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Annotation of 43BSD/sys/vax/clock.c, revision 1.1

1.1     ! root        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: }

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