gps/soc/software/gps_system/tests/test_gps_assistance_data.c

#include <assert.h>
#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>

#include "gps/gps_assistance_data.h"

static gps_ephemeris_t make_ephemeris(
	unsigned int prn,
	int current_week,
	double toe_sec,
	unsigned int issue)
{
	gps_ephemeris_t ephemeris;
	memset(&ephemeris, 0, sizeof(ephemeris));
	ephemeris.WN = (unsigned int)current_week & 0x3ffu;
	ephemeris.toe.sec = toe_sec;
	ephemeris.toc.sec = toe_sec;
	ephemeris.sqrta = 5153.795;
	ephemeris.A = ephemeris.sqrta * ephemeris.sqrta;
	ephemeris.ecc = 0.01;
	ephemeris.iodc = issue;
	ephemeris.iode = (unsigned char)issue;
	ephemeris.SVID = (unsigned char)prn;
	ephemeris.ephemeris_valid = true;
	ephemeris.abs_sample = 123456789.25;
	return ephemeris;
}

static void test_fresh_mixed_ephemeris_restore_and_true_remaining_age(void)
{
	const gpstime_t saved_time = {.week = 2300, .sec = 100000.0};
	gps_ephemeris_cache_t source;
	gps_ephemeris_cache_init(&source, GPS_EPHEMERIS_CACHE_MAX_AGE_TICKS);
	for(unsigned int prn = 0u ; prn < 7u ; prn++)
	{
		double age_sec = (prn == 6u) ? 3.0 * 3600.0 :
		                 (double)(prn + 1u) * 600.0;
		gps_ephemeris_t ephemeris = make_ephemeris(
			prn, saved_time.week, saved_time.sec - age_sec,
			40u + prn);
		assert(gps_ephemeris_cache_store(
			&source, prn, &ephemeris, 100u));
	}
	gps_almanac_cache_t source_almanac;
	gps_almanac_cache_init(
		&source_almanac, GPS_ALMANAC_CACHE_MAX_AGE_TICKS);
	gps_assistance_payload_t payload;
	gps_assistance_payload_build(
		&payload, &source, &source_almanac, NULL, NULL, saved_time);
	assert(payload.ephemeris[0].abs_sample == 0.0);

	gps_ephemeris_cache_t restored_cache;
	gps_ephemeris_cache_init(
		&restored_cache, GPS_EPHEMERIS_CACHE_MAX_AGE_TICKS);
	gps_almanac_cache_t restored_almanac;
	gps_almanac_cache_init(
		&restored_almanac, GPS_ALMANAC_CACHE_MAX_AGE_TICKS);
	gps_assistance_restore_result_t result;
	const uint64_t boot_now = 10u;
	assert(gps_assistance_restore(
		&payload, saved_time, boot_now,
		&restored_cache, &restored_almanac, &result));
	assert(result.ephemeris_mask == UINT32_C(0x3f));
	assert(!restored_cache.entry[0].time_anchor.valid);

	gps_ephemeris_t output;
	assert(gps_ephemeris_cache_restore(
		&restored_cache, 0u, boot_now, &output));
	/* PRN0 was already 10 minutes old. It has 110 minutes, not a newly
	 * granted two hours, after reboot. */
	uint64_t remaining_ticks = GPS_EPHEMERIS_CACHE_MAX_AGE_TICKS -
	                           600u * GPS_SYSTICK_HZ;
	assert(gps_ephemeris_cache_restore(
		&restored_cache, 0u, boot_now + remaining_ticks, &output));
	assert(!gps_ephemeris_cache_restore(
		&restored_cache, 0u, boot_now + remaining_ticks + 1u, &output));
}

static void test_issue_check_is_per_satellite_and_per_subframe(void)
{
	gps_ephemeris_t ephemeris = make_ephemeris(3u, 2300, 90000.0, 0x155u);
	unsigned int words[10] = {0};
	words[2] = ((ephemeris.iodc >> 8) & 0x03u) << 6;
	words[7] = (ephemeris.iodc & 0xffu) << 22;
	assert(gps_assistance_ephemeris_issue_matches(
		&ephemeris, 1u, words));
	words[7] ^= UINT32_C(1) << 22;
	assert(!gps_assistance_ephemeris_issue_matches(
		&ephemeris, 1u, words));

	memset(words, 0, sizeof(words));
	words[2] = (uint32_t)ephemeris.iode << 22;
	assert(gps_assistance_ephemeris_issue_matches(
		&ephemeris, 2u, words));
	words[2] += UINT32_C(1) << 22;
	assert(!gps_assistance_ephemeris_issue_matches(
		&ephemeris, 2u, words));
	assert(gps_assistance_ephemeris_issue_matches(
		&ephemeris, 4u, words));
}

static void test_iono_position_and_almanac_independent_staleness(void)
{
	const gpstime_t saved_time = {.week = 2400, .sec = 200000.0};
	gps_ephemeris_cache_t source;
	gps_ephemeris_cache_init(&source, GPS_EPHEMERIS_CACHE_MAX_AGE_TICKS);
	gps_almanac_cache_t almanac;
	gps_almanac_cache_init(&almanac, GPS_ALMANAC_CACHE_MAX_AGE_TICKS);
	almanac.reference_valid = true;
	almanac.reference_week_mod256 = (unsigned int)saved_time.week & 0xffu;
	almanac.reference_toa_sec = saved_time.sec - 86400.0;
	almanac.reference_tick = 50u;
	ionoutc_t ionoutc = {.enable = true, .vflg = true, .dtls = 18};
	gps_assistance_position_t position = {
		.ecef_m = {4200000.0, 2800000.0, 3900000.0},
		.latitude_deg = 41.0,
		.longitude_deg = 29.0,
		.height_m = 100.0,
		.gps_time = saved_time,
		.valid = true
	};
	gps_assistance_payload_t payload;
	gps_assistance_payload_build(
		&payload, &source, &almanac, &ionoutc, &position, saved_time);

	gps_ephemeris_cache_t output_eph;
	gps_almanac_cache_t output_almanac;
	gps_ephemeris_cache_init(
		&output_eph, GPS_EPHEMERIS_CACHE_MAX_AGE_TICKS);
	gps_almanac_cache_init(
		&output_almanac, GPS_ALMANAC_CACHE_MAX_AGE_TICKS);
	gps_assistance_restore_result_t result;
	gpstime_t current = saved_time;
	current.sec += 2.0 * 86400.0;
	assert(gps_assistance_restore(
		&payload, current, 20u,
		&output_eph, &output_almanac, &result));
	assert(result.almanac_restored);
	assert(result.ionoutc_restored);
	assert(result.position_restored);
	assert(result.ionoutc.dtls == 18);

	/* Eight days rejects almanac and iono, while a coarse position remains a
	 * safe acquisition/WLS seed under the separate 30-day policy. */
	current = saved_time;
	current.week += 1;
	current.sec += 86400.0;
	if(current.sec >= 604800.0)
	{
		current.sec -= 604800.0;
		current.week++;
	}
	gps_ephemeris_cache_init(
		&output_eph, GPS_EPHEMERIS_CACHE_MAX_AGE_TICKS);
	gps_almanac_cache_init(
		&output_almanac, GPS_ALMANAC_CACHE_MAX_AGE_TICKS);
	assert(gps_assistance_restore(
		&payload, current, 20u,
		&output_eph, &output_almanac, &result));
	assert(!result.almanac_restored);
	assert(!result.ionoutc_restored);
	assert(result.position_restored);
}

int main(void)
{
	test_fresh_mixed_ephemeris_restore_and_true_remaining_age();
	test_issue_check_is_per_satellite_and_per_subframe();
	test_iono_position_and_almanac_independent_staleness();
	puts("gps assistance freshness/issue tests passed");
	return 0;
}