michael@0: /*  GRAPHITE2 LICENSING
michael@0: 
michael@0:     Copyright 2011, SIL International
michael@0:     All rights reserved.
michael@0: 
michael@0:     This library is free software; you can redistribute it and/or modify
michael@0:     it under the terms of the GNU Lesser General Public License as published
michael@0:     by the Free Software Foundation; either version 2.1 of License, or
michael@0:     (at your option) any later version.
michael@0: 
michael@0:     This program is distributed in the hope that it will be useful,
michael@0:     but WITHOUT ANY WARRANTY; without even the implied warranty of
michael@0:     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
michael@0:     Lesser General Public License for more details.
michael@0: 
michael@0:     You should also have received a copy of the GNU Lesser General Public
michael@0:     License along with this library in the file named "LICENSE".
michael@0:     If not, write to the Free Software Foundation, 51 Franklin Street,
michael@0:     Suite 500, Boston, MA 02110-1335, USA or visit their web page on the
michael@0:     internet at http://www.fsf.org/licenses/lgpl.html.
michael@0: 
michael@0: Alternatively, the contents of this file may be used under the terms of the
michael@0: Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public
michael@0: License, as published by the Free Software Foundation, either version 2
michael@0: of the License or (at your option) any later version.
michael@0: */
michael@0: 
michael@0: /*
michael@0: Description:
michael@0:     A set of fast template based decoders for decoding values of any C integer
michael@0:     type up to long int size laid out with most significant byte first or least
michael@0:     significant byte first (aka big endian or little endian).  These are CPU
michael@0:     byte order agnostic and will function the same regardless of the CPUs native
michael@0:     byte order.
michael@0: 
michael@0:     Being template based means if the either le or be class is not used then
michael@0:     template code of unused functions will not be instantiated by the compiler
michael@0:     and thus shouldn't cause any overhead.
michael@0: */
michael@0: 
michael@0: #include <cstddef>
michael@0: 
michael@0: #pragma once
michael@0: 
michael@0: 
michael@0: class be
michael@0: {
michael@0:     template<int S>
michael@0:     inline static unsigned long int _peek(const unsigned char * p) {
michael@0:         return _peek<S/2>(p) << (S/2)*8 | _peek<S/2>(p+S/2);
michael@0:     }
michael@0: public:
michael@0:     template<typename T>
michael@0:     inline static T peek(const void * p) {
michael@0:         return T(_peek<sizeof(T)>(static_cast<const unsigned char *>(p)));
michael@0:     }
michael@0: 
michael@0:     template<typename T>
michael@0:     inline static T read(const unsigned char * &p) {
michael@0:         const T r = T(_peek<sizeof(T)>(p)); 
michael@0:         p += sizeof r;
michael@0:         return r;
michael@0:     }
michael@0:     
michael@0:     template<typename T>
michael@0:     inline static T swap(const T x) {
michael@0:         return T(_peek<sizeof(T)>(reinterpret_cast<const unsigned char *>(&x)));
michael@0:     }
michael@0: 
michael@0:     template<typename T>
michael@0:     inline static void skip(const unsigned char * &p, size_t n=1) {
michael@0:         p += sizeof(T)*n;
michael@0:     }
michael@0: };
michael@0: 
michael@0: template<>
michael@0: inline unsigned long int be::_peek<1>(const unsigned char * p) { return *p; }
michael@0: 
michael@0: 
michael@0: class le 
michael@0: {
michael@0:     template<int S>
michael@0:     inline static unsigned long int _peek(const unsigned char * p) {
michael@0:         return _peek<S/2>(p) | _peek<S/2>(p+S/2)  << (S/2)*8;
michael@0:     }
michael@0: public:
michael@0:     template<typename T>
michael@0:     inline static T peek(const void * p) {
michael@0:         return T(_peek<sizeof(T)>(static_cast<const unsigned char *>(p)));
michael@0:     }
michael@0: 
michael@0:     template<typename T>
michael@0:     inline static T read(const unsigned char * &p) {
michael@0:         const T r = T(_peek<sizeof(T)>(p)); 
michael@0:         p += sizeof r;
michael@0:         return r;
michael@0:     }
michael@0:     
michael@0:     template<typename T>
michael@0:     inline static T swap(const T x) {
michael@0:         return T(_peek<sizeof(T)>(reinterpret_cast<const unsigned char *>(&x)));
michael@0:     }
michael@0: 
michael@0:     template<typename T>
michael@0:     inline static void skip(const unsigned char * &p, size_t n=1) {
michael@0:         p += sizeof(T)*n;
michael@0:     }
michael@0: };
michael@0: 
michael@0: template<>
michael@0: inline unsigned long int le::_peek<1>(const unsigned char * p) { return *p; }
michael@0: