github.com/mitghi/x@v0.0.0-20191206171256-71e86edf750d/pointers/base.go (about)

     1  /* MIT License
     2  *
     3  * Copyright (c) 2018 Mike Taghavi <mitghi[at]gmail.com>
     4  *
     5  * Permission is hereby granted, free of charge, to any person obtaining a copy
     6  * of this software and associated documentation files (the "Software"), to deal
     7  * in the Software without restriction, including without limitation the rights
     8  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     9  * copies of the Software, and to permit persons to whom the Software is
    10  * furnished to do so, subject to the following conditions:
    11  * The above copyright notice and this permission notice shall be included in all
    12  * copies or substantial portions of the Software.
    13  *
    14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    17  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    19  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    20  * SOFTWARE.
    21   */
    22  
    23  // packge pointers provide facilities for working with
    24  // pointers and atomics.
    25  package pointers
    26  
    27  import (
    28  	"errors"
    29  	"unsafe"
    30  )
    31  
    32  /**
    33  * TODO
    34  * . extend to cover 64bit spare bits ( 19 bits )
    35  **/
    36  
    37  const (
    38  	ArchADDRSIZE = 32 << uintptr(^uintptr(0)>>63)
    39  	ArchWORDSIZE = ArchADDRSIZE >> 3
    40  	ArchMAXTAG   = ArchWORDSIZE - 1
    41  	ArchPTRMASK  = ^uintptr((ArchADDRSIZE >> 5) + 1)
    42  )
    43  
    44  var (
    45  	EPTRINVAL  error = errors.New("pointer: invalid.")
    46  	EPTRINVALT error = errors.New("pointer: invalid tag.")
    47  )
    48  
    49  var (
    50  	_PTR_         unsafe.Pointer
    51  	_INTERFACE_   interface{}
    52  	ArchPTRSIZE   uintptr = unsafe.Sizeof(_PTR_)
    53  	sizeINTERFACE uintptr = unsafe.Sizeof(_INTERFACE_)
    54  )