usr/src/lib/libc/vax/gen/setjmp.s

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#ifdef LIBC_SCCS
        .asciz  "@(#)setjmp.s   5.5 (Berkeley) 3/9/86"
#endif LIBC_SCCS

/*
 * C library -- setjmp, longjmp
 *
 *      longjmp(a,v)
 * will generate a "return(v)" from
 * the last call to
 *      setjmp(a)
 * by restoring registers from the stack,
 * and a struct sigcontext, see <signal.h>
 */

#include "DEFS.h"

ENTRY(setjmp, R6)
        movl    4(ap),r6                # construct sigcontext
        subl2   $8,sp                   # space for current struct sigstack
        pushl   sp                      # get current values
        pushl   $0                      # no new values
        calls   $3,_sigstack            # pop args plus signal stack value
        movl    (sp)+,(r6)+             # save onsigstack status of caller
        pushl   $0
        calls   $1,_sigblock            # get signal mask
        movl    r0,(r6)+                # save signal mask of caller
        movl    (ap),r0
        moval   4(ap)[r0],(r6)+         # save sp of caller
        movl    12(fp),(r6)+            # save frame pointer of caller
        movl    8(fp),(r6)+             # save argument pointer of caller
        movl    16(fp),(r6)+            # save pc of caller
        movpsl  (r6)                    # save psl of caller
        movw    4(fp),(r6)
        clrl    r0
        ret

ENTRY(longjmp, 0)
        movl    8(ap),r0                # return(v)
        movl    4(ap),r1                # fetch buffer
        tstl    12(r1)
        beql    botch
loop:
        cmpl    12(r1),fp               # are we there yet?
        beql    done
        blssu   botch
        moval   20(fp),r2
        blbc    6(fp),1f                # was r0 saved?
        movl    r0,(r2)+
1:
        bbc     $1,6(fp),2f             # was r1 saved?
        movl    r1,(r2)
2:
        movl    $loop,16(fp)
        ret                             # pop another frame

done:

#ifndef NOCOMPAT
/*
 * This code checks to see if it can use the new sigreturn.
 * If it finds that sigtramp is using the new system call,
 * it will also use it. Otherwise it uses the old system call
 * to preserve compatibility.
 */
#include <vax/machparam.h>
#define U (0x80000000-UPAGES*NBPG)
#define PCB_SIGC 0x6c
#define CHMKINS 7
        cmpl    3f,U+PCB_SIGC+CHMKINS   # check to see how sigtramp returns
        beql    4f                      # sigtramp uses the new system call
        pushl   r1                      # must use the old signal return
        chmk    $139                    # restore previous context
        jmp     *20(r1)                 # done, return
3:
        chmk    $103                    # the new system call for sigreturn
4:
#endif NOCOMPAT

        pushl   r1                      # pointer to sigcontext
        calls   $1,_sigreturn           # restore previous context
                                        # we should never return
botch:
        calls   $0,_longjmperror
        halt