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diff --git a/src/VBox/Runtime/common/asm/ASMBitNextSet.asm b/src/VBox/Runtime/common/asm/ASMBitNextSet.asm
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+; $Id: ASMBitNextSet.asm $
+;; @file
+; IPRT - ASMBitNextSet().
+;
+
+;
+; 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/asmdefs.mac"
+
+BEGINCODE
+
+;;
+; Finds the next set bit in a bitmap.
+;
+; @returns (32/64:eax, 16:ax+dx) Index of the first zero bit.
+; @returns (32/64:eax, 16:ax+dx) -1 if no set bit was found.
+; @param msc:rcx gcc:rdi pvBitmap Pointer to the bitmap.
+; @param msc:edx gcc:rsi cBits The number of bits in the bitmap. Multiple of 32.
+; @param msc:r8d gcc:rcx iBitPrev The previous bit, start searching after it.
+;
+; @remarks Not quite sure how much sense it makes to do this in assembly, but
+; it started out with the ASMBit* API, so that's why we still have it.
+;
+RT_BEGINPROC ASMBitNextSet
+%if ARCH_BITS == 16
+ push bp
+ mov bp, sp
+%endif
+ push xDI
+
+ ;
+ ; Align input registers: rdi=pvBitmap, ecx=iPrevBit
+ ;
+%if ARCH_BITS == 64
+ %ifdef ASM_CALL64_GCC
+ ; ecx = iBitPrev param, rdi=pvBitmap param.
+ %else
+ mov rdi, rcx ; rdi=pvBits
+ mov ecx, r8d ; ecx=iPrevBit
+ mov r8d, edx ; r8d=cBits (saved for .scan_dwords)
+ %endif
+ mov r9, rdi ; Save rdi for bit calculation.
+%elif ARCH_BITS == 32
+ mov edi, [esp + 8] ; edi=pvBits
+ mov ecx, [esp + 8 + 8] ; edx=iPrevBit
+%elif ARCH_BITS == 16
+ mov ax, [bp + 4 + 2]
+ mov es, ax
+ mov di, [bp + 4] ; es:di=pvBits
+ mov ecx, [bp + 4 + 8] ; edx=iPrevBit
+%endif
+
+ ;
+ ; If iPrevBit and iPrevBit + 1 are in the same dword, inspect it for further bits.
+ ;
+ inc ecx
+ mov eax, ecx
+ shr eax, 5
+ shl eax, 2 ; eax=byte offset into bitmap of current dword.
+ add xDI, xAX ; xDI=current dword address (of iPrevBit + 1).
+ and ecx, 31
+ jz .scan_dwords
+
+%if ARCH_BITS == 16
+ mov edx, [es:di] ; edx = current dword
+%else
+ mov edx, [xDI] ; edx = current dword
+%endif
+ shr edx, cl ; Shift out bits that we have searched.
+ jz .next_dword ; If zero, nothing to find. Go rep scasd.
+ shl edx, cl ; Shift it back so bsf will return the right index.
+
+ bsf edx, edx ; edx=index of first set bit
+
+ shl eax, 3 ; Turn eax back into a bit offset of the current dword.
+ add eax, edx ; eax=bit offset
+
+.return:
+ pop xDI
+%if ARCH_BITS == 16
+ mov edx, eax
+ shr edx, 16
+ leave
+%endif
+ ret
+
+ ;
+ ; Do dword scan.
+ ;
+
+ ; Skip empty dword.
+.next_dword:
+ add xDI, 4 ; Skip the empty dword.
+ add eax, 4
+
+.scan_dwords:
+ ; First load and align bit count.
+%if ARCH_BITS == 64
+ %ifdef ASM_CALL64_GCC
+ mov ecx, esi
+ %else
+ mov ecx, r8d
+ %endif
+%elif ARCH_BITS == 32
+ mov ecx, [esp + 8 + 4]
+%elif ARCH_BITS == 16
+ mov ecx, [bp + 4 + 4]
+%endif
+ add ecx, 31
+ shr ecx, 5 ; ecx=bitmap size in dwords.
+
+ ; Adjust ecx to how many dwords there are left to scan. (eax = current byte offset)
+ shr eax, 2 ; eax=current dword offset.
+ sub ecx, eax
+ jbe .return_failure
+
+ ; Do the scanning.
+ xor eax, eax
+ repe scasd
+ je .return_failure
+
+ ; Find the bit in question.
+ sub xDI, 4 ; One step back.
+%if ARCH_BITS == 16
+ movzx edi, di
+ mov eax, [es:xDI]
+%else
+ mov eax, [xDI]
+%endif
+ bsf eax, eax
+ jz .return_failure ; race paranoia
+
+ ; Calc the bit offset.
+%if ARCH_BITS == 16
+ sub di, [bp + 4]
+ movzx edi, di
+%elif ARCH_BITS == 32
+ sub xDI, [esp + 4]
+%elif ARCH_BITS == 64
+ sub xDI, r9
+%endif
+ shl edi, 3 ; edi=bit offset of current dword.
+ add eax, edi
+ jmp .return
+
+.return_failure:
+ mov eax, 0ffffffffh
+ jmp .return
+ENDPROC ASMBitNextSet
+