1 /*
2 File: CARingBuffer.cpp
3 Abstract: CARingBuffer.h
4 Version: 1.1
5
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34
35 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL
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44 Copyright (C) 2014 Apple Inc. All Rights Reserved.
45
46 */
47 #include "CARingBuffer.h"
48 #include "CABitOperations.h"
49 #include "CAAutoDisposer.h"
50 #include "CAAtomic.h"
51
52 #include <stdlib.h>
53 #include <string.h>
54 #include <algorithm>
55 #include <libkern/OSAtomic.h>
56
CARingBuffer()57 CARingBuffer::CARingBuffer() :
58 mBuffers(NULL), mNumberChannels(0), mCapacityFrames(0), mCapacityBytes(0)
59 {
60
61 }
62
~CARingBuffer()63 CARingBuffer::~CARingBuffer()
64 {
65 Deallocate();
66 }
67
68
Allocate(int nChannels,UInt32 bytesPerFrame,UInt32 capacityFrames)69 void CARingBuffer::Allocate(int nChannels, UInt32 bytesPerFrame, UInt32 capacityFrames)
70 {
71 Deallocate();
72
73 capacityFrames = NextPowerOfTwo(capacityFrames);
74
75 mNumberChannels = nChannels;
76 mBytesPerFrame = bytesPerFrame;
77 mCapacityFrames = capacityFrames;
78 mCapacityFramesMask = capacityFrames - 1;
79 mCapacityBytes = bytesPerFrame * capacityFrames;
80
81 // put everything in one memory allocation, first the pointers, then the deinterleaved channels
82 UInt32 allocSize = (mCapacityBytes + sizeof(Byte *)) * nChannels;
83 Byte *p = (Byte *)CA_malloc(allocSize);
84 memset(p, 0, allocSize);
85 mBuffers = (Byte **)p;
86 p += nChannels * sizeof(Byte *);
87 for (int i = 0; i < nChannels; ++i) {
88 mBuffers[i] = p;
89 p += mCapacityBytes;
90 }
91
92 for (UInt32 i = 0; i<kGeneralRingTimeBoundsQueueSize; ++i)
93 {
94 mTimeBoundsQueue[i].mStartTime = 0;
95 mTimeBoundsQueue[i].mEndTime = 0;
96 mTimeBoundsQueue[i].mUpdateCounter = 0;
97 }
98 mTimeBoundsQueuePtr = 0;
99 }
100
Deallocate()101 void CARingBuffer::Deallocate()
102 {
103 if (mBuffers) {
104 free(mBuffers);
105 mBuffers = NULL;
106 }
107 mNumberChannels = 0;
108 mCapacityBytes = 0;
109 mCapacityFrames = 0;
110 }
111
ZeroRange(Byte ** buffers,int nchannels,int offset,int nbytes)112 inline void ZeroRange(Byte **buffers, int nchannels, int offset, int nbytes)
113 {
114 while (--nchannels >= 0) {
115 memset(*buffers + offset, 0, nbytes);
116 ++buffers;
117 }
118 }
119
StoreABL(Byte ** buffers,int destOffset,const AudioBufferList * abl,int srcOffset,int nbytes)120 inline void StoreABL(Byte **buffers, int destOffset, const AudioBufferList *abl, int srcOffset, int nbytes)
121 {
122 int nchannels = abl->mNumberBuffers;
123 const AudioBuffer *src = abl->mBuffers;
124 while (--nchannels >= 0) {
125 if (srcOffset > (int)src->mDataByteSize) continue;
126 memcpy(*buffers + destOffset, (Byte *)src->mData + srcOffset, std::min(nbytes, (int)src->mDataByteSize - srcOffset));
127 ++buffers;
128 ++src;
129 }
130 }
131
FetchABL(AudioBufferList * abl,int destOffset,Byte ** buffers,int srcOffset,int nbytes)132 inline void FetchABL(AudioBufferList *abl, int destOffset, Byte **buffers, int srcOffset, int nbytes)
133 {
134 int nchannels = abl->mNumberBuffers;
135 AudioBuffer *dest = abl->mBuffers;
136 while (--nchannels >= 0) {
137 if (destOffset > (int)dest->mDataByteSize) continue;
138 memcpy((Byte *)dest->mData + destOffset, *buffers + srcOffset, std::min(nbytes, (int)dest->mDataByteSize - destOffset));
139 ++buffers;
140 ++dest;
141 }
142 }
143
ZeroABL(AudioBufferList * abl,int destOffset,int nbytes)144 inline void ZeroABL(AudioBufferList *abl, int destOffset, int nbytes)
145 {
146 int nBuffers = abl->mNumberBuffers;
147 AudioBuffer *dest = abl->mBuffers;
148 while (--nBuffers >= 0) {
149 if (destOffset > (int)dest->mDataByteSize) continue;
150 memset((Byte *)dest->mData + destOffset, 0, std::min(nbytes, (int)dest->mDataByteSize - destOffset));
151 ++dest;
152 }
153 }
154
155
Store(const AudioBufferList * abl,UInt32 framesToWrite,SampleTime startWrite)156 CARingBufferError CARingBuffer::Store(const AudioBufferList *abl, UInt32 framesToWrite, SampleTime startWrite)
157 {
158 if (framesToWrite == 0)
159 return kCARingBufferError_OK;
160
161 if (framesToWrite > mCapacityFrames)
162 return kCARingBufferError_TooMuch; // too big!
163
164 SampleTime endWrite = startWrite + framesToWrite;
165
166 if (startWrite < EndTime()) {
167 // going backwards, throw everything out
168 SetTimeBounds(startWrite, startWrite);
169 } else if (endWrite - StartTime() <= mCapacityFrames) {
170 // the buffer has not yet wrapped and will not need to
171 } else {
172 // advance the start time past the region we are about to overwrite
173 SampleTime newStart = endWrite - mCapacityFrames; // one buffer of time behind where we're writing
174 SampleTime newEnd = std::max(newStart, EndTime());
175 SetTimeBounds(newStart, newEnd);
176 }
177
178 // write the new frames
179 Byte **buffers = mBuffers;
180 int nchannels = mNumberChannels;
181 int offset0, offset1, nbytes;
182 SampleTime curEnd = EndTime();
183
184 if (startWrite > curEnd) {
185 // we are skipping some samples, so zero the range we are skipping
186 offset0 = FrameOffset(curEnd);
187 offset1 = FrameOffset(startWrite);
188 if (offset0 < offset1)
189 ZeroRange(buffers, nchannels, offset0, offset1 - offset0);
190 else {
191 ZeroRange(buffers, nchannels, offset0, mCapacityBytes - offset0);
192 ZeroRange(buffers, nchannels, 0, offset1);
193 }
194 offset0 = offset1;
195 } else {
196 offset0 = FrameOffset(startWrite);
197 }
198
199 offset1 = FrameOffset(endWrite);
200 if (offset0 < offset1)
201 StoreABL(buffers, offset0, abl, 0, offset1 - offset0);
202 else {
203 nbytes = mCapacityBytes - offset0;
204 StoreABL(buffers, offset0, abl, 0, nbytes);
205 StoreABL(buffers, 0, abl, nbytes, offset1);
206 }
207
208 // now update the end time
209 SetTimeBounds(StartTime(), endWrite);
210
211 return kCARingBufferError_OK; // success
212 }
213
SetTimeBounds(SampleTime startTime,SampleTime endTime)214 void CARingBuffer::SetTimeBounds(SampleTime startTime, SampleTime endTime)
215 {
216 UInt32 nextPtr = mTimeBoundsQueuePtr + 1;
217 UInt32 index = nextPtr & kGeneralRingTimeBoundsQueueMask;
218
219 mTimeBoundsQueue[index].mStartTime = startTime;
220 mTimeBoundsQueue[index].mEndTime = endTime;
221 mTimeBoundsQueue[index].mUpdateCounter = nextPtr;
222 CAAtomicCompareAndSwap32Barrier(mTimeBoundsQueuePtr, mTimeBoundsQueuePtr + 1, (SInt32*)&mTimeBoundsQueuePtr);
223 }
224
GetTimeBounds(SampleTime & startTime,SampleTime & endTime)225 CARingBufferError CARingBuffer::GetTimeBounds(SampleTime &startTime, SampleTime &endTime)
226 {
227 for (int i=0; i<8; ++i) // fail after a few tries.
228 {
229 UInt32 curPtr = mTimeBoundsQueuePtr;
230 UInt32 index = curPtr & kGeneralRingTimeBoundsQueueMask;
231 CARingBuffer::TimeBounds* bounds = mTimeBoundsQueue + index;
232
233 startTime = bounds->mStartTime;
234 endTime = bounds->mEndTime;
235 UInt32 newPtr = bounds->mUpdateCounter;
236
237 if (newPtr == curPtr)
238 return kCARingBufferError_OK;
239 }
240 return kCARingBufferError_CPUOverload;
241 }
242
ClipTimeBounds(SampleTime & startRead,SampleTime & endRead)243 CARingBufferError CARingBuffer::ClipTimeBounds(SampleTime& startRead, SampleTime& endRead)
244 {
245 SampleTime startTime, endTime;
246
247 CARingBufferError err = GetTimeBounds(startTime, endTime);
248 if (err) return err;
249
250 if (startRead > endTime || endRead < startTime) {
251 endRead = startRead;
252 return kCARingBufferError_OK;
253 }
254
255 startRead = std::max(startRead, startTime);
256 endRead = std::min(endRead, endTime);
257 endRead = std::max(endRead, startRead);
258
259 return kCARingBufferError_OK; // success
260 }
261
Fetch(AudioBufferList * abl,UInt32 nFrames,SampleTime startRead)262 CARingBufferError CARingBuffer::Fetch(AudioBufferList *abl, UInt32 nFrames, SampleTime startRead)
263 {
264 if (nFrames == 0)
265 return kCARingBufferError_OK;
266
267 startRead = std::max(0LL, startRead);
268
269 SampleTime endRead = startRead + nFrames;
270
271 SampleTime startRead0 = startRead;
272 SampleTime endRead0 = endRead;
273
274 CARingBufferError err = ClipTimeBounds(startRead, endRead);
275 if (err) return err;
276
277 if (startRead == endRead) {
278 ZeroABL(abl, 0, nFrames * mBytesPerFrame);
279 return kCARingBufferError_OK;
280 }
281
282 SInt32 byteSize = (SInt32)((endRead - startRead) * mBytesPerFrame);
283
284 SInt32 destStartByteOffset = std::max((SInt32)0, (SInt32)((startRead - startRead0) * mBytesPerFrame));
285
286 if (destStartByteOffset > 0) {
287 ZeroABL(abl, 0, std::min((SInt32)(nFrames * mBytesPerFrame), destStartByteOffset));
288 }
289
290 SInt32 destEndSize = std::max((SInt32)0, (SInt32)(endRead0 - endRead));
291 if (destEndSize > 0) {
292 ZeroABL(abl, destStartByteOffset + byteSize, destEndSize * mBytesPerFrame);
293 }
294
295 Byte **buffers = mBuffers;
296 int offset0 = FrameOffset(startRead);
297 int offset1 = FrameOffset(endRead);
298 int nbytes;
299
300 if (offset0 < offset1) {
301 nbytes = offset1 - offset0;
302 FetchABL(abl, destStartByteOffset, buffers, offset0, nbytes);
303 } else {
304 nbytes = mCapacityBytes - offset0;
305 FetchABL(abl, destStartByteOffset, buffers, offset0, nbytes);
306 FetchABL(abl, destStartByteOffset + nbytes, buffers, 0, offset1);
307 nbytes += offset1;
308 }
309
310 int nchannels = abl->mNumberBuffers;
311 AudioBuffer *dest = abl->mBuffers;
312 while (--nchannels >= 0)
313 {
314 dest->mDataByteSize = nbytes;
315 dest++;
316 }
317
318 return noErr;
319 }
320