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1 | /* Target-dependent code for Lynx running on i386's, for GDB. |
2 | Copyright 1988, 1989, 1991, 1992, 1993 | |
3 | Free Software Foundation, Inc. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program 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 | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
20 | ||
21 | #include "defs.h" | |
22 | #include "inferior.h" | |
23 | #include "target.h" | |
24 | ||
25 | /* Return the PC of the caller from the call frame. Assumes the subr prologue | |
26 | has already been executed, and the frame pointer setup. If this is the | |
27 | outermost frame, we check to see if we are in a system call by examining the | |
28 | previous instruction. If so, then the return PC is actually at SP+4 because | |
29 | system calls use a different calling sequence. */ | |
30 | ||
31 | CORE_ADDR | |
32 | i386lynx_saved_pc_after_call (frame) | |
33 | struct frame_info *frame; | |
34 | { | |
35 | char opcode[7]; | |
36 | static const char call_inst[] = {0x9a, 0, 0, 0, 0, 8, 0}; /* lcall 0x8,0x0 */ | |
37 | ||
38 | read_memory (frame->pc - 7, opcode, 7); | |
39 | if (memcmp (opcode, call_inst, 7) == 0) | |
40 | return read_memory_integer (read_register (SP_REGNUM) + 4, 4); | |
41 | ||
42 | return read_memory_integer (read_register (SP_REGNUM), 4); | |
43 | } |