/* generate an interrupt after the specified time (in microseconds) */
void
clock_generate_interrupt(uint64_t time)
{
uint64_t clock = clock_read();
while(timer_timeout(timer_device.ti, us_to_ticks(timer_device.frequency, clock + time)))
time *= 2;
}
/*
this program illustrates how to use void* as a generic pointer, how
to use pointer casts to get the generic pointer interpreted
according to what type of value it points to, and the danger of
making an incorrect cast
*/
int main (int argc, char ** argv)
{
struct tm now; /* standard struct for storing a time value */
double lightspeed;
Person * albert; /* pointer to our custom struct person */
void * generic_pointer;
/*
let's read the clock, it gets stored in a standard struct tm (from
the time.h header)
*/
if (0 != clock_read (&now)) {
printf ("failed to read the clock\n");
return 1;
}
/*
the speed of light as a double-precision floating point number
*/
lightspeed = 299792458.0;
/*
Albert Einstein was born on March 14, 1879. His age depends on
today's date...
*/
albert = person_create ("Albert Einstein",
(now.tm_mon >= 3 && now.tm_mday >= 14) ?
now.tm_year + 1901 - 1879 :
now.tm_year + 1900 - 1879);
/* **************************************************
* NOW FOR THE FUN PART *****************************
* **************************************************/
/*
the generic pointer can store the address of any of our variables
*/
generic_pointer = &now;
printf ("the date and time is\n");
clock_print (&now);
generic_pointer = &lightspeed;
printf ("the speed of light is\n %g m/s\n", *(double*)generic_pointer);
generic_pointer = albert;
printf ("the person is\n");
person_print (generic_pointer);
return 0;
}
/* Wait for the specified time (in microseconds) */
void
clock_wait(uint64_t time)
{
int error;
uint64_t clock = clock_read();
uint64_t timeout = clock + time;
error = okn_syscall_interrupt_register(CLOCK_IRQ);
assert(!error);
if (timer_timeout(timer_device.ti, us_to_ticks(timer_device.frequency, timeout))) {
error = okn_syscall_interrupt_deregister(CLOCK_IRQ);
assert(!error);
return; /* Already expired */
}
/* wait for the interrupt */
while(!device_interrupt(timer_device.di, okn_syscall_interrupt_wait()));
error = okn_syscall_interrupt_deregister(CLOCK_IRQ);
assert(!error);
}
uint8_t noinline input_nibble(uint8_t rs, uint8_t en)
{
/* WR setzen = lesen */
lcd_data |= _BV(HD44780_PCF8574x_WR);
/* Wenn rs gesetzt, */
if (rs) /* dann RS setzen */
lcd_data |= _BV(HD44780_PCF8574x_RS);
else /* sonst RS loeschen */
lcd_data &= ~(_BV(HD44780_PCF8574x_RS));
/* toggle EN, daten abholen */
uint8_t data = clock_read(en);
/* WR loeschen = schreiben */
lcd_data &= ~(_BV(HD44780_PCF8574x_WR));
return data;
}
uint8_t noinline input_nibble(uint8_t rs, uint8_t en)
{
/* configure data pins as input */
DATA_INPUT();
/* set write bit */
PIN_SET(HD44780_RW);
/* set rs, if given */
PIN_CLEAR(HD44780_RS);
if (rs)
PIN_SET(HD44780_RS);
uint8_t data = clock_read(en);
/* reconfigure data pins as output */
DATA_OUTPUT();
/* delete RW bit */
PIN_CLEAR(HD44780_RW);
return data;
}