im new to coding in c++, I only programmed in php and Java but I want to learn something more.
It may be not the best to start with Audio things but I already know how programming works.
But, I thought to test, get a bit of code from the Apple website and look what happens.
I pasted the beginning of the Code in my Project and got errors. And I dont really know what they mean and searching didnt give me any results.
Thats the code:
#include <iostream>
#include <CoreAudio/CoreAudio.h>
#include <AudioToolbox/AudioToolbox.h>
#include <AudioUnit/AudioUnit.h>
int main(int argc, const char * argv[]) {
// insert code here...
AudioComponent comp;
AudioComponentDescription desc;
AudioComponentInstance auHAL;
//There are several different types of Audio Units.
//Some audio units serve as Outputs, Mixers, or DSP
//units. See AUComponent.h for listing
desc.componentType = kAudioUnitType_Output;
//Every Component has a subType, which will give a clearer picture
//of what this components function will be.
desc.componentSubType = kAudioUnitSubType_HALOutput;
//all Audio Units in AUComponent.h must use
//"kAudioUnitManufacturer_Apple" as the Manufacturer
desc.componentManufacturer = kAudioUnitManufacturer_Apple;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;
//Finds a component that meets the desc spec's
comp = AudioComponentFindNext(NULL, & desc);
if (comp == NULL) exit(-1);
//gains access to the services provided by the component
AudioComponentInstanceNew(comp, & auHAL);
return 0;
}
and those are the errors i get:
Undefined symbols for architecture x86_64:
"_AudioComponentFindNext", referenced from:
_main in main.o
"_AudioComponentInstanceNew", referenced from:
_main in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
thanks for helping me out!
You'll need to add the AudioUnit, CoreAudio and AudioToolbox frameworks to your project. See this answer for help on how to do that.
You are definitely jumping in the deep end if this is your first experience with C++. Good luck!
Related
I'm working on a PHP 7 extension using Swig and am trying to link to libphp7.so. From my CMakeLists.txt file:
find_library(php7_lib php7 PATHS "/usr/local/Cellar/php/7.3.0/lib/httpd/modules" NO_DEFAULT_PATH)
target_link_libraries(navdb_php7_client_api ${php7_lib} dl)
But I get an error:
[100%] Linking CXX shared module .../lib/libnavdb_php7_client_api.so
...
ld: can't link with bundle (MH_BUNDLE) only dylibs (MH_DYLIB) file '/usr/local/Cellar/php/7.3.0/lib/httpd/modules/libphp7.so' for architecture x86_64
The file I'm trying to link to:
$ file /usr/local/Cellar/php/7.3.0/lib/httpd/modules/libphp7.so
/usr/local/Cellar/php/7.3.0/lib/httpd/modules/libphp7.so: Mach-O 64-bit bundle x86_64
Any ideas on how to resolve this?
Although Apple recommends bundles be given the extension .bundle many developers give them the .so extension for the sake of cross-platform familiarity. On Linux, no distinction is made between a shared module (a bundle on MacOS) and a shared library (a dylib on MacOS.)
Understanding that, as ld states, you cannot link to an MH_BUNDLE on MacOS. It either needs to be a dylib to link it, or you need to load the .so using the dyld APIs.
This link gives an example of how to dynamically load a bundle on MacOS:
#include <stdio.h>
#import <mach-o/dyld.h>
int main( )
{
int the_answer;
int rc; // Success or failure result value
NSObjectFileImage img; // Represents the bundle's object file
NSModule handle; // Handle to the loaded bundle
NSSymbol sym; // Represents a symbol in the bundle
int (*get_answer) (void); // Function pointer for get_answer
/* Get an object file for the bundle. */
rc = NSCreateObjectFileImageFromFile("libanswer.bundle", &img);
if (rc != NSObjectFileImageSuccess) {
fprintf(stderr, "Could not load libanswer.bundle.\n");
exit(-1);
}
/* Get a handle for the bundle. */
handle = NSLinkModule(img, "libanswer.bundle", FALSE);
/* Look up the get_answer function. */
sym = NSLookupSymbolInModule(handle, "_get_answer");
if (sym == NULL)
{
fprintf(stderr, "Could not find symbol: _get_answer.\n");
exit(-2);
}
/* Get the address of the function. */
get_answer = NSAddressOfSymbol(sym);
/* Invoke the function and display the answer. */
the_answer = get_answer( );
printf("The answer is... %d\n", the_answer);
fprintf(stderr, "%d??!!\n", the_answer);
return 0;
}
I found out how/what to do from this link:
Clang and undefined symbols when building a library
The libphp7.so doesn't need to be linked to at compile time, run-time works fine. This can be enabled by setting a CXX_FLAG (see the link for details).
Goal: I want to use thread STL of C++11 in Matlab mex file (R2013a) using Xcode 4.6
I modified ~/.matlab/R2013a/mexopts.sh
CC='clang++' # was llvm-gcc-4.2
CXX='clang++' # was llvm-g++-4.2
MACOSX_DEPLOYMENT_TARGET='10.8' # was 10.5. C++11 is supported >=10.7
CXXFLAGS="$CXXFLAGS -std=gnu++11 -stdlib=libc++" # additional flags
Normal mex files without C++11 features are compiled well. Further, STL is well detected by the compiler except linking failure.
>> mex mextest.cpp
Undefined symbols for architecture x86_64:
"std::__1::__thread_struct::__thread_struct()", referenced from:
void* std::__1::__thread_proxy<std::__1::tuple<void (*)()> >(void*) in mextest.o
"std::__1::__thread_struct::~__thread_struct()", referenced from:
void* std::__1::__thread_proxy<std::__1::tuple<void (*)()> >(void*) in mextest.o
"std::__1::__thread_local_data()", referenced from:
void* std::__1::__thread_proxy<std::__1::tuple<void (*)()> >(void*) in mextest.o
"std::__1::__throw_system_error(int, char const*)", referenced from:
_mexFunction in mextest.o
"std::__1::thread::join()", referenced from:
_mexFunction in mextest.o
"std::__1::thread::~thread()", referenced from:
_mexFunction in mextest.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
mex: link of ' "mextest.mexmaci64"' failed.
Error using mex (line 206)
Unable to complete successfully.
The actual source code is shown below. The details are not important because it compiles well in Matlab R2013 WINDOWS version with Visual Studio 2012 Express. An equivalent cpp was also well compiled with "clang++ -std=gnu++11 -stdlib=libc++ clangtest.cpp". So, at least, there is no logical error in the codes (I'm not saying it is safe codes. It is just a test.)
#include "mex.h"
#include <thread>
#include <stdio.h>
int count_thread1 = 0;
int count_thread2 = 0;
void hello()
{
count_thread2 = 0;
for(int i=0; i<=10000; i++){
for (int j=1;j<=20000;j++){
count_thread2 = i-j-1;
}
count_thread2++;
printf("2: %d , %d\n", count_thread1, count_thread2); // Not sure if printf is thread-safe in Matlab. But it works in this particular example
}
}
void mexFunction(int nlhs,mxArray *plhs[],int nrhs,const mxArray *prhs[])
{
count_thread1 = 0;
std::thread t(hello);
for (int i=1;i<=10000;i++)
{
for (int j=1;j<=20000;j++){
count_thread1 = -i+j-1;
}
count_thread1++;
mexPrintf("1: %d , %d\n", count_thread1, count_thread2);
}
mexPrintf("\n");
t.join();
mexPrintf("Done\n");
}
It seems like I have to replace some include directories and/or library directories. What kind of options should be modify?
Thank you.
The error is due to compiling against -stdlib=libc++ but linking against -lstdc++. You can fix it in one of two ways:
Fix it in mexopts.sh. The most drastic and effective solution. Located in ~/.matlab/${MATLAB_VERSION}/mexopts.sh, this determines all compiler options. Simply find/replace all stdc++ to c++.
Patchwork solution: Simply add -lc++ to the tail end of CXXLIBS. I'm not sure what the effect of linking against multiple versions of the standard libraries is, but it seems to work. In your mex invocation, add the argument CXXLIBS="\$CXXLIBS -lc++".
As a secondary issue, I believe you're completely overwriting the value of CXXFLAGS; you must escape the $ symbol as I did above with the libraries.
I need to change reference of a function in a Mac OS process at runtime to a custom function defined in my own custom dylib. I kept the new function signature same as the original.
For example I need to change "open" function to "myopen" function.
I tried processing __LINKEDIT segment to get the dynamic symbol table and string table.
I used following pointers,
1. the VMAddrress from __LINKEDIT segment,
2. mach_header and vmaddr_slide from the "_dyld_register_func_for_add_image" callback,
3. symoff and stroff from symtab_command.
But I am unable to get the symbol table and string table mentioned in the __LINKEDIT segment.
Can someone throw some light on this?
Thanks in advance.
If the function in question is a library function, and not statically compiled into the executable, you don't need to do any of that - you can use function interposing, instead. Specifically, add this to your library:
// The attribute creates a Mach-O Section in your library - q.v. libgmalloc.dylib for
// a nice example
static const interpose_t interposing_functions[] \
__attribute__ ((section("__DATA, __interpose"))) = {
{ (void *)my_open, (void *)open },
{ (void *)my_close, (void *)close }, // .. etc
};
int my_open(const char *path, int flags, mode_t mode)
{
int rc;
// Prolog - do something before open
rc = open(path, flags, mode); // call real open
// Epilog - record rc, etc..
return rc;
}
There are several excellent books on OS X internals which can provide you with samples, though apparently according to S.O site policies we can't link you to them. That said, the above code snippet should work. Bear in mind, that this won't work on calls to open performed by other dylibs (though there are more complicated ways to get that, as well)
I have installed opencv with macports following the directions here: Compile OpenCV (2.3.1+) for OS X Lion / Mountain Lion with Xcode
I have also search and tried every other variation of this on stackexchange and google, but this seems to get me closest.
It seems to work for some things, but not for sample code that ships with 2.4.2. Note that I have added ALL opencv 2.4.2 dylibs Link Binary with Libraries.
For example, the following will compile and run:
#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
int main ( int argc, char **argv )
{
cvNamedWindow( "My Window", 1 );
IplImage *img = cvCreateImage( cvSize( 640, 480 ), IPL_DEPTH_8U, 1 );
CvFont font;
double hScale = 1.0;
double vScale = 1.0;
int lineWidth = 1;
cvInitFont( &font, CV_FONT_HERSHEY_SIMPLEX | CV_FONT_ITALIC,
hScale, vScale, 0, lineWidth );
cvPutText( img, "Hello World!", cvPoint( 200, 400 ), &font,
cvScalar( 255, 255, 0 ) );
cvShowImage( "My Window", img );
cvWaitKey();
return 0;
}
However, when I try to build any of the samples, such as the display_image.cpp, example, as follows, I get link errors.
-DOES NOT WORK-
#include <stdio.h>
#include <iostream>
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/flann/miniflann.hpp"
using namespace cv; // all the new API is put into "cv" namespace. Export its content
using namespace std;
using namespace cv::flann;
static void help()
{
cout <<
"\nThis program shows how to use cv::Mat and IplImages converting back and forth.\n"
"It shows reading of images, converting to planes and merging back, color conversion\n"
"and also iterating through pixels.\n"
"Call:\n"
"./image [image-name Default: lena.jpg]\n" << endl;
}
int main(int argc, char *argv[])
{
help();
const char* imagename = argc > 1 ? argv[1] : "lena.jpg";
Mat img = imread(imagename); // the newer cvLoadImage alternative, MATLAB-style function
if(img.empty())
{
fprintf(stderr, "Can not load image %s\n", imagename);
return -1;
}
if( !img.data ) // check if the image has been loaded properly
return -1;
Mat img_yuv;
cvtColor(img, img_yuv, CV_BGR2YCrCb); // convert image to YUV color space. The output image will be created automatically
vector<Mat> planes; // Vector is template vector class, similar to STL's vector. It can store matrices too.
split(img_yuv, planes); // split the image into separate color planes
imshow("image with grain", img);
waitKey();
return 0;
}
I get the following errors:
Undefined symbols for architecture x86_64:
"cv::split(cv::Mat const&, std::__1::vector<cv::Mat, std::__1::allocator<cv::Mat> >&)", referenced from:
_main in main1.o
"cv::imread(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int)", referenced from:
_main in main1.o
"cv::imshow(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, cv::_InputArray const&)", referenced from:
_main in main1.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Any idea how to resolve this?
I had the same problem. A build setting default seems to be different in Xcode 4.5.
Under "Build Settings"--> Apple LLVM compiler 4.1 - Language >
C++ Standard Library:=
Change from libc++ (LLVM ...) to libstdc++ (GNU C++ ...).
It's very likely that OpenCV has not been compiled with C++11 settings, while the program is.
Set the build of your tool without C++11 switches (i.e. -std=c++11 -stdlib=libc++).
Try to manually add the directory where port puts all the dylibs (/opt/local/lib if I'm not getting wrong) in Build Settings->Library search path. This should fix the linking problem.
I thought one feature of dynamic libraries (and by extension Apple's Mach-O Frameworks) was to leave some symbols (methods) undefined until the using application gets linked, but it appears all symbols have to be resolved for clang++ to successfully build a Framework.
For example, in building a framework for flight simulations, one might leave a C routine named aero undefined (but with an 'extern aero()' specification.) But XCode 4.2 refuses to build the framework, calling _aero an "undefined symbol."
Here's the header file included by both Objective-C and ANSI-C routines:
// FlightVehicleCAdapter_data.h
#ifndef FlightVehicleCAdapter_data_h
#define FlightVehicleCAdapter_data_h
#ifdef __cplusplus
external "C" {
#endif
extern void aero( void );
#ifdef __cplusplus
}
#endif
And here is where it gets called:
// FlightVehicleCAdapter.m
-(void) calcAero {
aero();
[self setBodyAeroForce_lb: [lsVector3 vectorFromScalarX:fv_data->f_aero_v.x
Y:fv_data->f_aero_v.y
Z:fv_data->f_aero_v.z]];
[self setBodyAeroMoment_ftlb:[lsVector3 vectorFromScalarX:fv_data->m_aero_v.x
Y:fv_data->m_aero_v.y
Z:fv_data->m_aero_v.z]];
}
I had hoped to be able to define the real aero() routine in the application that would link this framework, but when trying to build the framework itself the linker refuses to build it without a concrete aero() implementation:
Undefined symbols for architecture [i386|x86_64]:
"_aero", referenced from:
-[FlightVehicleCAdapter calcAero] in FlightVehicleCAdapter.o
So I then defined a dummy aero() routine:
// dummy_aero.c
// not showing fv_data structure definition for clarity
void aero(void){
fv_data->f_aero_v.x = 0.0;
fv_data->f_aero_v.y = 0.0;
fv_data->f_aero_v.z = 0.0;
fv_data->m_aero_v.x = 0.0;
fv_data->m_aero_v.y = 0.0;
fv_data->m_aero_v.z = 0.0;
}
This definition of aero() satisfies clang++ such that the Mach-O framework (dynamic library) is successfully built. But when I link the resulting framework with the application target which includes a non-trivial aero() routine, the framework's dummy aero() is being called instead of the application's aero().
You need to pass the -bundle_loader <executable> option to the linker, although I'm not sure that works for frameworks. Alternatively, you can use -undefined dynamic_lookup.
You need to do this for aero():
#ifdef __cplusplus
extern "C" {
#endif
extern void aero( void );
#ifdef __cplusplus
}
#endif
This makes sure the function is declared in C++ to have a C-resolvable name. C++ builds names differently than C does.
Note that then aero() can be linked at runtime.