84 lines
3 KiB
C
84 lines
3 KiB
C
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/**
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* PANDA 3D SOFTWARE
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* Copyright (c) Carnegie Mellon University. All rights reserved.
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*
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* All use of this software is subject to the terms of the revised BSD
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* license. You should have received a copy of this license along
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* with this source code in a file named "LICENSE."
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*
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* @file contextSwitch.h
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* @author drose
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* @date 2007-06-21
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*/
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#ifndef CONTEXTSWITCH_H
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#define CONTEXTSWITCH_H
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#include "pandabase.h"
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#include "selectThreadImpl.h"
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/* This file defines the code to perform fundamental context switches
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between different threads of execution within user space code. It
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does this by saving and restoring the register state, including
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transferring to a new stack. */
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/* The code in this file is all written in C code, rather than C++, to
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reduce possible conflicts from longjmp implementations that attempt
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to be smart with respect to C++ destructors and exception
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handling. */
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#ifdef THREAD_SIMPLE_IMPL
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struct ThreadContext;
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef void ContextFunction(struct ThreadContext *from_context, void *);
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typedef void ThreadFunction(void *);
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extern const int needs_stack_prealloc;
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extern const int is_os_threads;
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/* Call this to fill in the appropriate values in context. If
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needs_stack_prealloc (above) is true, the stack must already have
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been allocated; if needs_stack_prealloc is false, the stack pointer
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is not used and may be NULL. The context will be initialized so
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that when switch_to_thread_context() is called, it will begin
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executing thread_func(data), which should not return. This
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function will return normally. */
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void init_thread_context(struct ThreadContext *context,
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unsigned char *stack, size_t stack_size,
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ThreadFunction *thread_func, void *data);
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/* Call this to save the current thread context. This function does
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not return until switch_to_thread_context() is called. Instead it
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immediately calls next_context(data), which should not return. */
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void save_thread_context(struct ThreadContext *context,
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ContextFunction *next_context, void *data);
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/* Call this to resume executing a previously saved context.
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from_context must be the currently-executing context, and
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to_context is the context to resume. When called, it will return
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from save_thread_context() in the saved stack (or begin executing
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thread_func()). */
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void switch_to_thread_context(struct ThreadContext *from_context,
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struct ThreadContext *to_context);
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/* Use this pair of functions to transparently allocate and destroy an
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opaque ThreadContext object of the appropriate size. These
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functions allocate memory, and initialize the context as
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appropriate for the main thread. See init_main_context() to finish
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the initialization for a new thread. */
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struct ThreadContext *alloc_thread_context();
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void free_thread_context(struct ThreadContext *context);
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#ifdef __cplusplus
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}
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#endif
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#endif /* THREAD_SIMPLE_IMPL */
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#endif /* CONTEXTSWITCH_H */
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