ps/2 mouse problem in nios system

[Altera_Forum]

Hi there! 

I'm doing 1 small demo : detect the movement and button states from a ps2 mouse in nios system, I use the university IP core. nios build project no error, but when run, the console display nothing. Is the problem in read 3 byte (code c) or the printf function. Have you give me some advice or the code reference (read 3 byte from FIFO). Thank!  the code below : # include "altera_up_avalon_ps2.h"# include "altera_up_ps2_mouse.h"# include <alt_types.h># include <stdio.h># include <system.h>  int maxmin(int no, int max, int min) {  if(no>max) {no=max;}  if(no<min) {no=min;}   return(no); }  int main(void) {   alt_up_ps2_dev * ps2_dev;  ps2_dev = alt_up_ps2_open_dev("/dev/ps2_0");   alt_up_ps2_init(ps2_dev);  alt_up_ps2_clear_fifo(ps2_dev);    unsigned char byte1, byte2, byte3, byte1_x, byte1_y;  alt_u8 X, Y, X1, Y1;  int pX=320, pY=240, B=0;  while(1)   {  alt_up_ps2_read_data_byte(ps2_dev, &byte1);//read 1 byte  alt_up_ps2_read_data_byte(ps2_dev, &byte2);  alt_up_ps2_read_data_byte(ps2_dev, &byte3);  byte1_x = byte1&0x10;  byte1_y = byte1&0x30;  B = (int)byte1&0x07;  if(byte1_x == 0)  { X = byte2;  pX = pX + X;}  else   { X1 = (~byte2) + 1;  pX = pX - X1;}  if(byte1_y == 0)  { Y = byte3;  pY = pY + Y;}  else   { Y1 = (~byte3) + 1;  pY = pY - Y1;}  pX=maxmin(pX,639,0);  pY=maxmin(pY,479,0);  printf("%d%d\n",pX,pY);  printf("%d\n",B ) ;  }  return 0; }