src/add-ons/media/plugins/ape_reader/MAClib/CircleBuffer.cpp

   1 #include "All.h"
   2 #include "CircleBuffer.h"
   3
   4 CCircleBuffer::CCircleBuffer()
   5 {
   6     m_pBuffer = NULL;
   7     m_nTotal = 0;
   8     m_nHead = 0;
   9     m_nTail = 0;
  10     m_nEndCap = 0;
  11     m_nMaxDirectWriteBytes = 0;
  12 }
  13
  14 CCircleBuffer::~CCircleBuffer()
  15 {
  16     SAFE_ARRAY_DELETE(m_pBuffer)
  17 }
  18
  19 void CCircleBuffer::CreateBuffer(int nBytes, int nMaxDirectWriteBytes)
  20 {
  21     SAFE_ARRAY_DELETE(m_pBuffer)
  22
  23     m_nMaxDirectWriteBytes = nMaxDirectWriteBytes;
  24     m_nTotal = nBytes + 1 + nMaxDirectWriteBytes;
  25     m_pBuffer = new unsigned char [m_nTotal];
  26     m_nHead = 0;
  27     m_nTail = 0;
  28     m_nEndCap = m_nTotal;
  29 }
  30
  31 int CCircleBuffer::MaxAdd()
  32 {
  33     int nMaxAdd = (m_nTail >= m_nHead) ? (m_nTotal - 1 - m_nMaxDirectWriteBytes) - (m_nTail - m_nHead) : m_nHead - m_nTail - 1;
  34     return nMaxAdd;
  35 }
  36
  37 int CCircleBuffer::MaxGet()
  38 {
  39     return (m_nTail >= m_nHead) ? m_nTail - m_nHead : (m_nEndCap - m_nHead) + m_nTail;
  40 }
  41
  42 int CCircleBuffer::Get(unsigned char * pBuffer, int nBytes)
  43 {
  44     int nTotalGetBytes = 0;
  45
  46     if (pBuffer != NULL && nBytes > 0)
  47     {
  48         int nHeadBytes = min(m_nEndCap - m_nHead, nBytes);
  49         int nFrontBytes = nBytes - nHeadBytes;
  50
  51         memcpy(&pBuffer[0], &m_pBuffer[m_nHead], nHeadBytes);
  52         nTotalGetBytes = nHeadBytes;
  53
  54         if (nFrontBytes > 0)
  55         {
  56             memcpy(&pBuffer[nHeadBytes], &m_pBuffer[0], nFrontBytes);
  57             nTotalGetBytes += nFrontBytes;
  58         }
  59
  60         RemoveHead(nBytes);
  61     }
  62
  63     return nTotalGetBytes;
  64 }
  65
  66 void CCircleBuffer::Empty()
  67 {
  68     m_nHead = 0;
  69     m_nTail = 0;
  70     m_nEndCap = m_nTotal;
  71 }
  72
  73 int CCircleBuffer::RemoveHead(int nBytes)
  74 {
  75     nBytes = min(MaxGet(), nBytes);
  76     m_nHead += nBytes;
  77     if (m_nHead >= m_nEndCap)
  78         m_nHead -= m_nEndCap;
  79     return nBytes;
  80 }
  81
  82 int CCircleBuffer::RemoveTail(int nBytes)
  83 {
  84     nBytes = min(MaxGet(), nBytes);
  85     m_nTail -= nBytes;
  86     if (m_nTail < 0)
  87         m_nTail += m_nEndCap;
  88     return nBytes;
  89 }