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/*
* COPYRIGHT (c) 1989-2009.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <tmacros.h>
#include <intrcritical.h>
#define INTERRUPT_CRITICAL_NAME rtems_build_name( 'I', 'C', 'R', 'I' )
typedef struct {
rtems_interval minimum;
rtems_interval maximum;
rtems_interval maximum_current;
rtems_timer_service_routine_entry tsr;
rtems_id timer;
uint64_t t0;
uint64_t t1;
} interrupt_critical_control;
static interrupt_critical_control interrupt_critical;
static rtems_interval estimate_busy_loop_maximum( void )
{
rtems_interval units = 0;
rtems_interval initial = rtems_clock_get_ticks_since_boot();
while ( initial == rtems_clock_get_ticks_since_boot() ) {
++units;
}
return units;
}
static rtems_interval wait_for_tick_change( void )
{
rtems_interval initial = rtems_clock_get_ticks_since_boot();
rtems_interval now;
do {
now = rtems_clock_get_ticks_since_boot();
} while ( now == initial );
return now;
}
/*
* It is important that we use actually use the same busy() function at the
* various places, since otherwise the obtained maximum value might be wrong.
* So the compiler must not inline this function.
*/
static __attribute__( ( noinline ) ) void busy( rtems_interval max )
{
rtems_interval i = 0;
do {
__asm__ volatile ("");
++i;
} while ( i < max );
}
static bool interrupt_critical_busy_wait( void )
{
rtems_interval max = interrupt_critical.maximum_current;
bool reset = max <= interrupt_critical.minimum;
if ( reset ) {
interrupt_critical.maximum_current = interrupt_critical.maximum;
} else {
interrupt_critical.maximum_current = max - 1;
}
busy( max );
return reset;
}
void interrupt_critical_section_test_support_initialize(
rtems_timer_service_routine_entry tsr
)
{
rtems_interval last;
rtems_interval now;
rtems_interval a;
rtems_interval b;
rtems_interval m;
interrupt_critical.tsr = tsr;
if ( tsr != NULL && interrupt_critical.timer == 0 ) {
rtems_status_code sc = rtems_timer_create(
INTERRUPT_CRITICAL_NAME,
&interrupt_critical.timer
);
rtems_test_assert( sc == RTEMS_SUCCESSFUL );
}
/* Choose a lower bound */
a = 1;
/* Estimate an upper bound */
wait_for_tick_change();
b = 2 * estimate_busy_loop_maximum();
while ( true ) {
last = wait_for_tick_change();
busy( b );
now = rtems_clock_get_ticks_since_boot();
if ( now != last ) {
break;
}
b *= 2;
last = now;
}
/* Find a good value */
do {
m = ( a + b ) / 2;
last = wait_for_tick_change();
busy( m );
now = rtems_clock_get_ticks_since_boot();
if ( now != last ) {
b = m;
} else {
a = m;
}
} while ( b - a > 1 );
interrupt_critical.minimum = 0;
interrupt_critical.maximum = m;
interrupt_critical.maximum_current = m;
}
static void timer_fire_after(void)
{
if ( interrupt_critical.tsr != NULL ) {
rtems_status_code sc = rtems_timer_fire_after(
interrupt_critical.timer,
1,
interrupt_critical.tsr,
NULL
);
rtems_test_assert( sc == RTEMS_SUCCESSFUL );
}
}
bool interrupt_critical_section_test_support_delay(void)
{
timer_fire_after();
return interrupt_critical_busy_wait();
}
static bool is_idle( const Thread_Control *thread )
{
return thread->Start.entry_point
== (Thread_Entry) rtems_configuration_get_idle_task();
}
static void thread_switch( Thread_Control *executing, Thread_Control *heir )
{
(void) executing;
(void) heir;
if ( interrupt_critical.t1 == 0 && is_idle( heir ) ) {
interrupt_critical.t1 = rtems_clock_get_uptime_nanoseconds();
}
}
static const rtems_extensions_table extensions = {
.thread_switch = thread_switch
};
bool interrupt_critical_section_test(
bool ( *test_body )( void * ),
void *test_body_arg,
rtems_timer_service_routine_entry tsr
)
{
bool done;
rtems_status_code sc;
rtems_id id;
uint64_t delta;
rtems_interval busy_delta;
int retries = 3;
interrupt_critical_section_test_support_initialize( tsr );
sc = rtems_extension_create(
INTERRUPT_CRITICAL_NAME,
&extensions,
&id
);
rtems_test_assert( sc == RTEMS_SUCCESSFUL );
wait_for_tick_change();
timer_fire_after();
/* Get estimate for test body duration */
interrupt_critical.t0 = rtems_clock_get_uptime_nanoseconds();
done = ( *test_body )( test_body_arg );
if ( interrupt_critical.t1 == 0 ) {
interrupt_critical.t1 = rtems_clock_get_uptime_nanoseconds();
}
/* Update minimum */
delta = interrupt_critical.t1 - interrupt_critical.t0;
busy_delta = (rtems_interval)
( ( interrupt_critical.maximum * ( 2 * delta ) )
/ rtems_configuration_get_nanoseconds_per_tick() );
if ( busy_delta < interrupt_critical.maximum ) {
interrupt_critical.minimum = interrupt_critical.maximum - busy_delta;
}
sc = rtems_extension_delete( id );
rtems_test_assert( sc == RTEMS_SUCCESSFUL );
while ( !done && retries >= 0 ) {
wait_for_tick_change();
if ( interrupt_critical_section_test_support_delay() ) {
--retries;
}
done = ( *test_body )( test_body_arg );
}
return done;
}
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