af062818b47340eef15700d2f0211576ba3506eevboxsync;; @file

af062818b47340eef15700d2f0211576ba3506eevboxsync; IPRT - ASMBitFirstClear().

af062818b47340eef15700d2f0211576ba3506eevboxsync;

af062818b47340eef15700d2f0211576ba3506eevboxsync

af062818b47340eef15700d2f0211576ba3506eevboxsync;

af062818b47340eef15700d2f0211576ba3506eevboxsync; Copyright (C) 2006-2007 Sun Microsystems, Inc.

af062818b47340eef15700d2f0211576ba3506eevboxsync;

af062818b47340eef15700d2f0211576ba3506eevboxsync; This file is part of VirtualBox Open Source Edition (OSE), as

af062818b47340eef15700d2f0211576ba3506eevboxsync; available from http://www.virtualbox.org. This file is free software;

af062818b47340eef15700d2f0211576ba3506eevboxsync; you can redistribute it and/or modify it under the terms of the GNU

af062818b47340eef15700d2f0211576ba3506eevboxsync; General Public License (GPL) as published by the Free Software

af062818b47340eef15700d2f0211576ba3506eevboxsync; Foundation, in version 2 as it comes in the "COPYING" file of the

af062818b47340eef15700d2f0211576ba3506eevboxsync; VirtualBox OSE distribution. VirtualBox OSE is distributed in the

af062818b47340eef15700d2f0211576ba3506eevboxsync; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.

af062818b47340eef15700d2f0211576ba3506eevboxsync;

af062818b47340eef15700d2f0211576ba3506eevboxsync; The contents of this file may alternatively be used under the terms

af062818b47340eef15700d2f0211576ba3506eevboxsync; of the Common Development and Distribution License Version 1.0

af062818b47340eef15700d2f0211576ba3506eevboxsync; (CDDL) only, as it comes in the "COPYING.CDDL" file of the

b955672b950093ff7416d1269dd4d3b69983bd8fvboxsync; VirtualBox OSE distribution, in which case the provisions of the

4b9d6701570cb98fd36e209314239d104ec584d3vboxsync; CDDL are applicable instead of those of the GPL.

4b9d6701570cb98fd36e209314239d104ec584d3vboxsync;

b955672b950093ff7416d1269dd4d3b69983bd8fvboxsync; You may elect to license modified versions of this file under the

b955672b950093ff7416d1269dd4d3b69983bd8fvboxsync; terms and conditions of either the GPL or the CDDL or both.

b955672b950093ff7416d1269dd4d3b69983bd8fvboxsync;

b955672b950093ff7416d1269dd4d3b69983bd8fvboxsync; Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa

b955672b950093ff7416d1269dd4d3b69983bd8fvboxsync; Clara, CA 95054 USA or visit http://www.sun.com if you need

b955672b950093ff7416d1269dd4d3b69983bd8fvboxsync; additional information or have any questions.

af062818b47340eef15700d2f0211576ba3506eevboxsync;

af062818b47340eef15700d2f0211576ba3506eevboxsync

af062818b47340eef15700d2f0211576ba3506eevboxsync

af062818b47340eef15700d2f0211576ba3506eevboxsync;*******************************************************************************

af062818b47340eef15700d2f0211576ba3506eevboxsync;* Header Files *

af062818b47340eef15700d2f0211576ba3506eevboxsync;*******************************************************************************

af062818b47340eef15700d2f0211576ba3506eevboxsync%include "iprt/asmdefs.mac"

af062818b47340eef15700d2f0211576ba3506eevboxsync

af062818b47340eef15700d2f0211576ba3506eevboxsyncBEGINCODE

af062818b47340eef15700d2f0211576ba3506eevboxsync

af062818b47340eef15700d2f0211576ba3506eevboxsync;;

af062818b47340eef15700d2f0211576ba3506eevboxsync; Finds the first clear bit in a bitmap.

af062818b47340eef15700d2f0211576ba3506eevboxsync;

af062818b47340eef15700d2f0211576ba3506eevboxsync; @returns eax Index of the first zero bit.

af062818b47340eef15700d2f0211576ba3506eevboxsync; @returns eax -1 if no clear bit was found.

af062818b47340eef15700d2f0211576ba3506eevboxsync; @param rcx pvBitmap Pointer to the bitmap.

af062818b47340eef15700d2f0211576ba3506eevboxsync; @param edx cBits The number of bits in the bitmap. Multiple of 32.

af062818b47340eef15700d2f0211576ba3506eevboxsync;

af062818b47340eef15700d2f0211576ba3506eevboxsyncBEGINPROC_EXPORTED ASMBitFirstClear

af062818b47340eef15700d2f0211576ba3506eevboxsync

af062818b47340eef15700d2f0211576ba3506eevboxsync ;if (cBits)

af062818b47340eef15700d2f0211576ba3506eevboxsync or edx, edx

af062818b47340eef15700d2f0211576ba3506eevboxsync jz short .failed

af062818b47340eef15700d2f0211576ba3506eevboxsync ;{

af062818b47340eef15700d2f0211576ba3506eevboxsync push rdi

af062818b47340eef15700d2f0211576ba3506eevboxsync

af062818b47340eef15700d2f0211576ba3506eevboxsync ; asm {...}

af062818b47340eef15700d2f0211576ba3506eevboxsync mov rdi, rcx ; rdi = start of scasd

af062818b47340eef15700d2f0211576ba3506eevboxsync mov ecx, edx

af062818b47340eef15700d2f0211576ba3506eevboxsync add ecx, 31 ; 32 bit aligned

af062818b47340eef15700d2f0211576ba3506eevboxsync shr ecx, 5 ; number of dwords to scan.

af062818b47340eef15700d2f0211576ba3506eevboxsync mov rdx, rdi ; rdx = saved pvBitmap

af062818b47340eef15700d2f0211576ba3506eevboxsync mov eax, 0ffffffffh

af062818b47340eef15700d2f0211576ba3506eevboxsync repe scasd ; Scan for the first dword with any clear bit.

je .failed_restore

; find the bit in question

lea rdi, [rdi - 4] ; one step back.

xor eax, [rdi] ; eax = NOT [rdi]

sub rdi, rdx

shl edi, 3 ; calc bit offset.

mov ecx, 0ffffffffh

bsf ecx, eax

add ecx, edi

mov eax, ecx

; return success

pop rdi

ret

; failure

;}

;return -1;

.failed_restore:

pop rdi

ret

.failed:

mov eax, 0ffffffffh

ret

ENDPROC ASMBitFirstClear