binutils-gdb/gdb/ns32k-tdep.c

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/* Print NS 32000 instructions for GDB, the GNU debugger.
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Copyright 1986, 1988, 1991, 1992, 1994, 1995, 1998, 1999, 2000, 2001
Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
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This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include "defs.h"
#include "frame.h"
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#include "gdbcore.h"
static int sign_extend (int value, int bits);
void
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_initialize_ns32k_tdep (void)
{
tm_print_insn = print_insn_ns32k;
}
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/* Advance PC across any function entry prologue instructions
to reach some "real" code. */
CORE_ADDR
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umax_skip_prologue (CORE_ADDR pc)
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{
register unsigned char op = read_memory_integer (pc, 1);
if (op == 0x82)
{
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op = read_memory_integer (pc + 2, 1);
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if ((op & 0x80) == 0)
pc += 3;
else if ((op & 0xc0) == 0x80)
pc += 4;
else
pc += 6;
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}
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return pc;
}
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/* Return number of args passed to a frame.
Can return -1, meaning no way to tell.
Encore's C compiler often reuses same area on stack for args,
so this will often not work properly. If the arg names
are known, it's likely most of them will be printed. */
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int
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umax_frame_num_args (struct frame_info *fi)
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{
int numargs;
CORE_ADDR pc;
CORE_ADDR enter_addr;
unsigned int insn;
unsigned int addr_mode;
int width;
numargs = -1;
enter_addr = ns32k_get_enter_addr ((fi)->pc);
if (enter_addr > 0)
{
pc = ((enter_addr == 1)
? SAVED_PC_AFTER_CALL (fi)
: FRAME_SAVED_PC (fi));
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insn = read_memory_integer (pc, 2);
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addr_mode = (insn >> 11) & 0x1f;
insn = insn & 0x7ff;
if ((insn & 0x7fc) == 0x57c
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&& addr_mode == 0x14) /* immediate */
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{
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if (insn == 0x57c) /* adjspb */
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width = 1;
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else if (insn == 0x57d) /* adjspw */
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width = 2;
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else if (insn == 0x57f) /* adjspd */
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width = 4;
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else
internal_error (__FILE__, __LINE__, "bad else");
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numargs = read_memory_integer (pc + 2, width);
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if (width > 1)
flip_bytes (&numargs, width);
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numargs = -sign_extend (numargs, width * 8) / 4;
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}
}
return numargs;
}
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static int
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sign_extend (int value, int bits)
{
value = value & ((1 << bits) - 1);
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return (value & (1 << (bits - 1))
? value | (~((1 << bits) - 1))
: value);
}
void
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flip_bytes (void *p, int count)
{
char tmp;
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char *ptr = 0;
while (count > 0)
{
tmp = *ptr;
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ptr[0] = ptr[count - 1];
ptr[count - 1] = tmp;
ptr++;
count -= 2;
}
}
/* Return the number of locals in the current frame given a pc
pointing to the enter instruction. This is used in the macro
FRAME_FIND_SAVED_REGS. */
int
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ns32k_localcount (CORE_ADDR enter_pc)
{
unsigned char localtype;
int localcount;
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localtype = read_memory_integer (enter_pc + 2, 1);
if ((localtype & 0x80) == 0)
localcount = localtype;
else if ((localtype & 0xc0) == 0x80)
localcount = (((localtype & 0x3f) << 8)
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| (read_memory_integer (enter_pc + 3, 1) & 0xff));
else
localcount = (((localtype & 0x3f) << 24)
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| ((read_memory_integer (enter_pc + 3, 1) & 0xff) << 16)
| ((read_memory_integer (enter_pc + 4, 1) & 0xff) << 8)
| (read_memory_integer (enter_pc + 5, 1) & 0xff));
return localcount;
}
/* Nonzero if instruction at PC is a return instruction. */
static int
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ns32k_about_to_return (CORE_ADDR pc)
{
return (read_memory_integer (pc, 1) == 0x12);
}
/*
* Get the address of the enter opcode for the function
* containing PC, if there is an enter for the function,
* and if the pc is between the enter and exit.
* Returns positive address if pc is between enter/exit,
* 1 if pc before enter or after exit, 0 otherwise.
*/
CORE_ADDR
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ns32k_get_enter_addr (CORE_ADDR pc)
{
CORE_ADDR enter_addr;
unsigned char op;
if (pc == 0)
return 0;
if (ns32k_about_to_return (pc))
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return 1; /* after exit */
enter_addr = get_pc_function_start (pc);
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if (pc == enter_addr)
return 1; /* before enter */
op = read_memory_integer (enter_addr, 1);
if (op != 0x82)
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return 0; /* function has no enter/exit */
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return enter_addr; /* pc is between enter and exit */
}