Roth

With Apple Silicon port on my mind from my day job, I wanted to inquire about how pointers to functions cast to 

) are called from Max. I assume they are usually called with pointers to function of type 

 or using object_method vs casting to a typed pointer or using object_method_direct.

, it would be undefined behavior in C or C++ to call this function with a pointer of type

, but I assume this is what Max does because historically this has worked with some caveats pointed out in the docs.

It seems as though when there is an Apple Silicon port of Max, this will no longer work:

The x86_64 and arm64 architectures have different calling conventions for variadic functions—functions with a variable number of parameters. On x86_64, the compiler treats fixed and variadic parameters the same, placing parameters in registers first and only using the stack when no more registers are available. On arm64, the compiler always places variadic parameters on the stack, regardless of whether registers are available. If you implement a function with fixed parameters, but redeclare it with variadic parameters, the mismatch causes unexpected behavior at runtime.

https://developer.apple.com/documentation/apple_silicon/addressing_architectural_differences_in_your_macos_code

If Max is calling our external methods as 

, it seems as though we should be defining our functions to match. From the docs, I'm wondering if there are some methods that are called from Max with explicit types (DSP perform methods? attributes? GIMME?).

Also, how are methods internal to Max defined? For example, is 

, or would we need to use object_method_direct to correctly call it on Apple Silicon?

In general, I'm curious what the plans for the Max SDK are on Apple Silicon re. variadic function parameters.

With Apple Silicon port on my mind from my day job, I wanted to inquire about how pointers to functions cast to method (i.e. void* (*)(void*, ...)) are called from Max. I assume they are usually called with pointers to function of type void* (*)(void*, ...) or using object_method vs casting to a typed pointer or using object_method_direct.

If I were to declare my "int" method as void my_int(t_object*, long), it would be undefined behavior in C or C++ to call this function with a pointer of type void* (*)(void*, ...), but I assume this is what Max does because historically this has worked with some caveats pointed out in the docs.

It seems as though when there is an Apple Silicon port of Max, this will no longer work:


The x86_64 and arm64 architectures have different calling conventions for variadic functions—functions with a variable number of parameters. On x86_64, the compiler treats fixed and variadic parameters the same, placing parameters in registers first and only using the stack when no more registers are available. On arm64, the compiler always places variadic parameters on the stack, regardless of whether registers are available. If you implement a function with fixed parameters, but redeclare it with variadic parameters, the mismatch causes unexpected behavior at runtime.

If Max is calling our external methods as void* (*)(void*, ...), it seems as though we should be defining our functions to match. From the docs, I'm wondering if there are some methods that are called from Max with explicit types (DSP perform methods? attributes? GIMME?).

Also, how are methods internal to Max defined? For example, is "dsp_add64" defined as void* (void*, ...), or would we need to use object_method_direct to correctly call it on Apple Silicon?

In general, I'm curious what the plans for the Max SDK are on Apple Silicon re. variadic function parameters.

With Apple Silicon port on my mind from my day job, I wanted to inquire about how pointers to functions cast to method (i.e. void* (*)(void*

method function pointer types and correct function prototypes