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Diffstat (limited to 'src/VBox/Runtime/common/math/exp2.asm')
| -rw-r--r-- | src/VBox/Runtime/common/math/exp2.asm | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/math/exp2.asm b/src/VBox/Runtime/common/math/exp2.asm new file mode 100644 index 00000000..dc818135 --- /dev/null +++ b/src/VBox/Runtime/common/math/exp2.asm @@ -0,0 +1,117 @@ +; $Id: exp2.asm $ +;; @file +; IPRT - No-CRT exp2 - AMD64 & X86. +; + +; +; Copyright (C) 2022-2023 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 +; + + +%define RT_ASM_WITH_SEH64 +%include "iprt/asmdefs.mac" +%include "iprt/x86.mac" + +BEGINCODE + +;; +; Calculate two to the power of @a rd. +; +; @returns st(0) / xmm0 +; @param rd [rbp + 8] / xmm0 +RT_NOCRT_BEGINPROC exp2 + push xBP + SEH64_PUSH_xBP + mov xBP, xSP + SEH64_SET_FRAME_xBP 0 +%ifdef RT_ARCH_AMD64 + sub xSP, 10h + SEH64_ALLOCATE_STACK 10h +%endif + SEH64_END_PROLOGUE + + ; + ; Load the value into st(0). + ; +%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 + test ax, X86_FSW_C2 ; C2 is clear for NaN (and Empty) but set for Infinity. + jz .return_val2 + test ax, X86_FSW_C1 ; C1 = sign bit + jz .return_val2 ; Not sign, return +Inf. +%ifndef RT_ARCH_AMD64 + ffreep st0 +%endif + fldz ; Signed, so return zero as that's a good approximation for 2**-Inf. + jmp .return_val +.input_ok: + + ; + ; Split the job in two on the fraction and integer input parts. + ; + fld st0 ; Push a copy of the input on the stack. + frndint ; st0 = (int)input + fsub st1, st0 ; st1 = input - (int)input; i.e. st1 = fraction, st0 = integer. + fxch ; st0 = fraction, st1 = integer. + + ; 1. Calculate on the fraction. + f2xm1 ; st0 = 2**fraction - 1.0 + fld1 + faddp ; st0 = 2**fraction + + ; 2. Apply the integer power of two. + fscale ; st0 = result; st1 = integer part of input. + fstp st1 ; st0 = result; no st1. + +.return_val: +%ifdef RT_ARCH_AMD64 + fstp qword [xSP] + movsd xmm0, [xSP] +%endif +.return_val2: + leave + ret +ENDPROC RT_NOCRT(exp2) + |