/* Copyright (c) Microsoft Corporation.
   Licensed under the MIT License. */

/***************************************************************************
	Author: ShonK
	Project: Kauai
	Reviewed:
	Copyright (c) Microsoft Corporation

	Windows memory management.

***************************************************************************/
#include "util.h"
ASSERTNAME


struct HQH
	{
	long cb;                        // size of client area
	long cactLock;          // lock count
	#ifdef DEBUG
		long lwMagic;   // for detecting memory trashing
	#endif //DEBUG
	};


#ifdef DEBUG
long vcactSuspendCheckPointers = 0;
#endif //DEBUG


/***************************************************************************
	Allocates a new moveable block.
***************************************************************************/
#ifdef DEBUG
bool FAllocHqDebug(HQ *phq, long cb, ulong grfmem, long mpr,
	PSZS pszsFile, long lwLine)
#else //!DEBUG
bool FAllocHq(HQ *phq, long cb, ulong grfmem, long mpr)
#endif //!DEBUG
{
	AssertVarMem(phq);
	AssertIn(cb, 0, kcbMax);
	HQH *phqh;

	if (!FAllocPvDebug((void **)&phqh, cb + size(HQH), grfmem, mpr,
			pszsFile, lwLine, &vdmglob.dmaglHq))
		{
		PushErc(ercOomHq);
		*phq = hqNil;
		}
	else
		{
		phqh->cb = cb;
		phqh->cactLock = 0;
		Debug( phqh->lwMagic = klwMagicMem; )
		*phq = (HQ)(phqh + 1);
		AssertHq(*phq);
		}

	return pvNil != *phq;
}


/***************************************************************************
	Resizes the given hq.  *phq may change.  If fmemClear, clears any
	newly added space.
***************************************************************************/
bool FResizePhq(HQ *phq, long cb, ulong grfmem, long mpr)
{
	AssertVarMem(phq);
	AssertHq(*phq);
	AssertIn(cb, 0, kcbMax);
	bool fRet = fFalse;
	HQH *phqh = (HQH *)PvSubBv(*phq, size(HQH));

	if (phqh->cactLock > 0)
		{
		Bug("Resizing locked HQ");
		PushErc(ercOomHq);
		}
	else if (!_FResizePpvDebug((void **)&phqh, cb + size(HQH),
			phqh->cb + size(HQH), grfmem, mpr, &vdmglob.dmaglHq))
		{
		PushErc(ercOomHq);
		AssertHq(*phq);
		}
	else
		{
		phqh->cb = cb;
		*phq = (HQ)(phqh + 1);
		AssertHq(*phq);
		fRet = fTrue;
		}

	return fRet;
}


/***************************************************************************
	If hq is not nil, frees it.
***************************************************************************/
void FreePhq(HQ *phq)
{
	AssertVarMem(phq);

	if (*phq == hqNil)
		return;

	AssertHq(*phq);
	HQH *phqh = (HQH *)PvSubBv(*phq, size(HQH));
	*phq = hqNil;
	Assert(phqh->cactLock == 0, "Freeing locked HQ");

	FreePpvDebug((void **)&phqh, &vdmglob.dmaglHq);
}


/***************************************************************************
	Create a new HQ the same size as hqSrc and copy hqSrc into it.
***************************************************************************/
bool FCopyHq(HQ hqSrc, HQ *phqDst, long mpr)
{
	AssertHq(hqSrc);
	AssertVarMem(phqDst);
	long cb;

	if (!FAllocHq(phqDst, cb = CbOfHq(hqSrc), fmemNil, mpr))
		return fFalse;
	CopyPb(QvFromHq(hqSrc), QvFromHq(*phqDst), cb);
	return fTrue;
}


/***************************************************************************
	Return the size of the hq (the client area of the block).
***************************************************************************/
long CbOfHq(HQ hq)
{
	AssertHq(hq);
	HQH *phqh = (HQH *)PvSubBv(hq, size(HQH));
	return phqh->cb;
}


#ifdef DEBUG
/***************************************************************************
	Returns a volatile pointer from an hq.
***************************************************************************/
void *QvFromHq(HQ hq)
{
	AssertHq(hq);
	return (void *)hq;
}
#endif //DEBUG


/***************************************************************************
	Lock the hq and return a pointer to the data.
***************************************************************************/
void *PvLockHq(HQ hq)
{
	AssertHq(hq);
	HQH *phqh = (HQH *)PvSubBv(hq, size(HQH));
	phqh->cactLock++;
	Assert(phqh->cactLock > 0, "overflow in cactLock");
	return (void *)hq;
}


/***************************************************************************
	Unlock the hq.  Asserts and does nothing if the lock count is zero.
***************************************************************************/
void UnlockHq(HQ hq)
{
	AssertHq(hq);
	HQH *phqh = (HQH *)PvSubBv(hq, size(HQH));
	Assert(phqh->cactLock > 0, "hq not locked");
	if (phqh->cactLock > 0)
		--phqh->cactLock;
}


#ifdef DEBUG
/***************************************************************************
	Assert that a given hq is valid.
***************************************************************************/
void AssertHq(HQ hq)
{
	// make sure hq isn't nil
	if (hq == hqNil)
		{
		Bug("hq is nil");
		return;
		}

	// verify the HQH
	HQH *phqh = (HQH *)PvSubBv(hq, size(HQH));
	if (phqh->lwMagic != klwMagicMem)
		{
		BugVar("beginning of hq block is trashed", phqh);
		return;
		}
	AssertIn(phqh->cactLock, 0, kcbMax);
	AssertPvAlloced(phqh, phqh->cb + size(HQH));
}


/***************************************************************************
	Increment the ref count on an hq.
***************************************************************************/
void MarkHq(HQ hq)
{
	if (hqNil != hq)
		{
		AssertHq(hq);
		MarkPv(PvSubBv(hq, size(HQH)));
		}
}


/***************************************************************************
	Make sure we can access a pointer's memory.  If cb is 0, pv can be
	anything (including nil).
***************************************************************************/
void AssertPvCb(void *pv, long cb)
{
	if (vcactSuspendCheckPointers == 0 && cb != 0)
		{
		AssertVar(!IsBadWritePtr(pv, cb), "no write access to ptr", &pv);
		// I (ShonK) am assuming that write access implies read access for
		// memory, so it would just be a waste of time to call this.
		// AssertVar(!IsBadReadPtr(pv, cb), "no read access to ptr", &pv);
		}
}
#endif //DEBUG