gdb/ns32k-tdep.c

   1 /* Print NS 32000 instructions for GDB, the GNU debugger.
   2    Copyright 1986, 1988, 1991, 1992, 1994, 1995
   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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 #include "defs.h"
  22
  23 void
  24 _initialize_ns32k_tdep ()
  25 {
  26   tm_print_insn = print_insn_ns32k;
  27 }
  28
  29 sign_extend (value, bits)
  30 {
  31   value = value & ((1 << bits) - 1);
  32   return (value & (1 << (bits-1))
  33           ? value | (~((1 << bits) - 1))
  34           : value);
  35 }
  36
  37 void
  38 flip_bytes (ptr, count)
  39      char *ptr;
  40      int count;
  41 {
  42   char tmp;
  43
  44   while (count > 0)
  45     {
  46       tmp = *ptr;
  47       ptr[0] = ptr[count-1];
  48       ptr[count-1] = tmp;
  49       ptr++;
  50       count -= 2;
  51     }
  52 }
  53
  54 /* Return the number of locals in the current frame given a pc
  55    pointing to the enter instruction.  This is used in the macro
  56    FRAME_FIND_SAVED_REGS.  */
  57
  58 int
  59 ns32k_localcount (enter_pc)
  60      CORE_ADDR enter_pc;
  61 {
  62   unsigned char localtype;
  63   int localcount;
  64
  65   localtype = read_memory_integer (enter_pc+2, 1);
  66   if ((localtype & 0x80) == 0)
  67     localcount = localtype;
  68   else if ((localtype & 0xc0) == 0x80)
  69     localcount = (((localtype & 0x3f) << 8)
  70                   | (read_memory_integer (enter_pc+3, 1) & 0xff));
  71   else
  72     localcount = (((localtype & 0x3f) << 24)
  73                   | ((read_memory_integer (enter_pc+3, 1) & 0xff) << 16)
  74                   | ((read_memory_integer (enter_pc+4, 1) & 0xff) << 8 )
  75                   | (read_memory_integer (enter_pc+5, 1) & 0xff));
  76   return localcount;
  77 }
  78
  79
  80 /* Nonzero if instruction at PC is a return instruction.  */
  81
  82 static int
  83 ns32k_about_to_return (pc)
  84      CORE_ADDR pc;
  85 {
  86   return (read_memory_integer (pc, 1) == 0x12);
  87 }
  88
  89
  90 /*
  91  * Get the address of the enter opcode for the function
  92  * containing PC, if there is an enter for the function,
  93  * and if the pc is between the enter and exit.
  94  * Returns positive address if pc is between enter/exit,
  95  * 1 if pc before enter or after exit, 0 otherwise.
  96  */
  97
  98 CORE_ADDR
  99 ns32k_get_enter_addr (pc)
 100      CORE_ADDR pc;
 101 {
 102   CORE_ADDR enter_addr;
 103   unsigned char op;
 104
 105   if (pc == 0)
 106     return 0;
 107
 108   if (ns32k_about_to_return (pc))
 109     return 1;           /* after exit */
 110
 111   enter_addr = get_pc_function_start (pc);
 112
 113   if (pc == enter_addr)
 114     return 1;           /* before enter */
 115
 116   op = read_memory_integer (enter_addr, 1);
 117
 118   if (op != 0x82)
 119     return 0;           /* function has no enter/exit */
 120
 121   return enter_addr;    /* pc is between enter and exit */
 122 }