// Copyright (c) 1994-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of the License "Eclipse Public License v1.0"
// which accompanies this distribution, and is available
// at the URL "http://www.eclipse.org/legal/epl-v10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
// e32\common\arm\cheap.cia
// 
//

#include <e32cia.h>
#include "../common.h"

#if defined(__HEAP_MACHINE_CODED__) && !defined(_DEBUG)
GLREF_C void RHeap_PanicBadAllocatedCellSize();
GLREF_C void RHeap_PanicBadNextCell();
GLREF_C void RHeap_PanicBadPrevCell();
GLREF_C void RHeap_PanicBadCellAddress();

IMPORT_D extern const TInt KHeapShrinkHysRatio;


__NAKED__ RHeap::SCell* RHeap::DoAlloc(TInt /*aSize*/, SCell*& /*aLastFree*/)
//
// Allocate a cell.
//
	{
	asm("stmfd sp!, {r4,r5,lr} ");
	asm("mov r4, r0 ");										// r4=this
	asm("add r3, r0, #%a0" : : "i" _FOFF(RHeap,iFree));		// r3=pP=&iFree
	asm("ldr r0, [r3, #4] ");								// r0=pC=pP->next
	asm("cmp r0, #0 ");
	asm("beq 0f ");								// if no free cells, alloc failed

	// optimised unfolded scanning loop
	asm("2: ");
	asm("ldmia r0, {r12,r14} ");				// r12=pC->size, r14=pC->next
	asm("cmp r1, r12 ");						// compare aSize to size
	asm("movhi r3, r0 ");						// if aSize>size, pP=pC
	asm("movhis r0, r14 ");						// and pC=pC->next
#ifndef __CPU_ARMV6 // don't unroll on armv6
	asm("ldmhiia r0, {r12,r14} ");				// r12=pC->size, r14=pC->next
	asm("cmphi r1, r12 ");						// compare aSize to size
	asm("movhi r3, r0 ");						// if aSize>size, pP=pC
	asm("movhis r0, r14 ");						// and pC=pC->next
#endif
	asm("bhi 2b ");								// branch back if scan not finished
	
	asm("1: ");
	asm("subs r5, r12, r1 ");					// r5 = pC->len - aSize
	asm("ldrhs r2, [r4, #%a0]" : : "i" _FOFF(RHeap,iMinCell));		// if big enough, r2=iMinCell
	asm("blo 0f ");								// branch if no free cell was big enough
	asm("cmp r5, r2 ");							// leftover big enough?
	asm("movlo r1, r12 ");						// if not, aSize=pC->len ...
	asm("strlo r14, [r3, #4] ");				// ... and pP->next = pC->next
	asm("addhs r2, r0, r1 ");					// else r2 = pE = address of new free cell ...
	asm("stmhsia r2, {r5, r14} ");				// ... pE->len = pC->len - aSize, pE->next = pC->next ...
	asm("strhs r2, [r3, #4] ");					// ... and pP->next = pE
	asm("str r1, [r0] ");						// pC->len = aSize
	__POPRET("r4,r5,");							// restore and exit, return pC

	asm("0: ");
	asm("str r3, [r2] ");						// alloc failed - aLastFree=pP
	asm("mov r0, #0 ");							// return NULL
	__POPRET("r4,r5,");
	}

__NAKED__ void RHeap::DoFree(SCell* /*pC*/)
//
// Free a cell.
//
	{
	asm("add r2, r0, #%a0" : : "i" _FOFF(RHeap,iFree));	// r2=pP=&iFree
	asm("ldr r3, [r2, #4] ");					// r3=pE=pP->next
	asm("stmfd sp!, {r4, r5} ");

	asm("1: ");
	asm("cmp r3, #0 ");						// check if pE=NULL
	asm("cmphi r1, r3 ");					// if not, check if pC>pE
	asm("movhi r2, r3 ");					// if so, pP=pE
	asm("ldrhi r3, [r3, #4] ");				// and pE=pE->next
#ifndef __CPU_ARMV6    // don't unroll on armv6
	asm("cmphi r3, #0 ");					// check if pE=NULL
	asm("cmphi r1, r3 ");					// if not, check if pC>pE
	asm("movhi r2, r3 ");					// if so, pP=pE
	asm("ldrhi r3, [r3, #4] ");				// and pE=pE->next
#endif
	asm("bhi 1b ");							// loop if free cell position not found

	asm("ldr r4, [r1, #0] ");				// r4=pC->len
	asm("cmp r3, #0 ");						// is there a following free cell ?
	asm("streq r3, [r1, #4] ");				// if not, pC->next=NULL
	asm("beq 2f ");							// and skip next section
	asm("add r5, r1, r4 ");					// r5=pN=pC + pC->len (cell after pC)
	asm("cmp r5, r3 ");						// compare pN with pE
	asm("ldmeqia r3, {r5, r12} ");			// if pN==pE, r5=pE->len, r12=pE->next
	asm("blhi " CSM_Z22RHeap_PanicBadNextCellv );	// if pN>pE, panic
	asm("strne r3, [r1, #4] ");				// if pN<pE, pC->next=pE
	asm("addeq r4, r4, r5 ");				// if pN==pE r4 = pC->len + pE->len
	asm("stmeqia r1, {r4,r12} ");			// if pN==pE pC->len+=pE->len, pC->next=pE->next
	asm("2: ");
	asm("ldr r3, [r2, #0] ");				// r3=pP->len
	asm("sub r5, r1, r2 ");					// r5=pC-pP (gap between preceding free cell and this one)
	asm("cmp r5, r3 ");						// compare gap with predecessor length
	asm("ldreq r12, [r1, #4] ");			// if predecessor is adjacent, r12=pC->next
	asm("bllo RHeap_PanicBadPrevCell__Fv ");	// if predecessor overlaps, panic
	asm("addeq r4, r4, r3 ");				// if predecessor is adjacent, r4=pC->len + pP->len
	asm("stmeqia r2, {r4,r12} ");			// if predecessor is adjacent, pP->len+=pC->len, pP->next=pC->next
	asm("strne r1, [r2, #4] ");				// else pP->next = pC
	asm("moveq r1, r2 ");					// if predecessor is adjacent, pC=pP (final amalgamated free cell)
	asm("3: ");
	asm("ldr r12, [r0, #%a0]" : : "i" _FOFF(RHeap,iTop));	// r12=iTop
	asm("add r3, r1, r4 ");					// end of amalgamated free cell
	asm("cmp r3, r12 ");					// end of amalgamated free cell = iTop ?
	asm("ldmneia sp!, {r4,r5} ");			// restore registers
	__JUMP(ne,lr);							// if not, finished
	asm("ldr r12, [r0, #%a0]" : : "i" _FOFF(RHeap,iFlags));	// r12=iFlags
	asm("tst r12, #%a0" : : "i" ((TInt)RAllocator::EFixedSize));	// check fixed size flag
	asm("ldmneia sp!, {r4,r5} ");			// restore registers
	__JUMP(ne,lr);							// if set, finished
	asm("ldr r2, [r0, #%a0]" : : "i" _FOFF(RHeap,iGrowBy));	// r2=iGrowBy
	asm("mov r3, r2, LSR #8");				// r3=iGrowBy>>8
	asm("ldr r2, const_addr");				// r2=&KHeapShrinkHysRatio
	asm("ldr r5, [r2]");					// r5=KHeapShrinkHysRatio
	asm("mul r2, r5, r3");					// r2=KHeapShrinkHysRatio*(iGrowBy>>8) - low order bits
	asm("cmp r4, r2");						// compare len(r4) to (iGrowBy>>8)*KHeapShrinkHysRatio(r2)
	asm("ldmia sp!, {r4,r5} ");				// restore registers
	__JUMP(lo,lr);							// if less, finished
	asm("b Reduce__5RHeapPQ25RHeap5SCell ");	// else reduce heap
	
	asm("const_addr:");
	asm(".word %a0" : : "i" ((TInt)&KHeapShrinkHysRatio));	
	}
#endif