sysdeps/vax/__longjmp.c

   1 /* Copyright (C) 1991, 1992, 1994, 1997 Free Software Foundation, Inc.
   2    Derived from @(#)_setjmp.s   5.7 (Berkeley) 6/27/88,
   3    Copyright (c) 1980 Regents of the University of California.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <setjmp.h>
  21
  22 #ifndef __GNUC__
  23   #error This file uses GNU C extensions; you must compile with GCC.
  24 #endif
  25
  26
  27 #define REI     02      /* Vax `rei' opcode.  */
  28
  29 /* Jump to the position specified by ENV, causing the
  30    setjmp call there to return VAL, or 1 if VAL is 0.  */
  31 __NORETURN
  32 void
  33 __longjmp (env, val)
  34      const __jmp_buf env;
  35      int val;
  36 {
  37   register long int *fp asm("fp");
  38   long int *regsave;
  39   unsigned long int flags;
  40
  41   if (env.__fp == NULL)
  42     __libc_fatal("longjmp: Invalid ENV argument.\n");
  43
  44   if (val == 0)
  45     val = 1;
  46
  47   asm volatile("loop:");
  48
  49   flags = *(long int *) (6 + (char *) fp);
  50   regsave = (long int *) (20 + (char *) fp);
  51   if (flags & 1)
  52     /* R0 was saved by the caller.
  53        Store VAL where it will be restored from.  */
  54     *regsave++ = val;
  55   if (flags & 2)
  56     /* R1 was saved by the caller.
  57        Store ENV where it will be restored from.  */
  58     *regsave = env;
  59
  60   /* Was the FP saved in the last call the same one in ENV?  */
  61   asm volatile("cmpl %0, 12(fp);"
  62                /* Yes, return to it.  */
  63                "beql done;"
  64                /* The FP in ENV is less than the one saved in the last call.
  65                   This means we have already returned from the function that
  66                   called `setjmp' with ENV!  */
  67                "blssu latejump;" : /* No outputs.  */ : "g" (env.__fp));
  68
  69   /* We are more than one level below the state in ENV.
  70      Return to where we will pop another stack frame.  */
  71   asm volatile("movl $loop, 16(fp);"
  72                "ret");
  73
  74   asm volatile("done:");
  75   {
  76     char return_insn asm("*16(fp)");
  77     if (return_insn == REI)
  78       /* We're returning with an `rei' instruction.
  79          Do a return with PSL-PC pop.  */
  80       asm volatile("movab 0f, 16(fp)");
  81     else
  82       /* Do a standard return.  */
  83       asm volatile("movab 1f, 16(fp)");
  84
  85     /* Return.  */
  86     asm volatile("ret");
  87   }
  88
  89   asm volatile("0:"     /* `rei' return.  */
  90                /* Compensate for PSL-PC push.  */
  91                "addl2 %0, sp;"
  92                "1:"     /* Standard return.  */
  93                /* Return to saved PC.  */
  94                "jmp %1" : /* No outputs.  */ :
  95                "g" (8), "g" (env.__pc));
  96
  97   /* Jump here when the FP saved in ENV points
  98      to a function that has already returned.  */
  99   asm volatile("latejump:");
 100   __libc_fatal("longjmp: Attempt to jump to a function that has returned.\n");
 101 }