mach_bridge_remote_time.c [plain text]
#include <sys/types.h>
#include <machine/cpu_capabilities.h>
#include <kern/remote_time.h>
#include <mach/mach_time.h>
#include "strings.h"
#include <TargetConditionals.h>
#define BT_RESET_SENTINEL_TS (~3ULL)
extern uint64_t __mach_bridge_remote_time(uint64_t local_time);
#if TARGET_OS_BRIDGE && defined(__arm64__)
static uint64_t
absolutetime_to_nanoseconds(uint64_t abs_time)
{
mach_timebase_info_data_t info;
mach_timebase_info(&info);
uint64_t time_in_ns = (uint64_t)(((double)info.numer / (double)info.denom) * abs_time);
return time_in_ns;
}
uint64_t
mach_bridge_remote_time(__unused uint64_t local_time)
{
uint64_t remote_time = 0;
uint64_t local_time_ns = 0;
uint64_t now = 0;
struct bt_params params = {};
volatile struct bt_params *commpage_bt_params_p = (struct bt_params *)_COMM_PAGE_REMOTETIME_PARAMS;
volatile uint64_t *base_local_ts_p = &commpage_bt_params_p->base_local_ts;
volatile uint64_t *base_remote_ts_p = &commpage_bt_params_p->base_remote_ts;
volatile double *rate_p = &commpage_bt_params_p->rate;
do {
params.base_local_ts = *base_local_ts_p;
if (*base_local_ts_p == BT_RESET_SENTINEL_TS) {
return 0;
}
now = mach_absolute_time();
params.base_remote_ts = *base_remote_ts_p;
params.rate = *rate_p;
__asm__ volatile ("dmb ishld" ::: "memory");
} while (params.base_local_ts && (params.base_local_ts != commpage_bt_params_p->base_local_ts));
if (!local_time) {
local_time = now;
}
local_time_ns = absolutetime_to_nanoseconds(local_time);
if (local_time_ns < params.base_local_ts) {
remote_time = __mach_bridge_remote_time(local_time);
} else {
remote_time = mach_bridge_compute_timestamp(local_time_ns, ¶ms);
}
return remote_time;
}
#endif