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+/*
+ IASIOThiscallResolver.cpp see the comments in iasiothiscallresolver.h for
+ the top level description - this comment describes the technical details of
+ the implementation.
+
+ The latest version of this file is available from:
+ http://www.audiomulch.com/~rossb/code/calliasio
+
+ please email comments to Ross Bencina <rossb@audiomulch.com>
+
+ BACKGROUND
+
+ The IASIO interface declared in the Steinberg ASIO 2 SDK declares
+ functions with no explicit calling convention. This causes MSVC++ to default
+ to using the thiscall convention, which is a proprietary convention not
+ implemented by some non-microsoft compilers - notably borland BCC,
+ C++Builder, and gcc. MSVC++ is the defacto standard compiler used by
+ Steinberg. As a result of this situation, the ASIO sdk will compile with
+ any compiler, however attempting to execute the compiled code will cause a
+ crash due to different default calling conventions on non-Microsoft
+ compilers.
+
+ IASIOThiscallResolver solves the problem by providing an adapter class that
+ delegates to the IASIO interface using the correct calling convention
+ (thiscall). Due to the lack of support for thiscall in the Borland and GCC
+ compilers, the calls have been implemented in assembly language.
+
+ A number of macros are defined for thiscall function calls with different
+ numbers of parameters, with and without return values - it may be possible
+ to modify the format of these macros to make them work with other inline
+ assemblers.
+
+
+ THISCALL DEFINITION
+
+ A number of definitions of the thiscall calling convention are floating
+ around the internet. The following definition has been validated against
+ output from the MSVC++ compiler:
+
+ For non-vararg functions, thiscall works as follows: the object (this)
+ pointer is passed in ECX. All arguments are passed on the stack in
+ right to left order. The return value is placed in EAX. The callee
+ clears the passed arguments from the stack.
+
+
+ FINDING FUNCTION POINTERS FROM AN IASIO POINTER
+
+ The first field of a COM object is a pointer to its vtble. Thus a pointer
+ to an object implementing the IASIO interface also points to a pointer to
+ that object's vtbl. The vtble is a table of function pointers for all of
+ the virtual functions exposed by the implemented interfaces.
+
+ If we consider a variable declared as a pointer to IASO:
+
+ IASIO *theAsioDriver
+
+ theAsioDriver points to:
+
+ object implementing IASIO
+ {
+ IASIOvtbl *vtbl
+ other data
+ }
+
+ in other words, theAsioDriver points to a pointer to an IASIOvtbl
+
+ vtbl points to a table of function pointers:
+
+ IASIOvtbl ( interface IASIO : public IUnknown )
+ {
+ (IUnknown functions)
+ 0 virtual HRESULT STDMETHODCALLTYPE (*QueryInterface)(REFIID riid, void **ppv) = 0;
+ 4 virtual ULONG STDMETHODCALLTYPE (*AddRef)() = 0;
+ 8 virtual ULONG STDMETHODCALLTYPE (*Release)() = 0;
+
+ (IASIO functions)
+ 12 virtual ASIOBool (*init)(void *sysHandle) = 0;
+ 16 virtual void (*getDriverName)(char *name) = 0;
+ 20 virtual long (*getDriverVersion)() = 0;
+ 24 virtual void (*getErrorMessage)(char *string) = 0;
+ 28 virtual ASIOError (*start)() = 0;
+ 32 virtual ASIOError (*stop)() = 0;
+ 36 virtual ASIOError (*getChannels)(long *numInputChannels, long *numOutputChannels) = 0;
+ 40 virtual ASIOError (*getLatencies)(long *inputLatency, long *outputLatency) = 0;
+ 44 virtual ASIOError (*getBufferSize)(long *minSize, long *maxSize,
+ long *preferredSize, long *granularity) = 0;
+ 48 virtual ASIOError (*canSampleRate)(ASIOSampleRate sampleRate) = 0;
+ 52 virtual ASIOError (*getSampleRate)(ASIOSampleRate *sampleRate) = 0;
+ 56 virtual ASIOError (*setSampleRate)(ASIOSampleRate sampleRate) = 0;
+ 60 virtual ASIOError (*getClockSources)(ASIOClockSource *clocks, long *numSources) = 0;
+ 64 virtual ASIOError (*setClockSource)(long reference) = 0;
+ 68 virtual ASIOError (*getSamplePosition)(ASIOSamples *sPos, ASIOTimeStamp *tStamp) = 0;
+ 72 virtual ASIOError (*getChannelInfo)(ASIOChannelInfo *info) = 0;
+ 76 virtual ASIOError (*createBuffers)(ASIOBufferInfo *bufferInfos, long numChannels,
+ long bufferSize, ASIOCallbacks *callbacks) = 0;
+ 80 virtual ASIOError (*disposeBuffers)() = 0;
+ 84 virtual ASIOError (*controlPanel)() = 0;
+ 88 virtual ASIOError (*future)(long selector,void *opt) = 0;
+ 92 virtual ASIOError (*outputReady)() = 0;
+ };
+
+ The numbers in the left column show the byte offset of each function ptr
+ from the beginning of the vtbl. These numbers are used in the code below
+ to select different functions.
+
+ In order to find the address of a particular function, theAsioDriver
+ must first be dereferenced to find the value of the vtbl pointer:
+
+ mov eax, theAsioDriver
+ mov edx, [theAsioDriver] // edx now points to vtbl[0]
+
+ Then an offset must be added to the vtbl pointer to select a
+ particular function, for example vtbl+44 points to the slot containing
+ a pointer to the getBufferSize function.
+
+ Finally vtbl+x must be dereferenced to obtain the value of the function
+ pointer stored in that address:
+
+ call [edx+44] // call the function pointed to by
+ // the value in the getBufferSize field of the vtbl
+
+
+ SEE ALSO
+
+ Martin Fay's OpenASIO DLL at http://www.martinfay.com solves the same
+ problem by providing a new COM interface which wraps IASIO with an
+ interface that uses portable calling conventions. OpenASIO must be compiled
+ with MSVC, and requires that you ship the OpenASIO DLL with your
+ application.
+
+
+ ACKNOWLEDGEMENTS
+
+ Ross Bencina: worked out the thiscall details above, wrote the original
+ Borland asm macros, and a patch for asio.cpp (which is no longer needed).
+ Thanks to Martin Fay for introducing me to the issues discussed here,
+ and to Rene G. Ceballos for assisting with asm dumps from MSVC++.
+
+ Antti Silvast: converted the original calliasio to work with gcc and NASM
+ by implementing the asm code in a separate file.
+
+ Fraser Adams: modified the original calliasio containing the Borland inline
+ asm to add inline asm for gcc i.e. Intel syntax for Borland and AT&T syntax
+ for gcc. This seems a neater approach for gcc than to have a separate .asm
+ file and it means that we only need one version of the thiscall patch.
+
+ Fraser Adams: rewrote the original calliasio patch in the form of the
+ IASIOThiscallResolver class in order to avoid modifications to files from
+ the Steinberg SDK, which may have had potential licence issues.
+
+ Andrew Baldwin: contributed fixes for compatibility problems with more
+ recent versions of the gcc assembler.
+*/
+
+
+// We only need IASIOThiscallResolver at all if we are on Win32. For other
+// platforms we simply bypass the IASIOThiscallResolver definition to allow us
+// to be safely #include'd whatever the platform to keep client code portable
+#if (defined(WIN32) || defined(_WIN32) || defined(__WIN32__)) && !defined(_WIN64)
+
+
+// If microsoft compiler we can call IASIO directly so IASIOThiscallResolver
+// is not used.
+#if !defined(_MSC_VER)
+
+
+#include <new>
+#include <assert.h>
+
+// We have a mechanism in iasiothiscallresolver.h to ensure that asio.h is
+// #include'd before it in client code, we do NOT want to do this test here.
+#define iasiothiscallresolver_sourcefile 1
+#include "iasiothiscallresolver.h"
+#undef iasiothiscallresolver_sourcefile
+
+// iasiothiscallresolver.h redefines ASIOInit for clients, but we don't want
+// this macro defined in this translation unit.
+#undef ASIOInit
+
+
+// theAsioDriver is a global pointer to the current IASIO instance which the
+// ASIO SDK uses to perform all actions on the IASIO interface. We substitute
+// our own forwarding interface into this pointer.
+extern IASIO* theAsioDriver;
+
+
+// The following macros define the inline assembler for BORLAND first then gcc
+
+#if defined(__BCPLUSPLUS__) || defined(__BORLANDC__)
+
+
+#define CALL_THISCALL_0( resultName, thisPtr, funcOffset )\
+ void *this_ = (thisPtr); \
+ __asm { \
+ mov ecx, this_ ; \
+ mov eax, [ecx] ; \
+ call [eax+funcOffset] ; \
+ mov resultName, eax ; \
+ }
+
+
+#define CALL_VOID_THISCALL_1( thisPtr, funcOffset, param1 )\
+ void *this_ = (thisPtr); \
+ __asm { \
+ mov eax, param1 ; \
+ push eax ; \
+ mov ecx, this_ ; \
+ mov eax, [ecx] ; \
+ call [eax+funcOffset] ; \
+ }
+
+
+#define CALL_THISCALL_1( resultName, thisPtr, funcOffset, param1 )\
+ void *this_ = (thisPtr); \
+ __asm { \
+ mov eax, param1 ; \
+ push eax ; \
+ mov ecx, this_ ; \
+ mov eax, [ecx] ; \
+ call [eax+funcOffset] ; \
+ mov resultName, eax ; \
+ }
+
+
+#define CALL_THISCALL_1_DOUBLE( resultName, thisPtr, funcOffset, param1 )\
+ void *this_ = (thisPtr); \
+ void *doubleParamPtr_ (&param1); \
+ __asm { \
+ mov eax, doubleParamPtr_ ; \
+ push [eax+4] ; \
+ push [eax] ; \
+ mov ecx, this_ ; \
+ mov eax, [ecx] ; \
+ call [eax+funcOffset] ; \
+ mov resultName, eax ; \
+ }
+
+
+#define CALL_THISCALL_2( resultName, thisPtr, funcOffset, param1, param2 )\
+ void *this_ = (thisPtr); \
+ __asm { \
+ mov eax, param2 ; \
+ push eax ; \
+ mov eax, param1 ; \
+ push eax ; \
+ mov ecx, this_ ; \
+ mov eax, [ecx] ; \
+ call [eax+funcOffset] ; \
+ mov resultName, eax ; \
+ }
+
+
+#define CALL_THISCALL_4( resultName, thisPtr, funcOffset, param1, param2, param3, param4 )\
+ void *this_ = (thisPtr); \
+ __asm { \
+ mov eax, param4 ; \
+ push eax ; \
+ mov eax, param3 ; \
+ push eax ; \
+ mov eax, param2 ; \
+ push eax ; \
+ mov eax, param1 ; \
+ push eax ; \
+ mov ecx, this_ ; \
+ mov eax, [ecx] ; \
+ call [eax+funcOffset] ; \
+ mov resultName, eax ; \
+ }
+
+
+#elif defined(__GNUC__)
+
+
+#define CALL_THISCALL_0( resultName, thisPtr, funcOffset ) \
+ __asm__ __volatile__ ("movl (%1), %%edx\n\t" \
+ "call *"#funcOffset"(%%edx)\n\t" \
+ :"=a"(resultName) /* Output Operands */ \
+ :"c"(thisPtr) /* Input Operands */ \
+ : "%edx" /* Clobbered Registers */ \
+ ); \
+
+
+#define CALL_VOID_THISCALL_1( thisPtr, funcOffset, param1 ) \
+ __asm__ __volatile__ ("pushl %0\n\t" \
+ "movl (%1), %%edx\n\t" \
+ "call *"#funcOffset"(%%edx)\n\t" \
+ : /* Output Operands */ \
+ :"r"(param1), /* Input Operands */ \
+ "c"(thisPtr) \
+ : "%edx" /* Clobbered Registers */ \
+ ); \
+
+
+#define CALL_THISCALL_1( resultName, thisPtr, funcOffset, param1 ) \
+ __asm__ __volatile__ ("pushl %1\n\t" \
+ "movl (%2), %%edx\n\t" \
+ "call *"#funcOffset"(%%edx)\n\t" \
+ :"=a"(resultName) /* Output Operands */ \
+ :"r"(param1), /* Input Operands */ \
+ "c"(thisPtr) \
+ : "%edx" /* Clobbered Registers */ \
+ ); \
+
+
+#define CALL_THISCALL_1_DOUBLE( resultName, thisPtr, funcOffset, param1 ) \
+ do { \
+ double param1f64 = param1; /* Cast explicitly to double */ \
+ double *param1f64Ptr = &param1f64; /* Make pointer to address */ \
+ __asm__ __volatile__ ("pushl 4(%1)\n\t" \
+ "pushl (%1)\n\t" \
+ "movl (%2), %%edx\n\t" \
+ "call *"#funcOffset"(%%edx);\n\t" \
+ : "=a"(resultName) /* Output Operands */ \
+ : "r"(param1f64Ptr), /* Input Operands */ \
+ "c"(thisPtr), \
+ "m"(*param1f64Ptr) /* Using address */ \
+ : "%edx" /* Clobbered Registers */ \
+ ); \
+ } while (0); \
+
+
+#define CALL_THISCALL_2( resultName, thisPtr, funcOffset, param1, param2 ) \
+ __asm__ __volatile__ ("pushl %1\n\t" \
+ "pushl %2\n\t" \
+ "movl (%3), %%edx\n\t" \
+ "call *"#funcOffset"(%%edx)\n\t" \
+ :"=a"(resultName) /* Output Operands */ \
+ :"r"(param2), /* Input Operands */ \
+ "r"(param1), \
+ "c"(thisPtr) \
+ : "%edx" /* Clobbered Registers */ \
+ ); \
+
+
+#define CALL_THISCALL_4( resultName, thisPtr, funcOffset, param1, param2, param3, param4 )\
+ __asm__ __volatile__ ("pushl %1\n\t" \
+ "pushl %2\n\t" \
+ "pushl %3\n\t" \
+ "pushl %4\n\t" \
+ "movl (%5), %%edx\n\t" \
+ "call *"#funcOffset"(%%edx)\n\t" \
+ :"=a"(resultName) /* Output Operands */ \
+ :"r"(param4), /* Input Operands */ \
+ "r"(param3), \
+ "r"(param2), \
+ "r"(param1), \
+ "c"(thisPtr) \
+ : "%edx" /* Clobbered Registers */ \
+ ); \
+
+#endif
+
+
+
+// Our static singleton instance.
+IASIOThiscallResolver IASIOThiscallResolver::instance;
+
+// Constructor called to initialize static Singleton instance above. Note that
+// it is important not to clear that_ incase it has already been set by the call
+// to placement new in ASIOInit().
+IASIOThiscallResolver::IASIOThiscallResolver()
+{
+}
+
+// Constructor called from ASIOInit() below
+IASIOThiscallResolver::IASIOThiscallResolver(IASIO* that)
+: that_( that )
+{
+}
+
+// Implement IUnknown methods as assert(false). IASIOThiscallResolver is not
+// really a COM object, just a wrapper which will work with the ASIO SDK.
+// If you wanted to use ASIO without the SDK you might want to implement COM
+// aggregation in these methods.
+HRESULT STDMETHODCALLTYPE IASIOThiscallResolver::QueryInterface(REFIID riid, void **ppv)
+{
+ (void)riid; // suppress unused variable warning
+
+ assert( false ); // this function should never be called by the ASIO SDK.
+
+ *ppv = NULL;
+ return E_NOINTERFACE;
+}
+
+ULONG STDMETHODCALLTYPE IASIOThiscallResolver::AddRef()
+{
+ assert( false ); // this function should never be called by the ASIO SDK.
+
+ return 1;
+}
+
+ULONG STDMETHODCALLTYPE IASIOThiscallResolver::Release()
+{
+ assert( false ); // this function should never be called by the ASIO SDK.
+
+ return 1;
+}
+
+
+// Implement the IASIO interface methods by performing the vptr manipulation
+// described above then delegating to the real implementation.
+ASIOBool IASIOThiscallResolver::init(void *sysHandle)
+{
+ ASIOBool result;
+ CALL_THISCALL_1( result, that_, 12, sysHandle );
+ return result;
+}
+
+void IASIOThiscallResolver::getDriverName(char *name)
+{
+ CALL_VOID_THISCALL_1( that_, 16, name );
+}
+
+long IASIOThiscallResolver::getDriverVersion()
+{
+ ASIOBool result;
+ CALL_THISCALL_0( result, that_, 20 );
+ return result;
+}
+
+void IASIOThiscallResolver::getErrorMessage(char *string)
+{
+ CALL_VOID_THISCALL_1( that_, 24, string );
+}
+
+ASIOError IASIOThiscallResolver::start()
+{
+ ASIOBool result;
+ CALL_THISCALL_0( result, that_, 28 );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::stop()
+{
+ ASIOBool result;
+ CALL_THISCALL_0( result, that_, 32 );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::getChannels(long *numInputChannels, long *numOutputChannels)
+{
+ ASIOBool result;
+ CALL_THISCALL_2( result, that_, 36, numInputChannels, numOutputChannels );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::getLatencies(long *inputLatency, long *outputLatency)
+{
+ ASIOBool result;
+ CALL_THISCALL_2( result, that_, 40, inputLatency, outputLatency );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::getBufferSize(long *minSize, long *maxSize,
+ long *preferredSize, long *granularity)
+{
+ ASIOBool result;
+ CALL_THISCALL_4( result, that_, 44, minSize, maxSize, preferredSize, granularity );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::canSampleRate(ASIOSampleRate sampleRate)
+{
+ ASIOBool result;
+ CALL_THISCALL_1_DOUBLE( result, that_, 48, sampleRate );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::getSampleRate(ASIOSampleRate *sampleRate)
+{
+ ASIOBool result;
+ CALL_THISCALL_1( result, that_, 52, sampleRate );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::setSampleRate(ASIOSampleRate sampleRate)
+{
+ ASIOBool result;
+ CALL_THISCALL_1_DOUBLE( result, that_, 56, sampleRate );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::getClockSources(ASIOClockSource *clocks, long *numSources)
+{
+ ASIOBool result;
+ CALL_THISCALL_2( result, that_, 60, clocks, numSources );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::setClockSource(long reference)
+{
+ ASIOBool result;
+ CALL_THISCALL_1( result, that_, 64, reference );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::getSamplePosition(ASIOSamples *sPos, ASIOTimeStamp *tStamp)
+{
+ ASIOBool result;
+ CALL_THISCALL_2( result, that_, 68, sPos, tStamp );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::getChannelInfo(ASIOChannelInfo *info)
+{
+ ASIOBool result;
+ CALL_THISCALL_1( result, that_, 72, info );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::createBuffers(ASIOBufferInfo *bufferInfos,
+ long numChannels, long bufferSize, ASIOCallbacks *callbacks)
+{
+ ASIOBool result;
+ CALL_THISCALL_4( result, that_, 76, bufferInfos, numChannels, bufferSize, callbacks );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::disposeBuffers()
+{
+ ASIOBool result;
+ CALL_THISCALL_0( result, that_, 80 );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::controlPanel()
+{
+ ASIOBool result;
+ CALL_THISCALL_0( result, that_, 84 );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::future(long selector,void *opt)
+{
+ ASIOBool result;
+ CALL_THISCALL_2( result, that_, 88, selector, opt );
+ return result;
+}
+
+ASIOError IASIOThiscallResolver::outputReady()
+{
+ ASIOBool result;
+ CALL_THISCALL_0( result, that_, 92 );
+ return result;
+}
+
+
+// Implement our substitute ASIOInit() method
+ASIOError IASIOThiscallResolver::ASIOInit(ASIODriverInfo *info)
+{
+ // To ensure that our instance's vptr is correctly constructed, even if
+ // ASIOInit is called prior to main(), we explicitly call its constructor
+ // (potentially over the top of an existing instance). Note that this is
+ // pretty ugly, and is only safe because IASIOThiscallResolver has no
+ // destructor and contains no objects with destructors.
+ new((void*)&instance) IASIOThiscallResolver( theAsioDriver );
+
+ // Interpose between ASIO client code and the real driver.
+ theAsioDriver = &instance;
+
+ // Note that we never need to switch theAsioDriver back to point to the
+ // real driver because theAsioDriver is reset to zero in ASIOExit().
+
+ // Delegate to the real ASIOInit
+ return ::ASIOInit(info);
+}
+
+
+#endif /* !defined(_MSC_VER) */
+
+#endif /* Win32 */
+
generated by cgit v1.2.1 (git 2.18.0) at 2024-11-01 11:28:56 +0000