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/* GETPID - USYS simulation of getpid().
**
**	Copyright (c) 1987 by Ken Harrenstien, SRI International
**
**	GFRKS% algorithm by Greg Satz / Stanford University / 15-Sep-84
**
**	See USYS.DOC for an explanation of the T20/10X PID encoding.
*/

#include "c-env.h"

#if SYS_T20+SYS_10X
#include "jsys.h"
#include "sys/usysig.h"
#endif

#if SYS_10X
#define	MAP_SIZE 100
struct fork_map {
	unsigned parap : 18;
	unsigned infp : 18;
	unsigned supp : 18;
	unsigned handle : 18;
	unsigned status;
	};
#endif /* 10X */

/* These must be externals so fork() and kill() can hack them. */

int _pidslf = 0;	/* Saved getpid() value for process */
int _pidpar = 0;	/* Saved parent PID from fork() */

int
getpid()
{
#if SYS_T10+SYS_WAITS
    /* PJOB returns job # */
    asm("\
	skipe 1,.pidslf\n\
	 popj 17,\n\
	pjob 1,\n\
	movem 1,.pidslf\n");	/* Get job # as return val and store it. */
#elif SYS_ITS
    /* Get user index # */
    asm("\
	skipe 1,.pidslf\n\
	 popj 17,\n\
	.suset [.ruind,,1]\n\
	movem 1,.pidslf\n");	/* Get user idx # as ret val and store it. */
#elif SYS_T20
    /* T20 and 10X need to be careful to suspend interrupts as otherwise
    ** successive calls might return different values if both decide
    ** to generate a PID!
    */
	int acs[5], argblk[3];
	USYS_BEG();
	if (_pidslf)		/* Check now that ints are off */
	    USYS_RET(_pidslf);
	acs[1] = 3;		/* Length of arg blk */
	acs[2] = (int)argblk;	/* Addr of arg blk */
	argblk[0] = _MUCRE;	/* Function: create new PID */
	argblk[1] = _FHSLF;	/* for this process */
	if (jsys(MUTIL, acs) <= 0	/* Get PID! */
	  || jsys(GJINF, acs) <= 0)	/* and job # */
	    USYS_RET(-1);
	_pidslf = (argblk[2] & ~0777777) | (acs[3] & 0777);
	USYS_RET(_pidslf);
#elif SYS_10X
	int cnt, ablock[5];
	struct fork_map *sup, *fmp, *count();
	struct fork_map fma[MAP_SIZE];

	USYS_BEG();		/* Disable interrupts */
	if (_pidslf)		/* Check now that ints are off */
	    USYS_RET(_pidslf);
	fmp = fma;
	ablock[1] = _FHTOP;
	ablock[2] = (int)fmp;
	if (jsys(GFRKS, ablock) <= 0	/* Get fork tree info */
	  || jsys(GJINF, ablock) <= 0)	/* Get job info */
		USYS_RET(-1);
	while (fmp->supp != 0)		/* find superior */
		fmp = (struct fork_map *) fmp->supp;
	sup = fmp;			/* save ptr to superior */
	cnt = 0;			/* initialize count */
	if (count(fmp, &cnt) == sup)	/* didn't find _FHSLF */
		USYS_RET(-1);
	/* Return job # and node cnt */
	_pidslf = (cnt << 18) | (ablock[3] & 0777);
	USYS_RET(_pidslf);
#else
#error getpid() not implemented for this system.
#endif
}

#if SYS_10X
/*
 * Count fork map in preorder
 */
static struct fork_map *
count(ptr, cnt)
struct fork_map *ptr;
int *cnt;
{
	struct fork_map *sptr = 0;

	(*cnt)++;		/* count fork */
	if (ptr->handle == _FHSLF)
		return ptr;

	if (ptr->infp != 0)		/* does inferior exist (left) */
		sptr = count((struct fork_map *)(ptr->infp), cnt);
	if (sptr == 0 && ptr->parap != 0)	/* check for parallel */
		sptr = count((struct fork_map *)(ptr->parap), cnt);
	return sptr;
}
#endif /* 10X */