Line data    Source code

       1             : /*  GRAPHITE2 LICENSING
       2             : 
       3             :     Copyright 2011, SIL International
       4             :     All rights reserved.
       5             : 
       6             :     This library is free software; you can redistribute it and/or modify
       7             :     it under the terms of the GNU Lesser General Public License as published
       8             :     by the Free Software Foundation; either version 2.1 of License, or
       9             :     (at your option) any later version.
      10             : 
      11             :     This program is distributed in the hope that it will be useful,
      12             :     but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             :     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14             :     Lesser General Public License for more details.
      15             : 
      16             :     You should also have received a copy of the GNU Lesser General Public
      17             :     License along with this library in the file named "LICENSE".
      18             :     If not, write to the Free Software Foundation, 51 Franklin Street,
      19             :     Suite 500, Boston, MA 02110-1335, USA or visit their web page on the
      20             :     internet at http://www.fsf.org/licenses/lgpl.html.
      21             : 
      22             : Alternatively, the contents of this file may be used under the terms of the
      23             : Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public
      24             : License, as published by the Free Software Foundation, either version 2
      25             : of the License or (at your option) any later version.
      26             : */
      27             : 
      28             : /*
      29             : Description:
      30             :     A set of fast template based decoders for decoding values of any C integer
      31             :     type up to long int size laid out with most significant byte first or least
      32             :     significant byte first (aka big endian or little endian).  These are CPU
      33             :     byte order agnostic and will function the same regardless of the CPUs native
      34             :     byte order.
      35             : 
      36             :     Being template based means if the either le or be class is not used then
      37             :     template code of unused functions will not be instantiated by the compiler
      38             :     and thus shouldn't cause any overhead.
      39             : */
      40             : 
      41             : #include <cstddef>
      42             : 
      43             : #pragma once
      44             : 
      45             : 
      46             : class be
      47             : {
      48             :     template<int S>
      49           0 :     inline static unsigned long int _peek(const unsigned char * p) {
      50           0 :         return _peek<S/2>(p) << (S/2)*8 | _peek<S/2>(p+S/2);
      51             :     }
      52             : public:
      53             :     template<typename T>
      54           0 :     inline static T peek(const void * p) {
      55           0 :         return T(_peek<sizeof(T)>(static_cast<const unsigned char *>(p)));
      56             :     }
      57             : 
      58             :     template<typename T>
      59           0 :     inline static T read(const unsigned char * &p) {
      60           0 :         const T r = T(_peek<sizeof(T)>(p)); 
      61           0 :         p += sizeof r;
      62           0 :         return r;
      63             :     }
      64             :     
      65             :     template<typename T>
      66           0 :     inline static T swap(const T x) {
      67           0 :         return T(_peek<sizeof(T)>(reinterpret_cast<const unsigned char *>(&x)));
      68             :     }
      69             : 
      70             :     template<typename T>
      71           0 :     inline static void skip(const unsigned char * &p, size_t n=1) {
      72           0 :         p += sizeof(T)*n;
      73           0 :     }
      74             : };
      75             : 
      76             : template<>
      77           0 : inline unsigned long int be::_peek<1>(const unsigned char * p) { return *p; }
      78             : 
      79             : 
      80             : class le 
      81             : {
      82             :     template<int S>
      83             :     inline static unsigned long int _peek(const unsigned char * p) {
      84             :         return _peek<S/2>(p) | _peek<S/2>(p+S/2)  << (S/2)*8;
      85             :     }
      86             : public:
      87             :     template<typename T>
      88             :     inline static T peek(const void * p) {
      89             :         return T(_peek<sizeof(T)>(static_cast<const unsigned char *>(p)));
      90             :     }
      91             : 
      92             :     template<typename T>
      93             :     inline static T read(const unsigned char * &p) {
      94             :         const T r = T(_peek<sizeof(T)>(p)); 
      95             :         p += sizeof r;
      96             :         return r;
      97             :     }
      98             :     
      99             :     template<typename T>
     100             :     inline static T swap(const T x) {
     101             :         return T(_peek<sizeof(T)>(reinterpret_cast<const unsigned char *>(&x)));
     102             :     }
     103             : 
     104             :     template<typename T>
     105             :     inline static void skip(const unsigned char * &p, size_t n=1) {
     106             :         p += sizeof(T)*n;
     107             :     }
     108             : };
     109             : 
     110             : template<>
     111             : inline unsigned long int le::_peek<1>(const unsigned char * p) { return *p; }
     112             :