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

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

	Data movement routines.
	WARNING: Must be in a fixed (pre-loaded) seg on Mac.

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


/***************************************************************************
	Fill a block with a specific byte value.
***************************************************************************/
void FillPb(void *pv, long cb, byte b)
{
	AssertIn(cb, 0, kcbMax);
	AssertPvCb(pv, cb);

#ifdef IN_80386

	__asm
		{
		// Setup the registers for using REP STOS instruction to set memory.
		// NOTE: Alignment does not effect the speed of STOS.
		//
		// edi -> memory to set
		// eax = value to store in destination
		// direction flag is clear for auto-increment

		mov		edi,pv
		mov		al,b

		// set the longs
		mov		ecx,cb
		shr		ecx,2
		jz		LBytes

		shl		eax,8
		mov		al,b
		mov		ebx,eax
		shl		eax,16
		mov		ax,bx

		rep		stosd

		// set the extra bytes
LBytes:
		mov		ecx,cb
		and		ecx,3
		rep		stosb
		}

#else //!IN_80386

	byte *pb;

	for (pb = (byte *)pv; cb != 0; cb--)
		*pb++ = b;

#endif //!IN_80386
}


/***************************************************************************
	Clear a block.
***************************************************************************/
void ClearPb(void *pv, long cb)
{
	AssertIn(cb, 0, kcbMax);
	AssertPvCb(pv, cb);

#ifdef IN_80386

	__asm
		{
		// Setup the registers for using REP STOS instruction to set memory.
		// NOTE: Alignment does not effect the speed of STOS.
		//
		// edi -> memory to set
		// eax = value to store in destination
		// direction flag is clear for auto-increment

		mov		edi,pv
		xor		eax,eax

		// clear the longs
		mov		ecx,cb
		shr		ecx,2
		rep		stosd

		// clear the extra bytes
		mov		ecx,cb
		and		ecx,3
		rep		stosb
		}

#else //!IN_80386

	byte *pb;

	for (pb = (byte *)pv; cb != 0; cb--)
		*pb++ = 0;

#endif //!IN_80386
}


/***************************************************************************
	Reverse a block. Useful for exchanging two blocks or avoiding
	recursion.
***************************************************************************/
void ReversePb(void *pv, long cb)
{
	AssertIn(cb, 0, kcbMax);
	AssertPvCb(pv, cb);

#ifdef IN_80386

	__asm
		{
		// esi - high end of block
		// edi - low end of block
		// ecx - number of bytes to swap

		mov		edi,pv
		mov		esi,edi
		add		esi,cb
		mov		ecx,cb
		shr		ecx,1

		or		ecx,ecx
		jz		LDone

LLoop:
		dec		esi
		mov		al,[edi]
		mov		bl,[esi]
		mov		[edi],bl
		mov		[esi],al

		inc		edi
		dec		ecx
		jnz		LLoop
LDone:
		}

#else //!IN_80386

	byte *pb1, *pb2;
	byte b;

	for (pb2 = (pb1 = (byte *)pv) + cb - 1; pb1 < pb2; )
		{
		b = *pb1;
		*pb1++ = *pb2;
		*pb2-- = b;
		}

#endif //!IN_80386
}


/***************************************************************************
	Reverse a list of shorts.
***************************************************************************/
void ReverseRgsw(void *pv, long csw)
{
	AssertIn(csw, 0, kcbMax);
	AssertPvCb(pv, csw * size(short));

#ifdef IN_80386

	__asm
		{
		// esi - high end of block
		// edi - low end of block
		// ecx - number of shorts to swap

		mov		edi,pv
		mov		esi,edi
		mov		ecx,csw
		shl		ecx,1
		add		esi,ecx
		shr		ecx,2

		or		ecx,ecx
		jz		LDone

LLoop:
		sub		esi,2
		mov		ax,[edi]
		mov		bx,[esi]
		mov		[edi],bx
		mov		[esi],ax

		add		edi,2
		dec		ecx
		jnz		LLoop
LDone:
		}

#else //!IN_80386

	long *psw1, *psw2;
	long sw;

	for (psw2 = (psw1 = (short *)pv) + csw - 1; psw1 < psw2; )
		{
		sw = *psw1;
		*psw1++ = *psw2;
		*psw2-- = sw;
		}

#endif //!IN_80386
}


/***************************************************************************
	Reverse a list of longs.
***************************************************************************/
void ReverseRglw(void *pv, long clw)
{
	AssertIn(clw, 0, kcbMax);
	AssertPvCb(pv, clw * size(long));

#ifdef IN_80386

	__asm
		{
		// esi - high end of block
		// edi - low end of block
		// ecx - number of longs to swap

		mov		edi,pv
		mov		esi,edi
		mov		ecx,clw
		shl		ecx,2
		add		esi,ecx
		shr		ecx,3

		or		ecx,ecx
		jz		LDone

LLoop:
		sub		esi,4
		mov		eax,[edi]
		mov		ebx,[esi]
		mov		[edi],ebx
		mov		[esi],eax

		add		edi,4
		dec		ecx
		jnz		LLoop
LDone:
		}

#else //!IN_80386

	long *plw1, *plw2;
	long lw;

	for (plw2 = (plw1 = (long *)pv) + clw - 1; plw1 < plw2; )
		{
		lw = *plw1;
		*plw1++ = *plw2;
		*plw2-- = lw;
		}

#endif //!IN_80386
}


/***************************************************************************
	Swap two adjacent blocks of size cb1 and cb2 respectively.
***************************************************************************/
void SwapBlocks(void *pv, long cb1, long cb2)
{
	AssertIn(cb1, 0, kcbMax);
	AssertIn(cb2, 0, kcbMax);
	AssertPvCb(pv, cb1 + cb2);

	ReversePb(pv, cb1);
	ReversePb(PvAddBv(pv, cb1), cb2);
	ReversePb(pv, cb1 + cb2);
}


/***************************************************************************
	Swap the contents of two blocks of the same size.
***************************************************************************/
void SwapPb(void *pv1, void *pv2, long cb)
{
	AssertPvCb(pv1, cb);
	AssertPvCb(pv2, cb);
	AssertIn(cb, 0, kcbMax);

#ifdef IN_80386

	__asm
		{
		// edi -> memory to swap, first pointer
		// esi -> memory to swap, second pointer

		mov		edi,pv1
		mov		esi,pv2

		mov		ecx,cb
		shr		ecx,2
		jz		LBytes

LLongLoop:
		mov		eax,[edi]
		mov		ebx,[esi]
		mov		[edi],ebx
		mov		[esi],eax

		add		edi,4
		add		esi,4
		dec		ecx
		jnz		LLongLoop;

LBytes:
		mov		ecx,cb
		and		ecx,3
		jz		LDone

LByteLoop:
		mov		al,[edi]
		mov		bl,[esi]
		mov		[edi],bl
		mov		[esi],al
		inc		edi
		inc		esi
		dec		ecx
		jnz		LByteLoop

LDone:
		}

#else //!IN_80386

	byte *pb1 = (byte *)pv1;
	byte *pb2 = (byte *)pv2;
	byte b;

	Assert(pb1 + cb <= pb2 || pb2 + cb <= pb1, "blocks overlap");
	while (cb-- > 0)
		{
		b = *pb1;
		*pb1++ = *pb2;
		*pb2++ = b;
		}

#endif //!IN_80386
}


/***************************************************************************
	Move the entry at ivSrc to be immediately before the element that is
	currently at ivTarget. If ivTarget > ivSrc, the entry actually ends
	up at (ivTarget - 1) and the entry at ivTarget doesn't move. If
	ivTarget < ivSrc, the entry ends up at ivTarget and the entry at
	ivTarget moves to (ivTarget + 1). Everything in between is shifted
	appropriately. prgv is the array of elements and cbElement is the
	size of each element.
***************************************************************************/
void MoveElement(void *prgv, long cbElement, long ivSrc, long ivTarget)
{
	AssertIn(cbElement, 0, kcbMax);
	AssertIn(ivSrc, 0, kcbMax);
	AssertIn(ivTarget, 0, kcbMax);
	AssertPvCb(prgv, LwMul(cbElement, ivSrc + 1));
	AssertPvCb(prgv, LwMul(cbElement, ivTarget));

	if (ivTarget == ivSrc || ivTarget == ivSrc + 1)
		return;

	//swap the blocks
	if (ivSrc < ivTarget)
		{
		SwapBlocks(PvAddBv(prgv, LwMul(ivSrc, cbElement)),
			cbElement, LwMul(ivTarget - 1 - ivSrc, cbElement));
		}
	else
		{
		SwapBlocks(PvAddBv(prgv, LwMul(ivTarget, cbElement)),
			LwMul(ivSrc - ivTarget, cbElement), cbElement);
		}
}


/***************************************************************************
	Check for equality of two blocks.
***************************************************************************/
bool FEqualRgb(void *pv1, void *pv2, long cb)
{
	AssertIn(cb, 0, kcbMax);
	AssertPvCb(pv1, cb);
	AssertPvCb(pv2, cb);

#ifdef IN_80386

	bool fRet;

	__asm
		{
		// edi -> memory to compare, first pointer
		// esi -> memory to compare, second pointer

		xor		eax,eax		//assume false return
		mov		edi,pv1
		mov		esi,pv2

		// compare longs
		mov		ecx,cb		// (ecx) = length in bytes
		shr		ecx,2		// (ecx) = length in longs
		repe	cmpsd		// compare longs
		jnz		LDone		// mismatch, go report

		// compare extra bytes
		mov		ecx,cb
		and		ecx,3		// (ecx) = length mod 4
		repe	cmpsb		// compare odd bytes
		jnz		LDone		// mismatch, go report

		inc		eax			// successful compare

LDone:
		mov		fRet,eax
		}

	return fRet;

#else //!IN_80386

	byte *pb1 = (byte *)pv1;
	byte *pb2 = (byte *)pv2;

	while (cb != 0 && *pb1++ == *pb2++)
		cb--;
	return cb == 0;

#endif //!IN_80386
}


/***************************************************************************
	Compare the two buffers byte for byte and return a the number of bytes
	that match.
***************************************************************************/
long CbEqualRgb(void *pv1, void *pv2, long cb)
{
	AssertIn(cb, 0, kcbMax);
	AssertPvCb(pv1, cb);
	AssertPvCb(pv2, cb);

#ifdef IN_80386

	byte *pb;

	__asm
		{
		// edi -> memory to swap, first pointer
		// esi -> memory to swap, second pointer

		mov		edi,pv1
		mov		esi,pv2

		// compare extra bytes.
		mov		ecx,cb
		and		ecx,3	// (ecx) = length mod 4
		repe	cmpsb	// compare odd bytes
		jnz		LMiss	// mismatch, go report how far we got

		// compare longs
		mov		ecx,cb	// (ecx) = length in bytes
		shr		ecx,2	// (ecx) = length in longs
		repe	cmpsd	// compare longs
		jz		LHit	// matched all the way

		// esi (and edi) points to the long after the one which caused the
		// mismatch. Back up 1 long and find the byte. Since we know the
		// long didn't match, we can assume one of the bytes won't.
		sub		esi,4	// back up
		sub		edi,4	// back up
		mov		ecx,5	// ensure that ecx doesn't count out
		repe	cmpsb	// find mismatch byte

		// esi points to the byte after the one that did not match.
LMiss:
		dec		esi
		dec		edi
		mov		pb,edi
		}

	return pb - (byte *)pv1;

LHit:
	// We matched all the way to the end.
	return cb;

#else //!IN_80386

	byte *pb1 = (byte *)pv1;
	byte *pb2 = (byte *)pv2;

	for ( ; cb-- > 0 && *pb1 == *pb2; pb1++, pb2++)
		;
	return pb1 - (byte *)pv1;

#endif //!IN_80386
}


/***************************************************************************
	Compare the two buffers byte for byte and return an fcmp indicating
	their relationship to each other.
***************************************************************************/
ulong FcmpCompareRgb(void *pv1, void *pv2, long cb)
{
	AssertIn(cb, 0, kcbMax);
	AssertPvCb(pv1, cb);
	AssertPvCb(pv2, cb);

	long cbMatch = CbEqualRgb(pv1, pv2, cb);

	AssertIn(cbMatch, 0, cb + 1);
	if (cb == cbMatch)
		return fcmpEq;

	return ((byte *)pv1)[cbMatch] < ((byte *)pv2)[cbMatch] ? fcmpLt : fcmpGt;
}


/***************************************************************************
	Copy data without overlap.
****************************************************************************/
void CopyPb(void *pv1, void *pv2, long cb)
{
	AssertIn(cb, 0, kcbMax);
	AssertPvCb(pv1, cb);
	AssertPvCb(pv2, cb);
	Assert((byte *)pv1 + cb <= (byte *)pv2 || (byte *)pv2 + cb <= (byte *)pv1,
		"blocks overlap");

#ifdef IN_80386

	__asm
		{
		// Setup the registers for using REP MOVS instruction to move memory.
		//
		// esi -> memory to move
		// edi -> destination of move
		// direction flag is clear for auto-increment
		mov		esi,pv1
		mov		edi,pv2

		// move the longs
		mov		ecx,cb
		shr		ecx,2
		rep		movsd

		// move the extra bytes
		mov		ecx,cb
		and		ecx,3
		rep		movsb
		}

#else //!IN_80386

	byte *pb1 = (byte *)pv1;
	byte *pb2 = (byte *)pv2;

	while (cb-- != 0)
		*pb2++ = *pb1++;

#endif //!IN_80386
}


/***************************************************************************
	Copy data with possible overlap.
***************************************************************************/
void BltPb(void *pv1, void *pv2, long cb)
{
	AssertIn(cb, 0, kcbMax);
	AssertPvCb(pv1, cb);
	AssertPvCb(pv2, cb);

#ifdef IN_80386

	__asm
		{
		// Setup the registers for using REP MOVS instruction to move memory.
		//
		// esi -> memory to move
		// edi -> destination of move
		// direction flag is clear for auto-increment

		mov		esi,pv1
		mov		edi,pv2
		mov		ecx,cb

		cmp		esi,edi
		ja		LForward	// if source > destination
		je		LDone		// if source == destination

		// source < destination, see if they overlap
		mov		eax,edi
		sub		eax,esi
		cmp		ecx,eax
		jbe		LForward

		// they overlap with source < destination, so have to do a backward copy
		std
		add		esi,ecx
		add		edi,ecx
		dec		esi
		dec		edi

		// move the extra bytes
		and		ecx,3
		rep		movsb

		// move the longs
		mov		ecx,cb
		shr		ecx,2
		jz		LDone
		sub		esi,3
		sub		edi,3
		rep		movsd
		jmp		LDone

LForward:
		// move the longs
		shr		ecx,2
		rep		movsd

		// move the extra bytes
		mov		ecx,cb
		and		ecx,3
		rep		movsb

LDone:
		cld
		}

#else //!IN_80386

	byte *pb1 = (byte *)pv1;
	byte *pb2 = (byte *)pv2;

	if (pb1 > pb2)
		{
		while (cb-- != 0)
			*pb2++ = *pb1++;
		}
	else
		{
		pb1 += cb;
		pb2 += cb;
		while (cb-- != 0)
			*--pb2 = *--pb1;
		}

#endif //!IN_80386
}