原创 Delays - text scrolling on an LCD panel

＃i nclude
"pt.h"

＃i nclude
"timer.h"

struct state {  char *text;

                    char *scrollptr;

                    struct pt pt;

                    struct
timer timer;};

PT_THREAD(display_text(struct state *s))

{

 
PT_BEGIN(&s->pt);

  /*
If the text is shorter than the display size, show it right away. */

  if(strlen(s->text)
<= LCD_SIZE) {lcd_display_text(s->text);}

else

{   

   
/* If the text is longer than the display, we should scroll in the text
from the right with a delay of one second per scroll step. We do this in a
for() loop, where the loop variable is the pointer to the first character to be
displayed. */

for(s->scrollptr
= s->text; strlen(s->scrollptr) > LCD_SIZE;     ++s->scrollptr)

{

     
lcd_display_text(s->scrollptr);

     
/* Wait for one second. */

      timer_set(&s->timer, ONE_SECOND);

     
PT_WAIT_UNTIL(&s->pt, timer_expired(&s->timer));

    }

  }

 
PT_END(&s->pt);

}