1 // SPDX-License-Identifier: GPL-2.0-only
15 #include <time.h>
24 #define MAX_PRECISION 500e-9
25 #define MAX_FREQ_ERROR 0.02e-6
26 #define MAX_STDDEV 50e-9
32 struct sample {  struct
34 	double time;  member
45 	return ts1->tv_sec - ts2->tv_sec + (ts1->tv_nsec - ts2->tv_nsec) / 1e9;  in diff_timespec()
48 static double get_sample(struct sample *sample)  in get_sample()  argument
59 		ts1.tv_sec -= mono_raw_base;  in get_sample()
60 		ts2.tv_sec -= mono_base;  in get_sample()
61 		ts3.tv_sec -= mono_raw_base;  in get_sample()
64 		if (delay <= 1e-9) {  in get_sample()
65 			i--;  in get_sample()
70 			sample->offset = diff_timespec(&ts2, &ts1);  in get_sample()
71 			sample->offset -= delay / 2.0;  in get_sample()
72 			sample->time = ts1.tv_sec + ts1.tv_nsec / 1e9;  in get_sample()
85 	txc.time.tv_sec = 0;  in reset_ntp_error()
86 	txc.time.tv_usec = 0;  in reset_ntp_error()
103 	txc.freq = (1e6 * freq - user_hz * tick_offset) * (1 << 16);  in set_frequency()
111 static void regress(struct sample *samples, int n, double *intercept,  in regress()
120 		x = samples[i].time;  in regress()
129 	*slope = (xy_sum - x_sum * y_sum / n) / (x2_sum - x_sum * x_sum / n);  in regress()
130 	*intercept = (y_sum - *slope * x_sum) / n;  in regress()
135 		x = samples[i].time;  in regress()
137 		r = fabs(x * *slope + *intercept - y);  in regress()
148 	struct sample samples[SAMPLES];  in run_test()
181 	freq_error1 = slope * (1.0 - mono_freq_offset) - mono_freq_offset -  in run_test()
186 	freq_error2 = slope * (1.0 - mono_freq_offset) - mono_freq_offset -  in run_test()
206 	struct sample sample;  in init_test()  local
224 	precision = get_sample(&sample) / 2.0;  in init_test()
249 	for (i = 2; i >= 0; i--) {  in main()
251 			freq_base = (rand() % (1 << 24) - (1 << 23)) / 65536e6;  in main()
252 			freq_step = 10e-6 * (1 << (6 * i));  in main()