| 1 | /* $Id: fma.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
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| 2 | /** @file
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| 3 | * IPRT - No-CRT - fma().
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2022-2023 Oracle and/or its affiliates.
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| 8 | *
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| 9 | * This file is part of VirtualBox base platform packages, as
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| 10 | * available from https://www.virtualbox.org.
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| 11 | *
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| 12 | * This program is free software; you can redistribute it and/or
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| 13 | * modify it under the terms of the GNU General Public License
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| 14 | * as published by the Free Software Foundation, in version 3 of the
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| 15 | * License.
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| 16 | *
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| 17 | * This program is distributed in the hope that it will be useful, but
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| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | * General Public License for more details.
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| 21 | *
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| 22 | * You should have received a copy of the GNU General Public License
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| 23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | *
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| 25 | * The contents of this file may alternatively be used under the terms
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| 26 | * of the Common Development and Distribution License Version 1.0
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| 27 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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| 28 | * in the VirtualBox distribution, in which case the provisions of the
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| 29 | * CDDL are applicable instead of those of the GPL.
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| 30 | *
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| 31 | * You may elect to license modified versions of this file under the
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| 32 | * terms and conditions of either the GPL or the CDDL or both.
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| 33 | *
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| 34 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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| 35 | */
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| 36 |
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| 37 |
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| 38 | /*********************************************************************************************************************************
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| 39 | * Header Files *
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| 40 | *********************************************************************************************************************************/
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| 41 | #define IPRT_NO_CRT_FOR_3RD_PARTY
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| 42 | #include "internal/nocrt.h"
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| 43 | #include <iprt/nocrt/math.h>
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| 44 | #include <iprt/assertcompile.h>
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| 45 | #if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
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| 46 | # include <iprt/asm-amd64-x86.h>
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| 47 | # include <iprt/x86.h>
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| 48 | #endif
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| 49 | #include <softfloat.h>
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| 50 |
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| 51 |
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| 52 | /*********************************************************************************************************************************
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| 53 | * External Symbols *
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| 54 | *********************************************************************************************************************************/
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| 55 | DECLASM(double) rtNoCrtMathFma3(double rdFactor1, double rdFactor2, double rdAddend);
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| 56 | DECLASM(double) rtNoCrtMathFma4(double rdFactor1, double rdFactor2, double rdAddend);
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| 57 |
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| 58 |
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| 59 | #undef fma
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| 60 | double RT_NOCRT(fma)(double rdFactor1, double rdFactor2, double rdAddend)
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| 61 | {
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| 62 | /*
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| 63 | * We prefer using native FMA instructions when available.
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| 64 | */
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| 65 | #if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
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| 66 | typedef enum { kCpuDetect = 0, kCpuWithFma3, kCpuWithFma4, kCpuWithoutFma } CPUFMASUPPORT;
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| 67 | static CPUFMASUPPORT volatile s_enmSup = kCpuDetect;
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| 68 | CPUFMASUPPORT enmSup = s_enmSup;
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| 69 | if (enmSup != kCpuDetect)
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| 70 | { }
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| 71 | else
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| 72 | {
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| 73 | if (ASMCpuId_ECX(1) & X86_CPUID_FEATURE_ECX_FMA)
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| 74 | enmSup = kCpuWithFma3;
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| 75 | else if (ASMCpuId_ECX(UINT32_C(0x80000001)) & X86_CPUID_AMD_FEATURE_ECX_FMA4)
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| 76 | enmSup = kCpuWithFma4;
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| 77 | else
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| 78 | enmSup = kCpuWithoutFma;
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| 79 | s_enmSup = enmSup;
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| 80 | }
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| 81 | if (enmSup == kCpuWithFma3)
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| 82 | return rtNoCrtMathFma3(rdFactor1, rdFactor2, rdAddend);
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| 83 | if (enmSup == kCpuWithFma4)
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| 84 | return rtNoCrtMathFma4(rdFactor1, rdFactor2, rdAddend);
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| 85 | #endif
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| 86 |
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| 87 | /*
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| 88 | * Fall back on SoftFloat.
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| 89 | */
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| 90 | AssertCompile(sizeof(rdFactor1) == sizeof(RTFLOAT64U));
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| 91 | softfloat_state_t State = SOFTFLOAT_STATE_INIT_DEFAULTS(); /** @todo init from MXCSR/FCW */
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| 92 | union { RTFLOAT64U Iprt; float64_t SoftFloat; } uFactor1, uFactor2, uAddend, uResult;
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| 93 | uFactor1.Iprt.rd = rdFactor1;
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| 94 | uFactor2.Iprt.rd = rdFactor2;
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| 95 | uAddend.Iprt.rd = rdAddend;
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| 96 | uResult.SoftFloat = f64_mulAdd(uFactor1.SoftFloat, uFactor2.SoftFloat, uAddend.SoftFloat, &State);
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| 97 | return uResult.Iprt.rd;
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| 98 | }
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| 99 | RT_ALIAS_AND_EXPORT_NOCRT_SYMBOL(fma);
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| 100 |
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