sysdeps/vax/__longjmp.c

   1 /* Copyright (C) 1991, 1992, 1994, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Derived from @(#)_setjmp.s   5.7 (Berkeley) 6/27/88,
   4    Copyright (c) 1980 Regents of the University of California.
   5    This file is part of the GNU C Library.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21
  22 #include <setjmp.h>
  23
  24 #ifndef __GNUC__
  25   #error This file uses GNU C extensions; you must compile with GCC.
  26 #endif
  27
  28
  29 #define REI     02      /* Vax `rei' opcode.  */
  30
  31 /* Jump to the position specified by ENV, causing the
  32    setjmp call there to return VAL, or 1 if VAL is 0.  */
  33 __NORETURN
  34 void
  35 __longjmp (env, val)
  36      const __jmp_buf env;
  37      int val;
  38 {
  39   register long int *fp asm("fp");
  40   long int *regsave;
  41   unsigned long int flags;
  42
  43   if (env.__fp == NULL)
  44     __libc_fatal("longjmp: Invalid ENV argument.\n");
  45
  46   if (val == 0)
  47     val = 1;
  48
  49   asm volatile("loop:");
  50
  51   flags = *(long int *) (6 + (char *) fp);
  52   regsave = (long int *) (20 + (char *) fp);
  53   if (flags & 1)
  54     /* R0 was saved by the caller.
  55        Store VAL where it will be restored from.  */
  56     *regsave++ = val;
  57   if (flags & 2)
  58     /* R1 was saved by the caller.
  59        Store ENV where it will be restored from.  */
  60     *regsave = env;
  61
  62   /* Was the FP saved in the last call the same one in ENV?  */
  63   asm volatile("cmpl %0, 12(fp);"
  64                /* Yes, return to it.  */
  65                "beql done;"
  66                /* The FP in ENV is less than the one saved in the last call.
  67                   This means we have already returned from the function that
  68                   called `setjmp' with ENV!  */
  69                "blssu latejump;" : /* No outputs.  */ : "g" (env.__fp));
  70
  71   /* We are more than one level below the state in ENV.
  72      Return to where we will pop another stack frame.  */
  73   asm volatile("movl $loop, 16(fp);"
  74                "ret");
  75
  76   asm volatile("done:");
  77   {
  78     char return_insn asm("*16(fp)");
  79     if (return_insn == REI)
  80       /* We're returning with an `rei' instruction.
  81          Do a return with PSL-PC pop.  */
  82       asm volatile("movab 0f, 16(fp)");
  83     else
  84       /* Do a standard return.  */
  85       asm volatile("movab 1f, 16(fp)");
  86
  87     /* Return.  */
  88     asm volatile("ret");
  89   }
  90
  91   asm volatile("0:"     /* `rei' return.  */
  92                /* Compensate for PSL-PC push.  */
  93                "addl2 %0, sp;"
  94                "1:"     /* Standard return.  */
  95                /* Return to saved PC.  */
  96                "jmp %1" : /* No outputs.  */ :
  97                "g" (8), "g" (env.__pc));
  98
  99   /* Jump here when the FP saved in ENV points
 100      to a function that has already returned.  */
 101   asm volatile("latejump:");
 102   __libc_fatal("longjmp: Attempt to jump to a function that has returned.\n");
 103 }