1  /* Define the machine-dependent type `jmp_buf'.  Alpha version.
       2     Copyright (C) 1992-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the 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     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library.  If not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef _BITS_SETJMP_H
      20  #define _BITS_SETJMP_H  1
      21  
      22  #if !defined _SETJMP_H && !defined _PTHREAD_H
      23  # error "Never include <bits/setjmp.h> directly; use <setjmp.h> instead."
      24  #endif
      25  
      26  /* The previous bits/setjmp.h had __jmp_buf defined as a structure.
      27     We use an array of 'long int' instead, to make writing the
      28     assembler easier. Naturally, user code should not depend on
      29     either representation. */
      30  
      31  /*
      32   * Integer registers:
      33   *    $0 is the return value (va);
      34   *    $1-$8, $22-$25, $28 are call-used (t0-t7, t8-t11, at);
      35   *    $9-$14 we save here (s0-s5);
      36   *    $15 is the FP and we save it here (fp or s6);
      37   *    $16-$21 are input arguments (call-used) (a0-a5);
      38   *    $26 is the return PC and we save it here (ra);
      39   *    $27 is the procedure value (i.e., the address of __setjmp) (pv or t12);
      40   *    $29 is the global pointer, which the caller will reconstruct
      41   *        from the return address restored in $26 (gp);
      42   *    $30 is the stack pointer and we save it here (sp);
      43   *    $31 is always zero (zero).
      44   *
      45   * Floating-point registers:
      46   *    $f0 is the floating return value;
      47   *    $f1, $f10-$f15, $f22-$f30 are call-used;
      48   *    $f2-$f9 we save here;
      49   *    $f16-$21 are input args (call-used);
      50   *    $f31 is always zero.
      51   *
      52   * Note that even on Alpha hardware that does not have an FPU (there
      53   * isn't such a thing currently) it is required to implement the FP
      54   * registers.
      55   */
      56  
      57  #ifndef __ASSEMBLY__
      58  typedef long int __jmp_buf[17];
      59  #endif
      60  
      61  #endif  /* bits/setjmp.h */