1 /* Define the machine-dependent type `jmp_buf'.  Alpha version.
2    Copyright (C) 1992-2022 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 */
62