github.com/miolini/go@v0.0.0-20160405192216-fca68c8cb408/src/runtime/lfstack_darwin_arm64.go (about)

     1  // Copyright 2014 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime
     6  
     7  import "unsafe"
     8  
     9  // In addition to the 16 bits taken from the top, we can take 3 from the
    10  // bottom, because node must be pointer-aligned, giving a total of 19 bits
    11  // of count.
    12  const (
    13  	addrBits = 48
    14  	cntBits  = 64 - addrBits + 3
    15  )
    16  
    17  func lfstackPack(node *lfnode, cnt uintptr) uint64 {
    18  	return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
    19  }
    20  
    21  func lfstackUnpack(val uint64) (node *lfnode, cnt uintptr) {
    22  	node = (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
    23  	cnt = uintptr(val & (1<<cntBits - 1))
    24  	return
    25  }