src/shims/priority.h - third_party/swift-corelibs-libdispatch - Git at Google

 /*
  * Copyright (c) 2008-2016 Apple Inc. All rights reserved.
  *
  * @APPLE_APACHE_LICENSE_HEADER_START@
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  * @APPLE_APACHE_LICENSE_HEADER_END@
  */

 /*
  * IMPORTANT: This header file describes INTERNAL interfaces to libdispatch
  * which are subject to change in future releases of Mac OS X. Any applications
  * relying on these interfaces WILL break.
  */

 #ifndef __DISPATCH_SHIMS_PRIORITY__
 #define __DISPATCH_SHIMS_PRIORITY__

 #if HAVE_PTHREAD_QOS_H && __has_include(<pthread/qos_private.h>)
 #include <pthread/qos.h>
 #include <pthread/qos_private.h>
 #ifndef _PTHREAD_PRIORITY_OVERCOMMIT_FLAG
 #define _PTHREAD_PRIORITY_OVERCOMMIT_FLAG 0x80000000
 #endif
 #ifndef _PTHREAD_PRIORITY_SCHED_PRI_FLAG
 #define _PTHREAD_PRIORITY_SCHED_PRI_FLAG 0x20000000
 #endif
 #ifndef _PTHREAD_PRIORITY_DEFAULTQUEUE_FLAG
 #define _PTHREAD_PRIORITY_DEFAULTQUEUE_FLAG 0x04000000
 #endif
 #ifndef _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG
 #define _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG 0x02000000
 #endif
 #ifndef _PTHREAD_PRIORITY_NEEDS_UNBIND_FLAG
 #define _PTHREAD_PRIORITY_NEEDS_UNBIND_FLAG 0x01000000
 #endif
 #else // HAVE_PTHREAD_QOS_H
 OS_ENUM(qos_class, unsigned int,
 	QOS_CLASS_USER_INTERACTIVE = 0x21,
 	QOS_CLASS_USER_INITIATED = 0x19,
 	QOS_CLASS_DEFAULT = 0x15,
 	QOS_CLASS_UTILITY = 0x11,
 	QOS_CLASS_BACKGROUND = 0x09,
 	QOS_CLASS_MAINTENANCE = 0x05,
 	QOS_CLASS_UNSPECIFIED = 0x00,
 );
 typedef unsigned long pthread_priority_t;
 #define QOS_MIN_RELATIVE_PRIORITY (-15)
 #define _PTHREAD_PRIORITY_FLAGS_MASK (~0xffffff)
 #define _PTHREAD_PRIORITY_QOS_CLASS_MASK 0x00ffff00
 #define _PTHREAD_PRIORITY_QOS_CLASS_SHIFT (8ull)
 #define _PTHREAD_PRIORITY_PRIORITY_MASK 0x000000ff
 #define _PTHREAD_PRIORITY_OVERCOMMIT_FLAG 0x80000000
 #define _PTHREAD_PRIORITY_SCHED_PRI_FLAG 0x20000000
 #define _PTHREAD_PRIORITY_DEFAULTQUEUE_FLAG 0x04000000
 #define _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG 0x02000000
 #define _PTHREAD_PRIORITY_NEEDS_UNBIND_FLAG 0x01000000
 #define _PTHREAD_PRIORITY_ENFORCE_FLAG  0x10000000

 #endif // HAVE_PTHREAD_QOS_H

 typedef uint32_t dispatch_qos_t;
 typedef uint32_t dispatch_priority_t;
 typedef uint32_t dispatch_priority_t;
 typedef uint16_t dispatch_priority_requested_t;

 #define DISPATCH_QOS_UNSPECIFIED            ((dispatch_qos_t)0)
 #define DISPATCH_QOS_MAINTENANCE            ((dispatch_qos_t)1)
 #define DISPATCH_QOS_BACKGROUND             ((dispatch_qos_t)2)
 #define DISPATCH_QOS_UTILITY                ((dispatch_qos_t)3)
 #define DISPATCH_QOS_DEFAULT                ((dispatch_qos_t)4)
 #define DISPATCH_QOS_USER_INITIATED         ((dispatch_qos_t)5)
 #define DISPATCH_QOS_USER_INTERACTIVE       ((dispatch_qos_t)6)
 #define DISPATCH_QOS_MAX                    DISPATCH_QOS_USER_INTERACTIVE
 #define DISPATCH_QOS_SATURATED              ((dispatch_qos_t)15)

 #define DISPATCH_PRIORITY_RELPRI_MASK        ((dispatch_priority_t)0x000000ff)
 #define DISPATCH_PRIORITY_RELPRI_SHIFT       0
 #define DISPATCH_PRIORITY_QOS_MASK           ((dispatch_priority_t)0x0000ff00)
 #define DISPATCH_PRIORITY_QOS_SHIFT          8
 #define DISPATCH_PRIORITY_REQUESTED_MASK     ((dispatch_priority_t)0x0000ffff)
 #define DISPATCH_PRIORITY_OVERRIDE_MASK      ((dispatch_priority_t)0x00ff0000)
 #define DISPATCH_PRIORITY_OVERRIDE_SHIFT     16
 #define DISPATCH_PRIORITY_FLAGS_MASK         ((dispatch_priority_t)0xff000000)

 #define DISPATCH_PRIORITY_SATURATED_OVERRIDE ((dispatch_priority_t)0x000f0000)

 #define DISPATCH_PRIORITY_FLAG_OVERCOMMIT    ((dispatch_priority_t)0x80000000) // _PTHREAD_PRIORITY_OVERCOMMIT_FLAG
 #define DISPATCH_PRIORITY_FLAG_DEFAULTQUEUE  ((dispatch_priority_t)0x04000000) // _PTHREAD_PRIORITY_DEFAULTQUEUE_FLAG
 #define DISPATCH_PRIORITY_FLAG_MANAGER       ((dispatch_priority_t)0x02000000) // _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG
 #define DISPATCH_PRIORITY_PTHREAD_PRIORITY_FLAGS_MASK \
 		(DISPATCH_PRIORITY_FLAG_OVERCOMMIT | DISPATCH_PRIORITY_FLAG_DEFAULTQUEUE | \
 		DISPATCH_PRIORITY_FLAG_MANAGER)

 // not passed to pthread
 #define DISPATCH_PRIORITY_FLAG_INHERIT       ((dispatch_priority_t)0x40000000) // _PTHREAD_PRIORITY_INHERIT_FLAG
 #define DISPATCH_PRIORITY_FLAG_ENFORCE       ((dispatch_priority_t)0x10000000) // _PTHREAD_PRIORITY_ENFORCE_FLAG
 #define DISPATCH_PRIORITY_FLAG_ROOTQUEUE     ((dispatch_priority_t)0x20000000) // _PTHREAD_PRIORITY_ROOTQUEUE_FLAG

 #pragma mark dispatch_qos

 DISPATCH_ALWAYS_INLINE
 static inline dispatch_qos_t
 _dispatch_qos_from_qos_class(qos_class_t cls)
 {
 	switch ((unsigned int)cls) {
 	case QOS_CLASS_USER_INTERACTIVE: return DISPATCH_QOS_USER_INTERACTIVE;
 	case QOS_CLASS_USER_INITIATED:   return DISPATCH_QOS_USER_INITIATED;
 	case QOS_CLASS_DEFAULT:          return DISPATCH_QOS_DEFAULT;
 	case QOS_CLASS_UTILITY:          return DISPATCH_QOS_UTILITY;
 	case QOS_CLASS_BACKGROUND:       return DISPATCH_QOS_BACKGROUND;
 	case QOS_CLASS_MAINTENANCE:      return DISPATCH_QOS_MAINTENANCE;
 	default: return DISPATCH_QOS_UNSPECIFIED;
 	}
 }

 DISPATCH_ALWAYS_INLINE
 static inline qos_class_t
 _dispatch_qos_to_qos_class(dispatch_qos_t qos)
 {
 	switch (qos) {
 	case DISPATCH_QOS_USER_INTERACTIVE: return QOS_CLASS_USER_INTERACTIVE;
 	case DISPATCH_QOS_USER_INITIATED:   return QOS_CLASS_USER_INITIATED;
 	case DISPATCH_QOS_DEFAULT:          return QOS_CLASS_DEFAULT;
 	case DISPATCH_QOS_UTILITY:          return QOS_CLASS_UTILITY;
 	case DISPATCH_QOS_BACKGROUND:       return QOS_CLASS_BACKGROUND;
 	case DISPATCH_QOS_MAINTENANCE:      return (qos_class_t)QOS_CLASS_MAINTENANCE;
 	default: return QOS_CLASS_UNSPECIFIED;
 	}
 }

 DISPATCH_ALWAYS_INLINE
 static inline dispatch_qos_t
 _dispatch_qos_from_queue_priority(long priority)
 {
 	switch (priority) {
 	case DISPATCH_QUEUE_PRIORITY_BACKGROUND:      return DISPATCH_QOS_BACKGROUND;
 	case DISPATCH_QUEUE_PRIORITY_NON_INTERACTIVE: return DISPATCH_QOS_UTILITY;
 	case DISPATCH_QUEUE_PRIORITY_LOW:             return DISPATCH_QOS_UTILITY;
 	case DISPATCH_QUEUE_PRIORITY_DEFAULT:         return DISPATCH_QOS_DEFAULT;
 	case DISPATCH_QUEUE_PRIORITY_HIGH:            return DISPATCH_QOS_USER_INITIATED;
 	default: return _dispatch_qos_from_qos_class((qos_class_t)priority);
 	}
 }

 DISPATCH_ALWAYS_INLINE
 static inline dispatch_qos_t
 _dispatch_qos_from_pp(pthread_priority_t pp)
 {
 	pp &= _PTHREAD_PRIORITY_QOS_CLASS_MASK;
 	pp >>= _PTHREAD_PRIORITY_QOS_CLASS_SHIFT;
 	return (dispatch_qos_t)__builtin_ffs((int)pp);
 }

 DISPATCH_ALWAYS_INLINE
 static inline pthread_priority_t
 _dispatch_qos_to_pp(dispatch_qos_t qos)
 {
 	pthread_priority_t pp;
 	pp = 1ul << ((qos - 1) + _PTHREAD_PRIORITY_QOS_CLASS_SHIFT);
 	return pp | _PTHREAD_PRIORITY_PRIORITY_MASK;
 }

 // including maintenance
 DISPATCH_ALWAYS_INLINE
 static inline bool
 _dispatch_qos_is_background(dispatch_qos_t qos)
 {
 	return qos && qos <= DISPATCH_QOS_BACKGROUND;
 }

 #pragma mark dispatch_priority

 #define _dispatch_priority_make(qos, relpri) \
 	(qos ? ((((qos) << DISPATCH_PRIORITY_QOS_SHIFT) & DISPATCH_PRIORITY_QOS_MASK) | \
 	 ((dispatch_priority_t)(relpri - 1) & DISPATCH_PRIORITY_RELPRI_MASK)) : 0)

 DISPATCH_ALWAYS_INLINE
 static inline dispatch_priority_t
 _dispatch_priority_with_override_qos(dispatch_priority_t pri,
 		dispatch_qos_t oqos)
 {
 	pri &= ~DISPATCH_PRIORITY_OVERRIDE_MASK;
 	pri |= oqos << DISPATCH_PRIORITY_OVERRIDE_SHIFT;
 	return pri;
 }

 DISPATCH_ALWAYS_INLINE
 static inline int
 _dispatch_priority_relpri(dispatch_priority_t dbp)
 {
 	if (dbp & DISPATCH_PRIORITY_QOS_MASK) {
 		return (int8_t)(dbp & DISPATCH_PRIORITY_RELPRI_MASK) + 1;
 	}
 	return 0;
 }

 DISPATCH_ALWAYS_INLINE
 static inline dispatch_qos_t
 _dispatch_priority_qos(dispatch_priority_t dbp)
 {
 	dbp &= DISPATCH_PRIORITY_QOS_MASK;
 	return dbp >> DISPATCH_PRIORITY_QOS_SHIFT;
 }

 DISPATCH_ALWAYS_INLINE
 static inline dispatch_qos_t
 _dispatch_priority_override_qos(dispatch_priority_t dbp)
 {
 	dbp &= DISPATCH_PRIORITY_OVERRIDE_MASK;
 	return dbp >> DISPATCH_PRIORITY_OVERRIDE_SHIFT;
 }

 DISPATCH_ALWAYS_INLINE
 static inline dispatch_priority_t
 _dispatch_priority_from_pp_impl(pthread_priority_t pp, bool keep_flags)
 {
 	dispatch_assert(!(pp & _PTHREAD_PRIORITY_SCHED_PRI_FLAG));

 	dispatch_priority_t dbp;
 	if (keep_flags) {
 		dbp = pp & (DISPATCH_PRIORITY_PTHREAD_PRIORITY_FLAGS_MASK |
 				DISPATCH_PRIORITY_RELPRI_MASK);
 	} else {
 		dbp = pp & DISPATCH_PRIORITY_RELPRI_MASK;
 	}

 	dbp |= _dispatch_qos_from_pp(pp) << DISPATCH_PRIORITY_QOS_SHIFT;
 	return dbp;
 }
 #define _dispatch_priority_from_pp(pp) \
 		_dispatch_priority_from_pp_impl(pp, true)
 #define _dispatch_priority_from_pp_strip_flags(pp) \
 		_dispatch_priority_from_pp_impl(pp, false)

 DISPATCH_ALWAYS_INLINE
 static inline pthread_priority_t
 _dispatch_priority_to_pp_impl(dispatch_priority_t dbp, bool keep_flags)
 {
 	pthread_priority_t pp;
 	if (keep_flags) {
 		pp = dbp & (DISPATCH_PRIORITY_PTHREAD_PRIORITY_FLAGS_MASK |
 				DISPATCH_PRIORITY_RELPRI_MASK);
 	} else {
 		pp = dbp & DISPATCH_PRIORITY_RELPRI_MASK;
 	}
 	dispatch_qos_t qos = _dispatch_priority_qos(dbp);
 	if (qos) {
 		pp |= (1ul << ((qos - 1) + _PTHREAD_PRIORITY_QOS_CLASS_SHIFT));
 	}
 	return pp;
 }
 #define _dispatch_priority_to_pp(pp) \
 		_dispatch_priority_to_pp_impl(pp, true)
 #define _dispatch_priority_to_pp_strip_flags(pp) \
 		_dispatch_priority_to_pp_impl(pp, false)

 #endif // __DISPATCH_SHIMS_PRIORITY__
	/*
	* Copyright (c) 2008-2016 Apple Inc. All rights reserved.
	*
	* @APPLE_APACHE_LICENSE_HEADER_START@
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*
	* @APPLE_APACHE_LICENSE_HEADER_END@
	*/

	/*
	* IMPORTANT: This header file describes INTERNAL interfaces to libdispatch
	* which are subject to change in future releases of Mac OS X. Any applications
	* relying on these interfaces WILL break.
	*/

	#ifndef __DISPATCH_SHIMS_PRIORITY__
	#define __DISPATCH_SHIMS_PRIORITY__

	#if HAVE_PTHREAD_QOS_H && __has_include(<pthread/qos_private.h>)
	#include <pthread/qos.h>
	#include <pthread/qos_private.h>
	#ifndef _PTHREAD_PRIORITY_OVERCOMMIT_FLAG
	#define _PTHREAD_PRIORITY_OVERCOMMIT_FLAG 0x80000000
	#endif
	#ifndef _PTHREAD_PRIORITY_SCHED_PRI_FLAG
	#define _PTHREAD_PRIORITY_SCHED_PRI_FLAG 0x20000000
	#endif
	#ifndef _PTHREAD_PRIORITY_DEFAULTQUEUE_FLAG
	#define _PTHREAD_PRIORITY_DEFAULTQUEUE_FLAG 0x04000000
	#endif
	#ifndef _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG
	#define _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG 0x02000000
	#endif
	#ifndef _PTHREAD_PRIORITY_NEEDS_UNBIND_FLAG
	#define _PTHREAD_PRIORITY_NEEDS_UNBIND_FLAG 0x01000000
	#endif
	#else // HAVE_PTHREAD_QOS_H
	OS_ENUM(qos_class, unsigned int,
	QOS_CLASS_USER_INTERACTIVE = 0x21,
	QOS_CLASS_USER_INITIATED = 0x19,
	QOS_CLASS_DEFAULT = 0x15,
	QOS_CLASS_UTILITY = 0x11,
	QOS_CLASS_BACKGROUND = 0x09,
	QOS_CLASS_MAINTENANCE = 0x05,
	QOS_CLASS_UNSPECIFIED = 0x00,
	);
	typedef unsigned long pthread_priority_t;
	#define QOS_MIN_RELATIVE_PRIORITY (-15)
	#define _PTHREAD_PRIORITY_FLAGS_MASK (~0xffffff)
	#define _PTHREAD_PRIORITY_QOS_CLASS_MASK 0x00ffff00
	#define _PTHREAD_PRIORITY_QOS_CLASS_SHIFT (8ull)
	#define _PTHREAD_PRIORITY_PRIORITY_MASK 0x000000ff
	#define _PTHREAD_PRIORITY_OVERCOMMIT_FLAG 0x80000000
	#define _PTHREAD_PRIORITY_SCHED_PRI_FLAG 0x20000000
	#define _PTHREAD_PRIORITY_DEFAULTQUEUE_FLAG 0x04000000
	#define _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG 0x02000000
	#define _PTHREAD_PRIORITY_NEEDS_UNBIND_FLAG 0x01000000
	#define _PTHREAD_PRIORITY_ENFORCE_FLAG 0x10000000

	#endif // HAVE_PTHREAD_QOS_H

	typedef uint32_t dispatch_qos_t;
	typedef uint32_t dispatch_priority_t;
	typedef uint32_t dispatch_priority_t;
	typedef uint16_t dispatch_priority_requested_t;

	#define DISPATCH_QOS_UNSPECIFIED ((dispatch_qos_t)0)
	#define DISPATCH_QOS_MAINTENANCE ((dispatch_qos_t)1)
	#define DISPATCH_QOS_BACKGROUND ((dispatch_qos_t)2)
	#define DISPATCH_QOS_UTILITY ((dispatch_qos_t)3)
	#define DISPATCH_QOS_DEFAULT ((dispatch_qos_t)4)
	#define DISPATCH_QOS_USER_INITIATED ((dispatch_qos_t)5)
	#define DISPATCH_QOS_USER_INTERACTIVE ((dispatch_qos_t)6)
	#define DISPATCH_QOS_MAX DISPATCH_QOS_USER_INTERACTIVE
	#define DISPATCH_QOS_SATURATED ((dispatch_qos_t)15)

	#define DISPATCH_PRIORITY_RELPRI_MASK ((dispatch_priority_t)0x000000ff)
	#define DISPATCH_PRIORITY_RELPRI_SHIFT 0
	#define DISPATCH_PRIORITY_QOS_MASK ((dispatch_priority_t)0x0000ff00)
	#define DISPATCH_PRIORITY_QOS_SHIFT 8
	#define DISPATCH_PRIORITY_REQUESTED_MASK ((dispatch_priority_t)0x0000ffff)
	#define DISPATCH_PRIORITY_OVERRIDE_MASK ((dispatch_priority_t)0x00ff0000)
	#define DISPATCH_PRIORITY_OVERRIDE_SHIFT 16
	#define DISPATCH_PRIORITY_FLAGS_MASK ((dispatch_priority_t)0xff000000)

	#define DISPATCH_PRIORITY_SATURATED_OVERRIDE ((dispatch_priority_t)0x000f0000)

	#define DISPATCH_PRIORITY_FLAG_OVERCOMMIT ((dispatch_priority_t)0x80000000) // _PTHREAD_PRIORITY_OVERCOMMIT_FLAG
	#define DISPATCH_PRIORITY_FLAG_DEFAULTQUEUE ((dispatch_priority_t)0x04000000) // _PTHREAD_PRIORITY_DEFAULTQUEUE_FLAG
	#define DISPATCH_PRIORITY_FLAG_MANAGER ((dispatch_priority_t)0x02000000) // _PTHREAD_PRIORITY_EVENT_MANAGER_FLAG
	#define DISPATCH_PRIORITY_PTHREAD_PRIORITY_FLAGS_MASK \
	(DISPATCH_PRIORITY_FLAG_OVERCOMMIT \| DISPATCH_PRIORITY_FLAG_DEFAULTQUEUE \| \
	DISPATCH_PRIORITY_FLAG_MANAGER)

	// not passed to pthread
	#define DISPATCH_PRIORITY_FLAG_INHERIT ((dispatch_priority_t)0x40000000) // _PTHREAD_PRIORITY_INHERIT_FLAG
	#define DISPATCH_PRIORITY_FLAG_ENFORCE ((dispatch_priority_t)0x10000000) // _PTHREAD_PRIORITY_ENFORCE_FLAG
	#define DISPATCH_PRIORITY_FLAG_ROOTQUEUE ((dispatch_priority_t)0x20000000) // _PTHREAD_PRIORITY_ROOTQUEUE_FLAG

	#pragma mark dispatch_qos

	DISPATCH_ALWAYS_INLINE
	static inline dispatch_qos_t
	_dispatch_qos_from_qos_class(qos_class_t cls)
	{
	switch ((unsigned int)cls) {
	case QOS_CLASS_USER_INTERACTIVE: return DISPATCH_QOS_USER_INTERACTIVE;
	case QOS_CLASS_USER_INITIATED: return DISPATCH_QOS_USER_INITIATED;
	case QOS_CLASS_DEFAULT: return DISPATCH_QOS_DEFAULT;
	case QOS_CLASS_UTILITY: return DISPATCH_QOS_UTILITY;
	case QOS_CLASS_BACKGROUND: return DISPATCH_QOS_BACKGROUND;
	case QOS_CLASS_MAINTENANCE: return DISPATCH_QOS_MAINTENANCE;
	default: return DISPATCH_QOS_UNSPECIFIED;
	}
	}

	DISPATCH_ALWAYS_INLINE
	static inline qos_class_t
	_dispatch_qos_to_qos_class(dispatch_qos_t qos)
	{
	switch (qos) {
	case DISPATCH_QOS_USER_INTERACTIVE: return QOS_CLASS_USER_INTERACTIVE;
	case DISPATCH_QOS_USER_INITIATED: return QOS_CLASS_USER_INITIATED;
	case DISPATCH_QOS_DEFAULT: return QOS_CLASS_DEFAULT;
	case DISPATCH_QOS_UTILITY: return QOS_CLASS_UTILITY;
	case DISPATCH_QOS_BACKGROUND: return QOS_CLASS_BACKGROUND;
	case DISPATCH_QOS_MAINTENANCE: return (qos_class_t)QOS_CLASS_MAINTENANCE;
	default: return QOS_CLASS_UNSPECIFIED;
	}
	}

	DISPATCH_ALWAYS_INLINE
	static inline dispatch_qos_t
	_dispatch_qos_from_queue_priority(long priority)
	{
	switch (priority) {
	case DISPATCH_QUEUE_PRIORITY_BACKGROUND: return DISPATCH_QOS_BACKGROUND;
	case DISPATCH_QUEUE_PRIORITY_NON_INTERACTIVE: return DISPATCH_QOS_UTILITY;
	case DISPATCH_QUEUE_PRIORITY_LOW: return DISPATCH_QOS_UTILITY;
	case DISPATCH_QUEUE_PRIORITY_DEFAULT: return DISPATCH_QOS_DEFAULT;
	case DISPATCH_QUEUE_PRIORITY_HIGH: return DISPATCH_QOS_USER_INITIATED;
	default: return _dispatch_qos_from_qos_class((qos_class_t)priority);
	}
	}

	DISPATCH_ALWAYS_INLINE
	static inline dispatch_qos_t
	_dispatch_qos_from_pp(pthread_priority_t pp)
	{
	pp &= _PTHREAD_PRIORITY_QOS_CLASS_MASK;
	pp >>= _PTHREAD_PRIORITY_QOS_CLASS_SHIFT;
	return (dispatch_qos_t)__builtin_ffs((int)pp);
	}

	DISPATCH_ALWAYS_INLINE
	static inline pthread_priority_t
	_dispatch_qos_to_pp(dispatch_qos_t qos)
	{
	pthread_priority_t pp;
	pp = 1ul << ((qos - 1) + _PTHREAD_PRIORITY_QOS_CLASS_SHIFT);
	return pp \| _PTHREAD_PRIORITY_PRIORITY_MASK;
	}

	// including maintenance
	DISPATCH_ALWAYS_INLINE
	static inline bool
	_dispatch_qos_is_background(dispatch_qos_t qos)
	{
	return qos && qos <= DISPATCH_QOS_BACKGROUND;
	}

	#pragma mark dispatch_priority

	#define _dispatch_priority_make(qos, relpri) \
	(qos ? ((((qos) << DISPATCH_PRIORITY_QOS_SHIFT) & DISPATCH_PRIORITY_QOS_MASK) \| \
	((dispatch_priority_t)(relpri - 1) & DISPATCH_PRIORITY_RELPRI_MASK)) : 0)

	DISPATCH_ALWAYS_INLINE
	static inline dispatch_priority_t
	_dispatch_priority_with_override_qos(dispatch_priority_t pri,
	dispatch_qos_t oqos)
	{
	pri &= ~DISPATCH_PRIORITY_OVERRIDE_MASK;
	pri \|= oqos << DISPATCH_PRIORITY_OVERRIDE_SHIFT;
	return pri;
	}

	DISPATCH_ALWAYS_INLINE
	static inline int
	_dispatch_priority_relpri(dispatch_priority_t dbp)
	{
	if (dbp & DISPATCH_PRIORITY_QOS_MASK) {
	return (int8_t)(dbp & DISPATCH_PRIORITY_RELPRI_MASK) + 1;
	}
	return 0;
	}

	DISPATCH_ALWAYS_INLINE
	static inline dispatch_qos_t
	_dispatch_priority_qos(dispatch_priority_t dbp)
	{
	dbp &= DISPATCH_PRIORITY_QOS_MASK;
	return dbp >> DISPATCH_PRIORITY_QOS_SHIFT;
	}

	DISPATCH_ALWAYS_INLINE
	static inline dispatch_qos_t
	_dispatch_priority_override_qos(dispatch_priority_t dbp)
	{
	dbp &= DISPATCH_PRIORITY_OVERRIDE_MASK;
	return dbp >> DISPATCH_PRIORITY_OVERRIDE_SHIFT;
	}

	DISPATCH_ALWAYS_INLINE
	static inline dispatch_priority_t
	_dispatch_priority_from_pp_impl(pthread_priority_t pp, bool keep_flags)
	{
	dispatch_assert(!(pp & _PTHREAD_PRIORITY_SCHED_PRI_FLAG));

	dispatch_priority_t dbp;
	if (keep_flags) {
	dbp = pp & (DISPATCH_PRIORITY_PTHREAD_PRIORITY_FLAGS_MASK \|
	DISPATCH_PRIORITY_RELPRI_MASK);
	} else {
	dbp = pp & DISPATCH_PRIORITY_RELPRI_MASK;
	}

	dbp \|= _dispatch_qos_from_pp(pp) << DISPATCH_PRIORITY_QOS_SHIFT;
	return dbp;
	}
	#define _dispatch_priority_from_pp(pp) \
	_dispatch_priority_from_pp_impl(pp, true)
	#define _dispatch_priority_from_pp_strip_flags(pp) \
	_dispatch_priority_from_pp_impl(pp, false)

	DISPATCH_ALWAYS_INLINE
	static inline pthread_priority_t
	_dispatch_priority_to_pp_impl(dispatch_priority_t dbp, bool keep_flags)
	{
	pthread_priority_t pp;
	if (keep_flags) {
	pp = dbp & (DISPATCH_PRIORITY_PTHREAD_PRIORITY_FLAGS_MASK \|
	DISPATCH_PRIORITY_RELPRI_MASK);
	} else {
	pp = dbp & DISPATCH_PRIORITY_RELPRI_MASK;
	}
	dispatch_qos_t qos = _dispatch_priority_qos(dbp);
	if (qos) {
	pp \|= (1ul << ((qos - 1) + _PTHREAD_PRIORITY_QOS_CLASS_SHIFT));
	}
	return pp;
	}
	#define _dispatch_priority_to_pp(pp) \
	_dispatch_priority_to_pp_impl(pp, true)
	#define _dispatch_priority_to_pp_strip_flags(pp) \
	_dispatch_priority_to_pp_impl(pp, false)

	#endif // __DISPATCH_SHIMS_PRIORITY__