Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | #ifndef _LINUX_JIFFIES_H |
| 2 | #define _LINUX_JIFFIES_H |
| 3 | |
Thomas Gleixner | 5cca761 | 2006-01-09 20:52:20 -0800 | [diff] [blame] | 4 | #include <linux/calc64.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 5 | #include <linux/kernel.h> |
| 6 | #include <linux/types.h> |
| 7 | #include <linux/time.h> |
| 8 | #include <linux/timex.h> |
| 9 | #include <asm/param.h> /* for HZ */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 10 | |
| 11 | /* |
| 12 | * The following defines establish the engineering parameters of the PLL |
| 13 | * model. The HZ variable establishes the timer interrupt frequency, 100 Hz |
| 14 | * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the |
| 15 | * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the |
| 16 | * nearest power of two in order to avoid hardware multiply operations. |
| 17 | */ |
| 18 | #if HZ >= 12 && HZ < 24 |
| 19 | # define SHIFT_HZ 4 |
| 20 | #elif HZ >= 24 && HZ < 48 |
| 21 | # define SHIFT_HZ 5 |
| 22 | #elif HZ >= 48 && HZ < 96 |
| 23 | # define SHIFT_HZ 6 |
| 24 | #elif HZ >= 96 && HZ < 192 |
| 25 | # define SHIFT_HZ 7 |
| 26 | #elif HZ >= 192 && HZ < 384 |
| 27 | # define SHIFT_HZ 8 |
| 28 | #elif HZ >= 384 && HZ < 768 |
| 29 | # define SHIFT_HZ 9 |
| 30 | #elif HZ >= 768 && HZ < 1536 |
| 31 | # define SHIFT_HZ 10 |
| 32 | #else |
| 33 | # error You lose. |
| 34 | #endif |
| 35 | |
| 36 | /* LATCH is used in the interval timer and ftape setup. */ |
| 37 | #define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */ |
| 38 | |
Jordan Hargrave | b20367a | 2006-04-07 19:50:18 +0200 | [diff] [blame] | 39 | #define LATCH_HPET ((HPET_TICK_RATE + HZ/2) / HZ) |
| 40 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | /* Suppose we want to devide two numbers NOM and DEN: NOM/DEN, the we can |
| 42 | * improve accuracy by shifting LSH bits, hence calculating: |
| 43 | * (NOM << LSH) / DEN |
| 44 | * This however means trouble for large NOM, because (NOM << LSH) may no |
| 45 | * longer fit in 32 bits. The following way of calculating this gives us |
| 46 | * some slack, under the following conditions: |
| 47 | * - (NOM / DEN) fits in (32 - LSH) bits. |
| 48 | * - (NOM % DEN) fits in (32 - LSH) bits. |
| 49 | */ |
Uwe Zeisberger | 0d94df5 | 2006-07-30 03:04:02 -0700 | [diff] [blame] | 50 | #define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \ |
| 51 | + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | |
| 53 | /* HZ is the requested value. ACTHZ is actual HZ ("<< 8" is for accuracy) */ |
| 54 | #define ACTHZ (SH_DIV (CLOCK_TICK_RATE, LATCH, 8)) |
| 55 | |
Jordan Hargrave | b20367a | 2006-04-07 19:50:18 +0200 | [diff] [blame] | 56 | #define ACTHZ_HPET (SH_DIV (HPET_TICK_RATE, LATCH_HPET, 8)) |
| 57 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | /* TICK_NSEC is the time between ticks in nsec assuming real ACTHZ */ |
| 59 | #define TICK_NSEC (SH_DIV (1000000UL * 1000, ACTHZ, 8)) |
| 60 | |
Jordan Hargrave | b20367a | 2006-04-07 19:50:18 +0200 | [diff] [blame] | 61 | #define TICK_NSEC_HPET (SH_DIV(1000000UL * 1000, ACTHZ_HPET, 8)) |
| 62 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | /* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */ |
| 64 | #define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ) |
| 65 | |
| 66 | /* TICK_USEC_TO_NSEC is the time between ticks in nsec assuming real ACTHZ and */ |
| 67 | /* a value TUSEC for TICK_USEC (can be set bij adjtimex) */ |
| 68 | #define TICK_USEC_TO_NSEC(TUSEC) (SH_DIV (TUSEC * USER_HZ * 1000, ACTHZ, 8)) |
| 69 | |
| 70 | /* some arch's have a small-data section that can be accessed register-relative |
| 71 | * but that can only take up to, say, 4-byte variables. jiffies being part of |
| 72 | * an 8-byte variable may not be correctly accessed unless we force the issue |
| 73 | */ |
| 74 | #define __jiffy_data __attribute__((section(".data"))) |
| 75 | |
| 76 | /* |
| 77 | * The 64-bit value is not volatile - you MUST NOT read it |
| 78 | * without sampling the sequence number in xtime_lock. |
| 79 | * get_jiffies_64() will do this for you as appropriate. |
| 80 | */ |
| 81 | extern u64 __jiffy_data jiffies_64; |
| 82 | extern unsigned long volatile __jiffy_data jiffies; |
| 83 | |
| 84 | #if (BITS_PER_LONG < 64) |
| 85 | u64 get_jiffies_64(void); |
| 86 | #else |
| 87 | static inline u64 get_jiffies_64(void) |
| 88 | { |
| 89 | return (u64)jiffies; |
| 90 | } |
| 91 | #endif |
| 92 | |
| 93 | /* |
| 94 | * These inlines deal with timer wrapping correctly. You are |
| 95 | * strongly encouraged to use them |
| 96 | * 1. Because people otherwise forget |
| 97 | * 2. Because if the timer wrap changes in future you won't have to |
| 98 | * alter your driver code. |
| 99 | * |
| 100 | * time_after(a,b) returns true if the time a is after time b. |
| 101 | * |
| 102 | * Do this with "<0" and ">=0" to only test the sign of the result. A |
| 103 | * good compiler would generate better code (and a really good compiler |
| 104 | * wouldn't care). Gcc is currently neither. |
| 105 | */ |
| 106 | #define time_after(a,b) \ |
| 107 | (typecheck(unsigned long, a) && \ |
| 108 | typecheck(unsigned long, b) && \ |
| 109 | ((long)(b) - (long)(a) < 0)) |
| 110 | #define time_before(a,b) time_after(b,a) |
| 111 | |
| 112 | #define time_after_eq(a,b) \ |
| 113 | (typecheck(unsigned long, a) && \ |
| 114 | typecheck(unsigned long, b) && \ |
| 115 | ((long)(a) - (long)(b) >= 0)) |
| 116 | #define time_before_eq(a,b) time_after_eq(b,a) |
| 117 | |
Dmitriy Zavin | 3b17167 | 2006-09-26 10:52:42 +0200 | [diff] [blame] | 118 | /* Same as above, but does so with platform independent 64bit types. |
| 119 | * These must be used when utilizing jiffies_64 (i.e. return value of |
| 120 | * get_jiffies_64() */ |
| 121 | #define time_after64(a,b) \ |
| 122 | (typecheck(__u64, a) && \ |
| 123 | typecheck(__u64, b) && \ |
| 124 | ((__s64)(b) - (__s64)(a) < 0)) |
| 125 | #define time_before64(a,b) time_after64(b,a) |
| 126 | |
| 127 | #define time_after_eq64(a,b) \ |
| 128 | (typecheck(__u64, a) && \ |
| 129 | typecheck(__u64, b) && \ |
| 130 | ((__s64)(a) - (__s64)(b) >= 0)) |
| 131 | #define time_before_eq64(a,b) time_after_eq64(b,a) |
| 132 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | /* |
| 134 | * Have the 32 bit jiffies value wrap 5 minutes after boot |
| 135 | * so jiffies wrap bugs show up earlier. |
| 136 | */ |
| 137 | #define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ)) |
| 138 | |
| 139 | /* |
| 140 | * Change timeval to jiffies, trying to avoid the |
| 141 | * most obvious overflows.. |
| 142 | * |
| 143 | * And some not so obvious. |
| 144 | * |
| 145 | * Note that we don't want to return MAX_LONG, because |
| 146 | * for various timeout reasons we often end up having |
| 147 | * to wait "jiffies+1" in order to guarantee that we wait |
| 148 | * at _least_ "jiffies" - so "jiffies+1" had better still |
| 149 | * be positive. |
| 150 | */ |
| 151 | #define MAX_JIFFY_OFFSET ((~0UL >> 1)-1) |
| 152 | |
| 153 | /* |
| 154 | * We want to do realistic conversions of time so we need to use the same |
| 155 | * values the update wall clock code uses as the jiffies size. This value |
| 156 | * is: TICK_NSEC (which is defined in timex.h). This |
| 157 | * is a constant and is in nanoseconds. We will used scaled math |
| 158 | * with a set of scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and |
| 159 | * NSEC_JIFFIE_SC. Note that these defines contain nothing but |
| 160 | * constants and so are computed at compile time. SHIFT_HZ (computed in |
| 161 | * timex.h) adjusts the scaling for different HZ values. |
| 162 | |
| 163 | * Scaled math??? What is that? |
| 164 | * |
| 165 | * Scaled math is a way to do integer math on values that would, |
| 166 | * otherwise, either overflow, underflow, or cause undesired div |
| 167 | * instructions to appear in the execution path. In short, we "scale" |
| 168 | * up the operands so they take more bits (more precision, less |
| 169 | * underflow), do the desired operation and then "scale" the result back |
| 170 | * by the same amount. If we do the scaling by shifting we avoid the |
| 171 | * costly mpy and the dastardly div instructions. |
| 172 | |
| 173 | * Suppose, for example, we want to convert from seconds to jiffies |
| 174 | * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE. The |
| 175 | * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We |
| 176 | * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we |
| 177 | * might calculate at compile time, however, the result will only have |
| 178 | * about 3-4 bits of precision (less for smaller values of HZ). |
| 179 | * |
| 180 | * So, we scale as follows: |
| 181 | * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE); |
| 182 | * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE; |
| 183 | * Then we make SCALE a power of two so: |
| 184 | * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE; |
| 185 | * Now we define: |
| 186 | * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) |
| 187 | * jiff = (sec * SEC_CONV) >> SCALE; |
| 188 | * |
| 189 | * Often the math we use will expand beyond 32-bits so we tell C how to |
| 190 | * do this and pass the 64-bit result of the mpy through the ">> SCALE" |
| 191 | * which should take the result back to 32-bits. We want this expansion |
| 192 | * to capture as much precision as possible. At the same time we don't |
| 193 | * want to overflow so we pick the SCALE to avoid this. In this file, |
| 194 | * that means using a different scale for each range of HZ values (as |
| 195 | * defined in timex.h). |
| 196 | * |
| 197 | * For those who want to know, gcc will give a 64-bit result from a "*" |
| 198 | * operator if the result is a long long AND at least one of the |
| 199 | * operands is cast to long long (usually just prior to the "*" so as |
| 200 | * not to confuse it into thinking it really has a 64-bit operand, |
| 201 | * which, buy the way, it can do, but it take more code and at least 2 |
| 202 | * mpys). |
| 203 | |
| 204 | * We also need to be aware that one second in nanoseconds is only a |
| 205 | * couple of bits away from overflowing a 32-bit word, so we MUST use |
| 206 | * 64-bits to get the full range time in nanoseconds. |
| 207 | |
| 208 | */ |
| 209 | |
| 210 | /* |
| 211 | * Here are the scales we will use. One for seconds, nanoseconds and |
| 212 | * microseconds. |
| 213 | * |
| 214 | * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and |
| 215 | * check if the sign bit is set. If not, we bump the shift count by 1. |
| 216 | * (Gets an extra bit of precision where we can use it.) |
| 217 | * We know it is set for HZ = 1024 and HZ = 100 not for 1000. |
| 218 | * Haven't tested others. |
| 219 | |
| 220 | * Limits of cpp (for #if expressions) only long (no long long), but |
| 221 | * then we only need the most signicant bit. |
| 222 | */ |
| 223 | |
| 224 | #define SEC_JIFFIE_SC (31 - SHIFT_HZ) |
| 225 | #if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000) |
| 226 | #undef SEC_JIFFIE_SC |
| 227 | #define SEC_JIFFIE_SC (32 - SHIFT_HZ) |
| 228 | #endif |
| 229 | #define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29) |
| 230 | #define USEC_JIFFIE_SC (SEC_JIFFIE_SC + 19) |
| 231 | #define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\ |
| 232 | TICK_NSEC -1) / (u64)TICK_NSEC)) |
| 233 | |
| 234 | #define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\ |
| 235 | TICK_NSEC -1) / (u64)TICK_NSEC)) |
| 236 | #define USEC_CONVERSION \ |
| 237 | ((unsigned long)((((u64)NSEC_PER_USEC << USEC_JIFFIE_SC) +\ |
| 238 | TICK_NSEC -1) / (u64)TICK_NSEC)) |
| 239 | /* |
| 240 | * USEC_ROUND is used in the timeval to jiffie conversion. See there |
| 241 | * for more details. It is the scaled resolution rounding value. Note |
| 242 | * that it is a 64-bit value. Since, when it is applied, we are already |
| 243 | * in jiffies (albit scaled), it is nothing but the bits we will shift |
| 244 | * off. |
| 245 | */ |
| 246 | #define USEC_ROUND (u64)(((u64)1 << USEC_JIFFIE_SC) - 1) |
| 247 | /* |
| 248 | * The maximum jiffie value is (MAX_INT >> 1). Here we translate that |
| 249 | * into seconds. The 64-bit case will overflow if we are not careful, |
| 250 | * so use the messy SH_DIV macro to do it. Still all constants. |
| 251 | */ |
| 252 | #if BITS_PER_LONG < 64 |
| 253 | # define MAX_SEC_IN_JIFFIES \ |
| 254 | (long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC) |
| 255 | #else /* take care of overflow on 64 bits machines */ |
| 256 | # define MAX_SEC_IN_JIFFIES \ |
| 257 | (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1) |
| 258 | |
| 259 | #endif |
| 260 | |
| 261 | /* |
| 262 | * Convert jiffies to milliseconds and back. |
| 263 | * |
| 264 | * Avoid unnecessary multiplications/divisions in the |
| 265 | * two most common HZ cases: |
| 266 | */ |
| 267 | static inline unsigned int jiffies_to_msecs(const unsigned long j) |
| 268 | { |
Nishanth Aravamudan | 84f902c | 2005-09-10 00:27:22 -0700 | [diff] [blame] | 269 | #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) |
| 270 | return (MSEC_PER_SEC / HZ) * j; |
| 271 | #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) |
| 272 | return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 273 | #else |
Nishanth Aravamudan | 84f902c | 2005-09-10 00:27:22 -0700 | [diff] [blame] | 274 | return (j * MSEC_PER_SEC) / HZ; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 275 | #endif |
| 276 | } |
| 277 | |
| 278 | static inline unsigned int jiffies_to_usecs(const unsigned long j) |
| 279 | { |
Nishanth Aravamudan | 84f902c | 2005-09-10 00:27:22 -0700 | [diff] [blame] | 280 | #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) |
| 281 | return (USEC_PER_SEC / HZ) * j; |
| 282 | #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) |
| 283 | return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 284 | #else |
Nishanth Aravamudan | 84f902c | 2005-09-10 00:27:22 -0700 | [diff] [blame] | 285 | return (j * USEC_PER_SEC) / HZ; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 286 | #endif |
| 287 | } |
| 288 | |
| 289 | static inline unsigned long msecs_to_jiffies(const unsigned int m) |
| 290 | { |
| 291 | if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) |
| 292 | return MAX_JIFFY_OFFSET; |
Nishanth Aravamudan | 84f902c | 2005-09-10 00:27:22 -0700 | [diff] [blame] | 293 | #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) |
| 294 | return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); |
| 295 | #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) |
| 296 | return m * (HZ / MSEC_PER_SEC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 297 | #else |
Nishanth Aravamudan | 84f902c | 2005-09-10 00:27:22 -0700 | [diff] [blame] | 298 | return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 299 | #endif |
| 300 | } |
| 301 | |
| 302 | static inline unsigned long usecs_to_jiffies(const unsigned int u) |
| 303 | { |
| 304 | if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) |
| 305 | return MAX_JIFFY_OFFSET; |
Nishanth Aravamudan | 84f902c | 2005-09-10 00:27:22 -0700 | [diff] [blame] | 306 | #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) |
| 307 | return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ); |
| 308 | #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) |
| 309 | return u * (HZ / USEC_PER_SEC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 310 | #else |
Nishanth Aravamudan | 84f902c | 2005-09-10 00:27:22 -0700 | [diff] [blame] | 311 | return (u * HZ + USEC_PER_SEC - 1) / USEC_PER_SEC; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 312 | #endif |
| 313 | } |
| 314 | |
| 315 | /* |
| 316 | * The TICK_NSEC - 1 rounds up the value to the next resolution. Note |
| 317 | * that a remainder subtract here would not do the right thing as the |
| 318 | * resolution values don't fall on second boundries. I.e. the line: |
| 319 | * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding. |
| 320 | * |
| 321 | * Rather, we just shift the bits off the right. |
| 322 | * |
| 323 | * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec |
| 324 | * value to a scaled second value. |
| 325 | */ |
| 326 | static __inline__ unsigned long |
| 327 | timespec_to_jiffies(const struct timespec *value) |
| 328 | { |
| 329 | unsigned long sec = value->tv_sec; |
| 330 | long nsec = value->tv_nsec + TICK_NSEC - 1; |
| 331 | |
| 332 | if (sec >= MAX_SEC_IN_JIFFIES){ |
| 333 | sec = MAX_SEC_IN_JIFFIES; |
| 334 | nsec = 0; |
| 335 | } |
| 336 | return (((u64)sec * SEC_CONVERSION) + |
| 337 | (((u64)nsec * NSEC_CONVERSION) >> |
| 338 | (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; |
| 339 | |
| 340 | } |
| 341 | |
| 342 | static __inline__ void |
| 343 | jiffies_to_timespec(const unsigned long jiffies, struct timespec *value) |
| 344 | { |
| 345 | /* |
| 346 | * Convert jiffies to nanoseconds and separate with |
| 347 | * one divide. |
| 348 | */ |
| 349 | u64 nsec = (u64)jiffies * TICK_NSEC; |
| 350 | value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec); |
| 351 | } |
| 352 | |
| 353 | /* Same for "timeval" |
| 354 | * |
| 355 | * Well, almost. The problem here is that the real system resolution is |
| 356 | * in nanoseconds and the value being converted is in micro seconds. |
| 357 | * Also for some machines (those that use HZ = 1024, in-particular), |
| 358 | * there is a LARGE error in the tick size in microseconds. |
| 359 | |
| 360 | * The solution we use is to do the rounding AFTER we convert the |
| 361 | * microsecond part. Thus the USEC_ROUND, the bits to be shifted off. |
| 362 | * Instruction wise, this should cost only an additional add with carry |
| 363 | * instruction above the way it was done above. |
| 364 | */ |
| 365 | static __inline__ unsigned long |
| 366 | timeval_to_jiffies(const struct timeval *value) |
| 367 | { |
| 368 | unsigned long sec = value->tv_sec; |
| 369 | long usec = value->tv_usec; |
| 370 | |
| 371 | if (sec >= MAX_SEC_IN_JIFFIES){ |
| 372 | sec = MAX_SEC_IN_JIFFIES; |
| 373 | usec = 0; |
| 374 | } |
| 375 | return (((u64)sec * SEC_CONVERSION) + |
| 376 | (((u64)usec * USEC_CONVERSION + USEC_ROUND) >> |
| 377 | (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; |
| 378 | } |
| 379 | |
| 380 | static __inline__ void |
| 381 | jiffies_to_timeval(const unsigned long jiffies, struct timeval *value) |
| 382 | { |
| 383 | /* |
| 384 | * Convert jiffies to nanoseconds and separate with |
| 385 | * one divide. |
| 386 | */ |
| 387 | u64 nsec = (u64)jiffies * TICK_NSEC; |
Thomas Gleixner | 5cca761 | 2006-01-09 20:52:20 -0800 | [diff] [blame] | 388 | long tv_usec; |
| 389 | |
| 390 | value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tv_usec); |
| 391 | tv_usec /= NSEC_PER_USEC; |
| 392 | value->tv_usec = tv_usec; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 393 | } |
| 394 | |
| 395 | /* |
| 396 | * Convert jiffies/jiffies_64 to clock_t and back. |
| 397 | */ |
| 398 | static inline clock_t jiffies_to_clock_t(long x) |
| 399 | { |
| 400 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 |
| 401 | return x / (HZ / USER_HZ); |
| 402 | #else |
| 403 | u64 tmp = (u64)x * TICK_NSEC; |
| 404 | do_div(tmp, (NSEC_PER_SEC / USER_HZ)); |
| 405 | return (long)tmp; |
| 406 | #endif |
| 407 | } |
| 408 | |
| 409 | static inline unsigned long clock_t_to_jiffies(unsigned long x) |
| 410 | { |
| 411 | #if (HZ % USER_HZ)==0 |
| 412 | if (x >= ~0UL / (HZ / USER_HZ)) |
| 413 | return ~0UL; |
| 414 | return x * (HZ / USER_HZ); |
| 415 | #else |
| 416 | u64 jif; |
| 417 | |
| 418 | /* Don't worry about loss of precision here .. */ |
| 419 | if (x >= ~0UL / HZ * USER_HZ) |
| 420 | return ~0UL; |
| 421 | |
| 422 | /* .. but do try to contain it here */ |
| 423 | jif = x * (u64) HZ; |
| 424 | do_div(jif, USER_HZ); |
| 425 | return jif; |
| 426 | #endif |
| 427 | } |
| 428 | |
| 429 | static inline u64 jiffies_64_to_clock_t(u64 x) |
| 430 | { |
| 431 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 |
| 432 | do_div(x, HZ / USER_HZ); |
| 433 | #else |
| 434 | /* |
| 435 | * There are better ways that don't overflow early, |
| 436 | * but even this doesn't overflow in hundreds of years |
| 437 | * in 64 bits, so.. |
| 438 | */ |
| 439 | x *= TICK_NSEC; |
| 440 | do_div(x, (NSEC_PER_SEC / USER_HZ)); |
| 441 | #endif |
| 442 | return x; |
| 443 | } |
| 444 | |
| 445 | static inline u64 nsec_to_clock_t(u64 x) |
| 446 | { |
| 447 | #if (NSEC_PER_SEC % USER_HZ) == 0 |
| 448 | do_div(x, (NSEC_PER_SEC / USER_HZ)); |
| 449 | #elif (USER_HZ % 512) == 0 |
| 450 | x *= USER_HZ/512; |
| 451 | do_div(x, (NSEC_PER_SEC / 512)); |
| 452 | #else |
| 453 | /* |
| 454 | * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024, |
| 455 | * overflow after 64.99 years. |
| 456 | * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ... |
| 457 | */ |
| 458 | x *= 9; |
| 459 | do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) |
| 460 | / USER_HZ)); |
| 461 | #endif |
| 462 | return x; |
| 463 | } |
| 464 | |
| 465 | #endif |