1 /* $NetBSD: subr_time.c,v 1.2 2007/11/29 18:04:46 ad 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 1.2 2007/11/29 18:04:46 ad 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 #ifdef __HAVE_TIMECOUNTER 46 /* 47 * Compute number of hz until specified time. Used to compute second 48 * argument to callout_reset() from an absolute time. 49 */ 50 int 51 hzto(struct timeval *tvp) 52 { 53 struct timeval now, tv; 54 55 tv = *tvp; /* Don't modify original tvp. */ 56 getmicrotime(&now); 57 timersub(&tv, &now, &tv); 58 return tvtohz(&tv); 59 } 60 #endif /* __HAVE_TIMECOUNTER */ 61 62 /* 63 * Compute number of ticks in the specified amount of time. 64 */ 65 int 66 tvtohz(struct timeval *tv) 67 { 68 unsigned long ticks; 69 long sec, usec; 70 71 /* 72 * If the number of usecs in the whole seconds part of the time 73 * difference fits in a long, then the total number of usecs will 74 * fit in an unsigned long. Compute the total and convert it to 75 * ticks, rounding up and adding 1 to allow for the current tick 76 * to expire. Rounding also depends on unsigned long arithmetic 77 * to avoid overflow. 78 * 79 * Otherwise, if the number of ticks in the whole seconds part of 80 * the time difference fits in a long, then convert the parts to 81 * ticks separately and add, using similar rounding methods and 82 * overflow avoidance. This method would work in the previous 83 * case, but it is slightly slower and assumes that hz is integral. 84 * 85 * Otherwise, round the time difference down to the maximum 86 * representable value. 87 * 88 * If ints are 32-bit, then the maximum value for any timeout in 89 * 10ms ticks is 248 days. 90 */ 91 sec = tv->tv_sec; 92 usec = tv->tv_usec; 93 94 if (usec < 0) { 95 sec--; 96 usec += 1000000; 97 } 98 99 if (sec < 0 || (sec == 0 && usec <= 0)) { 100 /* 101 * Would expire now or in the past. Return 0 ticks. 102 * This is different from the legacy hzto() interface, 103 * and callers need to check for it. 104 */ 105 ticks = 0; 106 } else if (sec <= (LONG_MAX / 1000000)) 107 ticks = (((sec * 1000000) + (unsigned long)usec + (tick - 1)) 108 / tick) + 1; 109 else if (sec <= (LONG_MAX / hz)) 110 ticks = (sec * hz) + 111 (((unsigned long)usec + (tick - 1)) / tick) + 1; 112 else 113 ticks = LONG_MAX; 114 115 if (ticks > INT_MAX) 116 ticks = INT_MAX; 117 118 return ((int)ticks); 119 } 120 121 #ifndef __HAVE_TIMECOUNTER 122 /* 123 * Compute number of hz until specified time. Used to compute second 124 * argument to callout_reset() from an absolute time. 125 */ 126 int 127 hzto(struct timeval *tv) 128 { 129 unsigned long ticks; 130 long sec, usec; 131 int s; 132 133 /* 134 * If the number of usecs in the whole seconds part of the time 135 * difference fits in a long, then the total number of usecs will 136 * fit in an unsigned long. Compute the total and convert it to 137 * ticks, rounding up and adding 1 to allow for the current tick 138 * to expire. Rounding also depends on unsigned long arithmetic 139 * to avoid overflow. 140 * 141 * Otherwise, if the number of ticks in the whole seconds part of 142 * the time difference fits in a long, then convert the parts to 143 * ticks separately and add, using similar rounding methods and 144 * overflow avoidance. This method would work in the previous 145 * case, but it is slightly slower and assume that hz is integral. 146 * 147 * Otherwise, round the time difference down to the maximum 148 * representable value. 149 * 150 * If ints are 32-bit, then the maximum value for any timeout in 151 * 10ms ticks is 248 days. 152 */ 153 s = splclock(); 154 sec = tv->tv_sec - time.tv_sec; 155 usec = tv->tv_usec - time.tv_usec; 156 splx(s); 157 158 if (usec < 0) { 159 sec--; 160 usec += 1000000; 161 } 162 163 if (sec < 0 || (sec == 0 && usec <= 0)) { 164 /* 165 * Would expire now or in the past. Return 0 ticks. 166 * This is different from the legacy hzto() interface, 167 * and callers need to check for it. 168 */ 169 ticks = 0; 170 } else if (sec <= (LONG_MAX / 1000000)) 171 ticks = (((sec * 1000000) + (unsigned long)usec + (tick - 1)) 172 / tick) + 1; 173 else if (sec <= (LONG_MAX / hz)) 174 ticks = (sec * hz) + 175 (((unsigned long)usec + (tick - 1)) / tick) + 1; 176 else 177 ticks = LONG_MAX; 178 179 if (ticks > INT_MAX) 180 ticks = INT_MAX; 181 182 return ((int)ticks); 183 } 184 #endif /* !__HAVE_TIMECOUNTER */ 185 186 /* 187 * Compute number of ticks in the specified amount of time. 188 */ 189 int 190 tstohz(struct timespec *ts) 191 { 192 struct timeval tv; 193 194 /* 195 * usec has great enough resolution for hz, so convert to a 196 * timeval and use tvtohz() above. 197 */ 198 TIMESPEC_TO_TIMEVAL(&tv, ts); 199 return tvtohz(&tv); 200 } 201 202 /* 203 * Check that a proposed value to load into the .it_value or 204 * .it_interval part of an interval timer is acceptable, and 205 * fix it to have at least minimal value (i.e. if it is less 206 * than the resolution of the clock, round it up.) 207 */ 208 int 209 itimerfix(struct timeval *tv) 210 { 211 212 if (tv->tv_sec < 0 || tv->tv_usec < 0 || tv->tv_usec >= 1000000) 213 return (EINVAL); 214 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick) 215 tv->tv_usec = tick; 216 return (0); 217 } 218 219 int 220 itimespecfix(struct timespec *ts) 221 { 222 223 if (ts->tv_sec < 0 || ts->tv_nsec < 0 || ts->tv_nsec >= 1000000000) 224 return (EINVAL); 225 if (ts->tv_sec == 0 && ts->tv_nsec != 0 && ts->tv_nsec < tick * 1000) 226 ts->tv_nsec = tick * 1000; 227 return (0); 228 } 229