sysdeps/vax/__longjmp.c

   1 /* Copyright (C) 1991, 1992, 1994 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
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <ansidecl.h>
  21 #include <setjmp.h>
  22
  23 #ifndef __GNUC__
  24   #error This file uses GNU C extensions; you must compile with GCC.
  25 #endif
  26
  27
  28 #define REI     02      /* Vax `rei' opcode.  */
  29
  30 /* Jump to the position specified by ENV, causing the
  31    setjmp call there to return VAL, or 1 if VAL is 0.  */
  32 __NORETURN
  33 void
  34 DEFUN(__longjmp, (env, val), CONST __jmp_buf env AND int val)
  35 {
  36   register long int *fp asm("fp");
  37   long int *regsave;
  38   unsigned long int flags;
  39
  40   if (env.__fp == NULL)
  41     __libc_fatal("longjmp: Invalid ENV argument.\n");
  42
  43   if (val == 0)
  44     val = 1;
  45
  46   asm volatile("loop:");
  47
  48   flags = *(long int *) (6 + (char *) fp);
  49   regsave = (long int *) (20 + (char *) fp);
  50   if (flags & 1)
  51     /* R0 was saved by the caller.
  52        Store VAL where it will be restored from.  */
  53     *regsave++ = val;
  54   if (flags & 2)
  55     /* R1 was saved by the caller.
  56        Store ENV where it will be restored from.  */
  57     *regsave = env;
  58
  59   /* Was the FP saved in the last call the same one in ENV?  */
  60   asm volatile("cmpl %0, 12(fp);"
  61                /* Yes, return to it.  */
  62                "beql done;"
  63                /* The FP in ENV is less than the one saved in the last call.
  64                   This means we have already returned from the function that
  65                   called `setjmp' with ENV!  */
  66                "blssu latejump;" : /* No outputs.  */ : "g" (env.__fp));
  67
  68   /* We are more than one level below the state in ENV.
  69      Return to where we will pop another stack frame.  */
  70   asm volatile("movl $loop, 16(fp);"
  71                "ret");
  72
  73   asm volatile("done:");
  74   {
  75     char return_insn asm("*16(fp)");
  76     if (return_insn == REI)
  77       /* We're returning with an `rei' instruction.
  78          Do a return with PSL-PC pop.  */
  79       asm volatile("movab 0f, 16(fp)");
  80     else
  81       /* Do a standard return.  */
  82       asm volatile("movab 1f, 16(fp)");
  83
  84     /* Return.  */
  85     asm volatile("ret");
  86   }
  87
  88   asm volatile("0:"     /* `rei' return.  */
  89                /* Compensate for PSL-PC push.  */
  90                "addl2 %0, sp;"
  91                "1:"     /* Standard return.  */
  92                /* Return to saved PC.  */
  93                "jmp %1" : /* No outputs.  */ :
  94                "g" (8), "g" (env.__pc));
  95
  96   /* Jump here when the FP saved in ENV points
  97      to a function that has already returned.  */
  98   asm volatile("latejump:");
  99   __libc_fatal("longjmp: Attempt to jump to a function that has returned.\n");
 100 }