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178 lines
3.8 KiB
178 lines
3.8 KiB
#include "precomp.h"
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//
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// SHM.C
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// Shared Memory Access, cpi32 and display driver sides both
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//
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// Copyright(c) Microsoft 1997-
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//
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//
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// SHM_StartAccess
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//
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LPVOID SHM_StartAccess(int block)
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{
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LPBUFFER_CONTROL pControl = NULL;
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LPVOID pMemBlock = NULL;
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DebugEntry(SHM_StartAccess);
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//
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// Test for shared memory present
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//
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ASSERT(g_asSharedMemory != NULL);
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//
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// Determine which data block we are handling...
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//
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switch (block)
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{
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case SHM_OA_DATA:
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pControl = &g_asSharedMemory->displayToCore;
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break;
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case SHM_OA_FAST:
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case SHM_BA_FAST:
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case SHM_CM_FAST:
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pControl = &g_asSharedMemory->fastPath;
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break;
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default:
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ERROR_OUT(("Unknown type %d", block));
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DC_QUIT;
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}
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//
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// Mark the double-buffer as busy.
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//
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pControl->busyFlag = 1;
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//
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// Set up the current buffer pointer if this is the first access to the
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// shared memory.
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//
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pControl->indexCount++;
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if (pControl->indexCount == 1)
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{
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//
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// Set up the 'in use' buffer pointer
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//
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pControl->currentBuffer = pControl->newBuffer;
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//
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// Mark the buffer as busy so that the Share Core knows where we
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// are.
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//
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pControl->bufferBusy[pControl->currentBuffer] = 1;
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}
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//
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// Get the pointer to the block to return
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//
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switch (block)
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{
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case SHM_OA_DATA:
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pMemBlock = g_poaData[pControl->currentBuffer];
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break;
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case SHM_OA_FAST:
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pMemBlock = &(g_asSharedMemory->oaFast[pControl->currentBuffer]);
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break;
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case SHM_BA_FAST:
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pMemBlock = &(g_asSharedMemory->baFast[pControl->currentBuffer]);
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break;
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case SHM_CM_FAST:
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pMemBlock = &(g_asSharedMemory->cmFast[pControl->currentBuffer]);
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break;
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default:
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ERROR_OUT(("Unknown type %d", block));
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DC_QUIT;
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}
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DC_EXIT_POINT:
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DebugExitPVOID(SHM_StartAccess, pMemBlock);
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return(pMemBlock);
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}
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//
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// SHM_StopAccess
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//
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void SHM_StopAccess(int block)
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{
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LPBUFFER_CONTROL pControl;
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DebugEntry(SHM_StopAccess);
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ASSERT(g_asSharedMemory != NULL);
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//
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// Determine which data block we are handling...
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//
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switch (block)
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{
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case SHM_OA_DATA:
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pControl = &g_asSharedMemory->displayToCore;
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break;
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case SHM_OA_FAST:
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case SHM_BA_FAST:
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case SHM_CM_FAST:
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pControl = &g_asSharedMemory->fastPath;
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break;
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default:
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ERROR_OUT(("Unknown type %d", block));
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DC_QUIT;
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}
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//
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// Decrement usage count - if we have finally finished with the memory,
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// clear the busy flags so that the Share Core knows it won't tread on
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// the display driver's toes.
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//
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pControl->indexCount--;
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if (pControl->indexCount == 0)
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{
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pControl->bufferBusy[pControl->currentBuffer] = 0;
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pControl->busyFlag = 0;
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}
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DC_EXIT_POINT:
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DebugExitVOID(SHM_StopAccess);
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}
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#ifdef _DEBUG
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//
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// SHM_CheckPointer - see shm.h
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//
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void SHM_CheckPointer(LPVOID ptr)
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{
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DebugEntry(SHMCheckPointer);
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if (ptr == NULL)
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{
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ERROR_OUT(("Null pointer"));
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DC_QUIT;
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}
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ASSERT(g_asSharedMemory);
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if (((LPBYTE)ptr - (LPBYTE)g_asSharedMemory < 0) ||
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((LPBYTE)ptr - (LPBYTE)g_asSharedMemory >= SHM_SIZE_USED))
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{
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ERROR_OUT(("Bad pointer"));
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}
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DC_EXIT_POINT:
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DebugExitVOID(SHM_CheckPointer);
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}
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#endif // _DEBUG
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