67e81eb826f3e7aa8548fcd614533d328e6ade47
[packages/old-time.git] / Foreign / Marshal / Alloc.hs
1 {-# OPTIONS_GHC -fno-implicit-prelude #-}
2 -----------------------------------------------------------------------------
3 -- |
4 -- Module : Foreign.Marshal.Alloc
5 -- Copyright : (c) The FFI task force 2001
6 -- License : BSD-style (see the file libraries/base/LICENSE)
7 --
8 -- Maintainer : ffi@haskell.org
9 -- Stability : provisional
10 -- Portability : portable
11 --
12 -- Marshalling support: basic routines for memory allocation
13 --
14 -----------------------------------------------------------------------------
15
16 module Foreign.Marshal.Alloc (
17 -- * Memory allocation
18 -- ** Local allocation
19 alloca, -- :: Storable a => (Ptr a -> IO b) -> IO b
20 allocaBytes, -- :: Int -> (Ptr a -> IO b) -> IO b
21
22 -- ** Dynamic allocation
23 malloc, -- :: Storable a => IO (Ptr a)
24 mallocBytes, -- :: Int -> IO (Ptr a)
25
26 realloc, -- :: Storable b => Ptr a -> IO (Ptr b)
27 reallocBytes, -- :: Ptr a -> Int -> IO (Ptr a)
28
29 free, -- :: Ptr a -> IO ()
30 finalizerFree -- :: FinalizerPtr a
31 ) where
32
33 import Data.Maybe
34 import Foreign.Ptr ( Ptr, nullPtr, FunPtr )
35 import Foreign.C.Types ( CSize )
36 import Foreign.Storable ( Storable(sizeOf) )
37
38 #ifdef __GLASGOW_HASKELL__
39 import Foreign.ForeignPtr ( FinalizerPtr )
40 import GHC.IOBase
41 import GHC.Real
42 import GHC.Ptr
43 import GHC.Err
44 import GHC.Base
45 import GHC.Num
46 #elif defined(__NHC__)
47 import NHC.FFI ( FinalizerPtr, CInt(..) )
48 import IO ( bracket )
49 #else
50 import Control.Exception ( bracket )
51 #endif
52
53 #ifdef __HUGS__
54 import Hugs.ForeignPtr ( FinalizerPtr )
55 #endif
56
57
58 -- exported functions
59 -- ------------------
60
61 -- |Allocate a block of memory that is sufficient to hold values of type
62 -- @a@. The size of the area allocated is determined by the 'sizeOf'
63 -- method from the instance of 'Storable' for the appropriate type.
64 --
65 -- The memory may be deallocated using 'free' or 'finalizerFree' when
66 -- no longer required.
67 --
68 malloc :: Storable a => IO (Ptr a)
69 malloc = doMalloc undefined
70 where
71 doMalloc :: Storable b => b -> IO (Ptr b)
72 doMalloc dummy = mallocBytes (sizeOf dummy)
73
74 -- |Allocate a block of memory of the given number of bytes.
75 -- The block of memory is sufficiently aligned for any of the basic
76 -- foreign types that fits into a memory block of the allocated size.
77 --
78 -- The memory may be deallocated using 'free' or 'finalizerFree' when
79 -- no longer required.
80 --
81 mallocBytes :: Int -> IO (Ptr a)
82 mallocBytes size = failWhenNULL "malloc" (_malloc (fromIntegral size))
83
84 -- |@'alloca' f@ executes the computation @f@, passing as argument
85 -- a pointer to a temporarily allocated block of memory sufficient to
86 -- hold values of type @a@.
87 --
88 -- The memory is freed when @f@ terminates (either normally or via an
89 -- exception), so the pointer passed to @f@ must /not/ be used after this.
90 --
91 alloca :: Storable a => (Ptr a -> IO b) -> IO b
92 alloca = doAlloca undefined
93 where
94 doAlloca :: Storable a' => a' -> (Ptr a' -> IO b') -> IO b'
95 doAlloca dummy = allocaBytes (sizeOf dummy)
96
97 -- |@'allocaBytes' n f@ executes the computation @f@, passing as argument
98 -- a pointer to a temporarily allocated block of memory of @n@ bytes.
99 -- The block of memory is sufficiently aligned for any of the basic
100 -- foreign types that fits into a memory block of the allocated size.
101 --
102 -- The memory is freed when @f@ terminates (either normally or via an
103 -- exception), so the pointer passed to @f@ must /not/ be used after this.
104 --
105 #ifdef __GLASGOW_HASKELL__
106 allocaBytes :: Int -> (Ptr a -> IO b) -> IO b
107 allocaBytes (I# size) action = IO $ \ s ->
108 case newPinnedByteArray# size s of { (# s, mbarr# #) ->
109 case unsafeFreezeByteArray# mbarr# s of { (# s, barr# #) ->
110 let addr = Ptr (byteArrayContents# barr#) in
111 case action addr of { IO action ->
112 case action s of { (# s, r #) ->
113 case touch# barr# s of { s ->
114 (# s, r #)
115 }}}}}
116 #else
117 allocaBytes :: Int -> (Ptr a -> IO b) -> IO b
118 allocaBytes size = bracket (mallocBytes size) free
119 #endif
120
121 -- |Resize a memory area that was allocated with 'malloc' or 'mallocBytes'
122 -- to the size needed to store values of type @b@. The returned pointer
123 -- may refer to an entirely different memory area, but will be suitably
124 -- aligned to hold values of type @b@. The contents of the referenced
125 -- memory area will be the same as of the original pointer up to the
126 -- minimum of the original size and the size of values of type @b@.
127 --
128 -- If the argument to 'realloc' is 'nullPtr', 'realloc' behaves like
129 -- 'malloc'.
130 --
131 realloc :: Storable b => Ptr a -> IO (Ptr b)
132 realloc = doRealloc undefined
133 where
134 doRealloc :: Storable b' => b' -> Ptr a' -> IO (Ptr b')
135 doRealloc dummy ptr = let
136 size = fromIntegral (sizeOf dummy)
137 in
138 failWhenNULL "realloc" (_realloc ptr size)
139
140 -- |Resize a memory area that was allocated with 'malloc' or 'mallocBytes'
141 -- to the given size. The returned pointer may refer to an entirely
142 -- different memory area, but will be sufficiently aligned for any of the
143 -- basic foreign types that fits into a memory block of the given size.
144 -- The contents of the referenced memory area will be the same as of
145 -- the original pointer up to the minimum of the original size and the
146 -- given size.
147 --
148 -- If the pointer argument to 'reallocBytes' is 'nullPtr', 'reallocBytes'
149 -- behaves like 'malloc'. If the requested size is 0, 'reallocBytes'
150 -- behaves like 'free'.
151 --
152 reallocBytes :: Ptr a -> Int -> IO (Ptr a)
153 reallocBytes ptr 0 = do free ptr; return nullPtr
154 reallocBytes ptr size =
155 failWhenNULL "realloc" (_realloc ptr (fromIntegral size))
156
157 -- |Free a block of memory that was allocated with 'malloc',
158 -- 'mallocBytes', 'realloc', 'reallocBytes', 'Foreign.Marshal.Utils.new'
159 -- or any of the @new@/X/ functions in "Foreign.Marshal.Array" or
160 -- "Foreign.C.String".
161 --
162 free :: Ptr a -> IO ()
163 free = _free
164
165
166 -- auxilliary routines
167 -- -------------------
168
169 -- asserts that the pointer returned from the action in the second argument is
170 -- non-null
171 --
172 failWhenNULL :: String -> IO (Ptr a) -> IO (Ptr a)
173 failWhenNULL name f = do
174 addr <- f
175 if addr == nullPtr
176 #ifdef __GLASGOW_HASKELL__
177 then ioException (IOError Nothing ResourceExhausted name
178 "out of memory" Nothing)
179 #else
180 then ioError (userError (name++": out of memory"))
181 #endif
182 else return addr
183
184 -- basic C routines needed for memory allocation
185 --
186 foreign import ccall unsafe "stdlib.h malloc" _malloc :: CSize -> IO (Ptr a)
187 foreign import ccall unsafe "stdlib.h realloc" _realloc :: Ptr a -> CSize -> IO (Ptr b)
188 foreign import ccall unsafe "stdlib.h free" _free :: Ptr a -> IO ()
189
190 -- | A pointer to a foreign function equivalent to 'free', which may be
191 -- used as a finalizer (cf 'Foreign.ForeignPtr.ForeignPtr') for storage
192 -- allocated with 'malloc', 'mallocBytes', 'realloc' or 'reallocBytes'.
193 foreign import ccall unsafe "stdlib.h &free" finalizerFree :: FinalizerPtr a