将 __asm 块定义为 C 宏时遇到错误

Question

When I try to define a multi-instruction shared byte obfuscating code with c macro, there is an error when compiling, the error codes are C2414 and C2400 If the c macro definition is not used, it can be compiled successfully

#include <stdio.h>
#define test __asm{\
__asm jmp $+5\
}

#define test1 __asm{\
__asm _emit 0xeb\
__asm _emit 0xff\
__asm _emit 0xc0\
__asm _emit 0x48\
}

int main()
{
    test1;
}

How can I use this obfuscating code inside a c macro?

Answer 1

According to this then multiple __asm on a single line should be ok. But after compiling your code in MSVC, the actual problem reported is:

(15): error C2059: syntax error: 'bad suffix on number'

And then we realize that your macro expands to __asm _emit 0xeb__asm _emit 0xff and so on, where 0xeb__asm is gibberish. Adding a space to each row like 0xeb \ made your code compile cleanly.