Category : C++ Source Code
Archive   : VMVCPP.ZIP
Filename : VMBM.H

/***
* vmbm.h -
*
* Copyright (c) 1989-1992, Microsoft Corporation. All rights reserved.
*
*******************************************************************************/

// These are the VMBM internal data structures ONLY, not public to the
// user of the VMBM!

#pragma pack(1)
typedef union {
struct {
unsigned short fAdjacent :1;
unsigned short fVoid :15;
};
unsigned short cbSize;
unsigned short cPage;
} SZBK; //* SiZe of allocated BlocK

typedef struct {
SZBK;
struct {
unsigned short cLock :8;
unsigned short fFree :1;
unsigned short fByPage :1;
};
} HDP; //* HeaDer info for a Page
typedef HDP far * PHDP;

typedef struct {
HDP;
SZBK szbkBack;
} HDB; //* HeaDer info for a Block
typedef HDB far * PHDB;

typedef struct {
HDB;
HBK hbkBackHdf;
HBK hbkNextHdf;
} HDF; //* Free HeaDer, at the start of
typedef HDF far * PHDF;

#pragma pack()

#define bitShift 4 // used to calculate cbClose and cbBig

#define cbClose (cbVmPage >> bitShift) // This says that cbClose bytes is
// close enough to a page boundary
// to go ahead an go to the next page
// this must be greater that
// sizeof(FHD)

#define cbBig (cbVmPage - sizeof(HDB))

#define cbMaxAlloc (0xFFFFFFFF - cbVmPage)
#define cbEndPage(a) (cbVmPage - ((a) % cbVmPage)) // nbr bytes from vp to end
// of the page

#define CbGetSize(a) (((unsigned short) (a)) & 0xFFFE)
#define CbMakeSize(a,b) ((((unsigned short) (a)) & 0xFFFE) | (((unsigned short) (b)) & 0x0001))
#define cbMaxFreeSize 0xFFFE
#define AddHbk(a,b) ((HBK) (((unsigned long) (a)) + (b)))

#define cMaxLock 255U

// the VMBM global variable structure.
typedef struct {
unsigned cbMaxFree; // how many bytes free in last block, must be first item in struct for initialization
unsigned long cFree; // nbr of free blocks known
HBK hbkFreeStart; // the first free block
HBK hbkFreeLast; // the last free block
HBK hbkLastBlock; // the last block in the list
} GVMBM;

extern GVMBM _gvmbm;

extern void VMFUNC __VmFreeLink(HBK, HBK);
extern void VMFUNC __VmFreeLinkIn(HBK, unsigned, HBK, HBK);
extern void VMFUNC __VmFreeLinkEnd(HBK, unsigned);

extern unsigned _near _fVmInit; /* TRUE when VM is initialized */
extern const VPVOID _hbkMin; /* lowest legal handle address */
extern const VPVOID _hbkMax; /* highest legal handle address */