mirror of
https://github.com/golang/go
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33 lines
948 B
Go
33 lines
948 B
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ppc64 ppc64le
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// +build linux
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package runtime
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import "unsafe"
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// On ppc64, Linux limits the user address space to 46 bits (see
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// TASK_SIZE_USER64 in the Linux kernel). This has grown over time,
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// so here we allow 48 bit addresses.
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//
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// In addition to the 16 bits taken from the top, we can take 3 from the
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// bottom, because node must be pointer-aligned, giving a total of 19 bits
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// of count.
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const (
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addrBits = 48
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cntBits = 64 - addrBits + 3
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)
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func lfstackPack(node *lfnode, cnt uintptr) uint64 {
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return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
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}
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func lfstackUnpack(val uint64) (node *lfnode, cnt uintptr) {
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node = (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
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cnt = uintptr(val & (1<<cntBits - 1))
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return
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}
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