在C语言中添加汇编

写法不对，参考文档spru187t的7.5.4节:

7.5.4 Using Inline Assembly Language
Within a C/C++ program, you can use the asm statement to insert a single line of assembly language into
the assembly language file created by the compiler. A series of asm statements places sequential lines of
assembly language into the compiler output with no intervening code. For more information, see
Section 6.8.
The asm statement is useful for inserting comments in the compiler output. Simply start the assembly
code string with a semicolon (;) as shown below:
asm(";*** this is an assembly language comment");
NOTE: Using the asm Statement
Keep the following in mind when using the asm statement:
• Be extremely careful not to disrupt the C/C++ environment. The compiler does not check
or analyze the inserted instructions.
• Avoid inserting jumps or labels into C/C++ code because they can produce
unpredictable results by confusing the register-tracking algorithms that the code
generator uses.
• Do not change the value of a C/C++ variable when using an asm statement. This is
because the compiler does not verify such statements. They are inserted as is into the
assembly code, and potentially can cause problems if you are not sure of their effect.
• Do not use the asm statement to insert assembler directives that change the assembly
environment.
• Avoid creating assembly macros in C code and compiling with the --symdebug:dwarf (or
-g) option. The C environment’s debug information and the assembly macro expansion
are not compatible.