// Function to read a byte from port unsigned char port_byte_in(unsigned short port) { unsigned char res; __asm__("in %%dx, %%al" : "=a" (res) : "d" (port)); return res; } // to write a byte to port void port_byte_out(unsigned short port, unsigned char data) { __asm__("out %%al, %%dx" : :"a" (data), "d" (port)); } // Read word from port unsigned short port_word_in(unsigned short port) { unsigned short res; __asm__("in %%dx, %%ax" : "=a" (res) : "d" (port)); return res; } // write word to port void port_word_out(unsigned short port, unsigned short data) { __asm__("out %%ax, %%dx" : :"a" (data), "d" (port)); }