ImportError:未定义符号: fftw_execute

Question

我试图建立一个使用gr_modtool的快速傅立叶变换和峰度能力的接收器块。

代码本身可以编译而没有错误。

但是，当我在GRC中运行流图时，它会产生以下错误消息。

问:如何解决这个错误？

我正在通过fftw3f路径，但是我得到了一个错误。

预先感谢您所能提供的任何指导。

Generating: '/home/nomo/gr-Kurtosis/kurtosis.py'

Executing: /usr/bin/python3 -u /home/nomo/gr-Kurtosis/kurtosis.py

Traceback (most recent call last):
  File "/home/nomo/gr-Kurtosis/kurtosis.py", line 34, in <module>
    import Kurtosis
  File "/usr/local/lib/python3/dist-packages/Kurtosis/__init__.py", line 30, in <module>
    from .Kurtosis_swig import *
  File "/usr/local/lib/python3/dist-packages/Kurtosis/Kurtosis_swig.py", line 13, in <module>
    from . import _Kurtosis_swig
ImportError: /usr/local/lib/x86_64-linux-gnu/libgnuradio-Kurtosis.so.1.0.0git: undefined symbol: fftw_execute

下面是实现源文件：

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <gnuradio/io_signature.h>
#include "Kurtosis_c_impl.h"

namespace gr {
  namespace Kurtosis {

    Kurtosis_c::sptr
    Kurtosis_c::make(int fftsize)
    {
      return gnuradio::get_initial_sptr
        (new Kurtosis_c_impl(fftsize));
    }


    /*
     * The private constructor
     */
    Kurtosis_c_impl::Kurtosis_c_impl(int fftsize)
      : gr::sync_block("Kurtosis_c",
              gr::io_signature::make(1, 1, sizeof(gr_complex)),
              gr::io_signature::make(0, 0, 0)),
              d_N(fftsize)
    {
      d_input = (fftw_complex*)fftw_malloc(sizeof(gr_complex) * d_N);
      K = (fftw_complex*)fftw_malloc(sizeof(gr_complex) * d_N);
      d_plan = fftw_plan_dft_1d(d_N, d_input, d_input, FFTW_BACKWARD, FFTW_ESTIMATE);
    }

    /*
     * Our virtual destructor.
     */
    Kurtosis_c_impl::~Kurtosis_c_impl()
    {
    }

    int
    Kurtosis_c_impl::work(int noutput_items,
        gr_vector_const_void_star &input_items,
        gr_vector_void_star &output_items)
    {
      const gr_complex *in = (const gr_complex*) input_items[0];

      for(int k = 0; k < noutput_items; k++)
      {
        for(int j = 0; j < M; j++)
        {
          for(int i = 0; i < d_N; i++)
          {
            d_input[i][0] = in[i].real();
            d_input[i][1] = in[i].imag();
          }
      
          fftw_execute(d_plan);
      
          M = 29296;
      
        
          for(int i = 0; i < d_N; i++)
          {   
            S1[i][0] = S1[i][0] + d_input[i][0];
            S1[i][1] = S1[i][1] + d_input[i][1];
        
            S2[i][0] = S2[i][0] + d_input[i][0] * d_input[i][0];
            S2[i][1] = S2[i][1] + d_input[i][1] * d_input[i][1];
        
            S3[i][0] = S3[i][0] + d_input[i][0] * d_input[i][0] * d_input[i][0];
            S3[i][1] = S3[i][1] + d_input[i][1] * d_input[i][1] * d_input[i][1];
        
            S4[i][0] = S4[i][0] + d_input[i][0] * d_input[i][0] * d_input[i][0] * d_input[i][0];
            S4[i][1] = S4[i][1] + d_input[i][1] * d_input[i][1] * d_input[i][1] * d_input[i][1];
        
            dc[i][0] = dc[i][0] + 1;
            dc[i][1] = dc[i][1] + 1;
          }
    
          for(int i = 0; i < d_N; i++)
          {
            Myu1[i][0] = S1[i][0] / dc[i][0];
            Myu1[i][1] = S1[i][1] / dc[i][1];
      
            Myu2[i][0] = S2[i][0] / dc[i][0];
            Myu2[i][1] = S2[i][1] / dc[i][1];
       
            Myu3[i][0] = S3[i][0] / dc[i][0];
            Myu3[i][1] = S3[i][1] / dc[i][1];
       
            Myu4[i][0] = S4[i][0] / dc[i][0];
            Myu4[i][1] = S4[i][1] / dc[i][1];
          }

    

          for(int i = 0; i < d_N; i++)
          {
            K[i][0] = (Myu4[i][0] - 4 * Myu3[i][0] * Myu1[i][0] + 6 * Myu2[i][0] * Myu1[i][0] 
                   * Myu1[i][0] - 3 * Myu1[i][0] * Myu1[i][0] * Myu1[i][0] * Myu1[i][0]) / 
                    ((Myu2[i][0] - Myu1[i][0] * Myu1[i][0]) * (Myu2[i][0] - Myu1[i][0] 
                      * Myu1[i][0]));
      
            K[i][1] = (Myu4[i][1] - 4 * Myu3[i][1] * Myu1[i][1] + 6 * Myu2[i][1] * Myu1[i][1] 
                   * Myu1[i][1] - 3 * Myu1[i][1] * Myu1[i][1] * Myu1[i][1] * Myu1[i][1]) / 
                    ((Myu2[i][1] - Myu1[i][1] * Myu1[i][1]) * (Myu2[i][1] - Myu1[i][1] 
                      * Myu1[i][1]));
          }
        }
      }
      // Tell runtime system how many output items we produced.
      return noutput_items;
    }

  } /* namespace Kurtosis1 */
} /* namespace gr */

下面是顶级CMakeLists.txt文件：

########################################################################
# Project setup
########################################################################
cmake_minimum_required(VERSION 3.8)
project(gr-Kurtosis CXX C)
enable_testing()

# Install to PyBOMBS target prefix if defined
if(DEFINED ENV{PYBOMBS_PREFIX})
    set(CMAKE_INSTALL_PREFIX $ENV{PYBOMBS_PREFIX})
    message(STATUS "PyBOMBS installed GNU Radio. Setting CMAKE_INSTALL_PREFIX to $ENV{PYBOMBS_PREFIX}")
endif()

# Select the release build type by default to get optimization flags
if(NOT CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE "Release")
   message(STATUS "Build type not specified: defaulting to release.")
endif(NOT CMAKE_BUILD_TYPE)
set(CMAKE_BUILD_TYPE ${CMAKE_BUILD_TYPE} CACHE STRING "")

# Make sure our local CMake Modules path comes first
list(INSERT CMAKE_MODULE_PATH 0 ${CMAKE_SOURCE_DIR}/cmake/Modules)

# Set the version information here
set(VERSION_MAJOR 1)
set(VERSION_API   0)
set(VERSION_ABI   0)
set(VERSION_PATCH git)

cmake_policy(SET CMP0011 NEW)

# Enable generation of compile_commands.json for code completion engines
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

########################################################################
# Compiler specific setup
########################################################################
if((CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR
    CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
    AND NOT WIN32)
    #http://gcc.gnu.org/wiki/Visibility
    add_definitions(-fvisibility=hidden)
endif()

IF(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
    SET(CMAKE_CXX_STANDARD 11)
ELSEIF(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
    SET(CMAKE_CXX_STANDARD 11)
ELSEIF(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
    SET(CMAKE_CXX_STANDARD 11)
ELSE()
    message(WARNING "C++ standard could not be set because compiler is not GNU, Clang or MSVC.")
ENDIF()

IF(CMAKE_C_COMPILER_ID STREQUAL "GNU")
    SET(CMAKE_C_STANDARD 11)
ELSEIF(CMAKE_C_COMPILER_ID MATCHES "Clang")
    SET(CMAKE_C_STANDARD 11)
ELSEIF(CMAKE_C_COMPILER_ID STREQUAL "MSVC")
    SET(CMAKE_C_STANDARD 11)
ELSE()
    message(WARNING "C standard could not be set because compiler is not GNU, Clang or MSVC.")
ENDIF()

########################################################################
# Install directories
########################################################################
find_package(Gnuradio "3.8" REQUIRED)
include(GrVersion)

include(GrPlatform) #define LIB_SUFFIX

find_package(FFTW3f)

if(NOT CMAKE_MODULES_DIR)
  set(CMAKE_MODULES_DIR lib${LIB_SUFFIX}/cmake)
endif(NOT CMAKE_MODULES_DIR)

set(GR_INCLUDE_DIR      include/Kurtosis)
set(GR_CMAKE_DIR        ${CMAKE_MODULES_DIR}/Kurtosis)
set(GR_PKG_DATA_DIR     ${GR_DATA_DIR}/${CMAKE_PROJECT_NAME})
set(GR_PKG_DOC_DIR      ${GR_DOC_DIR}/${CMAKE_PROJECT_NAME})
set(GR_PKG_CONF_DIR     ${GR_CONF_DIR}/${CMAKE_PROJECT_NAME}/conf.d)
set(GR_PKG_LIBEXEC_DIR  ${GR_LIBEXEC_DIR}/${CMAKE_PROJECT_NAME})
set(GR_REQUIRED_COMPONENTS RUNTIME FFTW3f)

########################################################################
# On Apple only, set install name and use rpath correctly, if not already set
########################################################################
if(APPLE)
    if(NOT CMAKE_INSTALL_NAME_DIR)
        set(CMAKE_INSTALL_NAME_DIR
            ${CMAKE_INSTALL_PREFIX}/${GR_LIBRARY_DIR} CACHE
            PATH "Library Install Name Destination Directory" FORCE)
    endif(NOT CMAKE_INSTALL_NAME_DIR)
    if(NOT CMAKE_INSTALL_RPATH)
        set(CMAKE_INSTALL_RPATH
            ${CMAKE_INSTALL_PREFIX}/${GR_LIBRARY_DIR} CACHE
            PATH "Library Install RPath" FORCE)
    endif(NOT CMAKE_INSTALL_RPATH)
    if(NOT CMAKE_BUILD_WITH_INSTALL_RPATH)
        set(CMAKE_BUILD_WITH_INSTALL_RPATH ON CACHE
            BOOL "Do Build Using Library Install RPath" FORCE)
    endif(NOT CMAKE_BUILD_WITH_INSTALL_RPATH)
endif(APPLE)

########################################################################
# Find gnuradio build dependencies
########################################################################
find_package(Doxygen)

########################################################################
# Setup doxygen option
########################################################################
if(DOXYGEN_FOUND)
    option(ENABLE_DOXYGEN "Build docs using Doxygen" ON)
else(DOXYGEN_FOUND)
    option(ENABLE_DOXYGEN "Build docs using Doxygen" OFF)
endif(DOXYGEN_FOUND)

########################################################################
# Create uninstall target
########################################################################
configure_file(
    ${CMAKE_SOURCE_DIR}/cmake/cmake_uninstall.cmake.in
    ${CMAKE_CURRENT_BINARY_DIR}/cmake_uninstall.cmake
@ONLY)

add_custom_target(uninstall
    ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_BINARY_DIR}/cmake_uninstall.cmake
    )


########################################################################
# Add subdirectories
########################################################################
add_subdirectory(include/Kurtosis)
add_subdirectory(lib)
add_subdirectory(apps)
add_subdirectory(docs)
add_subdirectory(swig)
add_subdirectory(python)
add_subdirectory(grc)

########################################################################
# Install cmake search helper for this library
########################################################################

install(FILES cmake/Modules/KurtosisConfig.cmake
    DESTINATION ${CMAKE_MODULES_DIR}/Kurtosis
)

下面是lib/CMakeLists.txt文件：

########################################################################
# Setup library
########################################################################
include(GrPlatform) #define LIB_SUFFIX

list(APPEND Kurtosis_sources
    Kurtosis_c_impl.cc
)

set(Kurtosis_sources "${Kurtosis_sources}" PARENT_SCOPE)
if(NOT Kurtosis_sources)
    MESSAGE(STATUS "No C++ sources... skipping lib/")
    return()
endif(NOT Kurtosis_sources)

add_library(gnuradio-Kurtosis SHARED ${Kurtosis_sources})
target_link_libraries(gnuradio-Kurtosis PUBLIC ${FFTW3F_LIBRARIES}
                      gnuradio::gnuradio-runtime fftw3f::fftw3f)
target_include_directories(gnuradio-Kurtosis
    PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../include>
    PUBLIC $<INSTALL_INTERFACE:include>
  )
link_directories(${FFTW3F_LIBRARY_DIRS})
set_target_properties(gnuradio-Kurtosis PROPERTIES DEFINE_SYMBOL "gnuradio_Kurtosis_EXPORTS")

if(APPLE)
    set_target_properties(gnuradio-Kurtosis PROPERTIES
        INSTALL_NAME_DIR "${CMAKE_INSTALL_PREFIX}/lib"
    )
endif(APPLE)

########################################################################
# Install built library files
########################################################################
include(GrMiscUtils)
GR_LIBRARY_FOO(gnuradio-Kurtosis FFTW3f)


########################################################################
# Print summary
########################################################################
message(STATUS "Using install prefix: ${CMAKE_INSTALL_PREFIX}")
message(STATUS "Building for version: ${VERSION} / ${LIBVER}")

########################################################################
# Build and register unit test
########################################################################
include(GrTest)

include_directories(${CPPUNIT_INCLUDE_DIRS})

# If your unit tests require special include paths, add them here
#include_directories()
# List all files that contain Boost.UTF unit tests here
list(APPEND test_Kurtosis_sources
)


# Anything we need to link to for the unit tests go here
list(APPEND GR_TEST_TARGET_DEPS gnuradio-Kurtosis)

if(NOT test_Kurtosis_sources)
    MESSAGE(STATUS "No C++ unit tests... skipping")
    return()
endif(NOT test_Kurtosis_sources)

foreach(qa_file ${test_Kurtosis_sources})
    GR_ADD_CPP_TEST("Kurtosis_${qa_file}"
        ${CMAKE_CURRENT_SOURCE_DIR}/${qa_file}
    )
endforeach(qa_file)

Answer 1

link_directories(${FFTW3F_LIBRARY_DIRS})

这不是一个好主意；您需要链接到库，而不仅仅是告诉链接器包含库的目录可能也很有趣。

相反，您可以使用现代的CMake接口来链接库:这已经告诉CMake链接，以及如何在链接时找到库。太棒了！您只需删除这行link_directories。

这里的问题是链接到FFTWf (请注意f:单精度，这对于SDR应用程序来说通常是足够的！)，但是要使用一些双精度例程。使用fftwf_execute和fftwf_complex！

这只是一种不必要复杂的内存复制方式：

      for(int i = 0; i < d_N; i++)
      {
        d_input[i][0] = in[i].real();
        d_input[i][1] = in[i].imag();
      }

gr_complex类型是真实的，假想的部分就在彼此后面，与fftwf_complex完全相同。计划您的DFT允许您选择您的输入内存，而不是必须将数据复制到固定位置。

更舒服的是:移除您自己的所有FFTW(f)处理，只需使用gr::fft::fft_complex_rev，它为您完成了所有这些操作：

在Kurtosis_c_impl.h中：

#include <gnuradio/fft/fft.h>
…
class Kurtosis_c {
…
   fft::fft_complex_rev d_fft;
…
};

在Kurtosis_c_impl.cc中：

…
// constructor gets shorter :)
Kurtosis_c_impl::Kurtosis_c_impl(int fftsize) //should be unsigned int, by the way
      : gr::sync_block("Kurtosis_c",
              gr::io_signature::make(1, 1, sizeof(gr_complex)),
              gr::io_signature::make(0, 0, 0)),
              d_N(fftsize),
              d_fft(fftsize) {}
…
// work function:
    int
    Kurtosis_c_impl::work(int noutput_items,
        gr_vector_const_void_star &input_items,
        gr_vector_void_star &output_items)
    {
      const gr_complex *in = (const gr_complex*) input_items[0];
      for(unsigned int idx = 0; idx < d_N; ++idx) {
        d_fft.get_inbuf()[idx] = in[idx];
      }
      d_fft.execute();

关于：

      for(int i = 0; i < d_N; i++)
      {   
        S1[i][0] = S1[i][0] + d_input[i][0];
        S1[i][1] = S1[i][1] + d_input[i][1];

你意识到在C++中有复数，你可以做复数运算吗？如果您的S1是gr_complex的数组/向量/其他容器(它只是std::complex<float>的别名，给定包含顺序，与fftwf_complex一样)，那么这可以归结为

for(unsigned int i = 0; i < d_N; ++i)
{
  S1[i] += d_input[i];
}

编写可读的代码是很重要的！在这种情况下，它是可以的，特别是因为你后来做了更高的力量的真实和想象部分的d_input，无论如何。

然而，

        dc[i][0] = dc[i][0] + 1;
        dc[i][1] = dc[i][1] + 1;

来一个。那太浪费了。与其把一个数字增加+1，N倍，不如把它增加N，一次。

      for(int i = 0; i < d_N; i++)
      {
        K[i][0] = (Myu4[i][0] - 4 * Myu3[i][0] * Myu1[i][0] + 6 * Myu2[i][0] * Myu1[i][0] 
               * Myu1[i][0] - 3 * Myu1[i][0] * Myu1[i][0] * Myu1[i][0] * Myu1[i][0]) / 
                ((Myu2[i][0] - Myu1[i][0] * Myu1[i][0]) * (Myu2[i][0] - Myu1[i][0] 
                  * Myu1[i][0]));
  
        K[i][1] = (Myu4[i][1] - 4 * Myu3[i][1] * Myu1[i][1] + 6 * Myu2[i][1] * Myu1[i][1] 
               * Myu1[i][1] - 3 * Myu1[i][1] * Myu1[i][1] * Myu1[i][1] * Myu1[i][1]) / 
                ((Myu2[i][1] - Myu1[i][1] * Myu1[i][1]) * (Myu2[i][1] - Myu1[i][1] 
                  * Myu1[i][1]));
      }

老实说，这是不可读的，你和你的主管将诅咒你下周，当你们中的任何一个试图阅读这篇文章。

      for(int i = 0; i < d_N; i++)
      {
        const auto& M1 = Myu1[i];
        const auto& M2 = Myu2[i];
        const auto& M3 = Myu3[i];
        const auto& M4 = Myu4[i];
        K[i].real() = (M4.real() - 4 * M3.real() * M1.real()  //comment on what this is
               + 6 * M2.real() * M1.real() * M1.real()  // comment
               - 3 * M1.real() * M1.real() * M1.real() * M1.real() /  // comment
                ((M2.real() - M1.real() * M1.real()) * (M2.real() - M1.real() * M1.real())); //comment
  
        K[i].imag() = /* This seems to be the exact same thing as above.
                          Clear indication that you should write a small inline
                          function that takes four float arguments and 
                          returns a flow to do this */
      }

请注意，这实际上产生了与您的编写方法相同的机器代码，因为这些.real()和.imag()函数只是编译到相同的内存访问中。以及像M1…这样的参考资料M4只是逻辑糖，也没有开销。

最重要的是，

  // Tell runtime system how many output items we produced.
  return noutput_items;

你没看过那个评论！您不会返回您生产的项目的数量(这与您生产的相同)。您的行为就好像您使用了所有的输入，即使您只是使用d_N！您甚至没有检查是否至少有d_N输入项。，这是必要的。 GNU电台将给你不同数量的输入项目，而不是总是相同的数字！