740 lines
36 KiB
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740 lines
36 KiB
HTML
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<head><title>35 Foreign.Ptr</title>
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<meta name="date" content="2010-07-20 13:11:00" />
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</head><body
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>
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<!--l. 1--><div class="crosslinks"><p class="noindent">[<a
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href="haskellch36.html" >next</a>] [<a
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href="haskellch34.html" >prev</a>] [<a
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href="haskellch34.html#tailhaskellch34.html" >prev-tail</a>] [<a
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href="#tailhaskellch35.html">tail</a>] [<a
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href="haskellpa2.html#haskellch35.html" >up</a>] </p></div>
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<h2 class="chapterHead"><span class="titlemark">Chapter 35</span><br /><a
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id="x43-30600035"></a><span
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class="pcrr7t-">Foreign.Ptr</span></h2>
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<div class="quote">
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<div class="verbatim" id="verbatim-449">
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module Foreign.Ptr (
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 <br />    Ptr,  nullPtr,  castPtr,  plusPtr,  alignPtr,  minusPtr,  FunPtr,
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 <br />    nullFunPtr,  castFunPtr,  castFunPtrToPtr,  castPtrToFunPtr,
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 <br />    freeHaskellFunPtr,  IntPtr,  ptrToIntPtr,  intPtrToPtr,  WordPtr,
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 <br />    ptrToWordPtr,  wordPtrToPtr
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 <br />  ) where
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</div>
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<p class="noindent"></div>
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<p class="noindent"> The module <span
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class="pcrr7t-">Foreign.Ptr </span>provides typed pointers to foreign entities. We distinguish two kinds of pointers:
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pointers to data and pointers to functions. It is understood that these two kinds of pointers may be represented
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differently as they may be references to data and text segments, respectively.
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<h3 class="sectionHead"><span class="titlemark">35.1 </span> <a
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id="x43-30700035.1"></a>Data pointers </h3>
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<p class="noindent">
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<dl> <dt class="haddockdesc">
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<!--tex4ht:inline--><div class="tabular"> <table id="TBL-569" class="tabular"
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cellspacing="0" cellpadding="0" rules="groups"
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><colgroup id="TBL-569-1g"><col
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id="TBL-569-1" /></colgroup><tr
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style="vertical-align:baseline;" id="TBL-569-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-569-1-1"
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class="td11"><span
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class="pcrb7t-">data</span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> a </span></td></tr></table> </div> <dd class="haddockdesc">
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A value of type <span
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class="pcrr7t-">Ptr</span><span
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class="pcrr7t-"> a </span>represents a pointer to an object, or an array of objects, which may be
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marshalled to or from Haskell values of type <span
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class="pcrr7t-">a</span>.
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<p class="noindent"> The type <span
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class="pcrr7t-">a </span>will often be an instance of class <span
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class="pcrr7t-">Foreign.Storable.Storable </span>which provides
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the marshalling operations. However this is not essential, and you can provide your own operations to
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access the pointer. For example you might write small foreign functions to get or set the fields of a C
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<span
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class="pcrr7t-">struct</span>.
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</dl>
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<p class="noindent">
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<dl> <dt class="haddockdesc">
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<!--tex4ht:inline--><div class="tabular"> <table id="TBL-570" class="tabular"
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cellspacing="0" cellpadding="0" rules="groups"
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><colgroup id="TBL-570-1g"><col
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id="TBL-570-1" /></colgroup><tr
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style="vertical-align:baseline;" id="TBL-570-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-570-1-1"
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class="td11"><span
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class="pcrb7t-">instance</span><span
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class="pcrb7t-"> Eq</span><span
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class="pcrb7t-"> (Ptr</span><span
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class="pcrb7t-"> a) </span></td>
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</tr><tr
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style="vertical-align:baseline;" id="TBL-570-2-"><td style="white-space:nowrap; text-align:left;" id="TBL-570-2-1"
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class="td11"><span
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class="pcrb7t-">instance</span><span
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class="pcrb7t-"> Ord</span><span
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class="pcrb7t-"> (Ptr</span><span
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class="pcrb7t-"> a) </span></td>
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</tr><tr
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style="vertical-align:baseline;" id="TBL-570-3-"><td style="white-space:nowrap; text-align:left;" id="TBL-570-3-1"
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class="td11"><span
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class="pcrb7t-">instance</span><span
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class="pcrb7t-"> Show</span><span
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class="pcrb7t-"> (Ptr</span><span
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class="pcrb7t-"> a) </span></td>
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</tr><tr
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style="vertical-align:baseline;" id="TBL-570-4-"><td style="white-space:nowrap; text-align:left;" id="TBL-570-4-1"
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class="td11"><span
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class="pcrb7t-">instance</span><span
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class="pcrb7t-"> Storable</span><span
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class="pcrb7t-"> (Ptr</span><span
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class="pcrb7t-"> a) </span></td>
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</tr></table> </div> <dd class="haddockdesc">
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</dl>
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<p class="noindent">
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<dl><dt class="haddockdesc">
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<!--tex4ht:inline--><div class="tabular"> <table id="TBL-571" class="tabular"
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cellspacing="0" cellpadding="0" rules="groups"
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><colgroup id="TBL-571-1g"><col
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id="TBL-571-1" /></colgroup><tr
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style="vertical-align:baseline;" id="TBL-571-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-571-1-1"
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class="td11"><span
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class="pcrb7t-">nullPtr</span><span
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class="pcrb7t-"> ::</span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> a </span></td></tr></table> </div> <dd class="haddockdesc">
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The constant <span
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class="pcrr7t-">nullPtr</span><a
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id="dx43-307001"></a> contains a distinguished value of <span
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class="pcrr7t-">Ptr</span><a
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id="dx43-307002"></a> that is not associated with a valid
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memory location.
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</dl>
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<p class="noindent">
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<dl> <dt class="haddockdesc">
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<!--tex4ht:inline--><div class="tabular"> <table id="TBL-572" class="tabular"
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cellspacing="0" cellpadding="0" rules="groups"
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><colgroup id="TBL-572-1g"><col
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id="TBL-572-1" /></colgroup><tr
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style="vertical-align:baseline;" id="TBL-572-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-572-1-1"
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class="td11"><span
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class="pcrb7t-">castPtr</span><span
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class="pcrb7t-"> ::</span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> a</span><span
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class="pcrb7t-"> -></span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> b </span></td></tr></table> </div> <dd class="haddockdesc">
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The <span
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class="pcrr7t-">castPtr</span><a
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id="dx43-307003"></a> function casts a pointer from one type to another.
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</dl>
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<p class="noindent">
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<dl> <dt class="haddockdesc">
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<!--tex4ht:inline--><div class="tabular"> <table id="TBL-573" class="tabular"
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cellspacing="0" cellpadding="0" rules="groups"
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><colgroup id="TBL-573-1g"><col
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id="TBL-573-1" /></colgroup><tr
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style="vertical-align:baseline;" id="TBL-573-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-573-1-1"
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class="td11"><span
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class="pcrb7t-">plusPtr</span><span
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class="pcrb7t-"> ::</span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> a</span><span
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class="pcrb7t-"> -></span><span
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class="pcrb7t-"> Int</span><span
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class="pcrb7t-"> -></span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> b </span></td>
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</tr></table> </div> <dd class="haddockdesc">
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Advances the given address by the given offset in bytes.
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</dl>
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<p class="noindent">
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<dl> <dt class="haddockdesc">
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<!--tex4ht:inline--><div class="tabular"> <table id="TBL-574" class="tabular"
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cellspacing="0" cellpadding="0" rules="groups"
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><colgroup id="TBL-574-1g"><col
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id="TBL-574-1" /></colgroup><tr
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style="vertical-align:baseline;" id="TBL-574-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-574-1-1"
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class="td11"><span
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class="pcrb7t-">alignPtr</span><span
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class="pcrb7t-"> ::</span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> a</span><span
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class="pcrb7t-"> -></span><span
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class="pcrb7t-"> Int</span><span
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class="pcrb7t-"> -></span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> a </span></td>
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</tr></table> </div> <dd class="haddockdesc">
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Given an arbitrary address and an alignment constraint, <span
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class="pcrr7t-">alignPtr</span><a
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id="dx43-307004"></a> yields the next higher address that
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fulfills the alignment constraint. An alignment constraint <span
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class="pcrr7t-">x </span>is fulfilled by any address divisible by <span
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class="pcrr7t-">x</span>.
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This operation is idempotent.
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</dl>
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<p class="noindent">
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<dl> <dt class="haddockdesc">
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<!--tex4ht:inline--><div class="tabular"> <table id="TBL-575" class="tabular"
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cellspacing="0" cellpadding="0" rules="groups"
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><colgroup id="TBL-575-1g"><col
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id="TBL-575-1" /></colgroup><tr
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style="vertical-align:baseline;" id="TBL-575-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-575-1-1"
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class="td11"><span
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class="pcrb7t-">minusPtr</span><span
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class="pcrb7t-"> ::</span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> a</span><span
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class="pcrb7t-"> -></span><span
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class="pcrb7t-"> Ptr</span><span
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class="pcrb7t-"> b</span><span
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class="pcrb7t-"> -></span><span
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class="pcrb7t-"> Int </span></td></tr></table> </div> <dd class="haddockdesc">
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Computes the offset required to get from the second to the first argument. We have
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<p class="noindent">
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<div class="quote">
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<div class="verbatim" id="verbatim-450">
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 p2 == p1 ‘plusPtr‘ (p2 ‘minusPtr‘ p1)
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</div>
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<p class="noindent"></div>
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</dl>
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<p class="noindent">
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<h3 class="sectionHead"><span class="titlemark">35.2 </span> <a
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id="x43-30800035.2"></a>Function pointers </h3>
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<p class="noindent">
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<dl> <dt class="haddockdesc">
|
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<!--tex4ht:inline--><div class="tabular"> <table id="TBL-576" class="tabular"
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cellspacing="0" cellpadding="0" rules="groups"
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><colgroup id="TBL-576-1g"><col
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id="TBL-576-1" /></colgroup><tr
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style="vertical-align:baseline;" id="TBL-576-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-576-1-1"
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class="td11"><span
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class="pcrb7t-">data</span><span
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class="pcrb7t-"> FunPtr</span><span
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class="pcrb7t-"> a </span></td></tr></table> </div> <dd class="haddockdesc">
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A value of type <span
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class="pcrr7t-">FunPtr</span><span
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class="pcrr7t-"> a </span>is a pointer to a function callable from foreign code. The type <span
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class="pcrr7t-">a </span>will
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normally be a <span
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class="ptmri7t-">foreign type</span>, a function type with zero or more arguments where
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<ul class="itemize1">
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<li class="itemize">the argument types are <span
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class="ptmri7t-">marshallable foreign types</span>, i.e. <span
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class="pcrr7t-">Char</span><a
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id="dx43-308001"></a>,
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<span
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class="pcrr7t-">Int</span><a
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id="dx43-308002"></a>, <span
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class="pcrr7t-">Double</span><a
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id="dx43-308003"></a>, <span
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class="pcrr7t-">Float</span><a
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id="dx43-308004"></a>, <span
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class="pcrr7t-">Bool</span><a
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id="dx43-308005"></a>, <span
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class="pcrr7t-">Data.Int.Int8</span>, <span
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class="pcrr7t-">Data.Int.Int16</span>, <span
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class="pcrr7t-">Data.Int.Int32</span>,
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<span
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class="pcrr7t-">Data.Int.Int64</span>, <span
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class="pcrr7t-">Data.Word.Word8</span>, <span
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class="pcrr7t-">Data.Word.Word16</span>, <span
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class="pcrr7t-">Data.Word.Word32</span>,
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<span
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class="pcrr7t-">Data.Word.Word64</span>, <span
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class="pcrr7t-">Ptr</span><span
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class="pcrr7t-"> a</span>, <span
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class="pcrr7t-">FunPtr</span><span
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class="pcrr7t-"> a</span>, <span
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class="pcrr7t-">Foreign.StablePtr.StablePtr</span><span
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class="pcrr7t-"> a </span>or a
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renaming of any of these using <span
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class="pcrr7t-">newtype</span>.
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</li>
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<li class="itemize">the return type is either a marshallable foreign type or has the form <span
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class="pcrr7t-">IO</span><span
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class="pcrr7t-"> t </span>where <span
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class="pcrr7t-">t </span>is a
|
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marshallable foreign type or <span
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class="pcrr7t-">()</span>.
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</li></ul>
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<p class="noindent"> A value of type <span
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class="pcrr7t-">FunPtr</span><span
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class="pcrr7t-"> a </span>may be a pointer to a foreign function, either returned by another foreign function
|
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or imported with a a static address import like
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<p class="noindent">
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<div class="quote">
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<div class="verbatim" id="verbatim-451">
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 foreign import ccall "stdlib.h &free"
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 <br />   p_free :: FunPtr (Ptr a -> IO ())
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</div>
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<p class="noindent"></div>
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<p class="noindent"> or a pointer to a Haskell function created using a <span
|
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class="ptmri7t-">wrapper </span>stub declared to produce a <span
|
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class="pcrr7t-">FunPtr</span><a
|
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id="dx43-308006"></a> of the correct
|
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type. For example:
|
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<p class="noindent">
|
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<div class="quote">
|
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|
|
|
|
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<div class="verbatim" id="verbatim-452">
|
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 type Compare = Int -> Int -> Bool
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 <br /> foreign import ccall "wrapper"
|
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 <br />   mkCompare :: Compare -> IO (FunPtr Compare)
|
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</div>
|
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<p class="noindent"></div>
|
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<p class="noindent"> Calls to wrapper stubs like <span
|
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class="pcrr7t-">mkCompare </span>allocate storage, which should be released with
|
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<span
|
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class="pcrr7t-">Foreign.Ptr.freeHaskellFunPtr </span>when no longer required.
|
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<p class="noindent"> To convert <span
|
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class="pcrr7t-">FunPtr</span><a
|
|
id="dx43-308007"></a> values to corresponding Haskell functions, one can define a <span
|
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class="ptmri7t-">dynamic </span>stub for the specific
|
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foreign type, e.g.
|
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<p class="noindent">
|
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<div class="quote">
|
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|
|
|
|
|
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<div class="verbatim" id="verbatim-453">
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 type IntFunction = CInt -> IO ()
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 <br /> foreign import ccall "dynamic"
|
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 <br />   mkFun :: FunPtr IntFunction -> IntFunction
|
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</div>
|
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<p class="noindent"></div>
|
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</dl>
|
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<p class="noindent">
|
|
<dl><dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-577" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-577-1g"><col
|
|
id="TBL-577-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-577-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-577-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Eq</span><span
|
|
class="pcrb7t-"> (FunPtr</span><span
|
|
class="pcrb7t-"> a) </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-577-2-"><td style="white-space:nowrap; text-align:left;" id="TBL-577-2-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Ord</span><span
|
|
class="pcrb7t-"> (FunPtr</span><span
|
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class="pcrb7t-"> a) </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-577-3-"><td style="white-space:nowrap; text-align:left;" id="TBL-577-3-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Show</span><span
|
|
class="pcrb7t-"> (FunPtr</span><span
|
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class="pcrb7t-"> a) </span></td>
|
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</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-577-4-"><td style="white-space:nowrap; text-align:left;" id="TBL-577-4-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Storable</span><span
|
|
class="pcrb7t-"> (FunPtr</span><span
|
|
class="pcrb7t-"> a) </span></td>
|
|
</tr></table> </div> <dd class="haddockdesc">
|
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</dl>
|
|
<p class="noindent">
|
|
<dl><dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-578" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-578-1g"><col
|
|
id="TBL-578-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-578-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-578-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">nullFunPtr</span><span
|
|
class="pcrb7t-"> ::</span><span
|
|
class="pcrb7t-"> FunPtr</span><span
|
|
class="pcrb7t-"> a </span></td></tr></table> </div> <dd class="haddockdesc">
|
|
The constant <span
|
|
class="pcrr7t-">nullFunPtr</span><a
|
|
id="dx43-308008"></a> contains a distinguished value of <span
|
|
class="pcrr7t-">FunPtr</span><a
|
|
id="dx43-308009"></a> that is not associated with a
|
|
valid memory location.
|
|
</dl>
|
|
<p class="noindent">
|
|
<dl> <dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-579" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-579-1g"><col
|
|
id="TBL-579-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-579-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-579-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">castFunPtr</span><span
|
|
class="pcrb7t-"> ::</span><span
|
|
class="pcrb7t-"> FunPtr</span><span
|
|
class="pcrb7t-"> a</span><span
|
|
class="pcrb7t-"> -></span><span
|
|
class="pcrb7t-"> FunPtr</span><span
|
|
class="pcrb7t-"> b </span></td></tr></table> </div> <dd class="haddockdesc">
|
|
Casts a <span
|
|
class="pcrr7t-">FunPtr</span><a
|
|
id="dx43-308010"></a> to a <span
|
|
class="pcrr7t-">FunPtr</span><a
|
|
id="dx43-308011"></a> of a different type.
|
|
</dl>
|
|
<p class="noindent">
|
|
<dl> <dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-580" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-580-1g"><col
|
|
id="TBL-580-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-580-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-580-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">castFunPtrToPtr</span><span
|
|
class="pcrb7t-"> ::</span><span
|
|
class="pcrb7t-"> FunPtr</span><span
|
|
class="pcrb7t-"> a</span><span
|
|
class="pcrb7t-"> -></span><span
|
|
class="pcrb7t-"> Ptr</span><span
|
|
class="pcrb7t-"> b </span></td></tr></table> </div> <dd class="haddockdesc">
|
|
Casts a <span
|
|
class="pcrr7t-">FunPtr</span><a
|
|
id="dx43-308012"></a> to a <span
|
|
class="pcrr7t-">Ptr</span><a
|
|
id="dx43-308013"></a>.
|
|
<p class="noindent"> <span
|
|
class="ptmri7t-">Note: </span>this is valid only on architectures where data and function pointers range over the same set of
|
|
addresses, and should only be used for bindings to external libraries whose interface already relies on
|
|
this assumption.
|
|
</dl>
|
|
<p class="noindent">
|
|
|
|
|
|
|
|
<dl> <dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-581" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-581-1g"><col
|
|
id="TBL-581-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-581-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-581-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">castPtrToFunPtr</span><span
|
|
class="pcrb7t-"> ::</span><span
|
|
class="pcrb7t-"> Ptr</span><span
|
|
class="pcrb7t-"> a</span><span
|
|
class="pcrb7t-"> -></span><span
|
|
class="pcrb7t-"> FunPtr</span><span
|
|
class="pcrb7t-"> b </span></td></tr></table> </div> <dd class="haddockdesc">
|
|
Casts a <span
|
|
class="pcrr7t-">Ptr</span><a
|
|
id="dx43-308014"></a> to a <span
|
|
class="pcrr7t-">FunPtr</span><a
|
|
id="dx43-308015"></a>.
|
|
<p class="noindent"> <span
|
|
class="ptmri7t-">Note: </span>this is valid only on architectures where data and function pointers range over the same set of
|
|
addresses, and should only be used for bindings to external libraries whose interface already relies on
|
|
this assumption.
|
|
</dl>
|
|
<p class="noindent">
|
|
<dl> <dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-582" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-582-1g"><col
|
|
id="TBL-582-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-582-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-582-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">freeHaskellFunPtr</span><span
|
|
class="pcrb7t-"> ::</span><span
|
|
class="pcrb7t-"> FunPtr</span><span
|
|
class="pcrb7t-"> a</span><span
|
|
class="pcrb7t-"> -></span><span
|
|
class="pcrb7t-"> IO</span><span
|
|
class="pcrb7t-"> () </span></td>
|
|
</tr></table> </div> <dd class="haddockdesc">
|
|
Release the storage associated with the given <span
|
|
class="pcrr7t-">FunPtr</span><a
|
|
id="dx43-308016"></a>, which must have been obtained from a wrapper
|
|
stub. This should be called whenever the return value from a foreign import wrapper function is no
|
|
longer required; otherwise, the storage it uses will leak.
|
|
</dl>
|
|
<p class="noindent">
|
|
<h3 class="sectionHead"><span class="titlemark">35.3 </span> <a
|
|
id="x43-30900035.3"></a>Integral types with lossless conversion to and from pointers </h3>
|
|
<p class="noindent">
|
|
<dl> <dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-583" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-583-1g"><col
|
|
id="TBL-583-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-583-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-583-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">data</span><span
|
|
class="pcrb7t-"> IntPtr </span></td></tr></table> </div> <dd class="haddockdesc">
|
|
A signed integral type that can be losslessly converted to and from <span
|
|
class="pcrr7t-">Ptr</span>. This type is also compatible
|
|
with the C99 type <span
|
|
class="pcrr7t-">intptr_t</span>, and can be marshalled to and from that type safely.
|
|
</dl>
|
|
<p class="noindent">
|
|
<dl> <dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-584" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-584-1g"><col
|
|
id="TBL-584-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-584-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Bounded</span><span
|
|
class="pcrb7t-"> IntPtr </span></td></tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-2-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-2-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Enum</span><span
|
|
class="pcrb7t-"> IntPtr</span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-3-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-3-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Eq</span><span
|
|
class="pcrb7t-"> IntPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-4-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-4-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Integral</span><span
|
|
class="pcrb7t-"> IntPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-5-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-5-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Num</span><span
|
|
class="pcrb7t-"> IntPtr </span></td></tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-6-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-6-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Ord</span><span
|
|
class="pcrb7t-"> IntPtr</span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-7-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-7-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Read</span><span
|
|
class="pcrb7t-"> IntPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-8-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-8-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Real</span><span
|
|
class="pcrb7t-"> IntPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-9-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-9-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Show</span><span
|
|
class="pcrb7t-"> IntPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-10-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-10-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Storable</span><span
|
|
class="pcrb7t-"> IntPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-584-11-"><td style="white-space:nowrap; text-align:left;" id="TBL-584-11-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Bits</span><span
|
|
class="pcrb7t-"> IntPtr </span></td>
|
|
</tr></table> </div> <dd class="haddockdesc">
|
|
</dl>
|
|
<p class="noindent">
|
|
<dl><dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-585" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-585-1g"><col
|
|
id="TBL-585-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-585-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-585-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">ptrToIntPtr</span><span
|
|
class="pcrb7t-"> ::</span><span
|
|
class="pcrb7t-"> Ptr</span><span
|
|
class="pcrb7t-"> a</span><span
|
|
class="pcrb7t-"> -></span><span
|
|
class="pcrb7t-"> IntPtr </span></td>
|
|
</tr></table> </div> <dd class="haddockdesc">
|
|
casts a <span
|
|
class="pcrr7t-">Ptr </span>to an <span
|
|
class="pcrr7t-">IntPtr</span>
|
|
</dl>
|
|
|
|
|
|
|
|
<p class="noindent">
|
|
<dl><dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-586" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-586-1g"><col
|
|
id="TBL-586-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-586-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-586-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">intPtrToPtr</span><span
|
|
class="pcrb7t-"> ::</span><span
|
|
class="pcrb7t-"> IntPtr</span><span
|
|
class="pcrb7t-"> -></span><span
|
|
class="pcrb7t-"> Ptr</span><span
|
|
class="pcrb7t-"> a </span></td></tr></table> </div> <dd class="haddockdesc">
|
|
casts an <span
|
|
class="pcrr7t-">IntPtr </span>to a <span
|
|
class="pcrr7t-">Ptr</span>
|
|
</dl>
|
|
<p class="noindent">
|
|
<dl><dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-587" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-587-1g"><col
|
|
id="TBL-587-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-587-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-587-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">data</span><span
|
|
class="pcrb7t-"> WordPtr </span></td></tr></table> </div> <dd class="haddockdesc">
|
|
An unsigned integral type that can be losslessly converted to and from <span
|
|
class="pcrr7t-">Ptr</span>. This type is also
|
|
compatible with the C99 type <span
|
|
class="pcrr7t-">uintptr_t</span>, and can be marshalled to and from that type safely.
|
|
</dl>
|
|
<p class="noindent">
|
|
<dl> <dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-588" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-588-1g"><col
|
|
id="TBL-588-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-588-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Bounded</span><span
|
|
class="pcrb7t-"> WordPtr </span></td></tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-2-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-2-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Enum</span><span
|
|
class="pcrb7t-"> WordPtr</span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-3-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-3-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Eq</span><span
|
|
class="pcrb7t-"> WordPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-4-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-4-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Integral</span><span
|
|
class="pcrb7t-"> WordPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-5-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-5-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Num</span><span
|
|
class="pcrb7t-"> WordPtr </span></td></tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-6-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-6-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Ord</span><span
|
|
class="pcrb7t-"> WordPtr</span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-7-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-7-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Read</span><span
|
|
class="pcrb7t-"> WordPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-8-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-8-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Real</span><span
|
|
class="pcrb7t-"> WordPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-9-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-9-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Show</span><span
|
|
class="pcrb7t-"> WordPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-10-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-10-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Storable</span><span
|
|
class="pcrb7t-"> WordPtr </span></td>
|
|
</tr><tr
|
|
style="vertical-align:baseline;" id="TBL-588-11-"><td style="white-space:nowrap; text-align:left;" id="TBL-588-11-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">instance</span><span
|
|
class="pcrb7t-"> Bits</span><span
|
|
class="pcrb7t-"> WordPtr </span></td>
|
|
</tr></table> </div> <dd class="haddockdesc">
|
|
</dl>
|
|
<p class="noindent">
|
|
<dl><dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-589" class="tabular"
|
|
cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-589-1g"><col
|
|
id="TBL-589-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-589-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-589-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">ptrToWordPtr</span><span
|
|
class="pcrb7t-"> ::</span><span
|
|
class="pcrb7t-"> Ptr</span><span
|
|
class="pcrb7t-"> a</span><span
|
|
class="pcrb7t-"> -></span><span
|
|
class="pcrb7t-"> WordPtr </span></td>
|
|
</tr></table> </div> <dd class="haddockdesc">
|
|
casts a <span
|
|
class="pcrr7t-">Ptr </span>to a <span
|
|
class="pcrr7t-">WordPtr</span>
|
|
</dl>
|
|
<p class="noindent">
|
|
<dl><dt class="haddockdesc">
|
|
<!--tex4ht:inline--><div class="tabular"> <table id="TBL-590" class="tabular"
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cellspacing="0" cellpadding="0" rules="groups"
|
|
><colgroup id="TBL-590-1g"><col
|
|
id="TBL-590-1" /></colgroup><tr
|
|
style="vertical-align:baseline;" id="TBL-590-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-590-1-1"
|
|
class="td11"><span
|
|
class="pcrb7t-">wordPtrToPtr</span><span
|
|
class="pcrb7t-"> ::</span><span
|
|
class="pcrb7t-"> WordPtr</span><span
|
|
class="pcrb7t-"> -></span><span
|
|
class="pcrb7t-"> Ptr</span><span
|
|
class="pcrb7t-"> a </span></td></tr></table> </div> <dd class="haddockdesc">
|
|
casts a <span
|
|
class="pcrr7t-">WordPtr </span>to a <span
|
|
class="pcrr7t-">Ptr</span>
|
|
</dl>
|
|
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