This file provides implementation of timestamp_test()
Scope of the Test

This tests whether timestamp API works.
API tested:
This file is pjlib-test/timestamp.c
/* 
 * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
 * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
#include "test.h"
#include <pj/os.h>
#include <pj/log.h>
#include <pj/rand.h>
 
 
#if INCLUDE_TIMESTAMP_TEST
 
#define THIS_FILE   "timestamp"
 
static int timestamp_accuracy()
{
    pj_timestamp freq, t1, t2;
    pj_time_val tv1, tv2, tvtmp;
    pj_int64_t msec, tics;
    pj_int64_t diff;
 
    PJ_LOG(3,(THIS_FILE, "...testing frequency accuracy (pls wait)"));
 
    pj_get_timestamp_freq(&freq);
 
    /* Get the start time */
    pj_gettimeofday(&tvtmp);
    do {
        pj_gettimeofday(&tv1);
    } while (PJ_TIME_VAL_EQ(tvtmp, tv1));
    pj_get_timestamp(&t1);
 
    /* Sleep for 10 seconds */
    pj_thread_sleep(10000);
 
    /* Get end time */
    pj_gettimeofday(&tvtmp);
    do {
        pj_gettimeofday(&tv2);
    } while (PJ_TIME_VAL_EQ(tvtmp, tv2));
    pj_get_timestamp(&t2);
 
    /* Get the elapsed time */
    PJ_TIME_VAL_SUB(tv2, tv1);
    msec = PJ_TIME_VAL_MSEC(tv2);
 
    /* Check that the frequency match the elapsed time */
    tics = t2.u64 - t1.u64;
    diff = tics - (msec * freq.u64 / 1000);
    if (diff < 0)
        diff = -diff;
 
    /* Only allow 1 msec mismatch */
    if (diff > (pj_int64_t)(freq.u64 / 1000)) {
        PJ_LOG(3,(THIS_FILE, "....error: timestamp drifted by %d usec after "
                             "%d msec", 
                             (pj_uint32_t)(diff * 1000000 / freq.u64), 
                             msec));
        return -2000;
 
    /* Otherwise just print warning if timestamp drifted by >1 usec */
    } else if (diff > (pj_int64_t)(freq.u64 / 1000000)) {
        PJ_LOG(3,(THIS_FILE, "....warning: timestamp drifted by %d usec after "
                             "%d msec", 
                             (pj_uint32_t)(diff * 1000000 / freq.u64), 
                             msec));
    } else {
        PJ_LOG(3,(THIS_FILE, "....good. Timestamp is accurate down to"
                             " nearest usec."));
    }
 
    return 0;
}
 
 
int timestamp_test(void)
{
    enum { CONSECUTIVE_LOOP = 100 };
    volatile unsigned i;
    pj_timestamp freq, t1, t2;
    pj_time_val tv1, tv2;
    unsigned elapsed;
    pj_status_t rc;
 
    PJ_LOG(3,(THIS_FILE, "...Testing timestamp (high res time)"));
    
    /* Get and display timestamp frequency. */
    if ((rc=pj_get_timestamp_freq(&freq)) != PJ_SUCCESS) {
        app_perror("...ERROR: get timestamp freq", rc);
        return -1000;
    }
 
    PJ_LOG(3,(THIS_FILE, "....frequency: hiword=%lu loword=%lu", 
                        freq.u32.hi, freq.u32.lo));
 
    PJ_LOG(3,(THIS_FILE, "...checking if time can run backwards (pls wait).."));
 
    /*
     * Check if consecutive readings should yield timestamp value
     * that is bigger than previous value.
     * First we get the first timestamp.
     */
    rc = pj_get_timestamp(&t1);
    if (rc != PJ_SUCCESS) {
        app_perror("...ERROR: pj_get_timestamp", rc);
        return -1001;
    }
    rc = pj_gettimeofday(&tv1);
    if (rc != PJ_SUCCESS) {
        app_perror("...ERROR: pj_gettimeofday", rc);
        return -1002;
    }
    for (i=0; i<CONSECUTIVE_LOOP; ++i) {
        
        pj_thread_sleep(pj_rand() % 100);
 
        rc = pj_get_timestamp(&t2);
        if (rc != PJ_SUCCESS) {
            app_perror("...ERROR: pj_get_timestamp", rc);
            return -1003;
        }
        rc = pj_gettimeofday(&tv2);
        if (rc != PJ_SUCCESS) {
            app_perror("...ERROR: pj_gettimeofday", rc);
            return -1004;
        }
 
        /* compare t2 with t1, expecting t2 >= t1. */
        if (t2.u32.hi < t1.u32.hi ||
            (t2.u32.hi == t1.u32.hi && t2.u32.lo < t1.u32.lo))
        {
            PJ_LOG(3,(THIS_FILE, "...ERROR: timestamp run backwards!"));
            return -1005;
        }
 
        /* compare tv2 with tv1, expecting tv2 >= tv1. */
        if (PJ_TIME_VAL_LT(tv2, tv1)) {
            PJ_LOG(3,(THIS_FILE, "...ERROR: time run backwards!"));
            return -1006;
        }
    }
 
    /* 
     * Simple test to time some loop. 
     */
    PJ_LOG(3,(THIS_FILE, "....testing simple 1000000 loop"));
 
 
    /* Mark start time. */
    if ((rc=pj_get_timestamp(&t1)) != PJ_SUCCESS) {
        app_perror("....error: cat't get timestamp", rc);
        return -1010;
    }
 
    /* Loop.. */
    for (i=0; i<1000000; ++i) {
        /* Try to do something so that smart compilers wont
         * remove this silly loop.
         */
        null_func();
    }
 
    pj_thread_sleep(0);
 
    /* Mark end time. */
    pj_get_timestamp(&t2);
 
    /* Get elapsed time in usec. */
    elapsed = pj_elapsed_usec(&t1, &t2);
    PJ_LOG(3,(THIS_FILE, "....elapsed: %u usec", (unsigned)elapsed));
 
    /* See if elapsed time is "reasonable". 
     * This should be good even on 50Mhz embedded powerpc.
     */
    if (elapsed < 1 || elapsed > 1000000) {
        PJ_LOG(3,(THIS_FILE, "....error: elapsed time outside window (%u, "
                             "t1.u32.hi=%u, t1.u32.lo=%u, "
                             "t2.u32.hi=%u, t2.u32.lo=%u)",
                             elapsed, 
                             t1.u32.hi, t1.u32.lo, t2.u32.hi, t2.u32.lo));
        return -1030;
    }
 
    /* Testing time/timestamp accuracy */
    rc = timestamp_accuracy();
    if (rc != 0)
        return rc;
 
    return 0;
}
 
 
#else
/* To prevent warning about "translation unit is empty"
 * when this test is disabled. 
 */
int dummy_timestamp_test;
#endif  /* INCLUDE_TIMESTAMP_TEST */
 