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1 %//////////////////////////////////////////////////////////////////////////////
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2 %
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3 % Copyright (c) 2007,2013 Daniel Adler <dadler@uni-goettingen.de>,
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4 % Tassilo Philipp <tphilipp@potion-studios.com>
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5 %
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6 % Permission to use, copy, modify, and distribute this software for any
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7 % purpose with or without fee is hereby granted, provided that the above
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8 % copyright notice and this permission notice appear in all copies.
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9 %
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10 % THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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11 % WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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12 % MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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13 % ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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14 % WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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15 % ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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16 % OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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17 %
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18 %//////////////////////////////////////////////////////////////////////////////
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19
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20 \newpage
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21 \section{\emph{Dyncallback} C library API}
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22
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23 This library extends \product{dyncall} with function callback support, allowing
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24 the user to dynamically create a callback object that can be called directly,
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25 or passed to functions expecting a function-pointer as argument.\\
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26 \\
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27 Invoking a \product{dyncallback} calls into a user-defined unified handler that
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28 permits iteration and thus dynamic handling over the called-back-function's
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29 parameters.\\
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30 \\
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31 The flexibility is constrained by the set of supported types, though.\\
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32 \\
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33 For style conventions and supported types, see \product{dyncall} API section.
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34 In order to use \product{dyncallback}, include {\tt "dyncall\_callback.h"}.
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35
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36 \subsection{Callback Object}
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37
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38 The \emph{Callback Object} is the core component to this library.
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39
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40 \paragraph{Types}
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41
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42 \begin{lstlisting}[language=c]
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43 typedef struct DCCallback DCCallback;
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44 \end{lstlisting}
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45
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46 \paragraph{Details}
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47 The \emph{Callback Object} is an object that mimics a fully typed function
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48 call to another function (a generic callback handler, in this case).\\
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49 \\
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50 This means, a pointer to this object is passed to a function accepting a pointer
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51 to a callback function \emph{as the very callback function pointer itself}.
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52 Or, if called directly, cast a pointer to this object to a function pointer and
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53 issue a call.
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54
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55
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56 \subsection{Allocation}
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57
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58 \paragraph{Functions}
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59
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60 \begin{lstlisting}[language=c]
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61 DCCallback* dcbNewCallback(const char* signature,
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62 DCCallbackHandler* funcptr,
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63 void* userdata);
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64 void dcbFreeCallback(DCCallback* pcb);
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65 \end{lstlisting}
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66
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67 \lstinline{dcbNewCallback} creates and initializes a new \emph{Callback} object,
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68 where \lstinline{signature} is the needed function signature (format is the
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69 one outlined in the language bindings-section of this manual, see \ref{sigchar})
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70 of the function to mimic, \lstinline{funcptr} is a pointer to a callback handler,
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71 and \lstinline{userdata} a pointer to custom data that might be useful in the
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72 handler.
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73 Use \lstinline{dcbFreeCallback} to destroy the \emph{Callback} object.\\
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74 \\
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75 As with \capi{dcNewCallVM}/\capi{dcFree}, this will allocate memory using the
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76 system allocators or custom overrides.
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77
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78
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79 \subsection{Callback handler}
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80
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81 The unified callback handler's declaration used when creating a \capi{DCCallback}
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82 is:
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83
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84 \begin{lstlisting}
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85 char cbHandler(DCCallback* cb,
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86 DCArgs* args,
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87 DCValue* result,
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88 void* userdata);
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89 \end{lstlisting}
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90
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91 \capi{cb} is a pointer to the \capi{DCCallback} object in use, \capi{args} allows
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92 for dynamic iteration over the called-back-function's arguments (input) and
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93 \capi{result} is a pointer to a \capi{DCValue} object in order to store the
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94 callback's return value (output, to be set by handler).\\
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95 Finally, \capi{userdata} is a pointer to some user defined data that can be
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96 set when creating the callback object.
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97 The handler itself returns a signature character (see \ref{sigchar}) specifying the
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98 data type used for \capi{result}.
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99
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