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CPI_CircleBuffer.c
资源名称：VC++视频传输.rar　[点击查看]
上传用户：hxb_1234
上传日期：2010-03-30
资源大小：8328k
文件大小：7k
源码类别：

VC书籍

开发平台：

Visual C++

CPI_CircleBuffer.c：源码内容
  5. #include "stdafx.h"
  6. #include "globals.h"
  7. #include "CPI_CircleBuffer.h"
  10. #define CIC_WAITTIMEOUT 3000
  11. void CircleBufferUninitialise(CPs_CircleBuffer* pCBuffer);
  12. void CircleBufferWrite(CPs_CircleBuffer* pCBuffer, const void* pSourceBuffer, const unsigned int iNumBytes);
  13. BOOL CircleBufferRead(CPs_CircleBuffer* pCBuffer, void* pDestBuffer, const unsigned int iBytesToRead, unsigned int* pbBytesRead);
  14. void CircleFlush(CPs_CircleBuffer* pCBuffer);
  15. unsigned int CircleGetFreeSpace(CPs_CircleBuffer* pCBuffer);
  16. unsigned int CircleGetUsedSpace(CPs_CircleBuffer* pCBuffer);
  17. void CircleSetComplete(CPs_CircleBuffer* pCBuffer);
  18. BOOL CircleIsComplete(CPs_CircleBuffer* pCBuffer);
  19. ////////////////////////////////////////////////////////////////////////////////
  21. CPs_CircleBuffer* CP_CreateCircleBuffer(const unsigned int iBufferSize)
  22. {
  23.     CPs_CircleBuffer* pNewBuffer = (CPs_CircleBuffer*)malloc(sizeof(CPs_CircleBuffer));
  25.     pNewBuffer->Uninitialise = CircleBufferUninitialise;
  26.     pNewBuffer->Write = CircleBufferWrite;
  27.     pNewBuffer->Read = CircleBufferRead;
  28.     pNewBuffer->Flush = CircleFlush;
  29.     pNewBuffer->GetUsedSize = CircleGetUsedSpace;
  30.     pNewBuffer->GetFreeSize = CircleGetFreeSpace;
  31.     pNewBuffer->SetComplete = CircleSetComplete;
  32.     pNewBuffer->IsComplete = CircleIsComplete;
  34.     pNewBuffer->m_iBufferSize = iBufferSize;
  35.     pNewBuffer->m_pBuffer = (BYTE*)malloc(iBufferSize);
  36.     pNewBuffer->m_iReadCursor = 0;
  37.     pNewBuffer->m_iWriteCursor = 0;
  38.     pNewBuffer->m_bComplete = FALSE;
  39.     pNewBuffer->m_evtDataAvailable = CreateEvent(NULL, FALSE, FALSE, NULL);
  40.     InitializeCriticalSection(&pNewBuffer->m_csCircleBuffer);
  42.     return pNewBuffer;
  43. }
  44. //
  45. //
  46. //
  47. void CircleBufferUninitialise(CPs_CircleBuffer* pCBuffer)
  48. {
  49.     CP_CHECKOBJECT(pCBuffer);
  50.     DeleteCriticalSection(&pCBuffer->m_csCircleBuffer);
  51.     CloseHandle(pCBuffer->m_evtDataAvailable);
  52.     free(pCBuffer->m_pBuffer);
  53.     free(pCBuffer);
  54. }
  55. //
  56. //
  57. //
  58. void CircleBufferWrite(CPs_CircleBuffer* pCBuffer, const void* _pSourceBuffer, const unsigned int _iNumBytes)
  59. {
  60.     unsigned int iBytesToWrite = _iNumBytes;
  61.     BYTE* pReadCursor = (BYTE*)_pSourceBuffer;
  63.     CP_ASSERT(iBytesToWrite <= pCBuffer->GetFreeSize(pCBuffer));
  64.     CP_ASSERT(pCBuffer->m_bComplete == FALSE);
  66.     EnterCriticalSection(&pCBuffer->m_csCircleBuffer);
  68.     if(pCBuffer->m_iWriteCursor >= pCBuffer->m_iReadCursor)
  69.     {
  70.         unsigned int iChunkSize = pCBuffer->m_iBufferSize - pCBuffer->m_iWriteCursor;
  71.         if(iChunkSize > iBytesToWrite)
  72.             iChunkSize = iBytesToWrite;
  74.         memcpy(pCBuffer->m_pBuffer + pCBuffer->m_iWriteCursor,
  75.                pReadCursor, iChunkSize);
  76.         pReadCursor += iChunkSize;
  77.         iBytesToWrite -= iChunkSize;
  79.         pCBuffer->m_iWriteCursor += iChunkSize;
  80.         if(pCBuffer->m_iWriteCursor >= pCBuffer->m_iBufferSize)
  81.             pCBuffer->m_iWriteCursor -= pCBuffer->m_iBufferSize;
  82.     }
  84.     if(iBytesToWrite)
  85.     {
  86.         memcpy(pCBuffer->m_pBuffer + pCBuffer->m_iWriteCursor,
  87.                pReadCursor, iBytesToWrite);
  88.         pCBuffer->m_iWriteCursor += iBytesToWrite;
  89.         CP_ASSERT(pCBuffer->m_iWriteCursor < pCBuffer->m_iBufferSize);
  90.     }
  92.     SetEvent(pCBuffer->m_evtDataAvailable);
  93.     LeaveCriticalSection(&pCBuffer->m_csCircleBuffer);
  94. }
  95. //
  97. BOOL CircleBufferRead(CPs_CircleBuffer* pCBuffer, void* pDestBuffer, const unsigned int _iBytesToRead, unsigned int* pbBytesRead)
  98. {
  99.     unsigned int iBytesToRead = _iBytesToRead;
  100.     unsigned int iBytesRead = 0;
  101.     DWORD dwWaitResult;
  102.     BOOL bComplete = FALSE;
  103.     CP_CHECKOBJECT(pCBuffer);
  105.     while(iBytesToRead > 0 && bComplete == FALSE)
  106.     {
  107.         dwWaitResult = WaitForSingleObject(pCBuffer->m_evtDataAvailable, CIC_WAITTIMEOUT);
  108.         if(dwWaitResult == WAIT_TIMEOUT)
  109.         {
  110.             CP_TRACE0("Circle buffer - did not fill in time!");
  111.             *pbBytesRead = iBytesRead;
  112.             return FALSE;
  113.         }
  115.         EnterCriticalSection(&pCBuffer->m_csCircleBuffer);
  117.         if(pCBuffer->m_iReadCursor > pCBuffer->m_iWriteCursor)
  118.         {
  119.             unsigned int iChunkSize = pCBuffer->m_iBufferSize - pCBuffer->m_iReadCursor;
  120.             if(iChunkSize > iBytesToRead)
  121.                 iChunkSize = iBytesToRead;
  123.             memcpy((BYTE*)pDestBuffer + iBytesRead,
  124.                    pCBuffer->m_pBuffer + pCBuffer->m_iReadCursor,
  125.                    iChunkSize);
  127.             iBytesRead += iChunkSize;
  128.             iBytesToRead -= iChunkSize;
  130.             pCBuffer->m_iReadCursor += iChunkSize;
  131.             if(pCBuffer->m_iReadCursor >= pCBuffer->m_iBufferSize)
  132.                 pCBuffer->m_iReadCursor -= pCBuffer->m_iBufferSize;
  133.         }
  135.         if(iBytesToRead && pCBuffer->m_iReadCursor < pCBuffer->m_iWriteCursor)
  136.         {
  137.             unsigned int iChunkSize = pCBuffer->m_iWriteCursor - pCBuffer->m_iReadCursor;
  138.             if(iChunkSize > iBytesToRead)
  139.                 iChunkSize = iBytesToRead;
  141.             memcpy((BYTE*)pDestBuffer + iBytesRead,
  142.                    pCBuffer->m_pBuffer + pCBuffer->m_iReadCursor,
  143.                    iChunkSize);
  145.             iBytesRead += iChunkSize;
  146.             iBytesToRead -= iChunkSize;
  147.             pCBuffer->m_iReadCursor += iChunkSize;
  148.         }
  150.         if(pCBuffer->m_iReadCursor == pCBuffer->m_iWriteCursor)
  151.         {
  152.             if(pCBuffer->m_bComplete)
  153.                 bComplete = TRUE;
  154.         }
  155.         else
  156.             SetEvent(pCBuffer->m_evtDataAvailable);
  158.         LeaveCriticalSection(&pCBuffer->m_csCircleBuffer);
  159.     }
  161.     *pbBytesRead = iBytesRead;
  162.     return bComplete ? FALSE : TRUE;
  163. }
  164. //
  165. //
  166. //
  167. void CircleFlush(CPs_CircleBuffer* pCBuffer)
  168. {
  169.     CP_CHECKOBJECT(pCBuffer);
  171.     EnterCriticalSection(&pCBuffer->m_csCircleBuffer);
  172.     pCBuffer->m_iReadCursor = 0;
  173.     pCBuffer->m_iWriteCursor = 0;
  174.     LeaveCriticalSection(&pCBuffer->m_csCircleBuffer);
  175. }
  176. //
  177. //
  178. //
  179. unsigned int CircleGetFreeSpace(CPs_CircleBuffer* pCBuffer)
  180. {
  181.     unsigned int iNumBytesFree;
  183.     CP_CHECKOBJECT(pCBuffer);
  184.     EnterCriticalSection(&pCBuffer->m_csCircleBuffer);
  186.     if(pCBuffer->m_iWriteCursor < pCBuffer->m_iReadCursor)
  187.         iNumBytesFree = (pCBuffer->m_iReadCursor-1) - pCBuffer->m_iWriteCursor;
  188.     else if(pCBuffer->m_iWriteCursor == pCBuffer->m_iReadCursor)
  189.         iNumBytesFree = pCBuffer->m_iBufferSize;
  190.     else
  191.         iNumBytesFree = (pCBuffer->m_iReadCursor-1) + (pCBuffer->m_iBufferSize - pCBuffer->m_iWriteCursor);
  193.     LeaveCriticalSection(&pCBuffer->m_csCircleBuffer);
  194.     return iNumBytesFree;
  195. }
  196. //
  197. //
  198. //
  199. unsigned int CircleGetUsedSpace(CPs_CircleBuffer* pCBuffer)
  200. {
  201.     return pCBuffer->m_iBufferSize - CircleGetFreeSpace(pCBuffer);
  202. }
  203. //
  204. //
  205. //
  206. void CircleSetComplete(CPs_CircleBuffer* pCBuffer)
  207. {
  208.     CP_CHECKOBJECT(pCBuffer);
  210.     EnterCriticalSection(&pCBuffer->m_csCircleBuffer);
  211.     pCBuffer->m_bComplete = TRUE;
  212.     SetEvent(pCBuffer->m_evtDataAvailable);
  213.     LeaveCriticalSection(&pCBuffer->m_csCircleBuffer);
  214. }
  215. //
  216. //
  217. //
  218. BOOL CircleIsComplete(CPs_CircleBuffer* pCBuffer)
  219. {
  220.     return pCBuffer->m_bComplete;
  221. }
  222. //
  223. //
  224. //