forked from glenfe/boost.config
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathcstdint.qbk
146 lines (92 loc) · 5.6 KB
/
cstdint.qbk
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
[section:cstdint Standard Integer Types]
[section Overview]
The header [^[@../../../../boost/cstdint.hpp <boost/cstdint.hpp>]] provides the typedef's useful
for writing portable code that requires certain integer widths. All typedef's are in namespace boost.
The specifications for these types are based on the ISO/IEC 9899:1999 C Language standard header <stdint.h>.
The 64-bit types required by the C standard are ['not required] in the boost header,
and may not be supplied for all platforms/compilers, because [^long long] is not [yet] included in the C++ standard.
See [@../../test/cstdint_test.cpp cstdint_test.cpp] for a test program.
[endsect]
[section:rationale Rationale]
The organization of the Boost.Integer headers and classes is designed to take advantage of <stdint.h> types from the
1999 C standard without causing undefined behavior in terms of the 1998 C++ standard.
The header <boost/cstdint.hpp> makes the standard integer types safely available in namespace [^boost]
without placing any names in namespace [^std]. The intension is to complement rather than compete
with the C++ Standard Library. Should some future C++ standard include <stdint.h> and <cstdint>,
then <boost/cstdint.hpp> will continue to function, but will become redundant and may be safely deprecated.
Because these are boost headers, their names conform to boost header naming conventions rather than
C++ Standard Library header naming conventions.
[endsect]
[section:ce ['Caveat emptor]]
As an implementation artifact, certain C <limits.h> macro names may possibly be
visible to users of <boost/cstdint.hpp>. Don't use these macros; they are not part of
any Boost-specified interface. Use [^boost::integer_traits<>] or [^std::numeric_limits<>] instead.
As another implementation artifact, certain C <stdint.h> typedef names may possibly be visible
in the global namespace to users of <boost/cstdint.hpp>. Don't use these names, they are not part of
any Boost-specified interface. Use the respective names in namespace [^boost] instead.
[endsect]
[section Exact-width integer types]
The typedef [^int#_t], with # replaced by the width, designates a signed integer type of exactly # bits;
for example [^int8_t] denotes an 8-bit signed integer type. Similarly, the typedef [^uint#_t] designates an unsigned
integer type of exactly # bits.
These types are optional. However, if a platform supports integer types with widths of
8, 16, 32, 64, or any combination thereof, then <boost/cstdint.hpp> does provide the
corresponding typedefs.
The absence of int64_t and uint64_t is indicated by the macro `BOOST_NO_INT64_T`.
[endsect]
[section Minimum-width integer types]
The typedef [^int_least#_t], with # replaced by the width, designates a signed integer type with a width
of at least # bits, such that no signed integer type with lesser size has at least the specified width.
Thus, [^int_least32_t] denotes the smallest signed integer type with a width of at least 32 bits.
Similarly, the typedef name [^uint_least#_t] designates an unsigned integer type with a width of at least # bits,
such that no unsigned integer type with lesser size has at least the specified width.
The following minimum-width integer types are provided for all platforms:
* [^int_least8_t]
* [^int_least16_t]
* [^int_least32_t]
* [^uint_least8_t]
* [^uint_least16_t]
* [^uint_least32_t]
The following types are available only if, after including <boost/cstdint.hpp>, the macro BOOST_NO_INT64_T is not defined:
* [^int_least64_t]
* [^uint_least64_t]
All other minimum-width integer types are optional.
[endsect]
[section Fastest minimum-width integer types]
The typedef [^int_fast#_t], with # replaced by the width, designates the fastest signed integer type
with a width of at least # bits. Similarly, the typedef name [^uint_fast#_t] designates the fastest
unsigned integer type with a width of at least # bits.
There is no guarantee that these types are fastest for all purposes. In any case, however, they satisfy
the signedness and width requirements.
The following fastest minimum-width integer types are provided for all platforms:
* [^int_fast8_t]
* [^int_fast16_t]
* [^int_fast32_t]
* [^uint_fast8_t]
* [^uint_fast16_t]
* [^uint_fast32_t]
The following types are available only if, after including <boost/cstdint.hpp>, the macro BOOST_NO_INT64_T is not defined:
* [^int_fast64_t]
* [^uint_fast64_t]
All other fastest minimum-width integer types are optional.
[endsect]
[section Greatest-width integer types]
The typedef [^intmax_t ]designates a signed integer type capable of representing any value of any signed integer type.
The typedef [^uintmax_t] designates an unsigned integer type capable of representing any value of any unsigned integer type.
These types are provided for all platforms.
[endsect]
[section Integer Constant Macros]
The following macros are always defined after inclusion of this header, these allow
integer constants of at least the specified width to be declared:
INT8_C, UINT8_C, INT16_C, UINT16_C, INT32_C, UINT32_C, INTMAX_C, UINTMAX_C.
The macros INT64_C and UINT64_C are also defined if the the macro BOOST_NO_INT64_T is not defined.
The C99 macro __STDC_CONSTANT_MACROS is also defined as an artifact of the implementation.
For example:
#include <boost/cstdint.hpp>
// Here the constant 0x1FFFFFFFF has the correct suffix applied:
static const boost::uint64_t c = INT64_C(0x1FFFFFFFF);
[endsect]
[section:intptr Integers for Storing Pointers]
The typedefs [^intptr_t] and [^uintptr_t] defined signed and unsigned integers respectively each capable of storing a pointer. The macro [^BOOST_HAS_INTPTR_T] is set when these types are available.
[endsect]
[endsect]