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 /* Advance PC across any function entry prologue instructions
  30    to reach some "real" code.  */
  31
  32 CORE_ADDR
  33 merlin_skip_prologue (pc)
  34      CORE_ADDR pc;
  35 {
  36   register int op = read_memory_integer (pc, 1);
  37   if (op == 0x82)
  38     {
  39       op = read_memory_integer (pc+2,1);
  40       if ((op & 0x80) == 0)
  41         pc += 3;
  42       else if ((op & 0xc0) == 0x80)
  43         pc += 4;
  44       else pc += 6;
  45     }
  46   return pc;
  47 }
  48
  49 CORE_ADDR
  50 umax_skip_prologue (pc)
  51      CORE_ADDR pc;
  52 {
  53   register unsigned char op = read_memory_integer (pc, 1);
  54   if (op == 0x82)
  55     {
  56       op = read_memory_integer (pc+2,1);
  57       if ((op & 0x80) == 0)
  58         pc += 3;
  59       else if ((op & 0xc0) == 0x80)
  60         pc += 4;
  61       else
  62         pc += 6;
  63     }
  64   return pc;
  65 }
  66
  67
  68
  69 sign_extend (value, bits)
  70 {
  71   value = value & ((1 << bits) - 1);
  72   return (value & (1 << (bits-1))
  73           ? value | (~((1 << bits) - 1))
  74           : value);
  75 }
  76
  77 void
  78 flip_bytes (ptr, count)
  79      char *ptr;
  80      int count;
  81 {
  82   char tmp;
  83
  84   while (count > 0)
  85     {
  86       tmp = *ptr;
  87       ptr[0] = ptr[count-1];
  88       ptr[count-1] = tmp;
  89       ptr++;
  90       count -= 2;
  91     }
  92 }
  93
  94 /* Return the number of locals in the current frame given a pc
  95    pointing to the enter instruction.  This is used in the macro
  96    FRAME_FIND_SAVED_REGS.  */
  97
  98 int
  99 ns32k_localcount (enter_pc)
 100      CORE_ADDR enter_pc;
 101 {
 102   unsigned char localtype;
 103   int localcount;
 104
 105   localtype = read_memory_integer (enter_pc+2, 1);
 106   if ((localtype & 0x80) == 0)
 107     localcount = localtype;
 108   else if ((localtype & 0xc0) == 0x80)
 109     localcount = (((localtype & 0x3f) << 8)
 110                   | (read_memory_integer (enter_pc+3, 1) & 0xff));
 111   else
 112     localcount = (((localtype & 0x3f) << 24)
 113                   | ((read_memory_integer (enter_pc+3, 1) & 0xff) << 16)
 114                   | ((read_memory_integer (enter_pc+4, 1) & 0xff) << 8 )
 115                   | (read_memory_integer (enter_pc+5, 1) & 0xff));
 116   return localcount;
 117 }
 118
 119
 120 /* Nonzero if instruction at PC is a return instruction.  */
 121
 122 static int
 123 ns32k_about_to_return (pc)
 124      CORE_ADDR pc;
 125 {
 126   return (read_memory_integer (pc, 1) == 0x12);
 127 }
 128
 129
 130 /*
 131  * Get the address of the enter opcode for the function
 132  * containing PC, if there is an enter for the function,
 133  * and if the pc is between the enter and exit.
 134  * Returns positive address if pc is between enter/exit,
 135  * 1 if pc before enter or after exit, 0 otherwise.
 136  */
 137
 138 CORE_ADDR
 139 ns32k_get_enter_addr (pc)
 140      CORE_ADDR pc;
 141 {
 142   CORE_ADDR enter_addr;
 143   unsigned char op;
 144
 145   if (pc == 0)
 146     return 0;
 147
 148   if (ns32k_about_to_return (pc))
 149     return 1;           /* after exit */
 150
 151   enter_addr = get_pc_function_start (pc);
 152
 153   if (pc == enter_addr)
 154     return 1;           /* before enter */
 155
 156   op = read_memory_integer (enter_addr, 1);
 157
 158   if (op != 0x82)
 159     return 0;           /* function has no enter/exit */
 160
 161   return enter_addr;    /* pc is between enter and exit */
 162 }