com32/menu/drain.c


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#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/cpu.h>

void drain_keyboard(void)
{
  /* Prevent "ghost typing" and keyboard buffer snooping */
  volatile char junk;
  int rv;
  
  do {
    rv = read(0, &junk, 1);
  } while (rv > 0);

  junk = 0;

  cli();
  *(volatile uint8_t *)0x419  = 0;	/* Alt-XXX keyboard area */
  *(volatile uint16_t *)0x41a = 0x1e;	/* Keyboard buffer empty */
  *(volatile uint16_t *)0x41c = 0x1e;
  memset((volatile void *)0x41e, 0, 32); /* Clear the actual keyboard buffer */
  sti();
}