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; $Id$
;; @file
; IPRT - No-CRT trunc - AMD64 & X86.
;
;
; Copyright (C) 2006-2022 Oracle Corporation
;
; This file is part of VirtualBox Open Source Edition (OSE), as
; available from http://www.virtualbox.org. This file is free software;
; you can redistribute it and/or modify it under the terms of the GNU
; General Public License (GPL) as published by the Free Software
; Foundation, in version 2 as it comes in the "COPYING" file of the
; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
; VirtualBox OSE 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.
;
%define RT_ASM_WITH_SEH64
%include "iprt/asmdefs.mac"
%include "iprt/x86.mac"
BEGINCODE
;;
; Round to truncated integer value.
; @returns 32-bit: st(0) 64-bit: xmm0
; @param rd 32-bit: [ebp + 8] 64-bit: xmm0
RT_NOCRT_BEGINPROC trunc
push xBP
SEH64_PUSH_xBP
mov xBP, xSP
SEH64_SET_FRAME_xBP 0
sub xSP, 10h
SEH64_ALLOCATE_STACK 10h
SEH64_END_PROLOGUE
;
; Load the value into st(0). This messes up SNaN values.
;
%ifdef RT_ARCH_AMD64
movsd [xSP], xmm0
fld qword [xSP]
%else
fld qword [xBP + xCB*2]
%endif
;
; Return immediately if NaN or infinity.
;
fxam
fstsw ax
test ax, X86_FSW_C0 ; C0 is set for NaN, Infinity and Empty register. The latter is not the case.
jz .input_ok
%ifdef RT_ARCH_AMD64
ffreep st0 ; return the xmm0 register value unchanged, as FLD changes SNaN to QNaN.
%endif
jmp .return_val
.input_ok:
;
; Make it truncate up by modifying the fpu control word.
;
fstcw [xBP - 10h]
mov eax, [xBP - 10h]
or eax, X86_FCW_RC_ZERO ; both bits set, so no need to clear anything first.
mov [xBP - 08h], eax
fldcw [xBP - 08h]
;
; Round ST(0) to integer.
;
frndint
;
; Restore the fpu control word and return.
;
fldcw [xBP - 10h]
%ifdef RT_ARCH_AMD64
fstp qword [xSP]
movsd xmm0, [xSP]
%endif
.return_val:
leave
ret
ENDPROC RT_NOCRT(trunc)
|
