1: /*
   2:  * Copyright (c) 1982, 1986 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  *
   6:  *	@(#)clock.c	7.1 (Berkeley) 6/5/86
   7:  */
   8: 
   9: #include "param.h"
  10: #include "time.h"
  11: #include "kernel.h"
  12: 
  13: #include "mtpr.h"
  14: #include "clock.h"
  15: #include "cpu.h"
  16: 
  17: /*
  18:  * Machine-dependent clock routines.
  19:  *
  20:  * Startrtclock restarts the real-time clock, which provides
  21:  * hardclock interrupts to kern_clock.c.
  22:  *
  23:  * Inittodr initializes the time of day hardware which provides
  24:  * date functions.  Its primary function is to use some file
  25:  * system information in case the hardare clock lost state.
  26:  *
  27:  * Resettodr restores the time of day hardware after a time change.
  28:  */
  29: 
  30: /*
  31:  * Start the real-time clock.
  32:  */
  33: startrtclock()
  34: {
  35: #ifdef VAX630
  36:     if (cpu == VAX_630) {
  37:         mtpr(ICCS, ICCS_IE);
  38:     } else {
  39: #endif
  40:         mtpr(NICR, -1000000/hz);
  41:         mtpr(ICCS, ICCS_RUN+ICCS_IE+ICCS_TRANS+ICCS_INT+ICCS_ERR);
  42: #ifdef VAX630
  43:     }
  44: #endif
  45: }
  46: 
  47: /*
  48:  * Initialze the time of day register, based on the time base which is, e.g.
  49:  * from a filesystem.  Base provides the time to within six months,
  50:  * and the time of year clock provides the rest.
  51:  */
  52: inittodr(base)
  53:     time_t base;
  54: {
  55:     register u_int todr = mfpr(TODR);
  56:     long deltat;
  57:     int year = YRREF;
  58: #if VAX630
  59:     /*
  60: 	 * If this is a Ka630, call ka630tod to handle the funny tod clock.
  61: 	 */
  62:     if (cpu == VAX_630) {
  63:         ka630tod(base);
  64:         return;
  65:     }
  66: #endif
  67:     if (base < 5*SECYR) {
  68:         printf("WARNING: preposterous time in file system");
  69:         time.tv_sec = 6*SECYR + 186*SECDAY + SECDAY/2;
  70:         resettodr();
  71:         goto check;
  72:     }
  73:     /*
  74: 	 * TODRZERO is base used by VMS, which runs on local time.
  75: 	 */
  76:     if (todr < TODRZERO) {
  77:         printf("WARNING: todr too small");
  78:         time.tv_sec = base;
  79:         /*
  80: 		 * Believe the time in the file system for lack of
  81: 		 * anything better, resetting the TODR.
  82: 		 */
  83:         resettodr();
  84:         goto check;
  85:     }
  86: 
  87:     /*
  88: 	 * Sneak to within 6 month of the time in the filesystem,
  89: 	 * by starting with the time of the year suggested by the TODR,
  90: 	 * and advancing through succesive years.  Adding the number of
  91: 	 * seconds in the current year takes us to the end of the current year
  92: 	 * and then around into the next year to the same position.
  93: 	 */
  94:     time.tv_sec = (todr-TODRZERO)/100;
  95:     while (time.tv_sec < base-SECYR/2) {
  96:         if (LEAPYEAR(year))
  97:             time.tv_sec += SECDAY;
  98:         year++;
  99:         time.tv_sec += SECYR;
 100:     }
 101: 
 102:     /*
 103: 	 * See if we gained/lost two or more days;
 104: 	 * if so, assume something is amiss.
 105: 	 */
 106:     deltat = time.tv_sec - base;
 107:     if (deltat < 0)
 108:         deltat = -deltat;
 109:     if (deltat < 2*SECDAY)
 110:         return;
 111:     printf("WARNING: clock %s %d days",
 112:         time.tv_sec < base ? "lost" : "gained", deltat / SECDAY);
 113: check:
 114:     printf(" -- CHECK AND RESET THE DATE!\n");
 115: }
 116: 
 117: /*
 118:  * Reset the TODR based on the time value; used when the TODR
 119:  * has a preposterous value and also when the time is reset
 120:  * by the stime system call.  Also called when the TODR goes past
 121:  * TODRZERO + 100*(SECYEAR+2*SECDAY) (e.g. on Jan 2 just after midnight)
 122:  * to wrap the TODR around.
 123:  */
 124: resettodr()
 125: {
 126:     int year = YRREF;
 127:     u_int secyr;
 128:     u_int yrtime = time.tv_sec;
 129: 
 130: #if VAX630
 131:     /*
 132: 	 * If this is a ka630, call ka630stod to set the funny tod clock.
 133: 	 */
 134:     if (cpu == VAX_630) {
 135:         ka630stod();
 136:         return;
 137:     }
 138: #endif
 139: 
 140:     /*
 141: 	 * Whittle the time down to an offset in the current year,
 142: 	 * by subtracting off whole years as long as possible.
 143: 	 */
 144:     for (;;) {
 145:         secyr = SECYR;
 146:         if (LEAPYEAR(year))
 147:             secyr += SECDAY;
 148:         if (yrtime < secyr)
 149:             break;
 150:         yrtime -= secyr;
 151:         year++;
 152:     }
 153:     mtpr(TODR, TODRZERO + yrtime*100);
 154: }

Defined functions

inittodr defined in line 52; used 1 times
resettodr defined in line 124; used 4 times
startrtclock defined in line 33; used 1 times
Last modified: 1986-06-05
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