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|
; $Id: ASMMultU64ByU32DivByU32.asm $
;; @file
; IPRT - Assembly Functions, ASMMultU64ByU32DivByU32.
;
;
; 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
;
%include "iprt/asmdefs.mac"
;;
; Multiple a 64-bit by a 32-bit integer and divide the result by a 32-bit integer
; using a 96 bit intermediate result.
;
; @returns (u64A * u32B) / u32C.
; @param u64A/rcx/rdi The 64-bit value.
; @param u32B/edx/esi The 32-bit value to multiple by A.
; @param u32C/r8d/edx The 32-bit value to divide A*B by.
;
; @cproto DECLASM(uint64_t) ASMMultU64ByU32DivByU32(uint64_t u64A, uint32_t u32B, uint32_t u32C);
;
RT_BEGINPROC ASMMultU64ByU32DivByU32
%if ARCH_BITS == 64
%ifdef ASM_CALL64_MSC
mov rax, rcx ; rax = u64A
mov r9d, edx ; should check the specs wrt to the high bits one day...
mov r8d, r8d ; be paranoid for the time being.
%else
mov rax, rdi ; rax = u64A
mov r9d, esi ; r9d = u32B
mov r8d, edx ; r8d = u32C
%endif
mul r9
div r8
%else ; 16 or 32 bit
;
; This implementation is converted from the GCC inline
; version of the code. Nothing additional has been done
; performance wise.
;
%if ARCH_BITS == 16
push bp
mov bp, sp
push eax ; push all return registers to preserve high value (paranoia)
push ebx
push ecx
push edx
%endif
push esi
push edi
%if ARCH_BITS == 16
%define u64A_Lo [bp + 4 + 04h]
%define u64A_Hi [bp + 4 + 08h]
%define u32B [bp + 4 + 0ch]
%define u32C [bp + 4 + 10h]
%else
%define u64A_Lo [esp + 04h + 08h]
%define u64A_Hi [esp + 08h + 08h]
%define u32B [esp + 0ch + 08h]
%define u32C [esp + 10h + 08h]
%endif
; Load parameters into registers.
mov eax, u64A_Lo
mov esi, u64A_Hi
mov ecx, u32B
mov edi, u32C
; The body, just like the in
mul ecx ; eax = u64Lo.lo = (u64A.lo * u32B).lo
; edx = u64Lo.hi = (u64A.lo * u32B).hi
xchg eax, esi ; esi = u64Lo.lo
; eax = u64A.hi
xchg edx, edi ; edi = u64Low.hi
; edx = u32C
xchg edx, ecx ; ecx = u32C
; edx = u32B
mul edx ; eax = u64Hi.lo = (u64A.hi * u32B).lo
; edx = u64Hi.hi = (u64A.hi * u32B).hi
add eax, edi ; u64Hi.lo += u64Lo.hi
adc edx, 0 ; u64Hi.hi += carry
div ecx ; eax = u64Hi / u32C
; edx = u64Hi % u32C
mov edi, eax ; edi = u64Result.hi = u64Hi / u32C
mov eax, esi ; eax = u64Lo.lo
div ecx ; u64Result.lo
mov edx, edi ; u64Result.hi
; epilogue
pop edi
pop esi
%if ARCH_BITS == 16
; DX:CX:BX:AX, where DX holds bits 15:0, CX bits 31:16, BX bits 47:32, and AX bits 63:48.
mov ax, [bp - 4*4] ; dx = bits 15:0
shr eax, 16
mov ax, [bp - 3*4] ; cx = bits 31:16
mov dx, [bp - 2*4] ; bx = bits 47:32
shr edx, 16
mov dx, [bp - 1*4] ; ax = bits 63:48
pop edx
pop ecx
pop ebx
pop eax
leave
%endif
%endif
ret
ENDPROC ASMMultU64ByU32DivByU32
|
