17 Mixing C and Assembly Code

Note: The examples presented in this section may not compile or assemble on all devices; however, they are illustrative of the concepts being presented.

This section describes how to use assembly language and C/C++ modules together. It gives examples of using C/C++ variables and functions in assembly code and examples of using assembly language variables and functions in C/C++.

Note:

Calling C++ from assembly function is complex: C++ member functions have an implicit this pointer as an argument and C++ functions have their names mangled.

Calling assembly functions from C++ is easier: Assembly functions will require that their names be prototyped with extern "C".

Items discussed are:

17.1 Mixing Assembly Language and C/C++ Variables and Functions – separate assembly language modules may be assembled then linked with compiled C/C++ modules.
17.2 Using Inline Assembly Language – assembly language instructions may be embedded directly into the C/C++ code. The inline assembler supports both simple (non-parameterized) assembly language statements, as well as extended (parameterized) statements (where C/C++ variables can be accessed as operands of an assembler instruction).
17.3 Predefined Assembly Macros – a list of predefined assembly-code macros to be used in C/C++ code is provided.