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/* $Id: ASMBitNextSet-generic.cpp $ */
/** @file
* IPRT - ASMBitNextSet - generic C implementation.
*/
/*
* Copyright (C) 2006-2023 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(int) ASMBitNextSet(const volatile void RT_FAR *pvBitmap, uint32_t cBits, uint32_t iBitPrev) RT_NOTHROW_DEF
{
const volatile uint32_t RT_FAR *pau32Bitmap = (const volatile uint32_t RT_FAR *)pvBitmap;
int iBit = ++iBitPrev & 31;
Assert(!(cBits & 31));
Assert(!((uintptr_t)pvBitmap & 3));
if (iBit)
{
/*
* Inspect the 32-bit word containing the unaligned bit.
*/
uint32_t u32 = RT_LE2H_U32(pau32Bitmap[iBitPrev / 32]) >> iBit;
if (u32)
return iBitPrev + ASMBitFirstSetU32(u32) - 1;
/*
* Skip ahead and see if there is anything left to search.
*/
iBitPrev |= 31;
iBitPrev++;
if (cBits <= (uint32_t)iBitPrev)
return -1;
}
/*
* 32-bit aligned search, let ASMBitFirstSet do the dirty work.
*/
iBit = ASMBitFirstSet(&pau32Bitmap[iBitPrev / 32], cBits - iBitPrev);
if (iBit >= 0)
iBit += iBitPrev;
return iBit;
}
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