1// SPDX-License-Identifier: MIT OR MPL-2.0 OR LGPL-2.1-or-later OR GPL-2.0-or-later
2// Copyright 2011, SIL International, All rights reserved.
3/*
4Description:
5 A set of fast template based decoders for decoding values of any C integer
6 type up to long int size laid out with most significant byte first or least
7 significant byte first (aka big endian or little endian). These are CPU
8 byte order agnostic and will function the same regardless of the CPUs native
9 byte order.
10
11 Being template based means if the either le or be class is not used then
12 template code of unused functions will not be instantiated by the compiler
13 and thus shouldn't cause any overhead.
14*/
15
16#include <cstddef>
17
18#pragma once
19
20
21class be
22{
23 template<int S>
24 inline static unsigned long int _peek(const unsigned char * p) {
25 return _peek<S/2>(p) << (S/2)*8 | _peek<S/2>(p+S/2);
26 }
27public:
28 template<typename T>
29 inline static T peek(const void * p) {
30 return T(_peek<sizeof(T)>(static_cast<const unsigned char *>(p)));
31 }
32
33 template<typename T>
34 inline static T read(const unsigned char * &p) {
35 const T r = T(_peek<sizeof(T)>(p));
36 p += sizeof r;
37 return r;
38 }
39
40 template<typename T>
41 inline static T swap(const T x) {
42 return T(_peek<sizeof(T)>(reinterpret_cast<const unsigned char *>(&x)));
43 }
44
45 template<typename T>
46 inline static void skip(const unsigned char * &p, size_t n=1) {
47 p += sizeof(T)*n;
48 }
49};
50
51template<>
52inline unsigned long int be::_peek<1>(const unsigned char * p) { return *p; }
53
54
55class le
56{
57 template<int S>
58 inline static unsigned long int _peek(const unsigned char * p) {
59 return _peek<S/2>(p) | _peek<S/2>(p+S/2) << (S/2)*8;
60 }
61public:
62 template<typename T>
63 inline static T peek(const void * p) {
64 return T(_peek<sizeof(T)>(static_cast<const unsigned char *>(p)));
65 }
66
67 template<typename T>
68 inline static T read(const unsigned char * &p) {
69 const T r = T(_peek<sizeof(T)>(p));
70 p += sizeof r;
71 return r;
72 }
73
74 template<typename T>
75 inline static T swap(const T x) {
76 return T(_peek<sizeof(T)>(reinterpret_cast<const unsigned char *>(&x)));
77 }
78
79 template<typename T>
80 inline static void skip(const unsigned char * &p, size_t n=1) {
81 p += sizeof(T)*n;
82 }
83};
84
85template<>
86inline unsigned long int le::_peek<1>(const unsigned char * p) { return *p; }
87