嵌入式linux:getchar() 非阻塞

#由于getchar()函数会一直阻塞，网上搜到下面的函数来实现非阻塞的读取。实际使用的时候只需要调用kbhit()函数即可。其他函数没有看是什么意思
    #include <stdio.h>
#include <string.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <termios.h>
#include <unistd.h>

static struct termios ori_attr, cur_attr;

static __inline
int tty_reset(void)
{
if (tcsetattr(STDIN_FILENO, TCSANOW, &ori_attr) != 0)
return -1;

return 0;
}

static __inline
int tty_set(void)
{

if ( tcgetattr(STDIN_FILENO, &ori_attr) )
return -1;

memcpy(&cur_attr, &ori_attr, sizeof(cur_attr) );
cur_attr.c_lflag &= ~ICANON;
//        cur_attr.c_lflag |= ECHO;
cur_attr.c_lflag &= ~ECHO;
cur_attr.c_cc[VMIN] = 1;
cur_attr.c_cc[VTIME] = 0;

if (tcsetattr(STDIN_FILENO, TCSANOW, &cur_attr) != 0)
return -1;

return 0;
}

static __inline
int kbhit(void)
{

fd_set rfds;
struct timeval tv;
int retval;

/* Watch stdin (fd 0) to see when it has input. */
FD_ZERO(&rfds);
FD_SET(0, &rfds);
/* Wait up to five seconds. */
tv.tv_sec  = 0;
tv.tv_usec = 0;

retval = select(1, &rfds, NULL, NULL, &tv);
/* Don't rely on the value of tv now! */

if (retval == -1) {
perror("select()");
return 0;
} else if (retval)
return 1;
/* FD_ISSET(0, &rfds) will be true. */
else
return 0;
return 0;
}

int main()
{
int tty_set_flag;
tty_set_flag = tty_set();
while(1) {

if( kbhit() ) {
const int key = getchar();
printf("%c pressed\n", key);
if(key == 'q')
break;
} else {
fprintf(stderr, "<no key detected>\n");
}
}

if(tty_set_flag == 0)
tty_reset();
return 0;
}