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glibc  2.9
__longjmp.c
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00001 /* Copyright (C) 1991, 1992, 1994, 1997 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003  
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  
00018 
00019    Derived from @(#)_setjmp.s      5.7 (Berkeley) 6/27/88,
00020    Copyright (C) 1980 Regents of the University of California.
00021    All rights reserved.
00022 
00023    Redistribution and use in source and binary forms, with or without
00024    modification, are permitted provided that the following conditions
00025    are met:
00026 
00027    1. Redistributions of source code must retain the above copyright
00028       notice, this list of conditions and the following disclaimer.
00029    2. Redistributions in binary form must reproduce the above copyright
00030       notice, this list of conditions and the following disclaimer in the
00031       documentation and/or other materials provided with the distribution.
00032    4. Neither the name of the University nor the names of its contributors
00033       may be used to endorse or promote products derived from this software
00034       without specific prior written permission.
00035    
00036    THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
00037    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00038    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00039    ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
00040    FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00041    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00042    OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00043    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00044    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00045    OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00046    SUCH DAMAGE.*/
00047 
00048 #include <setjmp.h>
00049 
00050 #ifndef       __GNUC__
00051   #error This file uses GNU C extensions; you must compile with GCC.
00052 #endif
00053 
00054 
00055 #define       REI    02     /* Vax `rei' opcode.  */
00056 
00057 /* Jump to the position specified by ENV, causing the
00058    setjmp call there to return VAL, or 1 if VAL is 0.  */
00059 __NORETURN
00060 void
00061 __longjmp (env, val)
00062      const __jmp_buf env;
00063      int val;
00064 {
00065   register long int *fp asm("fp");
00066   long int *regsave;
00067   unsigned long int flags;
00068 
00069   if (env.__fp == NULL)
00070     __libc_fatal("longjmp: Invalid ENV argument.\n");
00071 
00072   if (val == 0)
00073     val = 1;
00074 
00075   asm volatile("loop:");
00076 
00077   flags = *(long int *) (6 + (char *) fp);
00078   regsave = (long int *) (20 + (char *) fp);
00079   if (flags & 1)
00080     /* R0 was saved by the caller.
00081        Store VAL where it will be restored from.  */
00082     *regsave++ = val;
00083   if (flags & 2)
00084     /* R1 was saved by the caller.
00085        Store ENV where it will be restored from.  */
00086     *regsave = env;
00087 
00088   /* Was the FP saved in the last call the same one in ENV?  */
00089   asm volatile("cmpl %0, 12(fp);"
00090               /* Yes, return to it.  */
00091               "beql done;"
00092               /* The FP in ENV is less than the one saved in the last call.
00093                 This means we have already returned from the function that
00094                 called `setjmp' with ENV!  */
00095               "blssu latejump;" : /* No outputs.  */ : "g" (env.__fp));
00096 
00097   /* We are more than one level below the state in ENV.
00098      Return to where we will pop another stack frame.  */
00099   asm volatile("movl $loop, 16(fp);"
00100               "ret");
00101 
00102   asm volatile("done:");
00103   {
00104     char return_insn asm("*16(fp)");
00105     if (return_insn == REI)
00106       /* We're returning with an `rei' instruction.
00107         Do a return with PSL-PC pop.  */
00108       asm volatile("movab 0f, 16(fp)");
00109     else
00110       /* Do a standard return.  */
00111       asm volatile("movab 1f, 16(fp)");
00112 
00113     /* Return.  */
00114     asm volatile("ret");
00115   }
00116 
00117   asm volatile("0:"  /* `rei' return.  */
00118               /* Compensate for PSL-PC push.  */
00119               "addl2 %0, sp;"
00120               "1:"   /* Standard return.  */
00121               /* Return to saved PC.  */
00122               "jmp %1" : /* No outputs.  */ :
00123               "g" (8), "g" (env.__pc));
00124 
00125   /* Jump here when the FP saved in ENV points
00126      to a function that has already returned.  */
00127   asm volatile("latejump:");
00128   __libc_fatal("longjmp: Attempt to jump to a function that has returned.\n");
00129 }