forked from TrueCloudLab/tzhash
69 lines
2.2 KiB
Go
69 lines
2.2 KiB
Go
// Copyright (c) 2009 The Go Authors. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// +build 386 amd64 amd64p32
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package tz
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const (
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bitOSXSAVE = 1 << 27
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bitAVX = 1 << 28
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bitAVX2 = 1 << 5
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)
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func setFeatures() {
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maxID, _, _, _ := cpuid(0, 0)
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if maxID < 1 {
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return
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}
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_, _, ecx1, _ := cpuid(1, 0)
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hasOSXSAVE = isSet(ecx1, bitOSXSAVE)
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osSupportsAVX := false
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if hasOSXSAVE {
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eax, _ := xgetbv()
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osSupportsAVX = isSet(eax, 1<<1) && isSet(eax, 1<<2)
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}
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hasAVX = isSet(ecx1, bitAVX) && osSupportsAVX
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if maxID < 7 {
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return
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}
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_, ebx7, _, _ := cpuid(7, 0)
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hasAVX2 = isSet(ebx7, bitAVX2) && osSupportsAVX
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}
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func isSet(hwc uint32, value uint32) bool {
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return hwc&value != 0
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}
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func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
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func xgetbv() (eax, edx uint32)
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