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/*
*
* Copyright 2015 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#include <grpc/support/log.h>
#include <grpc/support/time.h>
#include <stdio.h>
#ifdef GRPC_TIMERS_RDTSC
#if defined(__i386__)
static void gpr_get_cycle_counter(int64_t int *clk) {
int64_t int ret;
__asm__ volatile("rdtsc" : "=A"(ret));
*clk = ret;
}
// ----------------------------------------------------------------
#elif defined(__x86_64__) || defined(__amd64__)
static void gpr_get_cycle_counter(int64_t *clk) {
uint64_t low, high;
__asm__ volatile("rdtsc" : "=a"(low), "=d"(high));
*clk = (int64_t)(high << 32) | (int64_t)low;
}
#endif
static double cycles_per_second = 0;
static int64_t start_cycle;
void gpr_precise_clock_init(void) {
time_t start;
int64_t end_cycle;
gpr_log(GPR_DEBUG, "Calibrating timers");
start = time(NULL);
while (time(NULL) == start)
;
gpr_get_cycle_counter(&start_cycle);
while (time(NULL) <= start + 10)
;
gpr_get_cycle_counter(&end_cycle);
cycles_per_second = (double)(end_cycle - start_cycle) / 10.0;
gpr_log(GPR_DEBUG, "... cycles_per_second = %f\n", cycles_per_second);
}
void gpr_precise_clock_now(gpr_timespec *clk) {
int64_t counter;
double secs;
gpr_get_cycle_counter(&counter);
secs = (double)(counter - start_cycle) / cycles_per_second;
clk->clock_type = GPR_CLOCK_PRECISE;
clk->tv_sec = (int64_t)secs;
clk->tv_nsec = (int32_t)(1e9 * (secs - (double)clk->tv_sec));
}
#else /* GRPC_TIMERS_RDTSC */
void gpr_precise_clock_init(void) {}
void gpr_precise_clock_now(gpr_timespec *clk) {
*clk = gpr_now(GPR_CLOCK_REALTIME);
clk->clock_type = GPR_CLOCK_PRECISE;
}
#endif /* GRPC_TIMERS_RDTSC */
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