51单片机IO口能做实参传递吗

可以的，但是一般性不这么用，不是所有的编译器都支持sfr（本质是地址）的传递。

你可以使用这样的东西：（这是我写的AVR类库）

void SETB(PORT port,unsigned char bit);//其他的源代码举一反三吧

记得定义：

#define PORT enum PORT
//方便输入
#define setb SETB
#define clrb CLRB
#define getb GETB
    PORT{
        PA,
        PB,
        PC,
        PD
    };

Port和bit的本质都是寄存器，一个是byte寻址一个是bit寻址而已，千万不要以为bit寻址就一定快，往往是byte要快一些。

附上源代码：

gpio.h

#ifndef AVR_GPIO_H
#define AVR_GPIO_H
#define PORT enum PORT
//方便输入
#define setb SETB
#define clrb CLRB
#define getb GETB
    PORT{
        //PA,
        PB,
        PC,
        PD
    };
    extern void SETB(PORT port,unsigned char bit);
    //相应端口置1,并设置为输出
    extern void CLRB(PORT port,unsigned char bit);
    //相应端口置0,并设置为输出
    extern unsigned char GETB(PORT port,unsigned char bit);
    //相应端口设置为输入并读取，返回0xff(1)与0x00(0),异常返回0xf0
    extern void SETD(PORT port,unsigned char bit);
    //相应端口设置为输出
    extern void CLRD(PORT port,unsigned char bit);
    //相应端口设置为输入
#endif

gpio.c

#include"inc.h"

void SETB(PORT port,unsigned char bit){
    if(bit<=7){
        switch(port){
            //case PA:
            //DDRA|=(1<            //PORTA|=(1<            //break;
            //use in Mega16
            case PB:
                DDRB|=(1<                PORTB|=(1<                break;
            case PC:
                DDRC|=(1<                PORTC|=(1<                break;
            case PD:
                DDRD|=(1<                PORTD|=(1<                break;
        }
    }
}

void CLRB(PORT port,unsigned char bit){
    if(bit<=7){
        switch(port){
            //case PA:
            //DDRA&=(1<            //PORTA&=(0xff-(1<            //break;
            //use in Mega16
            case PB:
                DDRB|=(1<                PORTB&=(0xff-(1<                break;
            case PC:
                DDRC|=(1<                PORTC&=(0xff-(1<                break;
            case PD:
                DDRD|=(1<                PORTD&=(0xff-(1<                break;
        }
    }
}

unsigned char GETB(PORT port,unsigned char bit){
    unsigned return_value=0;
    if(bit<=7){
        switch(port){
            //case PA:
            //DDRA|=(0xff-(1<            //return_value=PINA&(1<            //break;
            //use in Mega16
            case PB:
                DDRB|=(0xff-(1<                return_value=PINB&(1<                break;
            case PC:
                DDRC|=(0xff-(1<                return_value=PINC&(1<                break;
            case PD:
                DDRD|=(0xff-(1<                return_value=PIND&(1<                break;
        }
        if(return_value==0){
            return(0x00);
        }else{
            return(0xff);
        }
    }
    return(0xf0);
}

void SETD(PORT port,unsigned char bit){
    if(bit<=7){
        switch(port){
            //case PA:
                //DDRA|=(1<                //break;
            //use in Mega16
            case PB:
                DDRB|=(1<                break;
            case PC:
                DDRC|=(1<                break;
            case PD:
                DDRD|=(1<                break;
        }
    }
}

void CLRD(PORT port,unsigned char bit){
    if(bit<=7){
        switch(port){
            //case PA:
            //DDRA|=(0xff-(1<            //break;
            //use in Mega16
            case PB:
                DDRB|=(0xff-(1<                break;
            case PC:
                DDRC|=(0xff-(1<                break;
            case PD:
                DDRD|=(0xff-(1<                break;
        }
    }
}