1 /* $NetBSD: subr_time.c,v 1.8 2011/01/26 19:15:13 drochner Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 32 * @(#)kern_time.c 8.4 (Berkeley) 5/26/95 33 */ 34 35 #include <sys/cdefs.h> 36 __KERNEL_RCSID(0, "$NetBSD: subr_time.c,v 1.8 2011/01/26 19:15:13 drochner Exp $"); 37 38 #include <sys/param.h> 39 #include <sys/kernel.h> 40 #include <sys/timex.h> 41 #include <sys/time.h> 42 #include <sys/timetc.h> 43 #include <sys/intr.h> 44 45 /* 46 * Compute number of hz until specified time. Used to compute second 47 * argument to callout_reset() from an absolute time. 48 */ 49 int 50 tvhzto(const struct timeval *tvp) 51 { 52 struct timeval now, tv; 53 54 tv = *tvp; /* Don't modify original tvp. */ 55 getmicrotime(&now); 56 timersub(&tv, &now, &tv); 57 return tvtohz(&tv); 58 } 59 60 /* 61 * Compute number of ticks in the specified amount of time. 62 */ 63 int 64 tvtohz(const struct timeval *tv) 65 { 66 unsigned long ticks; 67 long sec, usec; 68 69 /* 70 * If the number of usecs in the whole seconds part of the time 71 * difference fits in a long, then the total number of usecs will 72 * fit in an unsigned long. Compute the total and convert it to 73 * ticks, rounding up and adding 1 to allow for the current tick 74 * to expire. Rounding also depends on unsigned long arithmetic 75 * to avoid overflow. 76 * 77 * Otherwise, if the number of ticks in the whole seconds part of 78 * the time difference fits in a long, then convert the parts to 79 * ticks separately and add, using similar rounding methods and 80 * overflow avoidance. This method would work in the previous 81 * case, but it is slightly slower and assumes that hz is integral. 82 * 83 * Otherwise, round the time difference down to the maximum 84 * representable value. 85 * 86 * If ints are 32-bit, then the maximum value for any timeout in 87 * 10ms ticks is 248 days. 88 */ 89 sec = tv->tv_sec; 90 usec = tv->tv_usec; 91 92 KASSERT(usec >= 0 && usec < 1000000); 93 94 /* catch overflows in conversion time_t->int */ 95 if (tv->tv_sec > INT_MAX) 96 return INT_MAX; 97 if (tv->tv_sec < 0) 98 return 0; 99 100 if (sec < 0 || (sec == 0 && usec == 0)) { 101 /* 102 * Would expire now or in the past. Return 0 ticks. 103 * This is different from the legacy tvhzto() interface, 104 * and callers need to check for it. 105 */ 106 ticks = 0; 107 } else if (sec <= (LONG_MAX / 1000000)) 108 ticks = (((sec * 1000000) + (unsigned long)usec + (tick - 1)) 109 / tick) + 1; 110 else if (sec <= (LONG_MAX / hz)) 111 ticks = (sec * hz) + 112 (((unsigned long)usec + (tick - 1)) / tick) + 1; 113 else 114 ticks = LONG_MAX; 115 116 if (ticks > INT_MAX) 117 ticks = INT_MAX; 118 119 return ((int)ticks); 120 } 121 122 int 123 tshzto(const struct timespec *tsp) 124 { 125 struct timespec now, ts; 126 127 ts = *tsp; /* Don't modify original tsp. */ 128 getnanotime(&now); 129 timespecsub(&ts, &now, &ts); 130 return tstohz(&ts); 131 } 132 /* 133 * Compute number of ticks in the specified amount of time. 134 */ 135 int 136 tstohz(const struct timespec *ts) 137 { 138 struct timeval tv; 139 140 /* 141 * usec has great enough resolution for hz, so convert to a 142 * timeval and use tvtohz() above. 143 */ 144 TIMESPEC_TO_TIMEVAL(&tv, ts); 145 return tvtohz(&tv); 146 } 147 148 /* 149 * Check that a proposed value to load into the .it_value or 150 * .it_interval part of an interval timer is acceptable, and 151 * fix it to have at least minimal value (i.e. if it is less 152 * than the resolution of the clock, round it up.) 153 */ 154 int 155 itimerfix(struct timeval *tv) 156 { 157 158 if (tv->tv_sec < 0 || tv->tv_usec < 0 || tv->tv_usec >= 1000000) 159 return (EINVAL); 160 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick) 161 tv->tv_usec = tick; 162 return (0); 163 } 164 165 int 166 itimespecfix(struct timespec *ts) 167 { 168 169 if (ts->tv_sec < 0 || ts->tv_nsec < 0 || ts->tv_nsec >= 1000000000) 170 return (EINVAL); 171 if (ts->tv_sec == 0 && ts->tv_nsec != 0 && ts->tv_nsec < tick * 1000) 172 ts->tv_nsec = tick * 1000; 173 return (0); 174 } 175 176 int 177 inittimeleft(struct timespec *ts, struct timespec *sleepts) 178 { 179 180 if (itimespecfix(ts)) { 181 return -1; 182 } 183 getnanouptime(sleepts); 184 return 0; 185 } 186 187 int 188 gettimeleft(struct timespec *ts, struct timespec *sleepts) 189 { 190 struct timespec sleptts; 191 192 /* 193 * Reduce ts by elapsed time based on monotonic time scale. 194 */ 195 getnanouptime(&sleptts); 196 timespecadd(ts, sleepts, ts); 197 timespecsub(ts, &sleptts, ts); 198 *sleepts = sleptts; 199 200 return tstohz(ts); 201 } 202 203 /* 204 * Calculate delta and convert from struct timespec to the ticks. 205 */ 206 int 207 abstimeout2timo(struct timespec *ts, int *timo) 208 { 209 struct timespec tsd; 210 int error; 211 212 getnanotime(&tsd); 213 timespecsub(ts, &tsd, &tsd); 214 if (tsd.tv_sec < 0 || (tsd.tv_sec == 0 && tsd.tv_nsec <= 0)) { 215 return ETIMEDOUT; 216 } 217 error = itimespecfix(&tsd); 218 if (error) { 219 return error; 220 } 221 *timo = tstohz(&tsd); 222 KASSERT(*timo != 0); 223 224 return 0; 225 } 226