util.go raw

   1  // Copyright 2016 Google Inc.  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 uuid
   6  
   7  import (
   8  	"io"
   9  )
  10  
  11  // randomBits completely fills slice b with random data.
  12  func randomBits(b []byte) {
  13  	if _, err := io.ReadFull(rander, b); err != nil {
  14  		panic(err.Error()) // rand should never fail
  15  	}
  16  }
  17  
  18  // xvalues returns the value of a byte as a hexadecimal digit or 255.
  19  var xvalues = [256]byte{
  20  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  21  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  22  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  23  	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 255, 255, 255, 255, 255, 255,
  24  	255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  25  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  26  	255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  27  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  28  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  29  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  30  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  31  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  32  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  33  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  34  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  35  	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
  36  }
  37  
  38  // xtob converts hex characters x1 and x2 into a byte.
  39  func xtob(x1, x2 byte) (byte, bool) {
  40  	b1 := xvalues[x1]
  41  	b2 := xvalues[x2]
  42  	return (b1 << 4) | b2, b1 != 255 && b2 != 255
  43  }
  44