js/src/jstypes.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8 ** File:                jstypes.h
   9 ** Description: Definitions of NSPR's basic types
  10 **
  11 ** Prototypes and macros used to make up for deficiencies in ANSI environments
  12 ** that we have found.
  13 **
  14 ** Since we do not wrap <stdlib.h> and all the other standard headers, authors
  15 ** of portable code will not know in general that they need these definitions.
  16 ** Instead of requiring these authors to find the dependent uses in their code
  17 ** and take the following steps only in those C files, we take steps once here
  18 ** for all C files.
  19 **/
  20
  21 #ifndef jstypes_h
  22 #define jstypes_h
  23
  24 #include "mozilla/Attributes.h"
  25 #include "mozilla/Casting.h"
  26 #include "mozilla/Types.h"
  27
  28 #include <stddef.h>
  29 #include <stdint.h>
  30
  31 // jstypes.h is (or should be!) included by every file in SpiderMonkey.
  32 // js-config.h also should be included by every file. So include it here.
  33 // XXX: including it in js/RequiredDefines.h should be a better option, since
  34 // that is by definition the header file that should be included in all
  35 // SpiderMonkey code.  However, Gecko doesn't do this!  See bug 909576.
  36 #include "js-config.h"
  37
  38 /*
  39  * The linkage of JS API functions differs depending on whether the file is
  40  * used within the JS library or not. Any source file within the JS
  41  * interpreter should define EXPORT_JS_API whereas any client of the library
  42  * should not. STATIC_JS_API is used to build JS as a static library.
  43  */
  44 #if defined(STATIC_JS_API)
  45 #  define JS_PUBLIC_API
  46 #  define JS_PUBLIC_DATA
  47 #  define JS_FRIEND_API
  48 #  define JS_FRIEND_DATA
  49 #elif defined(EXPORT_JS_API) || defined(STATIC_EXPORTABLE_JS_API)
  50 #  define JS_PUBLIC_API MOZ_EXPORT
  51 #  define JS_PUBLIC_DATA MOZ_EXPORT
  52 #  define JS_FRIEND_API MOZ_EXPORT
  53 #  define JS_FRIEND_DATA MOZ_EXPORT
  54 #else
  55 #  define JS_PUBLIC_API MOZ_IMPORT_API
  56 #  define JS_PUBLIC_DATA MOZ_IMPORT_DATA
  57 #  define JS_FRIEND_API MOZ_IMPORT_API
  58 #  define JS_FRIEND_DATA MOZ_IMPORT_DATA
  59 #endif
  60
  61 #if defined(_MSC_VER) && defined(_M_IX86)
  62 #  define JS_FASTCALL __fastcall
  63 #elif defined(__GNUC__) && defined(__i386__)
  64 #  define JS_FASTCALL __attribute__((fastcall))
  65 #else
  66 #  define JS_FASTCALL
  67 #  define JS_NO_FASTCALL
  68 #endif
  69
  70 /***********************************************************************
  71 ** MACROS:      JS_BEGIN_MACRO
  72 **              JS_END_MACRO
  73 ** DESCRIPTION:
  74 **      Macro body brackets so that macros with compound statement definitions
  75 **      behave syntactically more like functions when called.
  76 ***********************************************************************/
  77 #define JS_BEGIN_MACRO do {
  78 #define JS_END_MACRO \
  79   }                  \
  80   while (0)
  81
  82 /***********************************************************************
  83 ** FUNCTIONS:   Bit
  84 **              BitMask
  85 ** DESCRIPTION:
  86 ** Bit masking functions.  XXX n must be <= 31 to be portable
  87 ***********************************************************************/
  88 namespace js {
  89 constexpr uint32_t Bit(uint32_t n) { return uint32_t(1) << n; }
  90
  91 constexpr uint32_t BitMask(uint32_t n) { return Bit(n) - 1; }
  92 }  // namespace js
  93
  94 /***********************************************************************
  95 ** FUNCTIONS:   HowMany
  96 **              RoundUp
  97 **              RoundDown
  98 **              Round
  99 ** DESCRIPTION:
 100 **      Commonly used functions for operations on compatible types.
 101 ***********************************************************************/
 102 namespace js {
 103 constexpr size_t HowMany(size_t x, size_t y) { return (x + y - 1) / y; }
 104
 105 constexpr size_t RoundUp(size_t x, size_t y) { return HowMany(x, y) * y; }
 106
 107 constexpr size_t RoundDown(size_t x, size_t y) { return (x / y) * y; }
 108
 109 constexpr size_t Round(size_t x, size_t y) { return ((x + y / 2) / y) * y; }
 110 }  // namespace js
 111
 112 #if (defined(__SIZEOF_POINTER__) && __SIZEOF_POINTER__ == 8) || \
 113     (defined(UINTPTR_MAX) && UINTPTR_MAX == 0xFFFFFFFFFFFFFFFFu)
 114 #  define JS_BITS_PER_WORD 64
 115 #else
 116 #  define JS_BITS_PER_WORD 32
 117 #endif
 118
 119 static_assert(sizeof(void*) == 8 ? JS_BITS_PER_WORD == 64
 120                                  : JS_BITS_PER_WORD == 32,
 121               "preprocessor and compiler must agree");
 122
 123 /***********************************************************************
 124 ** MACROS:      JS_FUNC_TO_DATA_PTR
 125 **              JS_DATA_TO_FUNC_PTR
 126 ** DESCRIPTION:
 127 **      Macros to convert between function and data pointers of the same
 128 **      size. Use them like this:
 129 **
 130 **      JSGetterOp nativeGetter;
 131 **      JSObject* scriptedGetter;
 132 **      ...
 133 **      scriptedGetter = JS_FUNC_TO_DATA_PTR(JSObject*, nativeGetter);
 134 **      ...
 135 **      nativeGetter = JS_DATA_TO_FUNC_PTR(JSGetterOp, scriptedGetter);
 136 **
 137 ***********************************************************************/
 138
 139 #define JS_FUNC_TO_DATA_PTR(type, fun) (mozilla::BitwiseCast<type>(fun))
 140 #define JS_DATA_TO_FUNC_PTR(type, ptr) (mozilla::BitwiseCast<type>(ptr))
 141
 142 #endif /* jstypes_h */