Why can't I pass a value into a function on AVR ?

int lcd_command(char comm) // function to send command to LCD
{
lcd_data_pin=comm;
en(1);
rs(0);
rw(0);
_delay_ms(50);
en(0);
}

	rs(0);
		_delay_ms(100); //delay

		rs(1);
		_delay_ms(100); //delay

        rw(0);
		_delay_ms(100); //delay
		rw(1);
        _delay_ms(100); //delay

		en(0);
		_delay_ms(100); //delay

		en(1);
		_delay_ms(100); //delay

		lcd_data_pin = 0xFF;
		_delay_ms(100); //delay
		lcd_data_pin = 0x00;

#include <avr/io.h>
#include <util/delay.h>

// Define the bits in the port 
typedef struct 
{ 
   unsigned char bit0 : 1, 
                 bit1 : 1, 
                 bit2 : 1, 
                 bit3 : 1, 
                 bit4 : 1, 
                 bit5 : 1, 
                 bit6 : 1, 
                 bit7 : 1; 
} bit_field; 

// Define macro to get the value of each bit 
#define GET_BIT(port) (*(volatile bit_field *) (_SFR_ADDR(port))) 

// Define functions for each bit of the I/O ports in the program 


#define rs  GET_BIT(PORTC).bit0
#define rw  GET_BIT(PORTC).bit1
#define en  GET_BIT(PORTC).bit2
#define data_port PORTD
void test(unsigned char data1);

void test(unsigned char data1)
{
	data_port = data1;
	en = 1;
	_delay_ms(50);
	rs = 0;
	_delay_ms(50);
	rw = 0;
	_delay_ms(80);
	en = 0;
}

int main (void)
{
  	DDRC = 0xFF;
	DDRD = 0xFF;
   while(1)
    {
	
		PORTD = 0x38;
		_delay_ms(50);
		PORTD = 0x01;
		_delay_ms(50);
		/*
		test(0x38);
		_delay_ms(50);
		test(0x01);
        */

    }
}

		PORTD = 0x38;
		_delay_ms(50);
		PORTD = 0x01;
		_delay_ms(50);

		test(0x38);
		_delay_ms(50);
		test(0x01);