| 1 | #ifndef lint |
| 2 | static char *RCSid = "$Header: /f/osi/others/ntp/RCS/ntp_adjust.c,v 7.1 91/02/22 09:33:46 mrose Interim $"; |
| 3 | #endif |
| 4 | |
| 5 | /* |
| 6 | * This module implemenets the logical Local Clock, as described in section |
| 7 | * 5. of the NTP specification. |
| 8 | * based on the ntp 3.4 code, but modified for OSI etc. |
| 9 | * |
| 10 | * $Log: ntp_adjust.c,v $ |
| 11 | * Revision 7.1 91/02/22 09:33:46 mrose |
| 12 | * Interim 6.8 |
| 13 | * |
| 14 | * Revision 7.0 90/12/10 17:21:27 mrose |
| 15 | * *** empty log message *** |
| 16 | * |
| 17 | * Revision 1.1 89/06/15 20:36:55 jpo |
| 18 | * Initial revision |
| 19 | * |
| 20 | * |
| 21 | */ |
| 22 | |
| 23 | #include "ntp.h" |
| 24 | |
| 25 | #ifdef DEBUG |
| 26 | extern int debug; |
| 27 | #endif |
| 28 | |
| 29 | extern int doset; |
| 30 | extern int kern_tickadj; |
| 31 | extern char *ntoa(); |
| 32 | extern struct sysdata sys; |
| 33 | extern LLog *pgm_log; |
| 34 | |
| 35 | double drift_comp = 0.0, |
| 36 | compliance, |
| 37 | clock_adjust; |
| 38 | long update_timer = 0; |
| 39 | |
| 40 | int adj_precision; |
| 41 | double adj_residual; |
| 42 | int firstpass = 1; |
| 43 | |
| 44 | #define abs(x) ((x) < 0 ? -(x) : (x)) |
| 45 | |
| 46 | void |
| 47 | init_logical_clock() |
| 48 | { |
| 49 | if (kern_tickadj) |
| 50 | adj_precision = kern_tickadj; |
| 51 | else |
| 52 | adj_precision = 1; |
| 53 | /* |
| 54 | * If you have the "fix" for adjtime() installed in you kernel, you'll |
| 55 | * have to make sure that adj_precision is set to 1 here. |
| 56 | */ |
| 57 | } |
| 58 | |
| 59 | |
| 60 | /* |
| 61 | * 5.0 Logical clock procedure |
| 62 | * |
| 63 | * Only paramter is an offset to vary the clock by, in seconds. We'll either |
| 64 | * arrange for the clock to slew to accomodate the adjustment, or just preform |
| 65 | * a step adjustment if the offset is too large. |
| 66 | * |
| 67 | * The update which is to be performed is left in the external |
| 68 | * clock_adjust. |
| 69 | * |
| 70 | * Returns non-zero if clock was reset rather than slewed. |
| 71 | * |
| 72 | * Many thanks for Dennis Ferguson <dennis@gw.ccie.utoronto.ca> for his |
| 73 | * corrections to my code. |
| 74 | */ |
| 75 | |
| 76 | int |
| 77 | adj_logical(offset) |
| 78 | double offset; |
| 79 | { |
| 80 | struct timeval tv1, tv2; |
| 81 | #ifdef XADJTIME2 |
| 82 | struct timeval delta, olddelta; |
| 83 | #endif |
| 84 | |
| 85 | /* |
| 86 | * Now adjust the logical clock |
| 87 | */ |
| 88 | if (!doset) |
| 89 | return 0; |
| 90 | |
| 91 | adj_residual = 0.0; |
| 92 | if (offset > CLOCK_MAX || offset < -CLOCK_MAX) { |
| 93 | double steptime = offset; |
| 94 | |
| 95 | (void) gettimeofday(&tv2, (struct timezone *) 0); |
| 96 | steptime += tv2.tv_sec; |
| 97 | steptime += tv2.tv_usec / 1000000.0; |
| 98 | tv1.tv_sec = steptime; |
| 99 | tv1.tv_usec = (steptime - tv1.tv_sec) * 1000000; |
| 100 | #ifdef DEBUG |
| 101 | if (debug > 2) { |
| 102 | steptime = (tv1.tv_sec + tv1.tv_usec/1000000.0) - |
| 103 | (tv2.tv_sec + tv2.tv_usec/1000000.0); |
| 104 | TRACE (2, ("adj_logical: %f %f", offset, steptime)); |
| 105 | } |
| 106 | #endif |
| 107 | if (settimeofday(&tv1, (struct timezone *) 0) < 0) { |
| 108 | advise (LLOG_EXCEPTIONS, NULLCP, "Can't set time: %m"); |
| 109 | return(-1); |
| 110 | } |
| 111 | else { |
| 112 | TRACE (1, ("set time of day")); |
| 113 | } |
| 114 | clock_adjust = 0.0; |
| 115 | firstpass = 1; |
| 116 | update_timer = 0; |
| 117 | return (1); /* indicate that step adjustment was done */ |
| 118 | } else { |
| 119 | double ai; |
| 120 | |
| 121 | /* |
| 122 | * If this is our very first adjustment, don't touch |
| 123 | * the drift compensation (this is f in the spec |
| 124 | * equations), else update using the *old* value |
| 125 | * of the compliance. |
| 126 | */ |
| 127 | clock_adjust = offset; |
| 128 | if (firstpass) |
| 129 | firstpass = 0; |
| 130 | else if (update_timer > 0) { |
| 131 | ai = abs(compliance); |
| 132 | ai = (double)(1<<CLOCK_COMP) - |
| 133 | (double)(1<<CLOCK_FACTOR) * ai; |
| 134 | if (ai < 1.0) /* max(... , 1.0) */ |
| 135 | ai = 1.0; |
| 136 | drift_comp += offset / (ai * (double)update_timer); |
| 137 | } |
| 138 | |
| 139 | /* |
| 140 | * Set the timer to zero. adj_host_clock() increments it |
| 141 | * so we can tell the period between updates. |
| 142 | */ |
| 143 | update_timer = 0; |
| 144 | |
| 145 | /* |
| 146 | * Now update the compliance. The compliance is h in the |
| 147 | * equations. |
| 148 | */ |
| 149 | compliance += (offset - compliance)/(double)(1<<CLOCK_TRACK); |
| 150 | |
| 151 | #ifdef XADJTIME2 |
| 152 | delta.tv_sec = offset; |
| 153 | delta.tv_usec = (offset - delta.tv_sec) * 1000; |
| 154 | (void) adjtime2(&delta, &olddelta); |
| 155 | #endif |
| 156 | return(0); |
| 157 | } |
| 158 | } |
| 159 | |
| 160 | #ifndef XADJTIME2 |
| 161 | extern int adjtime(); |
| 162 | |
| 163 | /* |
| 164 | * This is that routine that performs the periodic clock adjustment. |
| 165 | * The procedure is best described in the the NTP document. In a |
| 166 | * nutshell, we prefer to do lots of small evenly spaced adjustments. |
| 167 | * The alternative, one large adjustment, creates two much of a |
| 168 | * clock disruption and as a result oscillation. |
| 169 | * |
| 170 | * This function is called every 2**CLOCK_ADJ seconds. |
| 171 | * |
| 172 | */ |
| 173 | |
| 174 | /* |
| 175 | * global for debugging? |
| 176 | */ |
| 177 | double adjustment; |
| 178 | |
| 179 | void |
| 180 | adj_host_clock(n) |
| 181 | int n; |
| 182 | { |
| 183 | |
| 184 | struct timeval delta, olddelta; |
| 185 | |
| 186 | if (!doset) |
| 187 | return; |
| 188 | |
| 189 | /* |
| 190 | * Add update period into timer so we know how long it |
| 191 | * took between the last update and the next one. |
| 192 | */ |
| 193 | update_timer += n; |
| 194 | /* |
| 195 | * Should check to see if update_timer > 1 day here? |
| 196 | */ |
| 197 | |
| 198 | /* |
| 199 | * Compute phase part of adjustment here and update clock_adjust. |
| 200 | * Note that the equations used here are implicit in the last |
| 201 | * two equations in the spec (in particular, look at the equation |
| 202 | * for g and figure out how to find the k==1 term given the k==0 term.) |
| 203 | */ |
| 204 | adjustment = clock_adjust / (double)(1<<CLOCK_PHASE); |
| 205 | clock_adjust -= adjustment; |
| 206 | |
| 207 | /* |
| 208 | * Now add in the frequency component. Be careful to note that |
| 209 | * the ni occurs in the last equation since those equations take |
| 210 | * you from 64 second update to 64 second update (ei is the total |
| 211 | * adjustment done over 64 seconds) and we're only deal in the |
| 212 | * little 4 second adjustment interval here. |
| 213 | */ |
| 214 | adjustment += drift_comp / (double)(1<<CLOCK_FREQ); |
| 215 | |
| 216 | /* |
| 217 | * Add in old adjustment residual |
| 218 | */ |
| 219 | adjustment += adj_residual; |
| 220 | |
| 221 | /* |
| 222 | * Simplify. Adjustment shouldn't be bigger than 2 ms. Hope |
| 223 | * writer of spec was truth telling. |
| 224 | */ |
| 225 | #ifdef DEBUG |
| 226 | delta.tv_sec = adjustment; |
| 227 | if (debug && delta.tv_sec) abort(); |
| 228 | #else |
| 229 | delta.tv_sec = 0; |
| 230 | #endif |
| 231 | delta.tv_usec = ((long)(adjustment * 1000000.0) / adj_precision) |
| 232 | * adj_precision; |
| 233 | |
| 234 | adj_residual = adjustment - (double) delta.tv_usec / 1000000.0; |
| 235 | |
| 236 | if (delta.tv_usec == 0) |
| 237 | return; |
| 238 | |
| 239 | if (adjtime(&delta, &olddelta) < 0) |
| 240 | advise (LLOG_EXCEPTIONS, NULLCP, "Can't adjust time: %m"); |
| 241 | |
| 242 | TRACE (2, ("adj: %ld us %f %f", |
| 243 | delta.tv_usec, drift_comp, clock_adjust)); |
| 244 | } |
| 245 | #endif |