| 1 | /* $Id: bs3-cmn-SlabAllocEx.c 59941 2016-03-07 15:13:51Z vboxsync $ */
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| 2 | /** @file
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| 3 | * BS3Kit - Bs3SlabAllocEx
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2007-2016 Oracle Corporation
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| 8 | *
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| 9 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 10 | * available from http://www.virtualbox.org. This file is free software;
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| 11 | * you can redistribute it and/or modify it under the terms of the GNU
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| 12 | * General Public License (GPL) as published by the Free Software
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| 13 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 14 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 15 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 16 | *
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| 17 | * The contents of this file may alternatively be used under the terms
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| 18 | * of the Common Development and Distribution License Version 1.0
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| 19 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 20 | * VirtualBox OSE distribution, in which case the provisions of the
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| 21 | * CDDL are applicable instead of those of the GPL.
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| 22 | *
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| 23 | * You may elect to license modified versions of this file under the
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| 24 | * terms and conditions of either the GPL or the CDDL or both.
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| 25 | */
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| 26 |
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| 27 | /*********************************************************************************************************************************
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| 28 | * Header Files *
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| 29 | *********************************************************************************************************************************/
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| 30 | #include "bs3kit-template-header.h"
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| 31 | #include <iprt/asm.h>
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| 32 |
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| 33 |
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| 34 | BS3_DECL(void BS3_FAR *) Bs3SlabAllocEx(PBS3SLABCTL pSlabCtl, uint16_t cChunks, uint16_t fFlags)
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| 35 | {
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| 36 | BS3_ASSERT(cChunks > 0);
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| 37 | if (pSlabCtl->cFreeChunks >= cChunks)
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| 38 | {
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| 39 | int32_t iBit = ASMBitFirstClear(&pSlabCtl->bmAllocated, pSlabCtl->cChunks);
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| 40 | if (iBit >= 0)
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| 41 | {
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| 42 | BS3_ASSERT(!ASMBitTest(&pSlabCtl->bmAllocated, iBit));
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| 43 |
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| 44 | while ((uint32_t)iBit + cChunks <= pSlabCtl->cChunks)
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| 45 | {
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| 46 | /* Check that we've got the requested number of free chunks here. */
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| 47 | uint16_t i;
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| 48 | for (i = 1; i < cChunks; i++)
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| 49 | if (ASMBitTest(&pSlabCtl->bmAllocated, iBit + i))
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| 50 | break;
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| 51 | if (i == cChunks)
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| 52 | {
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| 53 | /* Check if the chunks are all in the same tiled segment. */
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| 54 | BS3_XPTR_AUTO(void, pvRet);
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| 55 | BS3_XPTR_SET_FLAT(void, pvRet,
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| 56 | BS3_XPTR_GET_FLAT(uint8_t, pSlabCtl->pbStart) + ((uint32_t)iBit << pSlabCtl->cChunkShift));
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| 57 | if ( !(fFlags & BS3_SLAB_ALLOC_F_SAME_TILE)
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| 58 | || (BS3_XPTR_GET_FLAT(void, pvRet) >> 16)
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| 59 | == ((BS3_XPTR_GET_FLAT(void, pvRet) + ((uint32_t)cChunks << pSlabCtl->cChunkShift) - 1) >> 16) )
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| 60 | {
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| 61 | /* Complete the allocation. */
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| 62 | void *fpRet;
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| 63 | for (i = 0; i < cChunks; i++)
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| 64 | ASMBitSet(&pSlabCtl->bmAllocated, iBit + i);
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| 65 | pSlabCtl->cFreeChunks -= cChunks;
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| 66 | fpRet = BS3_XPTR_GET(void, pvRet);
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| 67 | #if ARCH_BITS == 16
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| 68 | BS3_ASSERT(fpRet != NULL);
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| 69 | #endif
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| 70 | return fpRet;
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| 71 | }
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| 72 |
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| 73 | /*
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| 74 | * We're crossing a tiled segment boundrary.
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| 75 | * Skip to the start of the next segment and retry there.
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| 76 | * (We already know that the first chunk in the next tiled
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| 77 | * segment is free, otherwise we wouldn't have a crossing.)
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| 78 | */
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| 79 | BS3_ASSERT(((uint32_t)cChunks << pSlabCtl->cChunkShift) <= _64K);
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| 80 | i = BS3_XPTR_GET_FLAT_LOW(void, pvRet);
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| 81 | i = UINT16_C(0) - i;
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| 82 | i >>= pSlabCtl->cChunkShift;
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| 83 | iBit += i;
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| 84 | }
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| 85 | else
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| 86 | {
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| 87 | /*
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| 88 | * Continue searching.
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| 89 | */
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| 90 | iBit = ASMBitNextClear(&pSlabCtl->bmAllocated, pSlabCtl->cChunks, iBit + i);
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| 91 | if (iBit < 0)
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| 92 | break;
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| 93 | }
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| 94 | }
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| 95 | }
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| 96 | }
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| 97 | return NULL;
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| 98 | }
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| 99 |
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