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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 16:49:04 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 16:49:04 +0000 |
commit | 16f504a9dca3fe3b70568f67b7d41241ae485288 (patch) | |
tree | c60f36ada0496ba928b7161059ba5ab1ab224f9d /src/VBox/Runtime/common/asm/ASMBitFirstSet-generic.cpp | |
parent | Initial commit. (diff) | |
download | virtualbox-16f504a9dca3fe3b70568f67b7d41241ae485288.tar.xz virtualbox-16f504a9dca3fe3b70568f67b7d41241ae485288.zip |
Adding upstream version 7.0.6-dfsg.upstream/7.0.6-dfsgupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/VBox/Runtime/common/asm/ASMBitFirstSet-generic.cpp')
-rw-r--r-- | src/VBox/Runtime/common/asm/ASMBitFirstSet-generic.cpp | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/asm/ASMBitFirstSet-generic.cpp b/src/VBox/Runtime/common/asm/ASMBitFirstSet-generic.cpp new file mode 100644 index 00000000..e8cacab8 --- /dev/null +++ b/src/VBox/Runtime/common/asm/ASMBitFirstSet-generic.cpp @@ -0,0 +1,107 @@ +/* $Id: ASMBitFirstSet-generic.cpp $ */ +/** @file + * IPRT - ASMBitFirstSet - generic C implementation. + */ + +/* + * Copyright (C) 2006-2022 Oracle and/or its affiliates. + * + * This file is part of VirtualBox base platform packages, as + * available from https://www.virtualbox.org. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, in version 3 of the + * License. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <https://www.gnu.org/licenses>. + * + * The contents of this file may alternatively be used under the terms + * of the Common Development and Distribution License Version 1.0 + * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included + * in the VirtualBox distribution, in which case the provisions of the + * CDDL are applicable instead of those of the GPL. + * + * You may elect to license modified versions of this file under the + * terms and conditions of either the GPL or the CDDL or both. + * + * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0 + */ + + +/********************************************************************************************************************************* +* Header Files * +*********************************************************************************************************************************/ +#include <iprt/asm.h> +#include "internal/iprt.h" + +#include <iprt/assert.h> + + +RTDECL(int32_t) ASMBitFirstSet(const volatile void RT_FAR *pvBitmap, uint32_t cBits) RT_NOTHROW_DEF +{ + const volatile size_t RT_FAR *pu = (const volatile size_t RT_FAR *)pvBitmap; + Assert(!(cBits & 31)); + Assert(!((uintptr_t)pvBitmap & 3)); + +#if ARCH_BITS > 32 + /* Deal with misaligned bitmaps (happens all the time via ASMBitNextClear()). */ + if (!((uintptr_t)pvBitmap & 7) && cBits >= 32) + { + uint32_t u32 = *(const volatile uint32_t RT_FAR *)pu; + if (u32 != 0) + { + size_t const iBaseBit = ((uintptr_t)pu - (uintptr_t)pvBitmap) * 8; + return iBaseBit + ASMBitFirstSetU32(RT_LE2H_U32(u32)) - 1; + } + pu = (const volatile size_t RT_FAR *)((uintptr_t)pu + sizeof(uint32_t)); + cBits -= 32; + } +#endif + + /* Main search loop: */ + while (cBits >= sizeof(size_t) * 8) + { + size_t u = *pu; + if (u == 0) + { } + else + { + size_t const iBaseBit = ((uintptr_t)pu - (uintptr_t)pvBitmap) * 8; +#if ARCH_BITS == 32 + return iBaseBit + ASMBitFirstSetU32(RT_LE2H_U32(u)) - 1; +#elif ARCH_BITS == 64 + return iBaseBit + ASMBitFirstSetU64(RT_LE2H_U64(u)) - 1; +#else +# error "ARCH_BITS is not supported" +#endif + } + + pu++; + cBits -= sizeof(size_t) * 8; + } + +#if ARCH_BITS > 32 + /* Final 32-bit item (unlikely)? */ + if (cBits < 32) + { } + else + { + uint32_t u32 = *(const volatile uint32_t RT_FAR *)pu; + if (u32 != 0) + { + size_t const iBaseBit = ((uintptr_t)pu - (uintptr_t)pvBitmap) * 8; + return iBaseBit + ASMBitFirstSetU32(RT_LE2H_U32(u32)) - 1; + } + } +#endif + + return -1; +} + |