1/* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#include <inttypes.h> 18 19#define LOG_TAG "MonoPipe" 20//#define LOG_NDEBUG 0 21 22#include <common_time/cc_helper.h> 23#include <cutils/atomic.h> 24#include <cutils/compiler.h> 25#include <utils/LinearTransform.h> 26#include <utils/Log.h> 27#include <utils/Trace.h> 28#include <media/AudioBufferProvider.h> 29#include <media/nbaio/MonoPipe.h> 30#include <media/nbaio/roundup.h> 31 32 33namespace android { 34 35static uint64_t cacheN; // output of CCHelper::getLocalFreq() 36static bool cacheValid; // whether cacheN is valid 37static pthread_once_t cacheOnceControl = PTHREAD_ONCE_INIT; 38 39static void cacheOnceInit() 40{ 41 CCHelper tmpHelper; 42 status_t res; 43 if (OK != (res = tmpHelper.getLocalFreq(&cacheN))) { 44 ALOGE("Failed to fetch local time frequency when constructing a" 45 " MonoPipe (res = %d). getNextWriteTimestamp calls will be" 46 " non-functional", res); 47 return; 48 } 49 cacheValid = true; 50} 51 52MonoPipe::MonoPipe(size_t reqFrames, const NBAIO_Format& format, bool writeCanBlock) : 53 NBAIO_Sink(format), 54 mUpdateSeq(0), 55 mReqFrames(reqFrames), 56 mMaxFrames(roundup(reqFrames)), 57 mBuffer(malloc(mMaxFrames * Format_frameSize(format))), 58 mFront(0), 59 mRear(0), 60 mWriteTsValid(false), 61 // mWriteTs 62 mSetpoint((reqFrames * 11) / 16), 63 mWriteCanBlock(writeCanBlock), 64 mIsShutdown(false), 65 // mTimestampShared 66 mTimestampMutator(&mTimestampShared), 67 mTimestampObserver(&mTimestampShared) 68{ 69 uint64_t N, D; 70 71 mNextRdPTS = AudioBufferProvider::kInvalidPTS; 72 73 mSamplesToLocalTime.a_zero = 0; 74 mSamplesToLocalTime.b_zero = 0; 75 mSamplesToLocalTime.a_to_b_numer = 0; 76 mSamplesToLocalTime.a_to_b_denom = 0; 77 78 D = Format_sampleRate(format); 79 80 (void) pthread_once(&cacheOnceControl, cacheOnceInit); 81 if (!cacheValid) { 82 // log has already been done 83 return; 84 } 85 N = cacheN; 86 87 LinearTransform::reduce(&N, &D); 88 static const uint64_t kSignedHiBitsMask = ~(0x7FFFFFFFull); 89 static const uint64_t kUnsignedHiBitsMask = ~(0xFFFFFFFFull); 90 if ((N & kSignedHiBitsMask) || (D & kUnsignedHiBitsMask)) { 91 ALOGE("Cannot reduce sample rate to local clock frequency ratio to fit" 92 " in a 32/32 bit rational. (max reduction is 0x%016" PRIx64 "/0x%016" PRIx64 93 "). getNextWriteTimestamp calls will be non-functional", N, D); 94 return; 95 } 96 97 mSamplesToLocalTime.a_to_b_numer = static_cast<int32_t>(N); 98 mSamplesToLocalTime.a_to_b_denom = static_cast<uint32_t>(D); 99} 100 101MonoPipe::~MonoPipe() 102{ 103 free(mBuffer); 104} 105 106ssize_t MonoPipe::availableToWrite() const 107{ 108 if (CC_UNLIKELY(!mNegotiated)) { 109 return NEGOTIATE; 110 } 111 // uses mMaxFrames not mReqFrames, so allows "over-filling" the pipe beyond requested limit 112 ssize_t ret = mMaxFrames - (mRear - android_atomic_acquire_load(&mFront)); 113 ALOG_ASSERT((0 <= ret) && (ret <= mMaxFrames)); 114 return ret; 115} 116 117ssize_t MonoPipe::write(const void *buffer, size_t count) 118{ 119 if (CC_UNLIKELY(!mNegotiated)) { 120 return NEGOTIATE; 121 } 122 size_t totalFramesWritten = 0; 123 while (count > 0) { 124 // can't return a negative value, as we already checked for !mNegotiated 125 size_t avail = availableToWrite(); 126 size_t written = avail; 127 if (CC_LIKELY(written > count)) { 128 written = count; 129 } 130 size_t rear = mRear & (mMaxFrames - 1); 131 size_t part1 = mMaxFrames - rear; 132 if (part1 > written) { 133 part1 = written; 134 } 135 if (CC_LIKELY(part1 > 0)) { 136 memcpy((char *) mBuffer + (rear * mFrameSize), buffer, part1 * mFrameSize); 137 if (CC_UNLIKELY(rear + part1 == mMaxFrames)) { 138 size_t part2 = written - part1; 139 if (CC_LIKELY(part2 > 0)) { 140 memcpy(mBuffer, (char *) buffer + (part1 * mFrameSize), part2 * mFrameSize); 141 } 142 } 143 android_atomic_release_store(written + mRear, &mRear); 144 totalFramesWritten += written; 145 } 146 if (!mWriteCanBlock || mIsShutdown) { 147 break; 148 } 149 count -= written; 150 buffer = (char *) buffer + (written * mFrameSize); 151 // Simulate blocking I/O by sleeping at different rates, depending on a throttle. 152 // The throttle tries to keep the mean pipe depth near the setpoint, with a slight jitter. 153 uint32_t ns; 154 if (written > 0) { 155 size_t filled = (mMaxFrames - avail) + written; 156 // FIXME cache these values to avoid re-computation 157 if (filled <= mSetpoint / 2) { 158 // pipe is (nearly) empty, fill quickly 159 ns = written * ( 500000000 / Format_sampleRate(mFormat)); 160 } else if (filled <= (mSetpoint * 3) / 4) { 161 // pipe is below setpoint, fill at slightly faster rate 162 ns = written * ( 750000000 / Format_sampleRate(mFormat)); 163 } else if (filled <= (mSetpoint * 5) / 4) { 164 // pipe is at setpoint, fill at nominal rate 165 ns = written * (1000000000 / Format_sampleRate(mFormat)); 166 } else if (filled <= (mSetpoint * 3) / 2) { 167 // pipe is above setpoint, fill at slightly slower rate 168 ns = written * (1150000000 / Format_sampleRate(mFormat)); 169 } else if (filled <= (mSetpoint * 7) / 4) { 170 // pipe is overflowing, fill slowly 171 ns = written * (1350000000 / Format_sampleRate(mFormat)); 172 } else { 173 // pipe is severely overflowing 174 ns = written * (1750000000 / Format_sampleRate(mFormat)); 175 } 176 } else { 177 ns = count * (1350000000 / Format_sampleRate(mFormat)); 178 } 179 if (ns > 999999999) { 180 ns = 999999999; 181 } 182 struct timespec nowTs; 183 bool nowTsValid = !clock_gettime(CLOCK_MONOTONIC, &nowTs); 184 // deduct the elapsed time since previous write() completed 185 if (nowTsValid && mWriteTsValid) { 186 time_t sec = nowTs.tv_sec - mWriteTs.tv_sec; 187 long nsec = nowTs.tv_nsec - mWriteTs.tv_nsec; 188 ALOGE_IF(sec < 0 || (sec == 0 && nsec < 0), 189 "clock_gettime(CLOCK_MONOTONIC) failed: was %ld.%09ld but now %ld.%09ld", 190 mWriteTs.tv_sec, mWriteTs.tv_nsec, nowTs.tv_sec, nowTs.tv_nsec); 191 if (nsec < 0) { 192 --sec; 193 nsec += 1000000000; 194 } 195 if (sec == 0) { 196 if ((long) ns > nsec) { 197 ns -= nsec; 198 } else { 199 ns = 0; 200 } 201 } 202 } 203 if (ns > 0) { 204 const struct timespec req = {0, static_cast<long>(ns)}; 205 nanosleep(&req, NULL); 206 } 207 // record the time that this write() completed 208 if (nowTsValid) { 209 mWriteTs = nowTs; 210 if ((mWriteTs.tv_nsec += ns) >= 1000000000) { 211 mWriteTs.tv_nsec -= 1000000000; 212 ++mWriteTs.tv_sec; 213 } 214 } 215 mWriteTsValid = nowTsValid; 216 } 217 mFramesWritten += totalFramesWritten; 218 return totalFramesWritten; 219} 220 221void MonoPipe::setAvgFrames(size_t setpoint) 222{ 223 mSetpoint = setpoint; 224} 225 226status_t MonoPipe::getNextWriteTimestamp(int64_t *timestamp) 227{ 228 int32_t front; 229 230 ALOG_ASSERT(NULL != timestamp); 231 232 if (0 == mSamplesToLocalTime.a_to_b_denom) 233 return UNKNOWN_ERROR; 234 235 observeFrontAndNRPTS(&front, timestamp); 236 237 if (AudioBufferProvider::kInvalidPTS != *timestamp) { 238 // If we have a valid read-pointer and next read timestamp pair, then 239 // use the current value of the write pointer to figure out how many 240 // frames are in the buffer, and offset the timestamp by that amt. Then 241 // next time we write to the MonoPipe, the data will hit the speakers at 242 // the next read timestamp plus the current amount of data in the 243 // MonoPipe. 244 size_t pendingFrames = (mRear - front) & (mMaxFrames - 1); 245 *timestamp = offsetTimestampByAudioFrames(*timestamp, pendingFrames); 246 } 247 248 return OK; 249} 250 251void MonoPipe::updateFrontAndNRPTS(int32_t newFront, int64_t newNextRdPTS) 252{ 253 // Set the MSB of the update sequence number to indicate that there is a 254 // multi-variable update in progress. Use an atomic store with an "acquire" 255 // barrier to make sure that the next operations cannot be re-ordered and 256 // take place before the change to mUpdateSeq is commited.. 257 int32_t tmp = mUpdateSeq | 0x80000000; 258 android_atomic_acquire_store(tmp, &mUpdateSeq); 259 260 // Update mFront and mNextRdPTS 261 mFront = newFront; 262 mNextRdPTS = newNextRdPTS; 263 264 // We are finished with the update. Compute the next sequnce number (which 265 // should be the old sequence number, plus one, and with the MSB cleared) 266 // and then store it in mUpdateSeq using an atomic store with a "release" 267 // barrier so our update operations cannot be re-ordered past the update of 268 // the sequence number. 269 tmp = (tmp + 1) & 0x7FFFFFFF; 270 android_atomic_release_store(tmp, &mUpdateSeq); 271} 272 273void MonoPipe::observeFrontAndNRPTS(int32_t *outFront, int64_t *outNextRdPTS) 274{ 275 // Perform an atomic observation of mFront and mNextRdPTS. Basically, 276 // atomically observe the sequence number, then observer the variables, then 277 // atomically observe the sequence number again. If the two observations of 278 // the sequence number match, and the update-in-progress bit was not set, 279 // then we know we have a successful atomic observation. Otherwise, we loop 280 // around and try again. 281 // 282 // Note, it is very important that the observer be a lower priority thread 283 // than the updater. If the updater is lower than the observer, or they are 284 // the same priority and running with SCHED_FIFO (implying that quantum 285 // based premption is disabled) then we run the risk of deadlock. 286 int32_t seqOne, seqTwo; 287 288 do { 289 seqOne = android_atomic_acquire_load(&mUpdateSeq); 290 *outFront = mFront; 291 *outNextRdPTS = mNextRdPTS; 292 seqTwo = android_atomic_release_load(&mUpdateSeq); 293 } while ((seqOne != seqTwo) || (seqOne & 0x80000000)); 294} 295 296int64_t MonoPipe::offsetTimestampByAudioFrames(int64_t ts, size_t audFrames) 297{ 298 if (0 == mSamplesToLocalTime.a_to_b_denom) 299 return AudioBufferProvider::kInvalidPTS; 300 301 if (ts == AudioBufferProvider::kInvalidPTS) 302 return AudioBufferProvider::kInvalidPTS; 303 304 int64_t frame_lt_duration; 305 if (!mSamplesToLocalTime.doForwardTransform(audFrames, 306 &frame_lt_duration)) { 307 // This should never fail, but if there is a bug which is causing it 308 // to fail, this message would probably end up flooding the logs 309 // because the conversion would probably fail forever. Log the 310 // error, but then zero out the ratio in the linear transform so 311 // that we don't try to do any conversions from now on. This 312 // MonoPipe's getNextWriteTimestamp is now broken for good. 313 ALOGE("Overflow when attempting to convert %zu audio frames to" 314 " duration in local time. getNextWriteTimestamp will fail from" 315 " now on.", audFrames); 316 mSamplesToLocalTime.a_to_b_numer = 0; 317 mSamplesToLocalTime.a_to_b_denom = 0; 318 return AudioBufferProvider::kInvalidPTS; 319 } 320 321 return ts + frame_lt_duration; 322} 323 324void MonoPipe::shutdown(bool newState) 325{ 326 mIsShutdown = newState; 327} 328 329bool MonoPipe::isShutdown() 330{ 331 return mIsShutdown; 332} 333 334status_t MonoPipe::getTimestamp(AudioTimestamp& timestamp) 335{ 336 if (mTimestampObserver.poll(timestamp)) { 337 return OK; 338 } 339 return INVALID_OPERATION; 340} 341 342} // namespace android 343