INSTDATA.C

/************************************************************************** 
 * 
 *  THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY 
 *  KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE 
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR 
 *  PURPOSE. 
 * 
 *  Copyright 1993 - 1998 Microsoft Corporation.  All Rights Reserved. 
 *  
 **************************************************************************/ 
 
/* 
 * instdata.c - Functions to allocate and free the instance 
 *      data structure passed to the low-level callback function. 
 */ 
 
#include <windows.h> 
#include <mmsystem.h> 
#include "midimon.h" 
#include "circbuf.h" 
#include "instdata.h" 
 
/* AllocCallbackInstanceData - Allocates a CALLBACKINSTANCEDATA 
 *      structure.  This structure is used to pass information to the 
 *      low-level callback function, each time it receives a message. 
 * 
 *      Because this structure is accessed by the low-level callback 
 *      function, it must be allocated using GlobalAlloc() with the  
 *      GMEM_SHARE and GMEM_MOVEABLE flags and page-locked with 
 *      GlobalPageLock(). 
 * 
 * Params:  void 
 * 
 * Return:  A pointer to the allocated CALLBACKINSTANCE data structure. 
 */ 
LPCALLBACKINSTANCEDATA FAR PASCAL AllocCallbackInstanceData(void) 
{ 
    HANDLE hMem; 
    LPCALLBACKINSTANCEDATA lpBuf; 
     
    /* Allocate and lock global memory. 
     */ 
    hMem = GlobalAlloc(GMEM_SHARE | GMEM_MOVEABLE, 
                       (DWORD)sizeof(CALLBACKINSTANCEDATA)); 
    if(hMem == NULL) 
        return NULL; 
     
    lpBuf = (LPCALLBACKINSTANCEDATA)GlobalLock(hMem); 
    if(lpBuf == NULL){ 
        GlobalFree(hMem); 
        return NULL; 
    } 
     
    /* Page lock the memory. 
     */ 
    //GlobalPageLock((HGLOBAL)HIWORD(lpBuf)); 
 
    /* Save the handle. 
     */ 
    lpBuf->hSelf = hMem; 
 
    return lpBuf; 
} 
 
/* FreeCallbackInstanceData - Frees the given CALLBACKINSTANCEDATA structure. 
 * 
 * Params:  lpBuf - Points to the CALLBACKINSTANCEDATA structure to be freed. 
 * 
 * Return:  void 
 */ 
void FAR PASCAL FreeCallbackInstanceData(LPCALLBACKINSTANCEDATA lpBuf) 
{ 
    HANDLE hMem; 
 
    /* Save the handle until we're through here. 
     */ 
    hMem = lpBuf->hSelf; 
 
    /* Free the structure. 
     */ 
    //GlobalPageUnlock((HGLOBAL)HIWORD(lpBuf)); 
    GlobalUnlock(hMem); 
    GlobalFree(hMem); 
}