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<title>Foreign/StablePtr.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>{-# OPTIONS_GHC -XNoImplicitPrelude #-}</span>
<a name="line-2"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span>
<a name="line-3"></a><span class='hs-comment'>-- |</span>
<a name="line-4"></a><span class='hs-comment'>-- Module : Foreign.StablePtr</span>
<a name="line-5"></a><span class='hs-comment'>-- Copyright : (c) The University of Glasgow 2001</span>
<a name="line-6"></a><span class='hs-comment'>-- License : BSD-style (see the file libraries/base/LICENSE)</span>
<a name="line-7"></a><span class='hs-comment'>-- </span>
<a name="line-8"></a><span class='hs-comment'>-- Maintainer : ffi@haskell.org</span>
<a name="line-9"></a><span class='hs-comment'>-- Stability : provisional</span>
<a name="line-10"></a><span class='hs-comment'>-- Portability : portable</span>
<a name="line-11"></a><span class='hs-comment'>--</span>
<a name="line-12"></a><span class='hs-comment'>-- This module is part of the Foreign Function Interface (FFI) and will usually</span>
<a name="line-13"></a><span class='hs-comment'>-- be imported via the module "Foreign".</span>
<a name="line-14"></a><span class='hs-comment'>--</span>
<a name="line-15"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span>
<a name="line-16"></a>
<a name="line-17"></a>
<a name="line-18"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Foreign</span><span class='hs-varop'>.</span><span class='hs-conid'>StablePtr</span>
<a name="line-19"></a> <span class='hs-layout'>(</span> <span class='hs-comment'>-- * Stable references to Haskell values</span>
<a name="line-20"></a> <span class='hs-conid'>StablePtr</span> <span class='hs-comment'>-- abstract</span>
<a name="line-21"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>newStablePtr</span> <span class='hs-comment'>-- :: a -> IO (StablePtr a)</span>
<a name="line-22"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>deRefStablePtr</span> <span class='hs-comment'>-- :: StablePtr a -> IO a</span>
<a name="line-23"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>freeStablePtr</span> <span class='hs-comment'>-- :: StablePtr a -> IO ()</span>
<a name="line-24"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>castStablePtrToPtr</span> <span class='hs-comment'>-- :: StablePtr a -> Ptr ()</span>
<a name="line-25"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>castPtrToStablePtr</span> <span class='hs-comment'>-- :: Ptr () -> StablePtr a</span>
<a name="line-26"></a> <span class='hs-layout'>,</span> <span class='hs-comment'>-- ** The C-side interface</span>
<a name="line-27"></a>
<a name="line-28"></a> <span class='hs-comment'>-- $cinterface</span>
<a name="line-29"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-30"></a>
<a name="line-31"></a><span class='hs-cpp'>#ifdef __GLASGOW_HASKELL__</span>
<a name="line-32"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>GHC</span><span class='hs-varop'>.</span><span class='hs-conid'>Stable</span>
<a name="line-33"></a><span class='hs-cpp'>#endif</span>
<a name="line-34"></a>
<a name="line-35"></a><span class='hs-cpp'>#ifdef __HUGS__</span>
<a name="line-36"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Hugs</span><span class='hs-varop'>.</span><span class='hs-conid'>StablePtr</span>
<a name="line-37"></a><span class='hs-cpp'>#endif</span>
<a name="line-38"></a>
<a name="line-39"></a><span class='hs-cpp'>#ifdef __NHC__</span>
<a name="line-40"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>NHC</span><span class='hs-varop'>.</span><span class='hs-conid'>FFI</span>
<a name="line-41"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>StablePtr</span>
<a name="line-42"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>newStablePtr</span>
<a name="line-43"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>deRefStablePtr</span>
<a name="line-44"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>freeStablePtr</span>
<a name="line-45"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>castStablePtrToPtr</span>
<a name="line-46"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>castPtrToStablePtr</span>
<a name="line-47"></a> <span class='hs-layout'>)</span>
<a name="line-48"></a><span class='hs-cpp'>#endif</span>
<a name="line-49"></a>
<a name="line-50"></a><span class='hs-comment'>-- $cinterface</span>
<a name="line-51"></a><span class='hs-comment'>--</span>
<a name="line-52"></a><span class='hs-comment'>-- The following definition is available to C programs inter-operating with</span>
<a name="line-53"></a><span class='hs-comment'>-- Haskell code when including the header @HsFFI.h@.</span>
<a name="line-54"></a><span class='hs-comment'>--</span>
<a name="line-55"></a><span class='hs-comment'>-- > typedef void *HsStablePtr; /* C representation of a StablePtr */</span>
<a name="line-56"></a><span class='hs-comment'>--</span>
<a name="line-57"></a><span class='hs-comment'>-- Note that no assumptions may be made about the values representing stable</span>
<a name="line-58"></a><span class='hs-comment'>-- pointers. In fact, they need not even be valid memory addresses. The only</span>
<a name="line-59"></a><span class='hs-comment'>-- guarantee provided is that if they are passed back to Haskell land, the</span>
<a name="line-60"></a><span class='hs-comment'>-- function 'deRefStablePtr' will be able to reconstruct the</span>
<a name="line-61"></a><span class='hs-comment'>-- Haskell value referred to by the stable pointer.</span>
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