115 lines
4.6 KiB
C
115 lines
4.6 KiB
C
/***********************************************************************/
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/* */
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/* Objective Caml */
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/* */
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/* Damien Doligez, projet Para, INRIA Rocquencourt */
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/* */
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/* Copyright 1996 Institut National de Recherche en Informatique et */
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/* en Automatique. All rights reserved. This file is distributed */
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/* under the terms of the GNU Library General Public License. */
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/* */
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/***********************************************************************/
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/* $Id$ */
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/* rotatecursor library, written by <Damien.Doligez@inria.fr>
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This file is in the public domain.
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version 1.12.2
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The goal of this library is to help implement cooperative multitasking
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for MPW tools: to make sure that your program calls RotateCursor often
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enough (about 20 times per second) but not too often (to avoid a big
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slowdown).
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It can also be used for applications with a little more work.
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Simple usage for MPW tools:
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^^^^^^^^^^^^^^^^^^^^^^^^^^^
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1. #include this file where appropriate
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2. Insert the following line in every loop of your program:
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ROTATECURSOR_MAGIC ();
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The overhead of this macro is only a few CPU cycles, so it can be
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used without problem even in tight loops.
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Simple usage for applications:
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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1. Write a function with prototype:
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pascal void myaction (long x);
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This functions should get and handle all events until the event
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queue is empty (i.e. until it gets a null event). It should also
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animate the cursor.
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2. #include this file where appropriate
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3. Add this line to the init code of your program:
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rotatecursor_options (NULL, 0, &myaction);
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4. Insert the following line in every loop of your program:
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ROTATECURSOR_MAGIC ();
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The overhead of this macro is only a few CPU cycles, so it can be
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used without problem even in tight loops.
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5. If there is no function called RotateCursor in your libraries, you
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will have to provide one that does nothing (it will not be called).
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See below for advanced options.
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*/
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#ifndef _rotatecursor_h_
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#define _rotatecursor_h_
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extern int volatile rotatecursor_flag;
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/*
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[rotatecursor_flag] will be automagically set to 1 when the time comes
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to call [rotatecursor_ticker].
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*/
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void rotatecursor_options (int volatile *p1, int period,
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pascal void (*action) (long));
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/*
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Use [rotatecursor_options] to change advanced parameters:
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1. [p1] is a pointer to another variable that will be set to 1 when
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the time is up, unless it is already nonzero. Typical use is when
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you already have a variable in your program that is set
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asynchronously for something else, and you want to avoid testing
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two different variables in your inner loop. Pass [NULL] in this
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argument if you don't need this feature.
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2. [period] is the interval (in milliseconds) between calls to
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RotateCursor. Reasonable values are between 10 and 200.
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If you pass 0 in this argument, the default value (50) will
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be used. This value is passed to PrimeTime, so a negative value
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represents a delay in microseconds (not very useful here...)
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3. [action] is the function that will be called at regular intervals
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by [rotatecursor_ticker]. If you pass [NULL] in this argument,
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the default function, [RotateCursor], will be called.
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*/
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int rotatecursor_ticker (void);
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/*
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[rotatecursor_ticker] calls your [action] function (or [RotateCursor]),
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resets [rotatecursor_flag] to 0, and rearms the Time Manager task that
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will set [rotatecursor_flag] to 1 after the appropriate delay.
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This function always returns 0. It returns an int so you can use
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it in an expression as well as a statement.
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*/
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#define ROTATECURSOR_MAGIC() (rotatecursor_flag ? rotatecursor_ticker () : 0)
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/*
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[ROTATECURSOR_MAGIC] is a simple interface to [rotatecursor_flag]
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and [rotatecursor_ticker]. Can be used as a statement (followed by
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a semicolon) or in an expression (followed by a comma).
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*/
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void rotatecursor_final (void);
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/*
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This function is set up (with [atexit]) to be called before your
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program finishes. If for any reason the [atexit] functions are not
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called before your program exits, you should call this function by hand.
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It is harmless to call [rotatecursor_final] twice.
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*/
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#endif /* _rotatecursor_h_ */
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