/* comGuidLib.c - vxcom GUID library *//* Copyright (c) 2001 Wind River Systems, Inc. *//*modification history--------------------01d,19nov01,nel  Add delay back into GUID creation routine.01c,01nov01,nel  SPR#71383. Correct time adjustment algorithm.01b,27jun01,dbs  fix compiler warnings01a,21jun01,nel  created*//*DESCRIPTIONA library for generated GUIDs as defined in the DCE spec. There is a protection mechanism against generating GUIDs to quickly for the timer granularity to cope with.*/typedef struct _GUID    {    unsigned long	timeLow;    unsigned short	timeMid;    unsigned short	timeHiAndVersion;    unsigned char	clockSeqHiAndReserved;    unsigned char	clockSeqLow;    unsigned char	node[6];    } GUID;/* * Various constants and masks used in uuid generation. */#define UUID_C_VERSION 			(1)#define CLOCK_SEQ_LOW_MASK		(0xff)#define CLOCK_SEQ_HIGH_MASK		(0x3f00)#define CLOCK_SEQ_HIGH_SHIFT_COUNT	(8)#define CLOCK_SEQ_FIRST			(1)#define CLOCK_SEQ_LAST			(0x3fff)	/* same as RAND_MASK */#define RAND_MASK			(CLOCK_SEQ_LAST)/* 'adjustment' for backwards clocks */static int			clockSeq = 0;/* Last time a UUID was generated or 0 if first time class is exectued. */static long unsigned long	last = 0;/* Adjustment to cope with reduced granularity of the clock. */static int			adjustment = 0;/* Used to store last uuid generated so that duplicates can be checked for. */static GUID lastGuid = { 0, };/* * Create's a new clock sequence value. This is a randomnly gerenated field * in the UUID which ensures that two UUIDs generated at the same time stand * some chance of being unique. */static void newClockSeq (void)    {    clockSeq = rand() & RAND_MASK;    clockSeq = (clockSeq + 1) & CLOCK_SEQ_LAST;    if (clockSeq == 0)        {        clockSeq++;        }    }static long unsigned long clockGet (void)    {    long unsigned long	usec;    long unsigned long	clockReg;    /* convert seconds to usecs */    usec = (long unsigned long)comSysTimeGet () * 1000000;     if (last == 0)	{	newClockSeq();	last = usec - 1;	}    if (usec < last )	{	clockSeq = (clockSeq + 1) & 0x1FFF;	adjustment = 0;	}    else if (usec == last)	{	if (adjustment >= 999)	    {	    newClockSeq ();	    adjustment = 0;	    }	else	    adjustment++;	}    else	adjustment = 0;    last = usec;    clockReg = usec * 10;    clockReg += adjustment;    clockReg += 0x01B21DD213814000LL; /* Difference between DTSS UTC and Unix */    				      /* DTSS starts October 15, 1582. */    return clockReg;    }void comSysGuidCreate     (    void *		result		/* Result that is mapped onto an */    					/* IDL GUID structure by higher layers*/    )    {    do        {        long unsigned long timeNow = clockGet ();        ((GUID *)result)->timeLow = timeNow & 0xffffffff;        ((GUID *)result)->timeMid = (timeNow >> 32) & 0xffff;        ((GUID *)result)->timeHiAndVersion = ((timeNow >> 48) & 0xffff) |         				      (UUID_C_VERSION << 12);        ((GUID *)result)->clockSeqLow = (short) (clockSeq & CLOCK_SEQ_LOW_MASK);        ((GUID *)result)->clockSeqHiAndReserved =                ((short) ((clockSeq & CLOCK_SEQ_HIGH_MASK) >>                     CLOCK_SEQ_HIGH_SHIFT_COUNT)) | 0x80;    	comSysAddressGet ( ((GUID *)result)->node );        /**         * check to see if the last guid has been duplicated, if it has then         * wait a bit and try again. this should ensure that the next guid         * generated is unique.         */        if (memcmp (&lastGuid, result, sizeof (GUID)) != 0)            {            /* last GUID is different from current GUID so is correct */            memcpy (&lastGuid, result, sizeof (GUID));            return;            }	taskDelay (1);        } while (1); /* loop until a vaild GUID is generated */    }