Category : Files from Magazines
Archive : MEMORY2A.ZIP
Filename : SUBMEM.C
Output of file : SUBMEM.C contained in archive : MEMORY2A.ZIP
/*----------------------------------------------------------
---*\
| SUB.C - Sub-segment allocation routines, for creating |
| local heaps in dynamically allocated segments. |
\*----------------------------------------------------------
---*/
#include
typedef DWORD HANDLE32;
/*----------------------------------------------------------
---*\
| Static Data Definitions. |
\*----------------------------------------------------------
---*/
HANDLE hSegment;
/*----------------------------------------------------------
---*\
| SubInitialize - Call first to allocate a segment from the |
| global heap. |
\*----------------------------------------------------------
---*/
BOOL FAR PASCAL SubInitialize(VOID)
{
BOOL bRetVal;
LPSTR lp;
WORD wSeg;
WORD wSize;
hSegment = GlobalAlloc (GMEM_MOVEABLE | GMEM_ZEROINIT,
4096);
if (!hSegment)
return FALSE;
lp = GlobalLock (hSegment);
if (!lp)
return FALSE;
wSeg = HIWORD (lp);
wSize = (WORD)GlobalSize (hSegment) - 16;
bRetVal = LocalInit (wSeg, 0, wSize);
GlobalUnlock (hSegment);
GlobalUnlock (hSegment); /* Undo LocalInit's GlobalLock. */
return bRetVal;
}
/*----------------------------------------------------------
---*\
| SubAlloc - Allocate a subsegment. |
| |
| Input: wFlags = local heap allocation flags. |
| wBytes = number of bytes to allocate. |
| |
| Returns: A 4-byte "handle", put together as: |
| HIWORD = Handle to global segment. |
| LOWORD = Handle to local object. |
\*----------------------------------------------------------
---*/
HANDLE32 FAR PASCAL SubAlloc(WORD wFlags, WORD wBytes)
{
HANDLE hMem;
LPSTR lp;
WORD wSeg;
lp = GlobalLock (hSegment);
if (!lp)
return 0L;
wSeg = HIWORD (lp);
_asm { push ds
mov ax, wSeg
mov ds, ax }
hMem = LocalAlloc (wFlags, wBytes);
_asm { pop ds }
GlobalUnlock (hSegment);
if (!hMem)
return 0L;
else
return MAKELONG (hMem, hSegment);
}
/*----------------------------------------------------------
---*\
| SubFree - Free a subsegment. |
| |
| Input: A 4-byte "handle", put together as: |
| HIWORD = Handle to global segment. |
| LOWORD = Handle to local object. |
| |
| Returns: The original handle, if successful. Otherwise, |
| returns NULL. |
\*----------------------------------------------------------
---*/
HANDLE32 FAR PASCAL SubFree(HANDLE32 hSubMem)
{
HANDLE hSeg;
HANDLE hMem;
LPSTR lp;
WORD wSeg;
hSeg = HIWORD (hSubMem);
hMem = LOWORD (hSubMem);
lp = GlobalLock (hSeg);
if (!lp)
return 0L;
wSeg = HIWORD (lp);
_asm { push ds
mov ax, wSeg
mov ds, ax }
hMem = LocalFree (hMem);
_asm { pop ds }
GlobalUnlock (hSeg);
if (!hMem)
return 0L;
else
return MAKELONG (hMem, hSeg);
}
/*----------------------------------------------------------
---*\
| SubLock - Lock a subsegment and the segment it lives in. |
| |
| Input: A 4-byte "handle", put together as: |
| HIWORD = Handle to global segment. |
| LOWORD = Handle to local object. |
| |
| Returns: A far pointer to the object. |
\*----------------------------------------------------------
---*/
LPSTR FAR PASCAL SubLock(HANDLE32 hSubMem)
{
HANDLE hSeg;
HANDLE hMem;
LPSTR lp;
PSTR p;
WORD wSeg;
hSeg = HIWORD (hSubMem);
hMem = LOWORD (hSubMem);
lp = GlobalLock (hSeg);
if (!lp)
return 0L;
wSeg = HIWORD (lp);
_asm { push ds
mov ax, wSeg
mov ds, ax }
p = LocalLock (hMem);
_asm { pop ds }
/* No Matching GlobalUnlock -- leave segment locked */
/* for caller to use. We'll unlock twice in SubUnlock. */
if (!p)
return (LPSTR)0;
else
return (LPSTR)MAKELONG (p, wSeg);
}
/*----------------------------------------------------------
---*\
| SubSize - Returns the size of a subsegment. |
| |
| Input: A 4-byte "handle", put together as: |
| HIWORD = Handle to global segment. |
| LOWORD = Handle to local object. |
| |
| Returns: a WORD value with the subsegment size, or zero |
| if the handle is invalid. |
\*----------------------------------------------------------
---*/
WORD FAR PASCAL SubSize(HANDLE32 hSubMem)
{
HANDLE hSeg;
HANDLE hMem;
LPSTR lp;
WORD wSeg;
WORD wSize;
hSeg = HIWORD (hSubMem);
hMem = LOWORD (hSubMem);
lp = GlobalLock (hSeg);
if (!lp)
return 0;
wSeg = HIWORD (lp);
_asm { push ds
mov ax, wSeg
mov ds, ax }
wSize = LocalSize (hMem);
_asm { pop ds }
GlobalUnlock (hSeg);
return wSize;
}
/*----------------------------------------------------------
---*\
| SubUnlock - Unlock a subsegment, and the segment it lives |
| in. |
| Input: A 4-byte "handle", put together as: |
| HIWORD = Handle to global segment. |
| LOWORD = Handle to local object. |
| |
| Returns: The LocalUnlock return value, which is zero if |
| the block's reference count was decreased to |
| zero, otherwise it is non-zero. |
\*----------------------------------------------------------
---*/
BOOL FAR PASCAL SubUnlock(HANDLE32 hSubMem)
{
BOOL bRetVal;
HANDLE hSeg;
HANDLE hMem;
LPSTR lp;
WORD wSeg;
hSeg = HIWORD (hSubMem);
hMem = LOWORD (hSubMem);
lp = GlobalLock (hSeg);
if (!lp)
return 0L;
wSeg = HIWORD (lp);
_asm { push ds
mov ax, wSeg
mov ds, ax }
bRetVal = LocalUnlock (hMem);
_asm { pop ds }
GlobalUnlock (hSeg);
GlobalUnlock (hSeg);
return bRetVal;
}
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