-/*\r
- IASIOThiscallResolver.cpp see the comments in iasiothiscallresolver.h for\r
- the top level description - this comment describes the technical details of\r
- the implementation.\r
-\r
- The latest version of this file is available from:\r
- http://www.audiomulch.com/~rossb/code/calliasio\r
-\r
- please email comments to Ross Bencina <rossb@audiomulch.com>\r
-\r
- BACKGROUND\r
-\r
- The IASIO interface declared in the Steinberg ASIO 2 SDK declares\r
- functions with no explicit calling convention. This causes MSVC++ to default\r
- to using the thiscall convention, which is a proprietary convention not\r
- implemented by some non-microsoft compilers - notably borland BCC,\r
- C++Builder, and gcc. MSVC++ is the defacto standard compiler used by\r
- Steinberg. As a result of this situation, the ASIO sdk will compile with\r
- any compiler, however attempting to execute the compiled code will cause a\r
- crash due to different default calling conventions on non-Microsoft\r
- compilers.\r
-\r
- IASIOThiscallResolver solves the problem by providing an adapter class that\r
- delegates to the IASIO interface using the correct calling convention\r
- (thiscall). Due to the lack of support for thiscall in the Borland and GCC\r
- compilers, the calls have been implemented in assembly language.\r
-\r
- A number of macros are defined for thiscall function calls with different\r
- numbers of parameters, with and without return values - it may be possible\r
- to modify the format of these macros to make them work with other inline\r
- assemblers.\r
-\r
-\r
- THISCALL DEFINITION\r
-\r
- A number of definitions of the thiscall calling convention are floating\r
- around the internet. The following definition has been validated against\r
- output from the MSVC++ compiler:\r
-\r
- For non-vararg functions, thiscall works as follows: the object (this)\r
- pointer is passed in ECX. All arguments are passed on the stack in\r
- right to left order. The return value is placed in EAX. The callee\r
- clears the passed arguments from the stack.\r
-\r
-\r
- FINDING FUNCTION POINTERS FROM AN IASIO POINTER\r
-\r
- The first field of a COM object is a pointer to its vtble. Thus a pointer\r
- to an object implementing the IASIO interface also points to a pointer to\r
- that object's vtbl. The vtble is a table of function pointers for all of\r
- the virtual functions exposed by the implemented interfaces.\r
-\r
- If we consider a variable declared as a pointer to IASO:\r
-\r
- IASIO *theAsioDriver\r
-\r
- theAsioDriver points to:\r
-\r
- object implementing IASIO\r
- {\r
- IASIOvtbl *vtbl\r
- other data\r
- }\r
-\r
- in other words, theAsioDriver points to a pointer to an IASIOvtbl\r
-\r
- vtbl points to a table of function pointers:\r
-\r
- IASIOvtbl ( interface IASIO : public IUnknown )\r
- {\r
- (IUnknown functions)\r
- 0 virtual HRESULT STDMETHODCALLTYPE (*QueryInterface)(REFIID riid, void **ppv) = 0;\r
- 4 virtual ULONG STDMETHODCALLTYPE (*AddRef)() = 0;\r
- 8 virtual ULONG STDMETHODCALLTYPE (*Release)() = 0; \r
-\r
- (IASIO functions)\r
- 12 virtual ASIOBool (*init)(void *sysHandle) = 0;\r
- 16 virtual void (*getDriverName)(char *name) = 0;\r
- 20 virtual long (*getDriverVersion)() = 0;\r
- 24 virtual void (*getErrorMessage)(char *string) = 0;\r
- 28 virtual ASIOError (*start)() = 0;\r
- 32 virtual ASIOError (*stop)() = 0;\r
- 36 virtual ASIOError (*getChannels)(long *numInputChannels, long *numOutputChannels) = 0;\r
- 40 virtual ASIOError (*getLatencies)(long *inputLatency, long *outputLatency) = 0;\r
- 44 virtual ASIOError (*getBufferSize)(long *minSize, long *maxSize,\r
- long *preferredSize, long *granularity) = 0;\r
- 48 virtual ASIOError (*canSampleRate)(ASIOSampleRate sampleRate) = 0;\r
- 52 virtual ASIOError (*getSampleRate)(ASIOSampleRate *sampleRate) = 0;\r
- 56 virtual ASIOError (*setSampleRate)(ASIOSampleRate sampleRate) = 0;\r
- 60 virtual ASIOError (*getClockSources)(ASIOClockSource *clocks, long *numSources) = 0;\r
- 64 virtual ASIOError (*setClockSource)(long reference) = 0;\r
- 68 virtual ASIOError (*getSamplePosition)(ASIOSamples *sPos, ASIOTimeStamp *tStamp) = 0;\r
- 72 virtual ASIOError (*getChannelInfo)(ASIOChannelInfo *info) = 0;\r
- 76 virtual ASIOError (*createBuffers)(ASIOBufferInfo *bufferInfos, long numChannels,\r
- long bufferSize, ASIOCallbacks *callbacks) = 0;\r
- 80 virtual ASIOError (*disposeBuffers)() = 0;\r
- 84 virtual ASIOError (*controlPanel)() = 0;\r
- 88 virtual ASIOError (*future)(long selector,void *opt) = 0;\r
- 92 virtual ASIOError (*outputReady)() = 0;\r
- };\r
-\r
- The numbers in the left column show the byte offset of each function ptr\r
- from the beginning of the vtbl. These numbers are used in the code below\r
- to select different functions.\r
-\r
- In order to find the address of a particular function, theAsioDriver\r
- must first be dereferenced to find the value of the vtbl pointer:\r
-\r
- mov eax, theAsioDriver\r
- mov edx, [theAsioDriver] // edx now points to vtbl[0]\r
-\r
- Then an offset must be added to the vtbl pointer to select a\r
- particular function, for example vtbl+44 points to the slot containing\r
- a pointer to the getBufferSize function.\r
-\r
- Finally vtbl+x must be dereferenced to obtain the value of the function\r
- pointer stored in that address:\r
-\r
- call [edx+44] // call the function pointed to by\r
- // the value in the getBufferSize field of the vtbl\r
-\r
-\r
- SEE ALSO\r
-\r
- Martin Fay's OpenASIO DLL at http://www.martinfay.com solves the same\r
- problem by providing a new COM interface which wraps IASIO with an\r
- interface that uses portable calling conventions. OpenASIO must be compiled\r
- with MSVC, and requires that you ship the OpenASIO DLL with your\r
- application.\r
-\r
- \r
- ACKNOWLEDGEMENTS\r
-\r
- Ross Bencina: worked out the thiscall details above, wrote the original\r
- Borland asm macros, and a patch for asio.cpp (which is no longer needed).\r
- Thanks to Martin Fay for introducing me to the issues discussed here,\r
- and to Rene G. Ceballos for assisting with asm dumps from MSVC++.\r
-\r
- Antti Silvast: converted the original calliasio to work with gcc and NASM\r
- by implementing the asm code in a separate file.\r
-\r
- Fraser Adams: modified the original calliasio containing the Borland inline\r
- asm to add inline asm for gcc i.e. Intel syntax for Borland and AT&T syntax\r
- for gcc. This seems a neater approach for gcc than to have a separate .asm\r
- file and it means that we only need one version of the thiscall patch.\r
-\r
- Fraser Adams: rewrote the original calliasio patch in the form of the\r
- IASIOThiscallResolver class in order to avoid modifications to files from\r
- the Steinberg SDK, which may have had potential licence issues.\r
-\r
- Andrew Baldwin: contributed fixes for compatibility problems with more\r
- recent versions of the gcc assembler.\r
-*/\r
-\r
-\r
-// We only need IASIOThiscallResolver at all if we are on Win32. For other\r
-// platforms we simply bypass the IASIOThiscallResolver definition to allow us\r
-// to be safely #include'd whatever the platform to keep client code portable\r
-#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__)\r
-\r
-\r
-// If microsoft compiler we can call IASIO directly so IASIOThiscallResolver\r
-// is not used.\r
-#if !defined(_MSC_VER)\r
-\r
-\r
-#include <new>\r
-#include <assert.h>\r
-\r
-// We have a mechanism in iasiothiscallresolver.h to ensure that asio.h is\r
-// #include'd before it in client code, we do NOT want to do this test here.\r
-#define iasiothiscallresolver_sourcefile 1\r
-#include "iasiothiscallresolver.h"\r
-#undef iasiothiscallresolver_sourcefile\r
-\r
-// iasiothiscallresolver.h redefines ASIOInit for clients, but we don't want\r
-// this macro defined in this translation unit.\r
-#undef ASIOInit\r
-\r
-\r
-// theAsioDriver is a global pointer to the current IASIO instance which the\r
-// ASIO SDK uses to perform all actions on the IASIO interface. We substitute\r
-// our own forwarding interface into this pointer.\r
-extern IASIO* theAsioDriver;\r
-\r
-\r
-// The following macros define the inline assembler for BORLAND first then gcc\r
-\r
-#if defined(__BCPLUSPLUS__) || defined(__BORLANDC__) \r
-\r
-\r
-#define CALL_THISCALL_0( resultName, thisPtr, funcOffset )\\r
- void *this_ = (thisPtr); \\r
- __asm { \\r
- mov ecx, this_ ; \\r
- mov eax, [ecx] ; \\r
- call [eax+funcOffset] ; \\r
- mov resultName, eax ; \\r
- }\r
-\r
-\r
-#define CALL_VOID_THISCALL_1( thisPtr, funcOffset, param1 )\\r
- void *this_ = (thisPtr); \\r
- __asm { \\r
- mov eax, param1 ; \\r
- push eax ; \\r
- mov ecx, this_ ; \\r
- mov eax, [ecx] ; \\r
- call [eax+funcOffset] ; \\r
- }\r
-\r
-\r
-#define CALL_THISCALL_1( resultName, thisPtr, funcOffset, param1 )\\r
- void *this_ = (thisPtr); \\r
- __asm { \\r
- mov eax, param1 ; \\r
- push eax ; \\r
- mov ecx, this_ ; \\r
- mov eax, [ecx] ; \\r
- call [eax+funcOffset] ; \\r
- mov resultName, eax ; \\r
- }\r
-\r
-\r
-#define CALL_THISCALL_1_DOUBLE( resultName, thisPtr, funcOffset, param1 )\\r
- void *this_ = (thisPtr); \\r
- void *doubleParamPtr_ (¶m1); \\r
- __asm { \\r
- mov eax, doubleParamPtr_ ; \\r
- push [eax+4] ; \\r
- push [eax] ; \\r
- mov ecx, this_ ; \\r
- mov eax, [ecx] ; \\r
- call [eax+funcOffset] ; \\r
- mov resultName, eax ; \\r
- }\r
-\r
-\r
-#define CALL_THISCALL_2( resultName, thisPtr, funcOffset, param1, param2 )\\r
- void *this_ = (thisPtr); \\r
- __asm { \\r
- mov eax, param2 ; \\r
- push eax ; \\r
- mov eax, param1 ; \\r
- push eax ; \\r
- mov ecx, this_ ; \\r
- mov eax, [ecx] ; \\r
- call [eax+funcOffset] ; \\r
- mov resultName, eax ; \\r
- }\r
-\r
-\r
-#define CALL_THISCALL_4( resultName, thisPtr, funcOffset, param1, param2, param3, param4 )\\r
- void *this_ = (thisPtr); \\r
- __asm { \\r
- mov eax, param4 ; \\r
- push eax ; \\r
- mov eax, param3 ; \\r
- push eax ; \\r
- mov eax, param2 ; \\r
- push eax ; \\r
- mov eax, param1 ; \\r
- push eax ; \\r
- mov ecx, this_ ; \\r
- mov eax, [ecx] ; \\r
- call [eax+funcOffset] ; \\r
- mov resultName, eax ; \\r
- }\r
-\r
-\r
-#elif defined(__GNUC__)\r
-\r
-\r
-#define CALL_THISCALL_0( resultName, thisPtr, funcOffset ) \\r
- __asm__ __volatile__ ("movl (%1), %%edx\n\t" \\r
- "call *"#funcOffset"(%%edx)\n\t" \\r
- :"=a"(resultName) /* Output Operands */ \\r
- :"c"(thisPtr) /* Input Operands */ \\r
- ); \\r
-\r
-\r
-#define CALL_VOID_THISCALL_1( thisPtr, funcOffset, param1 ) \\r
- __asm__ __volatile__ ("pushl %0\n\t" \\r
- "movl (%1), %%edx\n\t" \\r
- "call *"#funcOffset"(%%edx)\n\t" \\r
- : /* Output Operands */ \\r
- :"r"(param1), /* Input Operands */ \\r
- "c"(thisPtr) \\r
- ); \\r
-\r
-\r
-#define CALL_THISCALL_1( resultName, thisPtr, funcOffset, param1 ) \\r
- __asm__ __volatile__ ("pushl %1\n\t" \\r
- "movl (%2), %%edx\n\t" \\r
- "call *"#funcOffset"(%%edx)\n\t" \\r
- :"=a"(resultName) /* Output Operands */ \\r
- :"r"(param1), /* Input Operands */ \\r
- "c"(thisPtr) \\r
- ); \\r
-\r
-\r
-#define CALL_THISCALL_1_DOUBLE( resultName, thisPtr, funcOffset, param1 ) \\r
- __asm__ __volatile__ ("pushl 4(%1)\n\t" \\r
- "pushl (%1)\n\t" \\r
- "movl (%2), %%edx\n\t" \\r
- "call *"#funcOffset"(%%edx);\n\t" \\r
- :"=a"(resultName) /* Output Operands */ \\r
- :"a"(¶m1), /* Input Operands */ \\r
- /* Note: Using "r" above instead of "a" fails */ \\r
- /* when using GCC 3.3.3, and maybe later versions*/\\r
- "c"(thisPtr) \\r
- ); \\r
-\r
-\r
-#define CALL_THISCALL_2( resultName, thisPtr, funcOffset, param1, param2 ) \\r
- __asm__ __volatile__ ("pushl %1\n\t" \\r
- "pushl %2\n\t" \\r
- "movl (%3), %%edx\n\t" \\r
- "call *"#funcOffset"(%%edx)\n\t" \\r
- :"=a"(resultName) /* Output Operands */ \\r
- :"r"(param2), /* Input Operands */ \\r
- "r"(param1), \\r
- "c"(thisPtr) \\r
- ); \\r
-\r
-\r
-#define CALL_THISCALL_4( resultName, thisPtr, funcOffset, param1, param2, param3, param4 )\\r
- __asm__ __volatile__ ("pushl %1\n\t" \\r
- "pushl %2\n\t" \\r
- "pushl %3\n\t" \\r
- "pushl %4\n\t" \\r
- "movl (%5), %%edx\n\t" \\r
- "call *"#funcOffset"(%%edx)\n\t" \\r
- :"=a"(resultName) /* Output Operands */ \\r
- :"r"(param4), /* Input Operands */ \\r
- "r"(param3), \\r
- "r"(param2), \\r
- "r"(param1), \\r
- "c"(thisPtr) \\r
- ); \\r
-\r
-#endif\r
-\r
-\r
-\r
-// Our static singleton instance.\r
-IASIOThiscallResolver IASIOThiscallResolver::instance;\r
-\r
-// Constructor called to initialize static Singleton instance above. Note that\r
-// it is important not to clear that_ incase it has already been set by the call\r
-// to placement new in ASIOInit().\r
-IASIOThiscallResolver::IASIOThiscallResolver()\r
-{\r
-}\r
-\r
-// Constructor called from ASIOInit() below\r
-IASIOThiscallResolver::IASIOThiscallResolver(IASIO* that)\r
-: that_( that )\r
-{\r
-}\r
-\r
-// Implement IUnknown methods as assert(false). IASIOThiscallResolver is not\r
-// really a COM object, just a wrapper which will work with the ASIO SDK.\r
-// If you wanted to use ASIO without the SDK you might want to implement COM\r
-// aggregation in these methods.\r
-HRESULT STDMETHODCALLTYPE IASIOThiscallResolver::QueryInterface(REFIID riid, void **ppv)\r
-{\r
- (void)riid; // suppress unused variable warning\r
-\r
- assert( false ); // this function should never be called by the ASIO SDK.\r
-\r
- *ppv = NULL;\r
- return E_NOINTERFACE;\r
-}\r
-\r
-ULONG STDMETHODCALLTYPE IASIOThiscallResolver::AddRef()\r
-{\r
- assert( false ); // this function should never be called by the ASIO SDK.\r
-\r
- return 1;\r
-}\r
-\r
-ULONG STDMETHODCALLTYPE IASIOThiscallResolver::Release()\r
-{\r
- assert( false ); // this function should never be called by the ASIO SDK.\r
- \r
- return 1;\r
-}\r
-\r
-\r
-// Implement the IASIO interface methods by performing the vptr manipulation\r
-// described above then delegating to the real implementation.\r
-ASIOBool IASIOThiscallResolver::init(void *sysHandle)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_1( result, that_, 12, sysHandle );\r
- return result;\r
-}\r
-\r
-void IASIOThiscallResolver::getDriverName(char *name)\r
-{\r
- CALL_VOID_THISCALL_1( that_, 16, name );\r
-}\r
-\r
-long IASIOThiscallResolver::getDriverVersion()\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_0( result, that_, 20 );\r
- return result;\r
-}\r
-\r
-void IASIOThiscallResolver::getErrorMessage(char *string)\r
-{\r
- CALL_VOID_THISCALL_1( that_, 24, string );\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::start()\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_0( result, that_, 28 );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::stop()\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_0( result, that_, 32 );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::getChannels(long *numInputChannels, long *numOutputChannels)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_2( result, that_, 36, numInputChannels, numOutputChannels );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::getLatencies(long *inputLatency, long *outputLatency)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_2( result, that_, 40, inputLatency, outputLatency );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::getBufferSize(long *minSize, long *maxSize,\r
- long *preferredSize, long *granularity)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_4( result, that_, 44, minSize, maxSize, preferredSize, granularity );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::canSampleRate(ASIOSampleRate sampleRate)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_1_DOUBLE( result, that_, 48, sampleRate );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::getSampleRate(ASIOSampleRate *sampleRate)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_1( result, that_, 52, sampleRate );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::setSampleRate(ASIOSampleRate sampleRate)\r
-{ \r
- ASIOBool result;\r
- CALL_THISCALL_1_DOUBLE( result, that_, 56, sampleRate );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::getClockSources(ASIOClockSource *clocks, long *numSources)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_2( result, that_, 60, clocks, numSources );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::setClockSource(long reference)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_1( result, that_, 64, reference );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::getSamplePosition(ASIOSamples *sPos, ASIOTimeStamp *tStamp)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_2( result, that_, 68, sPos, tStamp );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::getChannelInfo(ASIOChannelInfo *info)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_1( result, that_, 72, info );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::createBuffers(ASIOBufferInfo *bufferInfos,\r
- long numChannels, long bufferSize, ASIOCallbacks *callbacks)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_4( result, that_, 76, bufferInfos, numChannels, bufferSize, callbacks );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::disposeBuffers()\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_0( result, that_, 80 );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::controlPanel()\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_0( result, that_, 84 );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::future(long selector,void *opt)\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_2( result, that_, 88, selector, opt );\r
- return result;\r
-}\r
-\r
-ASIOError IASIOThiscallResolver::outputReady()\r
-{\r
- ASIOBool result;\r
- CALL_THISCALL_0( result, that_, 92 );\r
- return result;\r
-}\r
-\r
-\r
-// Implement our substitute ASIOInit() method\r
-ASIOError IASIOThiscallResolver::ASIOInit(ASIODriverInfo *info)\r
-{\r
- // To ensure that our instance's vptr is correctly constructed, even if\r
- // ASIOInit is called prior to main(), we explicitly call its constructor\r
- // (potentially over the top of an existing instance). Note that this is\r
- // pretty ugly, and is only safe because IASIOThiscallResolver has no\r
- // destructor and contains no objects with destructors.\r
- new((void*)&instance) IASIOThiscallResolver( theAsioDriver );\r
-\r
- // Interpose between ASIO client code and the real driver.\r
- theAsioDriver = &instance;\r
-\r
- // Note that we never need to switch theAsioDriver back to point to the\r
- // real driver because theAsioDriver is reset to zero in ASIOExit().\r
-\r
- // Delegate to the real ASIOInit\r
- return ::ASIOInit(info);\r
-}\r
-\r
-\r
-#endif /* !defined(_MSC_VER) */\r
-\r
-#endif /* Win32 */\r
-\r
+/*
+ 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_ (¶m1); \
+ __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 = ¶m1f64; /* 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 */
+
projects / rtaudio-cdist.git / commitdiff