I/O 端口读写的实现

细心的读者会发现，C++Builder不再支持如inportb()、outportb()一类I/O端口读写指令了。准确地说，在Windows环境下，BorlandC++仅支持16位应用程序的端口操作，对32位应用程序的端口操作不再支持,而C++Builder开发出来的程序是32位的。我个人以为，这是C++Builder设计者的败笔。因为PC机中，I/O地址空间与内存地址空间从来都是各自独立的。看看Delphi，不就通过Port数组实现了对I/O端口的访问了吗？搞不清楚为什么C++Builder就没有提供类似的机制？下面这几个函数是笔者从网上淘下来的，经过验证，在Windows95环境下，的确可实现对I/O端口的读写。读者可以借鉴使用。
                    void outportb(unsigned short int port, unsigned char value)

                    {

                           // mov edx, *(&port);

                           __emit__(0x8b, 0x95, &port);

                           // mov al, *(&value);

                           __emit__(0x8a, 0x85, &value);

                           // out dx, al;

                           __emit__(0x66, 0xee);

                    }

                    void outportw(unsigned short  int port, unsigned short int value)

                    {

                           // mov edx, *(&port);

                           __emit__(0x8b, 0x95, &port);

                           // mov ax, *(&value);

                           __emit__(0x66, 0x8b, 0x85, &value);

                           // out dx, ax;

                           __emit__(0xef);

                    }

                    unsigned char inportb(unsigned short int port)

                    {

                           unsigned char value;

                           // mov edx, *(&port);

                           __emit__(0x8b, 0x95, &port);

                           // in al, dx;

                           __emit__(0x66, 0xec);

                           // mov *(&value), al;

                           __emit__(0x88, 0x85, &value);

                           return value;

                    }

                    unsigned short int inportw(unsigned short int port)

                    {

                           unsigned short int value;

                           // mov edx, *(&port);

                           __emit__(0x8b, 0x95, &port);

                           // in ax, dx

                           __emit__(0xed);

                           // mov *(&value), ax

                           __emit__(0x66, 0x89, 0x85, &value);

                           return value;

                    }