533d396761
Any number of readers may be in the critical section at a time and writers are mutually exclusive to all other threads. They are a better choice when data is rarely modified but often read and multiple threads can safely access it for reading. Priority inheritance is fully implemented along with other changes to the kernel to fully support it on multiowner objects. This also cleans up priority code in the kernel and updates some associated structures in existing objects to the cleaner form. Currently doesn't add the mrsw_lock.[ch] files since they're not yet needed by anything but the supporting improvements are still useful. This includes a typed bitarray API (bitarray.h) which is pretty basic for now. Change-Id: Idbe43dcd9170358e06d48d00f1c69728ff45b0e3 Reviewed-on: http://gerrit.rockbox.org/801 Reviewed-by: Michael Sevakis <jethead71@rockbox.org> Tested: Michael Sevakis <jethead71@rockbox.org>
415 lines
16 KiB
C
415 lines
16 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2002 by Ulf Ralberg
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#ifndef THREAD_H
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#define THREAD_H
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#include "config.h"
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#include <inttypes.h>
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#include <stddef.h>
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#include <stdbool.h>
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#include "gcc_extensions.h"
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#include "corelock.h"
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#include "bitarray.h"
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/* Priority scheduling (when enabled with HAVE_PRIORITY_SCHEDULING) works
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* by giving high priority threads more CPU time than lower priority threads
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* when they need it. Priority is differential such that the priority
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* difference between a lower priority runnable thread and the highest priority
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* runnable thread determines the amount of aging necessary for the lower
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* priority thread to be scheduled in order to prevent starvation.
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*
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* If software playback codec pcm buffer is going down to critical, codec
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* can gradually raise its own priority to override user interface and
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* prevent playback skipping.
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*/
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#define PRIORITY_RESERVED_HIGH 0 /* Reserved */
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#define PRIORITY_RESERVED_LOW 32 /* Reserved */
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#define HIGHEST_PRIORITY 1 /* The highest possible thread priority */
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#define LOWEST_PRIORITY 31 /* The lowest possible thread priority */
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/* Realtime range reserved for threads that will not allow threads of lower
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* priority to age and run (future expansion) */
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#define PRIORITY_REALTIME_1 1
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#define PRIORITY_REALTIME_2 2
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#define PRIORITY_REALTIME_3 3
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#define PRIORITY_REALTIME_4 4
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#define PRIORITY_REALTIME 4 /* Lowest realtime range */
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#define PRIORITY_BUFFERING 15 /* Codec buffering thread */
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#define PRIORITY_USER_INTERFACE 16 /* The main thread */
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#define PRIORITY_RECORDING 16 /* Recording thread */
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#define PRIORITY_PLAYBACK 16 /* Variable between this and MAX */
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#define PRIORITY_PLAYBACK_MAX 5 /* Maximum allowable playback priority */
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#define PRIORITY_SYSTEM 18 /* All other firmware threads */
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#define PRIORITY_BACKGROUND 20 /* Normal application threads */
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#define NUM_PRIORITIES 32
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#define PRIORITY_IDLE 32 /* Priority representative of no tasks */
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#define IO_PRIORITY_IMMEDIATE 0
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#define IO_PRIORITY_BACKGROUND 32
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#if CONFIG_CODEC == SWCODEC
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# ifdef HAVE_HARDWARE_CLICK
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# define BASETHREADS 17
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# else
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# define BASETHREADS 16
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# endif
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#else
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# define BASETHREADS 11
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#endif /* CONFIG_CODE == * */
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#ifndef TARGET_EXTRA_THREADS
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#define TARGET_EXTRA_THREADS 0
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#endif
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#define MAXTHREADS (BASETHREADS+TARGET_EXTRA_THREADS)
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BITARRAY_TYPE_DECLARE(threadbit_t, threadbit, MAXTHREADS)
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BITARRAY_TYPE_DECLARE(priobit_t, priobit, NUM_PRIORITIES)
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/*
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* We need more stack when we run under a host
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* maybe more expensive C lib functions?
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*
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* simulator (possibly) doesn't simulate stack usage anyway but well ... */
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#if defined(HAVE_SDL_THREADS) || defined(__PCTOOL__)
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struct regs
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{
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void *t; /* OS thread */
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void *told; /* Last thread in slot (explained in thead-sdl.c) */
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void *s; /* Semaphore for blocking and wakeup */
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void (*start)(void); /* Start function */
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};
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#define DEFAULT_STACK_SIZE 0x100 /* tiny, ignored anyway */
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#else
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#include "asm/thread.h"
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#endif /* HAVE_SDL_THREADS */
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/* NOTE: The use of the word "queue" may also refer to a linked list of
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threads being maintained that are normally dealt with in FIFO order
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and not necessarily kernel event_queue */
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enum
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{
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/* States without a timeout must be first */
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STATE_KILLED = 0, /* Thread is killed (default) */
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STATE_RUNNING, /* Thread is currently running */
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STATE_BLOCKED, /* Thread is indefinitely blocked on a queue */
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/* These states involve adding the thread to the tmo list */
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STATE_SLEEPING, /* Thread is sleeping with a timeout */
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STATE_BLOCKED_W_TMO, /* Thread is blocked on a queue with a timeout */
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/* Miscellaneous states */
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STATE_FROZEN, /* Thread is suspended and will not run until
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thread_thaw is called with its ID */
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THREAD_NUM_STATES,
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TIMEOUT_STATE_FIRST = STATE_SLEEPING,
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};
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#if NUM_CORES > 1
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/* Pointer value for name field to indicate thread is being killed. Using
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* an alternate STATE_* won't work since that would interfere with operation
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* while the thread is still running. */
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#define THREAD_DESTRUCT ((const char *)~(intptr_t)0)
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#endif
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/* Link information for lists thread is in */
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struct thread_entry; /* forward */
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struct thread_list
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{
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struct thread_entry *prev; /* Previous thread in a list */
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struct thread_entry *next; /* Next thread in a list */
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};
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/* Basic structure describing the owner of an object */
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struct blocker
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{
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struct thread_entry * volatile thread; /* thread blocking other threads
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(aka. object owner) */
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#ifdef HAVE_PRIORITY_SCHEDULING
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int priority; /* highest priority waiter */
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#endif
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};
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/* If a thread has a blocker but the blocker's registered thread is NULL,
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then it references this and the struct blocker pointer may be
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reinterpreted as such. */
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struct blocker_splay
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{
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struct blocker blocker; /* blocker info (first!) */
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#ifdef HAVE_PRIORITY_SCHEDULING
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threadbit_t mask; /* mask of nonzero tcounts */
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#if NUM_CORES > 1
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struct corelock cl; /* mutual exclusion */
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#endif
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#endif /* HAVE_PRIORITY_SCHEDULING */
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};
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#ifdef HAVE_PRIORITY_SCHEDULING
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/* Quick-disinherit of priority elevation. Must be a running thread. */
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void priority_disinherit(struct thread_entry *thread, struct blocker *bl);
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struct priority_distribution
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{
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uint8_t hist[NUM_PRIORITIES]; /* Histogram: Frequency for each priority */
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priobit_t mask; /* Bitmask of hist entries that are not zero */
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};
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#endif /* HAVE_PRIORITY_SCHEDULING */
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/* Information kept in each thread slot
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* members are arranged according to size - largest first - in order
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* to ensure both alignment and packing at the same time.
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*/
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struct thread_entry
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{
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struct regs context; /* Register context at switch -
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_must_ be first member */
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uintptr_t *stack; /* Pointer to top of stack */
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const char *name; /* Thread name */
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long tmo_tick; /* Tick when thread should be woken from
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timeout -
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states: STATE_SLEEPING/STATE_BLOCKED_W_TMO */
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struct thread_list l; /* Links for blocked/waking/running -
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circular linkage in both directions */
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struct thread_list tmo; /* Links for timeout list -
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Circular in reverse direction, NULL-terminated in
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forward direction -
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states: STATE_SLEEPING/STATE_BLOCKED_W_TMO */
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struct thread_entry **bqp; /* Pointer to list variable in kernel
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object where thread is blocked - used
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for implicit unblock and explicit wake
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states: STATE_BLOCKED/STATE_BLOCKED_W_TMO */
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#ifdef HAVE_CORELOCK_OBJECT
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struct corelock *obj_cl; /* Object corelock where thead is blocked -
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states: STATE_BLOCKED/STATE_BLOCKED_W_TMO */
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struct corelock waiter_cl; /* Corelock for thread_wait */
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struct corelock slot_cl; /* Corelock to lock thread slot */
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unsigned char core; /* The core to which thread belongs */
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#endif
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struct thread_entry *queue; /* List of threads waiting for thread to be
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removed */
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#ifdef HAVE_WAKEUP_EXT_CB
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void (*wakeup_ext_cb)(struct thread_entry *thread); /* Callback that
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performs special steps needed when being
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forced off of an object's wait queue that
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go beyond the standard wait queue removal
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and priority disinheritance */
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/* Only enabled when using queue_send for now */
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#endif
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#if defined(HAVE_SEMAPHORE_OBJECTS) || \
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defined(HAVE_EXTENDED_MESSAGING_AND_NAME) || \
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NUM_CORES > 1
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volatile intptr_t retval; /* Return value from a blocked operation/
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misc. use */
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#endif
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uint32_t id; /* Current slot id */
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int __errno; /* Thread error number (errno tls) */
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#ifdef HAVE_PRIORITY_SCHEDULING
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/* Priority summary of owned objects that support inheritance */
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struct blocker *blocker; /* Pointer to blocker when this thread is blocked
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on an object that supports PIP -
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states: STATE_BLOCKED/STATE_BLOCKED_W_TMO */
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struct priority_distribution pdist; /* Priority summary of owned objects
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that have blocked threads and thread's own
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base priority */
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int skip_count; /* Number of times skipped if higher priority
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thread was running */
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unsigned char base_priority; /* Base priority (set explicitly during
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creation or thread_set_priority) */
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unsigned char priority; /* Scheduled priority (higher of base or
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all threads blocked by this one) */
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#endif
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unsigned short stack_size; /* Size of stack in bytes */
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unsigned char state; /* Thread slot state (STATE_*) */
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#ifdef HAVE_SCHEDULER_BOOSTCTRL
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unsigned char cpu_boost; /* CPU frequency boost flag */
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#endif
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#ifdef HAVE_IO_PRIORITY
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unsigned char io_priority;
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#endif
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};
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/*** Macros for internal use ***/
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/* Thread ID, 32 bits = |VVVVVVVV|VVVVVVVV|VVVVVVVV|SSSSSSSS| */
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#define THREAD_ID_VERSION_SHIFT 8
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#define THREAD_ID_VERSION_MASK 0xffffff00
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#define THREAD_ID_SLOT_MASK 0x000000ff
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#define THREAD_ID_INIT(n) ((1u << THREAD_ID_VERSION_SHIFT) | (n))
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#define THREAD_ID_SLOT(id) ((id) & THREAD_ID_SLOT_MASK)
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#ifdef HAVE_CORELOCK_OBJECT
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/* Operations to be performed just before stopping a thread and starting
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a new one if specified before calling switch_thread */
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enum
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{
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TBOP_CLEAR = 0, /* No operation to do */
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TBOP_UNLOCK_CORELOCK, /* Unlock a corelock variable */
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TBOP_SWITCH_CORE, /* Call the core switch preparation routine */
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};
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struct thread_blk_ops
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{
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struct corelock *cl_p; /* pointer to corelock */
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unsigned char flags; /* TBOP_* flags */
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};
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#endif /* NUM_CORES > 1 */
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/* Information kept for each core
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* Members are arranged for the same reason as in thread_entry
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*/
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struct core_entry
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{
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/* "Active" lists - core is constantly active on these and are never
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locked and interrupts do not access them */
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struct thread_entry *running; /* threads that are running (RTR) */
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struct thread_entry *timeout; /* threads that are on a timeout before
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running again */
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struct thread_entry *block_task; /* Task going off running list */
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#ifdef HAVE_PRIORITY_SCHEDULING
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struct priority_distribution rtr; /* Summary of running and ready-to-run
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threads */
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#endif
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long next_tmo_check; /* soonest time to check tmo threads */
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#ifdef HAVE_CORELOCK_OBJECT
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struct thread_blk_ops blk_ops; /* operations to perform when
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blocking a thread */
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struct corelock rtr_cl; /* Lock for rtr list */
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#endif /* NUM_CORES */
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};
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extern void yield(void);
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extern unsigned sleep(unsigned ticks);
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#ifdef HAVE_PRIORITY_SCHEDULING
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#define IF_PRIO(...) __VA_ARGS__
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#define IFN_PRIO(...)
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#else
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#define IF_PRIO(...)
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#define IFN_PRIO(...) __VA_ARGS__
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#endif
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void core_idle(void);
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void core_wake(IF_COP_VOID(unsigned int core));
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/* Initialize the scheduler */
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void init_threads(void) INIT_ATTR;
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/* Allocate a thread in the scheduler */
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#define CREATE_THREAD_FROZEN 0x00000001 /* Thread is frozen at create time */
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unsigned int create_thread(void (*function)(void),
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void* stack, size_t stack_size,
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unsigned flags, const char *name
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IF_PRIO(, int priority)
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IF_COP(, unsigned int core));
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/* Set and clear the CPU frequency boost flag for the calling thread */
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#ifdef HAVE_SCHEDULER_BOOSTCTRL
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void trigger_cpu_boost(void);
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void cancel_cpu_boost(void);
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#else
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#define trigger_cpu_boost() do { } while(0)
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#define cancel_cpu_boost() do { } while(0)
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#endif
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/* Return thread entry from id */
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struct thread_entry *thread_id_entry(unsigned int thread_id);
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/* Make a frozed thread runnable (when started with CREATE_THREAD_FROZEN).
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* Has no effect on a thread not frozen. */
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void thread_thaw(unsigned int thread_id);
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/* Wait for a thread to exit */
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void thread_wait(unsigned int thread_id);
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/* Exit the current thread */
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void thread_exit(void) NORETURN_ATTR;
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#if defined(DEBUG) || defined(ROCKBOX_HAS_LOGF)
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#define ALLOW_REMOVE_THREAD
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/* Remove a thread from the scheduler */
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void remove_thread(unsigned int thread_id);
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#endif
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/* Switch to next runnable thread */
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void switch_thread(void);
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/* Blocks a thread for at least the specified number of ticks (0 = wait until
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* next tick) */
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void sleep_thread(int ticks);
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/* Blocks the current thread on a thread queue (< 0 == infinite) */
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void block_thread(struct thread_entry *current, int timeout);
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/* Return bit flags for thread wakeup */
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#define THREAD_NONE 0x0 /* No thread woken up (exclusive) */
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#define THREAD_OK 0x1 /* A thread was woken up */
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#define THREAD_SWITCH 0x2 /* Task switch recommended (one or more of
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higher priority than current were woken) */
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/* A convenience function for waking an entire queue of threads. */
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unsigned int thread_queue_wake(struct thread_entry **list,
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volatile int *count);
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/* Wakeup a thread at the head of a list */
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enum wakeup_thread_protocol
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{
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WAKEUP_DEFAULT,
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WAKEUP_TRANSFER,
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WAKEUP_RELEASE,
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WAKEUP_TRANSFER_MULTI,
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};
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unsigned int wakeup_thread_(struct thread_entry **list
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IF_PRIO(, enum wakeup_thread_protocol proto));
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#ifdef HAVE_PRIORITY_SCHEDULING
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#define wakeup_thread(list, proto) \
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wakeup_thread_((list), (proto))
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int thread_set_priority(unsigned int thread_id, int priority);
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int thread_get_priority(unsigned int thread_id);
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#else /* !HAVE_PRIORITY_SCHEDULING */
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#define wakeup_thread(list, proto...) \
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wakeup_thread_((list));
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#endif /* HAVE_PRIORITY_SCHEDULING */
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#ifdef HAVE_IO_PRIORITY
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void thread_set_io_priority(unsigned int thread_id, int io_priority);
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int thread_get_io_priority(unsigned int thread_id);
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#endif /* HAVE_IO_PRIORITY */
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#if NUM_CORES > 1
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unsigned int switch_core(unsigned int new_core);
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#endif
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/* Return the id of the calling thread. */
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unsigned int thread_self(void);
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/* Return the thread_entry for the calling thread.
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* INTERNAL: Intended for use by kernel and not for programs. */
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struct thread_entry* thread_self_entry(void);
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/* Debugging info - only! */
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int thread_stack_usage(const struct thread_entry *thread);
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#if NUM_CORES > 1
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int idle_stack_usage(unsigned int core);
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#endif
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void thread_get_name(char *buffer, int size,
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struct thread_entry *thread);
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#ifdef RB_PROFILE
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void profile_thread(void);
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#endif
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#endif /* THREAD_H */
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