[urcu.git] / formal-model / ticketlock / mem.spin

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (c) 2009 Mathieu Desnoyers
 */

/* 16 CPUs max (byte has 8 bits, divided in two) */

#ifndef CONFIG_BITS_PER_BYTE
#define BITS_PER_BYTE		8
#else
#define BITS_PER_BYTE		CONFIG_BITS_PER_BYTE
#endif

#define HBPB			(BITS_PER_BYTE / 2)	/* 4 */
#define HMASK			((1 << HBPB) - 1)	/* 0x0F */

/* for byte type */
#define LOW_HALF(val)		((val) & HMASK)
#define LOW_HALF_INC		1

#define HIGH_HALF(val)		((val) & (HMASK << HBPB))
#define HIGH_HALF_INC		(1 << HBPB)

byte lock = 0;
byte refcount = 0;

inline spin_lock(lock, ticket)
{
	atomic {
		ticket = HIGH_HALF(lock) >> HBPB;
		lock = lock + HIGH_HALF_INC;	/* overflow expected */
	}

	do
	:: 1 ->
		if
		:: (LOW_HALF(lock) == ticket) ->
			break;
		:: else ->
			skip;
		fi;
	od;
}

inline spin_unlock(lock)
{
	lock = HIGH_HALF(lock) | LOW_HALF(lock + LOW_HALF_INC);
}

proctype proc_X()
{
	byte ticket;

	do
	:: 1->
		spin_lock(lock, ticket);
		refcount = refcount + 1;
		refcount = refcount - 1;
		spin_unlock(lock);
	od;
}

init
{
	run proc_X();
	run proc_X();
	run proc_X();
	run proc_X();
	run proc_X();
}
Commit	Line	Data
	1	/*
	2	* This program is free software; you can redistribute it and/or modify
	3	* it under the terms of the GNU General Public License as published by
	4	* the Free Software Foundation; either version 2 of the License, or
	5	* (at your option) any later version.
	6	*
	7	* This program is distributed in the hope that it will be useful,
	8	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	9	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	10	* GNU General Public License for more details.
	11	*
	12	* You should have received a copy of the GNU General Public License
	13	* along with this program; if not, write to the Free Software
	14	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	15	*
	16	* Copyright (c) 2009 Mathieu Desnoyers
	17	*/
	18
	19	/* 16 CPUs max (byte has 8 bits, divided in two) */
	20
	21	#ifndef CONFIG_BITS_PER_BYTE
	22	#define BITS_PER_BYTE 8
	23	#else
	24	#define BITS_PER_BYTE CONFIG_BITS_PER_BYTE
	25	#endif
	26
	27	#define HBPB (BITS_PER_BYTE / 2) /* 4 */
	28	#define HMASK ((1 << HBPB) - 1) /* 0x0F */
	29
	30	/* for byte type */
	31	#define LOW_HALF(val) ((val) & HMASK)
	32	#define LOW_HALF_INC 1
	33
	34	#define HIGH_HALF(val) ((val) & (HMASK << HBPB))
	35	#define HIGH_HALF_INC (1 << HBPB)
	36
	37	byte lock = 0;
	38	byte refcount = 0;
	39
	40	inline spin_lock(lock, ticket)
	41	{
	42	atomic {
	43	ticket = HIGH_HALF(lock) >> HBPB;
	44	lock = lock + HIGH_HALF_INC; /* overflow expected */
	45	}
	46
	47	do
	48	:: 1 ->
	49	if
	50	:: (LOW_HALF(lock) == ticket) ->
	51	break;
	52	:: else ->
	53	skip;
	54	fi;
	55	od;
	56	}
	57
	58	inline spin_unlock(lock)
	59	{
	60	lock = HIGH_HALF(lock) \| LOW_HALF(lock + LOW_HALF_INC);
	61	}
	62
	63	proctype proc_X()
	64	{
	65	byte ticket;
	66
	67	do
	68	:: 1->
	69	spin_lock(lock, ticket);
	70	refcount = refcount + 1;
	71	refcount = refcount - 1;
	72	spin_unlock(lock);
	73	od;
	74	}
	75
	76	init
	77	{
	78	run proc_X();
	79	run proc_X();
	80	run proc_X();
	81	run proc_X();
	82	run proc_X();
	83	}