diff --git a/api/RingBuffer.h b/api/RingBuffer.h index b69c20d4..c30e39ca 100644 --- a/api/RingBuffer.h +++ b/api/RingBuffer.h @@ -1,5 +1,4 @@ /* - RingBuffer.h - Ring buffer implementation Copyright (c) 2014 Arduino. All right reserved. This library is free software; you can redistribute it and/or @@ -9,8 +8,8 @@ This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software @@ -37,10 +36,12 @@ template class RingBufferN { public: - uint8_t _aucBuffer[N] ; + uint8_t _aucBuffer[N + 1] ; // we need one extra byte for the empty/full distinction volatile int _iHead ; volatile int _iTail ; - volatile int _numElems; + // Instead of using a counter, we use the head and tail markers to determine the number of elements + // this makes it thread-safe, as the head and tail are only modified by one thread + //volatile int _numElems; public: RingBufferN( void ) ; @@ -54,7 +55,7 @@ class RingBufferN private: int nextIndex(int index); - inline bool isEmpty() const { return (_numElems == 0); } + inline bool isEmpty() const { return (_iHead == _iTail); } }; typedef RingBufferN RingBuffer; @@ -63,7 +64,7 @@ typedef RingBufferN RingBuffer; template RingBufferN::RingBufferN( void ) { - memset( _aucBuffer, 0, N ) ; + memset( _aucBuffer, 0, N + 1) ; clear(); } @@ -78,7 +79,7 @@ void RingBufferN::store_char( uint8_t c ) { _aucBuffer[_iHead] = c ; _iHead = nextIndex(_iHead); - _numElems = _numElems + 1; + //_numElems++; } } @@ -87,7 +88,7 @@ void RingBufferN::clear() { _iHead = 0; _iTail = 0; - _numElems = 0; + //_numElems = 0; } template @@ -98,7 +99,7 @@ int RingBufferN::read_char() uint8_t value = _aucBuffer[_iTail]; _iTail = nextIndex(_iTail); - _numElems = _numElems - 1; + //_numElems--; return value; } @@ -106,13 +107,16 @@ int RingBufferN::read_char() template int RingBufferN::available() { - return _numElems; + return ((_iHead >= _iTail) ? _iHead - _iTail : (N - _iTail + 1 + _iHead)); + // return _numElems; } template int RingBufferN::availableForStore() { - return (N - _numElems); + return (N - available()); + // return ((_iHead >= _iTail) ? N - (_iHead - _iTail) : (_iTail - 1 - _iHead)); + // return (N - _numElems); } template @@ -127,13 +131,14 @@ int RingBufferN::peek() template int RingBufferN::nextIndex(int index) { - return (uint32_t)(index + 1) % N; + return (uint32_t)(index + 1) % (N + 1); } template bool RingBufferN::isFull() { - return (_numElems == N); + return (0 == availableForStore()); + // return (_numElems == N); } } pFad - Phonifier reborn

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