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