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Diffstat (limited to 'src/lib/libssl/src/MacOS/Randomizer.cpp')
| -rw-r--r-- | src/lib/libssl/src/MacOS/Randomizer.cpp | 476 |
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diff --git a/src/lib/libssl/src/MacOS/Randomizer.cpp b/src/lib/libssl/src/MacOS/Randomizer.cpp deleted file mode 100644 index cceb6bde44..0000000000 --- a/src/lib/libssl/src/MacOS/Randomizer.cpp +++ /dev/null | |||
| @@ -1,476 +0,0 @@ | |||
| 1 | /* | ||
| 2 | ------- Strong random data generation on a Macintosh (pre - OS X) ------ | ||
| 3 | |||
| 4 | -- GENERAL: We aim to generate unpredictable bits without explicit | ||
| 5 | user interaction. A general review of the problem may be found | ||
| 6 | in RFC 1750, "Randomness Recommendations for Security", and some | ||
| 7 | more discussion, of general and Mac-specific issues has appeared | ||
| 8 | in "Using and Creating Cryptographic- Quality Random Numbers" by | ||
| 9 | Jon Callas (www.merrymeet.com/jon/usingrandom.html). | ||
| 10 | |||
| 11 | The data and entropy estimates provided below are based on my | ||
| 12 | limited experimentation and estimates, rather than by any | ||
| 13 | rigorous study, and the entropy estimates tend to be optimistic. | ||
| 14 | They should not be considered absolute. | ||
| 15 | |||
| 16 | Some of the information being collected may be correlated in | ||
| 17 | subtle ways. That includes mouse positions, timings, and disk | ||
| 18 | size measurements. Some obvious correlations will be eliminated | ||
| 19 | by the programmer, but other, weaker ones may remain. The | ||
| 20 | reliability of the code depends on such correlations being | ||
| 21 | poorly understood, both by us and by potential interceptors. | ||
| 22 | |||
| 23 | This package has been planned to be used with OpenSSL, v. 0.9.5. | ||
| 24 | It requires the OpenSSL function RAND_add. | ||
| 25 | |||
| 26 | -- OTHER WORK: Some source code and other details have been | ||
| 27 | published elsewhere, but I haven't found any to be satisfactory | ||
| 28 | for the Mac per se: | ||
| 29 | |||
| 30 | * The Linux random number generator (by Theodore Ts'o, in | ||
| 31 | drivers/char/random.c), is a carefully designed open-source | ||
| 32 | crypto random number package. It collects data from a variety | ||
| 33 | of sources, including mouse, keyboard and other interrupts. | ||
| 34 | One nice feature is that it explicitly estimates the entropy | ||
| 35 | of the data it collects. Some of its features (e.g. interrupt | ||
| 36 | timing) cannot be reliably exported to the Mac without using | ||
| 37 | undocumented APIs. | ||
| 38 | |||
| 39 | * Truerand by Don P. Mitchell and Matt Blaze uses variations | ||
| 40 | between different timing mechanisms on the same system. This | ||
| 41 | has not been tested on the Mac, but requires preemptive | ||
| 42 | multitasking, and is hardware-dependent, and can't be relied | ||
| 43 | on to work well if only one oscillator is present. | ||
| 44 | |||
| 45 | * Cryptlib's RNG for the Mac (RNDMAC.C by Peter Gutmann), | ||
| 46 | gathers a lot of information about the machine and system | ||
| 47 | environment. Unfortunately, much of it is constant from one | ||
| 48 | startup to the next. In other words, the random seed could be | ||
| 49 | the same from one day to the next. Some of the APIs are | ||
| 50 | hardware-dependent, and not all are compatible with Carbon (OS | ||
| 51 | X). Incidentally, the EGD library is based on the UNIX entropy | ||
| 52 | gathering methods in cryptlib, and isn't suitable for MacOS | ||
| 53 | either. | ||
| 54 | |||
| 55 | * Mozilla (and perhaps earlier versions of Netscape) uses the | ||
| 56 | time of day (in seconds) and an uninitialized local variable | ||
| 57 | to seed the random number generator. The time of day is known | ||
| 58 | to an outside interceptor (to within the accuracy of the | ||
| 59 | system clock). The uninitialized variable could easily be | ||
| 60 | identical between subsequent launches of an application, if it | ||
| 61 | is reached through the same path. | ||
| 62 | |||
| 63 | * OpenSSL provides the function RAND_screen(), by G. van | ||
| 64 | Oosten, which hashes the contents of the screen to generate a | ||
| 65 | seed. This is not useful for an extension or for an | ||
| 66 | application which launches at startup time, since the screen | ||
| 67 | is likely to look identical from one launch to the next. This | ||
| 68 | method is also rather slow. | ||
| 69 | |||
| 70 | * Using variations in disk drive seek times has been proposed | ||
| 71 | (Davis, Ihaka and Fenstermacher, world.std.com/~dtd/; | ||
| 72 | Jakobsson, Shriver, Hillyer and Juels, | ||
| 73 | www.bell-labs.com/user/shriver/random.html). These variations | ||
| 74 | appear to be due to air turbulence inside the disk drive | ||
| 75 | mechanism, and are very strongly unpredictable. Unfortunately | ||
| 76 | this technique is slow, and some implementations of it may be | ||
| 77 | patented (see Shriver's page above.) It of course cannot be | ||
| 78 | used with a RAM disk. | ||
| 79 | |||
| 80 | -- TIMING: On the 601 PowerPC the time base register is guaranteed | ||
| 81 | to change at least once every 10 addi instructions, i.e. 10 | ||
| 82 | cycles. On a 60 MHz machine (slowest PowerPC) this translates to | ||
| 83 | a resolution of 1/6 usec. Newer machines seem to be using a 10 | ||
| 84 | cycle resolution as well. | ||
| 85 | |||
| 86 | For 68K Macs, the Microseconds() call may be used. See Develop | ||
| 87 | issue 29 on the Apple developer site | ||
| 88 | (developer.apple.com/dev/techsupport/develop/issue29/minow.html) | ||
| 89 | for information on its accuracy and resolution. The code below | ||
| 90 | has been tested only on PowerPC based machines. | ||
| 91 | |||
| 92 | The time from machine startup to the launch of an application in | ||
| 93 | the startup folder has a variance of about 1.6 msec on a new G4 | ||
| 94 | machine with a defragmented and optimized disk, most extensions | ||
| 95 | off and no icons on the desktop. This can be reasonably taken as | ||
| 96 | a lower bound on the variance. Most of this variation is likely | ||
| 97 | due to disk seek time variability. The distribution of startup | ||
| 98 | times is probably not entirely even or uncorrelated. This needs | ||
| 99 | to be investigated, but I am guessing that it not a majpor | ||
| 100 | problem. Entropy = log2 (1600/0.166) ~= 13 bits on a 60 MHz | ||
| 101 | machine, ~16 bits for a 450 MHz machine. | ||
| 102 | |||
| 103 | User-launched application startup times will have a variance of | ||
| 104 | a second or more relative to machine startup time. Entropy >~22 | ||
| 105 | bits. | ||
| 106 | |||
| 107 | Machine startup time is available with a 1-second resolution. It | ||
| 108 | is predictable to no better a minute or two, in the case of | ||
| 109 | people who show up punctually to work at the same time and | ||
| 110 | immediately start their computer. Using the scheduled startup | ||
| 111 | feature (when available) will cause the machine to start up at | ||
| 112 | the same time every day, making the value predictable. Entropy | ||
| 113 | >~7 bits, or 0 bits with scheduled startup. | ||
| 114 | |||
| 115 | The time of day is of course known to an outsider and thus has 0 | ||
| 116 | entropy if the system clock is regularly calibrated. | ||
| 117 | |||
| 118 | -- KEY TIMING: A very fast typist (120 wpm) will have a typical | ||
| 119 | inter-key timing interval of 100 msec. We can assume a variance | ||
| 120 | of no less than 2 msec -- maybe. Do good typists have a constant | ||
| 121 | rhythm, like drummers? Since what we measure is not the | ||
| 122 | key-generated interrupt but the time at which the key event was | ||
| 123 | taken off the event queue, our resolution is roughly the time | ||
| 124 | between process switches, at best 1 tick (17 msec). I therefore | ||
| 125 | consider this technique questionable and not very useful for | ||
| 126 | obtaining high entropy data on the Mac. | ||
| 127 | |||
| 128 | -- MOUSE POSITION AND TIMING: The high bits of the mouse position | ||
| 129 | are far from arbitrary, since the mouse tends to stay in a few | ||
| 130 | limited areas of the screen. I am guessing that the position of | ||
| 131 | the mouse is arbitrary within a 6 pixel square. Since the mouse | ||
| 132 | stays still for long periods of time, it should be sampled only | ||
| 133 | after it was moved, to avoid correlated data. This gives an | ||
| 134 | entropy of log2(6*6) ~= 5 bits per measurement. | ||
| 135 | |||
| 136 | The time during which the mouse stays still can vary from zero | ||
| 137 | to, say, 5 seconds (occasionally longer). If the still time is | ||
| 138 | measured by sampling the mouse during null events, and null | ||
| 139 | events are received once per tick, its resolution is 1/60th of a | ||
| 140 | second, giving an entropy of log2 (60*5) ~= 8 bits per | ||
| 141 | measurement. Since the distribution of still times is uneven, | ||
| 142 | this estimate is on the high side. | ||
| 143 | |||
| 144 | For simplicity and compatibility across system versions, the | ||
| 145 | mouse is to be sampled explicitly (e.g. in the event loop), | ||
| 146 | rather than in a time manager task. | ||
| 147 | |||
| 148 | -- STARTUP DISK TOTAL FILE SIZE: Varies typically by at least 20k | ||
| 149 | from one startup to the next, with 'minimal' computer use. Won't | ||
| 150 | vary at all if machine is started again immediately after | ||
| 151 | startup (unless virtual memory is on), but any application which | ||
| 152 | uses the web and caches information to disk is likely to cause | ||
| 153 | this much variation or more. The variation is probably not | ||
| 154 | random, but I don't know in what way. File sizes tend to be | ||
| 155 | divisible by 4 bytes since file format fields are often | ||
| 156 | long-aligned. Entropy > log2 (20000/4) ~= 12 bits. | ||
| 157 | |||
| 158 | -- STARTUP DISK FIRST AVAILABLE ALLOCATION BLOCK: As the volume | ||
| 159 | gets fragmented this could be anywhere in principle. In a | ||
| 160 | perfectly unfragmented volume this will be strongly correlated | ||
| 161 | with the total file size on the disk. With more fragmentation | ||
| 162 | comes less certainty. I took the variation in this value to be | ||
| 163 | 1/8 of the total file size on the volume. | ||
| 164 | |||
| 165 | -- SYSTEM REQUIREMENTS: The code here requires System 7.0 and above | ||
| 166 | (for Gestalt and Microseconds calls). All the calls used are | ||
| 167 | Carbon-compatible. | ||
| 168 | */ | ||
| 169 | |||
| 170 | /*------------------------------ Includes ----------------------------*/ | ||
| 171 | |||
| 172 | #include "Randomizer.h" | ||
| 173 | |||
| 174 | // Mac OS API | ||
| 175 | #include <Files.h> | ||
| 176 | #include <Folders.h> | ||
| 177 | #include <Events.h> | ||
| 178 | #include <Processes.h> | ||
| 179 | #include <Gestalt.h> | ||
| 180 | #include <Resources.h> | ||
| 181 | #include <LowMem.h> | ||
| 182 | |||
| 183 | // Standard C library | ||
| 184 | #include <stdlib.h> | ||
| 185 | #include <math.h> | ||
| 186 | |||
| 187 | /*---------------------- Function declarations -----------------------*/ | ||
| 188 | |||
| 189 | // declared in OpenSSL/crypto/rand/rand.h | ||
| 190 | extern "C" void RAND_add (const void *buf, int num, double entropy); | ||
| 191 | |||
| 192 | unsigned long GetPPCTimer (bool is601); // Make it global if needed | ||
| 193 | // elsewhere | ||
| 194 | |||
| 195 | /*---------------------------- Constants -----------------------------*/ | ||
| 196 | |||
| 197 | #define kMouseResolution 6 // Mouse position has to differ | ||
| 198 | // from the last one by this | ||
| 199 | // much to be entered | ||
| 200 | #define kMousePositionEntropy 5.16 // log2 (kMouseResolution**2) | ||
| 201 | #define kTypicalMouseIdleTicks 300.0 // I am guessing that a typical | ||
| 202 | // amount of time between mouse | ||
| 203 | // moves is 5 seconds | ||
| 204 | #define kVolumeBytesEntropy 12.0 // about log2 (20000/4), | ||
| 205 | // assuming a variation of 20K | ||
| 206 | // in total file size and | ||
| 207 | // long-aligned file formats. | ||
| 208 | #define kApplicationUpTimeEntropy 6.0 // Variance > 1 second, uptime | ||
| 209 | // in ticks | ||
| 210 | #define kSysStartupEntropy 7.0 // Entropy for machine startup | ||
| 211 | // time | ||
| 212 | |||
| 213 | |||
| 214 | /*------------------------ Function definitions ----------------------*/ | ||
| 215 | |||
| 216 | CRandomizer::CRandomizer (void) | ||
| 217 | { | ||
| 218 | long result; | ||
| 219 | |||
| 220 | mSupportsLargeVolumes = | ||
| 221 | (Gestalt(gestaltFSAttr, &result) == noErr) && | ||
| 222 | ((result & (1L << gestaltFSSupports2TBVols)) != 0); | ||
| 223 | |||
| 224 | if (Gestalt (gestaltNativeCPUtype, &result) != noErr) | ||
| 225 | { | ||
| 226 | mIsPowerPC = false; | ||
| 227 | mIs601 = false; | ||
| 228 | } | ||
| 229 | else | ||
| 230 | { | ||
| 231 | mIs601 = (result == gestaltCPU601); | ||
| 232 | mIsPowerPC = (result >= gestaltCPU601); | ||
| 233 | } | ||
| 234 | mLastMouse.h = mLastMouse.v = -10; // First mouse will | ||
| 235 | // always be recorded | ||
| 236 | mLastPeriodicTicks = TickCount(); | ||
| 237 | GetTimeBaseResolution (); | ||
| 238 | |||
| 239 | // Add initial entropy | ||
| 240 | AddTimeSinceMachineStartup (); | ||
| 241 | AddAbsoluteSystemStartupTime (); | ||
| 242 | AddStartupVolumeInfo (); | ||
| 243 | AddFiller (); | ||
| 244 | } | ||
| 245 | |||
| 246 | void CRandomizer::PeriodicAction (void) | ||
| 247 | { | ||
| 248 | AddCurrentMouse (); | ||
| 249 | AddNow (0.0); // Should have a better entropy estimate here | ||
| 250 | mLastPeriodicTicks = TickCount(); | ||
| 251 | } | ||
| 252 | |||
| 253 | /*------------------------- Private Methods --------------------------*/ | ||
| 254 | |||
| 255 | void CRandomizer::AddCurrentMouse (void) | ||
| 256 | { | ||
| 257 | Point mouseLoc; | ||
| 258 | unsigned long lastCheck; // Ticks since mouse was last | ||
| 259 | // sampled | ||
| 260 | |||
| 261 | #if TARGET_API_MAC_CARBON | ||
| 262 | GetGlobalMouse (&mouseLoc); | ||
| 263 | #else | ||
| 264 | mouseLoc = LMGetMouseLocation(); | ||
| 265 | #endif | ||
| 266 | |||
| 267 | if (labs (mLastMouse.h - mouseLoc.h) > kMouseResolution/2 && | ||
| 268 | labs (mLastMouse.v - mouseLoc.v) > kMouseResolution/2) | ||
| 269 | AddBytes (&mouseLoc, sizeof (mouseLoc), | ||
| 270 | kMousePositionEntropy); | ||
| 271 | |||
| 272 | if (mLastMouse.h == mouseLoc.h && mLastMouse.v == mouseLoc.v) | ||
| 273 | mMouseStill ++; | ||
| 274 | else | ||
| 275 | { | ||
| 276 | double entropy; | ||
| 277 | |||
| 278 | // Mouse has moved. Add the number of measurements for | ||
| 279 | // which it's been still. If the resolution is too | ||
| 280 | // coarse, assume the entropy is 0. | ||
| 281 | |||
| 282 | lastCheck = TickCount() - mLastPeriodicTicks; | ||
| 283 | if (lastCheck <= 0) | ||
| 284 | lastCheck = 1; | ||
| 285 | entropy = log2l | ||
| 286 | (kTypicalMouseIdleTicks/(double)lastCheck); | ||
| 287 | if (entropy < 0.0) | ||
| 288 | entropy = 0.0; | ||
| 289 | AddBytes (&mMouseStill, sizeof (mMouseStill), entropy); | ||
| 290 | mMouseStill = 0; | ||
| 291 | } | ||
| 292 | mLastMouse = mouseLoc; | ||
| 293 | } | ||
| 294 | |||
| 295 | void CRandomizer::AddAbsoluteSystemStartupTime (void) | ||
| 296 | { | ||
| 297 | unsigned long now; // Time in seconds since | ||
| 298 | // 1/1/1904 | ||
| 299 | GetDateTime (&now); | ||
| 300 | now -= TickCount() / 60; // Time in ticks since machine | ||
| 301 | // startup | ||
| 302 | AddBytes (&now, sizeof (now), kSysStartupEntropy); | ||
| 303 | } | ||
| 304 | |||
| 305 | void CRandomizer::AddTimeSinceMachineStartup (void) | ||
| 306 | { | ||
| 307 | AddNow (1.5); // Uncertainty in app startup | ||
| 308 | // time is > 1.5 msec (for | ||
| 309 | // automated app startup). | ||
| 310 | } | ||
| 311 | |||
| 312 | void CRandomizer::AddAppRunningTime (void) | ||
| 313 | { | ||
| 314 | ProcessSerialNumber PSN; | ||
| 315 | ProcessInfoRec ProcessInfo; | ||
| 316 | |||
| 317 | ProcessInfo.processInfoLength = sizeof (ProcessInfoRec); | ||
| 318 | ProcessInfo.processName = nil; | ||
| 319 | ProcessInfo.processAppSpec = nil; | ||
| 320 | |||
| 321 | GetCurrentProcess (&PSN); | ||
| 322 | GetProcessInformation (&PSN, &ProcessInfo); | ||
| 323 | |||
| 324 | // Now add the amount of time in ticks that the current process | ||
| 325 | // has been active | ||
| 326 | |||
| 327 | AddBytes (&ProcessInfo, sizeof (ProcessInfoRec), | ||
| 328 | kApplicationUpTimeEntropy); | ||
| 329 | } | ||
| 330 | |||
| 331 | void CRandomizer::AddStartupVolumeInfo (void) | ||
| 332 | { | ||
| 333 | short vRefNum; | ||
| 334 | long dirID; | ||
| 335 | XVolumeParam pb; | ||
| 336 | OSErr err; | ||
| 337 | |||
| 338 | if (!mSupportsLargeVolumes) | ||
| 339 | return; | ||
| 340 | |||
| 341 | FindFolder (kOnSystemDisk, kSystemFolderType, kDontCreateFolder, | ||
| 342 | &vRefNum, &dirID); | ||
| 343 | pb.ioVRefNum = vRefNum; | ||
| 344 | pb.ioCompletion = 0; | ||
| 345 | pb.ioNamePtr = 0; | ||
| 346 | pb.ioVolIndex = 0; | ||
| 347 | err = PBXGetVolInfoSync (&pb); | ||
| 348 | if (err != noErr) | ||
| 349 | return; | ||
| 350 | |||
| 351 | // Base the entropy on the amount of space used on the disk and | ||
| 352 | // on the next available allocation block. A lot else might be | ||
| 353 | // unpredictable, so might as well toss the whole block in. See | ||
| 354 | // comments for entropy estimate justifications. | ||
| 355 | |||
| 356 | AddBytes (&pb, sizeof (pb), | ||
| 357 | kVolumeBytesEntropy + | ||
| 358 | log2l (((pb.ioVTotalBytes.hi - pb.ioVFreeBytes.hi) | ||
| 359 | * 4294967296.0D + | ||
| 360 | (pb.ioVTotalBytes.lo - pb.ioVFreeBytes.lo)) | ||
| 361 | / pb.ioVAlBlkSiz - 3.0)); | ||
| 362 | } | ||
| 363 | |||
| 364 | /* | ||
| 365 | On a typical startup CRandomizer will come up with about 60 | ||
| 366 | bits of good, unpredictable data. Assuming no more input will | ||
| 367 | be available, we'll need some more lower-quality data to give | ||
| 368 | OpenSSL the 128 bits of entropy it desires. AddFiller adds some | ||
| 369 | relatively predictable data into the soup. | ||
| 370 | */ | ||
| 371 | |||
| 372 | void CRandomizer::AddFiller (void) | ||
| 373 | { | ||
| 374 | struct | ||
| 375 | { | ||
| 376 | ProcessSerialNumber psn; // Front process serial | ||
| 377 | // number | ||
| 378 | RGBColor hiliteRGBValue; // User-selected | ||
| 379 | // highlight color | ||
| 380 | long processCount; // Number of active | ||
| 381 | // processes | ||
| 382 | long cpuSpeed; // Processor speed | ||
| 383 | long totalMemory; // Total logical memory | ||
| 384 | // (incl. virtual one) | ||
| 385 | long systemVersion; // OS version | ||
| 386 | short resFile; // Current resource file | ||
| 387 | } data; | ||
| 388 | |||
| 389 | GetNextProcess ((ProcessSerialNumber*) kNoProcess); | ||
| 390 | while (GetNextProcess (&data.psn) == noErr) | ||
| 391 | data.processCount++; | ||
| 392 | GetFrontProcess (&data.psn); | ||
| 393 | LMGetHiliteRGB (&data.hiliteRGBValue); | ||
| 394 | Gestalt (gestaltProcClkSpeed, &data.cpuSpeed); | ||
| 395 | Gestalt (gestaltLogicalRAMSize, &data.totalMemory); | ||
| 396 | Gestalt (gestaltSystemVersion, &data.systemVersion); | ||
| 397 | data.resFile = CurResFile (); | ||
| 398 | |||
| 399 | // Here we pretend to feed the PRNG completely random data. This | ||
| 400 | // is of course false, as much of the above data is predictable | ||
| 401 | // by an outsider. At this point we don't have any more | ||
| 402 | // randomness to add, but with OpenSSL we must have a 128 bit | ||
| 403 | // seed before we can start. We just add what we can, without a | ||
| 404 | // real entropy estimate, and hope for the best. | ||
| 405 | |||
| 406 | AddBytes (&data, sizeof(data), 8.0 * sizeof(data)); | ||
| 407 | AddCurrentMouse (); | ||
| 408 | AddNow (1.0); | ||
| 409 | } | ||
| 410 | |||
| 411 | //------------------- LOW LEVEL --------------------- | ||
| 412 | |||
| 413 | void CRandomizer::AddBytes (void *data, long size, double entropy) | ||
| 414 | { | ||
| 415 | RAND_add (data, size, entropy * 0.125); // Convert entropy bits | ||
| 416 | // to bytes | ||
| 417 | } | ||
| 418 | |||
| 419 | void CRandomizer::AddNow (double millisecondUncertainty) | ||
| 420 | { | ||
| 421 | long time = SysTimer(); | ||
| 422 | AddBytes (&time, sizeof (time), log2l (millisecondUncertainty * | ||
| 423 | mTimebaseTicksPerMillisec)); | ||
| 424 | } | ||
| 425 | |||
| 426 | //----------------- TIMING SUPPORT ------------------ | ||
| 427 | |||
| 428 | void CRandomizer::GetTimeBaseResolution (void) | ||
| 429 | { | ||
| 430 | #ifdef __powerc | ||
| 431 | long speed; | ||
| 432 | |||
| 433 | // gestaltProcClkSpeed available on System 7.5.2 and above | ||
| 434 | if (Gestalt (gestaltProcClkSpeed, &speed) != noErr) | ||
| 435 | // Only PowerPCs running pre-7.5.2 are 60-80 MHz | ||
| 436 | // machines. | ||
| 437 | mTimebaseTicksPerMillisec = 6000.0D; | ||
| 438 | // Assume 10 cycles per clock update, as in 601 spec. Seems true | ||
| 439 | // for later chips as well. | ||
| 440 | mTimebaseTicksPerMillisec = speed / 1.0e4D; | ||
| 441 | #else | ||
| 442 | // 68K VIA-based machines (see Develop Magazine no. 29) | ||
| 443 | mTimebaseTicksPerMillisec = 783.360D; | ||
| 444 | #endif | ||
| 445 | } | ||
| 446 | |||
| 447 | unsigned long CRandomizer::SysTimer (void) // returns the lower 32 | ||
| 448 | // bit of the chip timer | ||
| 449 | { | ||
| 450 | #ifdef __powerc | ||
| 451 | return GetPPCTimer (mIs601); | ||
| 452 | #else | ||
| 453 | UnsignedWide usec; | ||
| 454 | Microseconds (&usec); | ||
| 455 | return usec.lo; | ||
| 456 | #endif | ||
| 457 | } | ||
| 458 | |||
| 459 | #ifdef __powerc | ||
| 460 | // The timebase is available through mfspr on 601, mftb on later chips. | ||
| 461 | // Motorola recommends that an 601 implementation map mftb to mfspr | ||
| 462 | // through an exception, but I haven't tested to see if MacOS actually | ||
| 463 | // does this. We only sample the lower 32 bits of the timer (i.e. a | ||
| 464 | // few minutes of resolution) | ||
| 465 | |||
| 466 | asm unsigned long GetPPCTimer (register bool is601) | ||
| 467 | { | ||
| 468 | cmplwi is601, 0 // Check if 601 | ||
| 469 | bne _601 // if non-zero goto _601 | ||
| 470 | mftb r3 // Available on 603 and later. | ||
| 471 | blr // return with result in r3 | ||
| 472 | _601: | ||
| 473 | mfspr r3, spr5 // Available on 601 only. | ||
| 474 | // blr inserted automatically | ||
| 475 | } | ||
| 476 | #endif | ||
