

怎样增加产生的代码文件到应用编译过程。

例如：我们在编译过程中创建一个提前计算好平方根的表，然后将产生的表编译到我们的应用中。

在MathFunctions子目录中创建MakeTable.cxx文件，内容如下：

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

int main (int argc, char *argv[])

{

  int i;

  doubleresult;

 

  // make surewe have enough arguments

  if (argc <2)

    {

    return 1;

    }

 

  // open theoutput file

  FILE *fout =fopen(argv[1],"w");

  if (!fout)

    {

    return 1;

    }

 

  // create asource file with a table of square roots

 fprintf(fout,"double sqrtTable[] = {\n");

  for (i = 0; i< 10; ++i)

    {

    result =sqrt(static_cast<double>(i));

   fprintf(fout,"%g,\n",result);

    }

 

  // close the tablewith a zero

 fprintf(fout,"0};\n");

  fclose(fout);

  return 0;

}

子目录CMakeLists

接着增加合适的命令在MathFunctions的CMakeLists中来编译MakeTable可执行文件，然后作为编译过程。

如下：

# first we addthe executable that generates the table

add_executable(MakeTableMakeTable.cxx)

# add thecommand to generate the source code

add_custom_command(

  OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/Table.h

  COMMAND MakeTable${CMAKE_CURRENT_BINARY_DIR}/Table.h

  DEPENDS MakeTable

  )

# add thebinary tree directory to the search path for

# include files

include_directories(${CMAKE_CURRENT_BINARY_DIR} )

# add the mainlibrary

add_library(MathFunctionsmysqrt.cxx ${CMAKE_CURRENT_BINARY_DIR}/Table.h )

使得CMake知道mysqrt.cxx依赖于产生的Table.h，把table.h加到MathFunctions库的源列表中。把当前二进制库目录加到include目录中，这样table.h可以被找到，并被mysqrt.cxx包含。当项目编译的时候先编译MakeTable可执行文件，然后运行MakeTable来产生table.h.

最后编译mysqrt.cxx来产生MathFunctions库文件。

为此，主CMakeLists文件如下：

主C      MakeLists文件

cmake_minimum_required(VERSION 2.6)

project(Tutorial)
include(CTest)

# The versionnumber.

set(Tutorial_VERSION_MAJOR 1)

set(Tutorial_VERSION_MINOR 0)

 

# does thissystem provide the log and exp functions?

include(${CMAKE_ROOT}/Modules/CheckFunctionExists.cmake)

check_function_exists(log HAVE_LOG)

check_function_exists(exp HAVE_EXP)

# should weuse our own math functions

option(USE_MYMATH

  "Use tutorial provided mathimplementation" ON)

# configure aheader file to pass some of the CMake settings

# to thesource code

configure_file(

 "${PROJECT_SOURCE_DIR}/TutorialConfig.h"

  "${PROJECT_BINARY_DIR}/TutorialConfig.h"

  )

 

# add thebinary tree to the search path for include files

# so that wewill find TutorialConfig.h

include_directories("${PROJECT_BINARY_DIR}")

 

# add theMathFunctions library?

if(USE_MYMATH)

  include_directories("${PROJECT_SOURCE_DIR}/MathFunctions")

  add_subdirectory (MathFunctions)

  set (EXTRA_LIBS ${EXTRA_LIBS} MathFunctions)

endif(USE_MYMATH)

 

# add theexecutable

add_executable(Tutorial tutorial.cxx)

target_link_libraries(Tutorial  ${EXTRA_LIBS})

 

# add theinstall targets

install(TARGETS Tutorial DESTINATION bin)

install (FILES"${PROJECT_BINARY_DIR}/TutorialConfig.h"       

         DESTINATION include)

 

# does theapplication run

add_test(TutorialRuns Tutorial 25)

 

# does theusage message work?

add_test(TutorialUsage Tutorial)

set_tests_properties(TutorialUsage

  PROPERTIES

  PASS_REGULAR_EXPRESSION"Usage:.*number"

  )

 

 

#define amacro to simplify adding tests

macro (do_testarg result)

  add_test (TutorialComp${arg} Tutorial ${arg})

  set_tests_properties (TutorialComp${arg}

    PROPERTIES PASS_REGULAR_EXPRESSION${result}

    )

endmacro(do_test)

 

# do a bunchof result based tests

do_test (4"4 is 2")

do_test (9"9 is 3")

do_test (5"5 is 2.236")

do_test (7"7 is 2.645")

do_test (25"25 is 5")

do_test (-25"-25 is 0")

do_test(0.0001 "0.0001 is 0.01")

TutorialConfig.h文件如下

#defineTutorial_VERSION_MAJOR @Tutorial_VERSION_MAJOR@

#defineTutorial_VERSION_MINOR @Tutorial_VERSION_MINOR@

#cmakedefineUSE_MYMATH

 

//does the platform provide exp and log functions?

#cmakedefineHAVE_LOG

#cmakedefineHAVE_EXP

子目录MathFunctions中mysqrt.cxx如下

#include <math.h>

#include <stdio.h>

#include <stdlib.h>

#include <Table.h>

double mysqrt(double n) //用二分法

{

                  if(n<0)//小于0的按照你需要的处理

                                    returnn;

                  doublemid,last;

                  doublelow,up;

                  low=0,up=n;

                  mid=(low+up)/2;

                  do

                  {

                                    if(mid*mid>n)

                                                      up=mid;

                                    else

                                                      low=mid;

                                    last=mid;

                                    mid=(up+low)/2;

                  }while(abs(mid-last)> 0.01);//精度控制

                  returnsqrtTable[3];

}

此处为了测试，直接在最后一行返回了Table表中的值

return sqrtTable[3]

测试后如下：

F:\VS2010_ZHIZUO\cmake_zhizuo\Debug>Tutorial.exe6

The square root of 6 is 1.73205

F:\VS2010_ZHIZUO\cmake_zhizuo\Debug>Tutorial.exe6

The square root of 6 is 1.73205

F:\VS2010_ZHIZUO\cmake_zhizuo\Debug>Tutorial.exe3

The square root of 3 is 1.73205

F:\VS2010_ZHIZUO\cmake_zhizuo\Debug>Tutorial.exe2

The square root of 2 is 1.73205

F:\VS2010_ZHIZUO\cmake_zhizuo\Debug>Tutorial.exe1

The square root of 1 is 1.73205

F:\VS2010_ZHIZUO\cmake_zhizuo\Debug>Tutorial.exe5

The square root of 5 is 1.73205

F:\VS2010_ZHIZUO\cmake_zhizuo\Debug>Tutorial.exe6

The square root of 6 is 1.73205

都是返回同一个值，因为函数写死了。

实现了动态产生代码并加入到程序中了。