464 lines
14 KiB
C
464 lines
14 KiB
C
/**
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* \file
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* <!--
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* This file is part of BeRTOS.
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*
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* Bertos is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* As a special exception, you may use this file as part of a free software
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* library without restriction. Specifically, if other files instantiate
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* templates or use macros or inline functions from this file, or you compile
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* this file and link it with other files to produce an executable, this
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* file does not by itself cause the resulting executable to be covered by
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* the GNU General Public License. This exception does not however
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* invalidate any other reasons why the executable file might be covered by
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* the GNU General Public License.
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*
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* Copyright 2001, 2004 Develer S.r.l. (http://www.develer.com/)
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* Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
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* -->
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*
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* \defgroup kern_proc Process (Threads) management
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* \ingroup kern
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* \{
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*
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* \brief BeRTOS Kernel core (Process scheduler).
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*
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* This is the core kernel module. It allows you to create new processes
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* (which are called \b threads in other systems) and set the priority of
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* each process.
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*
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* A process needs a work area (called \b stack) to run. To create a process,
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* you need to declare a stack area, then create the process.
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* You may also pass NULL for the stack area, if you have enabled kernel heap:
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* in this case the stack will be automatically allocated.
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*
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* Example:
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* \code
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* PROC_DEFINE_STACK(stack1, 200);
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*
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* void NORETURN proc1_run(void)
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* {
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* while (1)
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* {
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* LOG_INFO("I'm alive!\n");
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* timer_delay(1000);
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* }
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* }
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*
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*
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* int main()
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* {
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* Process *p1 = proc_new(proc1_run, NULL, stack1, sizeof(stack1));
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* // here the process is already running
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* proc_setPri(p1, 2);
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* // ...
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* }
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* \endcode
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*
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* The Process struct must be regarded as an opaque data type, do not access
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* any of its members directly.
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*
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* The entry point function should be declared as NORETURN, because it will
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* remove a warning and enable compiler optimizations.
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*
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* You can temporarily disable preemption calling proc_forbid(); remember
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* to enable it again calling proc_permit().
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*
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* \note You should hardly need to manually release the CPU; however you
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* can do it using the cpu_relax() function. It is illegal to release
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* the CPU with preemption disabled.
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*
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* \author Bernie Innocenti <bernie@codewiz.org>
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*
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* $WIZ$ module_name = "kernel"
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* $WIZ$ module_configuration = "bertos/cfg/cfg_proc.h"
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* $WIZ$ module_depends = "switch_ctx"
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* $WIZ$ module_supports = "not atmega103"
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*/
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#ifndef KERN_PROC_H
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#define KERN_PROC_H
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#include "cfg/cfg_proc.h"
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#include "cfg/cfg_signal.h"
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#include "cfg/cfg_monitor.h"
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#include "sem.h"
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#include <struct/list.h> // Node, PriNode
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#include <cfg/compiler.h>
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#include <cfg/debug.h> // ASSERT()
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#include <cpu/types.h> // cpu_stack_t
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#include <cpu/frame.h> // CPU_SAVED_REGS_CNT
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/* The following silents warnings on nightly tests. We need to regenerate
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* all the projects before this can be removed.
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*/
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#ifndef CONFIG_KERN_PRI_INHERIT
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#define CONFIG_KERN_PRI_INHERIT 0
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#endif
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/*
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* WARNING: struct Process is considered private, so its definition can change any time
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* without notice. DO NOT RELY on any field defined here, use only the interface
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* functions below.
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*
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* You have been warned.
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*/
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typedef struct Process
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{
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#if CONFIG_KERN_PRI
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PriNode link; /**< Link Process into scheduler lists */
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# if CONFIG_KERN_PRI_INHERIT
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PriNode inh_link; /**< Link Process into priority inheritance lists */
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List inh_list; /**< Priority inheritance list for this Process */
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Semaphore *inh_blocked_by; /**< Semaphore blocking this Process */
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int orig_pri; /**< Process priority without considering inheritance */
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# endif
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#else
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Node link; /**< Link Process into scheduler lists */
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#endif
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cpu_stack_t *stack; /**< Per-process SP */
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iptr_t user_data; /**< Custom data passed to the process */
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#if CONFIG_KERN_SIGNALS
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Signal sig;
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#endif
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#if CONFIG_KERN_HEAP
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uint16_t flags; /**< Flags */
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#endif
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#if CONFIG_KERN_HEAP | CONFIG_KERN_MONITOR
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cpu_stack_t *stack_base; /**< Base of process stack */
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size_t stack_size; /**< Size of process stack */
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#endif
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/* The actual process entry point */
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void (*user_entry)(void);
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#if CONFIG_KERN_MONITOR
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struct ProcMonitor
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{
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Node link;
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const char *name;
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} monitor;
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#endif
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} Process;
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/**
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* Initialize the process subsystem (kernel).
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* It must be called before using any process related function.
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*/
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void proc_init(void);
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struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
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#if !CONFIG_KERN_MONITOR
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/**
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* Create a new named process and schedules it for execution.
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*
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* When defining the stacksize take into account that you may want at least:
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* \li save all the registers for each nested function call;
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* \li have memory for the struct Process, which is positioned at the bottom
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* of the stack;
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* \li have some memory for temporary variables inside called functions.
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*
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* The value given by KERN_MINSTACKSIZE is rather safe to use in the first place.
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*
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* \param entry Function that the process will execute.
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* \param data Pointer to user data.
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* \param size Length of the stack.
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* \param stack Pointer to the memory area to be used as a stack.
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*
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* \return Process structure of new created process
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* if successful, NULL otherwise.
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*/
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#define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
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#else
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#define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack))
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#endif
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/**
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* Terminate the execution of the current process.
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*/
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void proc_exit(void);
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/*
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* Public scheduling class methods.
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*/
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void proc_yield(void);
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#if CONFIG_KERN_PREEMPT
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bool proc_needPreempt(void);
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void proc_preempt(void);
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#else
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INLINE bool proc_needPreempt(void)
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{
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return false;
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}
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INLINE void proc_preempt(void)
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{
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}
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#endif
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void proc_rename(struct Process *proc, const char *name);
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const char *proc_name(struct Process *proc);
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const char *proc_currentName(void);
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/**
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* Return a pointer to the user data of the current process.
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*
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* To obtain user data, just call this function inside the process. Remember to cast
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* the returned pointer to the correct type.
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* \return Pointer to the user data of the current process.
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*/
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INLINE iptr_t proc_currentUserData(void)
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{
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extern struct Process *current_process;
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return current_process->user_data;
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}
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int proc_testSetup(void);
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int proc_testRun(void);
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int proc_testTearDown(void);
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/**
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* Return the context structure of the currently running process.
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*
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* The details of the Process structure are private to the scheduler.
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* The address returned by this function is an opaque pointer that can
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* be passed as an argument to other process-related functions.
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*/
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INLINE struct Process *proc_current(void)
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{
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extern struct Process *current_process;
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return current_process;
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}
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#if CONFIG_KERN_PRI
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void proc_setPri(struct Process *proc, int pri);
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#else
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INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
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{
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}
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#endif
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#if CONFIG_KERN_PREEMPT
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/**
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* Disable preemptive task switching.
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*
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* The scheduler maintains a global nesting counter. Task switching is
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* effectively re-enabled only when the number of calls to proc_permit()
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* matches the number of calls to proc_forbid().
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*
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* \note Calling functions that could sleep while task switching is disabled
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* is dangerous and unsupported.
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*
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* \note proc_permit() expands inline to 1-2 asm instructions, so it's a
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* very efficient locking primitive in simple but performance-critical
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* situations. In all other cases, semaphores offer a more flexible and
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* fine-grained locking primitive.
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*
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* \sa proc_permit()
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*/
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INLINE void proc_forbid(void)
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{
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extern cpu_atomic_t preempt_count;
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/*
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* We don't need to protect the counter against other processes.
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* The reason why is a bit subtle.
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*
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* If a process gets here, preempt_forbid_cnt can be either 0,
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* or != 0. In the latter case, preemption is already disabled
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* and no concurrency issues can occur.
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*
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* In the former case, we could be preempted just after reading the
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* value 0 from memory, and a concurrent process might, in fact,
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* bump the value of preempt_forbid_cnt under our nose!
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*
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* BUT: if this ever happens, then we won't get another chance to
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* run until the other process calls proc_permit() to re-enable
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* preemption. At this point, the value of preempt_forbid_cnt
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* must be back to 0, and thus what we had originally read from
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* memory happens to be valid.
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*
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* No matter how hard you think about it, and how complicated you
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* make your scenario, the above holds true as long as
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* "preempt_forbid_cnt != 0" means that no task switching is
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* possible.
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*/
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++preempt_count;
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/*
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* Make sure preempt_count is flushed to memory so the preemption
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* softirq will see the correct value from now on.
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*/
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MEMORY_BARRIER;
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}
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/**
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* Re-enable preemptive task switching.
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*
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* \sa proc_forbid()
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*/
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INLINE void proc_permit(void)
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{
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extern cpu_atomic_t preempt_count;
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/*
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* This is to ensure any global state changed by the process gets
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* flushed to memory before task switching is re-enabled.
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*/
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MEMORY_BARRIER;
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/* No need to protect against interrupts here. */
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ASSERT(preempt_count > 0);
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--preempt_count;
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/*
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* This ensures preempt_count is flushed to memory immediately so the
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* preemption interrupt sees the correct value.
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*/
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MEMORY_BARRIER;
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}
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/**
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* \return true if preemptive task switching is allowed.
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* \note This accessor is needed because preempt_count
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* must be absoultely private.
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*/
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INLINE bool proc_preemptAllowed(void)
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{
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extern cpu_atomic_t preempt_count;
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return (preempt_count == 0);
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}
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#else /* CONFIG_KERN_PREEMPT */
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#define proc_forbid() /* NOP */
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#define proc_permit() /* NOP */
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#define proc_preemptAllowed() (true)
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#endif /* CONFIG_KERN_PREEMPT */
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/** Deprecated, use the proc_preemptAllowed() macro. */
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#define proc_allowed() proc_preemptAllowed()
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/**
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* Execute a block of \a CODE atomically with respect to task scheduling.
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*/
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#define PROC_ATOMIC(CODE) \
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do { \
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proc_forbid(); \
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CODE; \
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proc_permit(); \
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} while(0)
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/**
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* Default stack size for each thread, in bytes.
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*
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* The goal here is to allow a minimal task to save all of its
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* registers twice, plus push a maximum of 32 variables on the
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* stack. We add also struct Process size since we save it into the process'
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* stack.
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*
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* The actual size computed by the default formula greatly depends on what
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* options are active and on the architecture.
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*
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* Note that on most 16bit architectures, interrupts will also
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* run on the stack of the currently running process. Nested
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* interrupts will greatly increases the amount of stack space
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* required per process. Use irqmanager to minimize stack
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* usage.
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*/
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#if (ARCH & ARCH_EMUL)
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/* We need a large stack because system libraries are bloated */
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#define KERN_MINSTACKSIZE 65536
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#else
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#if CONFIG_KERN_PREEMPT
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/*
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* A preemptible kernel needs a larger stack compared to the
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* cooperative case. A task can be interrupted anytime in each
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* node of the call graph, at any level of depth. This may
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* result in a higher stack consumption, to call the ISR, save
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* the current user context and to execute the kernel
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* preemption routines implemented as ISR prologue and
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* epilogue. All these calls are nested into the process stack.
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*
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* So, to reduce the risk of stack overflow/underflow problems
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* add a x2 to the portion stack reserved to the user process.
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*/
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#define KERN_MINSTACKSIZE \
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(sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
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+ 32 * sizeof(int) * 2)
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#else
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#define KERN_MINSTACKSIZE \
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(sizeof(Process) + CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
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+ 32 * sizeof(int))
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#endif /* CONFIG_KERN_PREEMPT */
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#endif
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#ifndef CONFIG_KERN_MINSTACKSIZE
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/* For backward compatibility */
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#define CONFIG_KERN_MINSTACKSIZE KERN_MINSTACKSIZE
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#else
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#warning FIXME: This macro is deprecated, use KERN_MINSTACKSIZE instead
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#endif
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/**
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* Utility macro to allocate a stack of size \a size.
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*
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* This macro define a static stack for one process and do
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* check if given stack size is enough to run process.
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* \note If you plan to use kprintf() and similar functions, you will need
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* at least KERN_MINSTACKSIZE * 2 bytes.
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*
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* \param name Variable name for the stack.
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* \param size Stack size in bytes. It must be at least KERN_MINSTACKSIZE.
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*/
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#define PROC_DEFINE_STACK(name, size) \
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cpu_stack_t name[((size) + sizeof(cpu_stack_t) - 1) / sizeof(cpu_stack_t)]; \
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STATIC_ASSERT((size) >= KERN_MINSTACKSIZE);
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/* Memory fill codes to help debugging */
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#if CONFIG_KERN_MONITOR
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#include <cpu/types.h>
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#if (SIZEOF_CPUSTACK_T == 1)
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/* 8bit cpu_stack_t */
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#define CONFIG_KERN_STACKFILLCODE 0xA5
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#define CONFIG_KERN_MEMFILLCODE 0xDB
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#elif (SIZEOF_CPUSTACK_T == 2)
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/* 16bit cpu_stack_t */
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#define CONFIG_KERN_STACKFILLCODE 0xA5A5
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#define CONFIG_KERN_MEMFILLCODE 0xDBDB
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#elif (SIZEOF_CPUSTACK_T == 4)
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/* 32bit cpu_stack_t */
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#define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
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#define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
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#elif (SIZEOF_CPUSTACK_T == 8)
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/* 64bit cpu_stack_t */
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#define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
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#define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
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#else
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#error No cpu_stack_t size supported!
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#endif
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#endif
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/** \} */ //defgroup kern_proc
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#endif /* KERN_PROC_H */
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