gdb/h8300-tdep.c

   1 /* Target-machine dependent code for Hitachi H8/300, for GDB.
   2    Copyright (C) 1988, 1990, 1991 Free Software Foundation, Inc.
   3
   4 This file is part of GDB.
   5
   6 This program is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2 of the License, or
   9 (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 /*
  21  Contributed by Steve Chamberlain
  22                 sac@cygnus.com
  23  */
  24
  25 #include "defs.h"
  26 #include "frame.h"
  27 #include "obstack.h"
  28 #include "symtab.h"
  29 #include <dis-asm.h>
  30 #undef NUM_REGS
  31 #define NUM_REGS 11
  32
  33 #define UNSIGNED_SHORT(X) ((X) & 0xffff)
  34
  35 /* an easy to debug H8 stack frame looks like:
  36 0x6df6          push    r6
  37 0x0d76          mov.w   r7,r6
  38 0x6dfn          push    reg
  39 0x7905 nnnn     mov.w  #n,r5    or   0x1b87  subs #2,sp
  40 0x1957          sub.w  r5,sp
  41
  42  */
  43
  44 #define IS_PUSH(x) ((x & 0xff00)==0x6d00)
  45 #define IS_PUSH_FP(x) (x == 0x6df6)
  46 #define IS_MOVE_FP(x) (x == 0x0d76)
  47 #define IS_MOV_SP_FP(x) (x == 0x0d76)
  48 #define IS_SUB2_SP(x) (x==0x1b87)
  49 #define IS_MOVK_R5(x) (x==0x7905)
  50 #define IS_SUB_R5SP(x) (x==0x1957)
  51
  52 static CORE_ADDR examine_prologue ();
  53
  54 void frame_find_saved_regs ();
  55 CORE_ADDR
  56 h8300_skip_prologue (start_pc)
  57      CORE_ADDR start_pc;
  58 {
  59   short int w;
  60
  61   w = read_memory_unsigned_integer (start_pc, 2);
  62   /* Skip past all push insns */
  63   while (IS_PUSH_FP (w))
  64     {
  65       start_pc += 2;
  66       w = read_memory_unsigned_integer (start_pc, 2);
  67     }
  68
  69   /* Skip past a move to FP */
  70   if (IS_MOVE_FP (w))
  71     {
  72       start_pc += 2;
  73       w = read_memory_unsigned_integer (start_pc, 2);
  74     }
  75
  76   /* Skip the stack adjust */
  77
  78   if (IS_MOVK_R5 (w))
  79     {
  80       start_pc += 2;
  81       w = read_memory_unsigned_integer (start_pc, 2);
  82     }
  83   if (IS_SUB_R5SP (w))
  84     {
  85       start_pc += 2;
  86       w = read_memory_unsigned_integer (start_pc, 2);
  87     }
  88   while (IS_SUB2_SP (w))
  89     {
  90       start_pc += 2;
  91       w = read_memory_unsigned_integer (start_pc, 2);
  92     }
  93
  94   return start_pc;
  95 }
  96
  97 int
  98 print_insn (memaddr, stream)
  99      CORE_ADDR memaddr;
 100      FILE *stream;
 101 {
 102   disassemble_info info;
 103   GDB_INIT_DISASSEMBLE_INFO(info, stream);
 104   if (HMODE)
 105     return print_insn_h8300h (memaddr, &info);
 106   else
 107     return print_insn_h8300 (memaddr, &info);
 108 }
 109
 110 /* Given a GDB frame, determine the address of the calling function's frame.
 111    This will be used to create a new GDB frame struct, and then
 112    INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame.
 113
 114    For us, the frame address is its stack pointer value, so we look up
 115    the function prologue to determine the caller's sp value, and return it.  */
 116
 117 FRAME_ADDR
 118 FRAME_CHAIN (thisframe)
 119      FRAME thisframe;
 120 {
 121   frame_find_saved_regs (thisframe, (struct frame_saved_regs *) 0);
 122   return thisframe->fsr->regs[SP_REGNUM];
 123 }
 124
 125 /* Put here the code to store, into a struct frame_saved_regs,
 126    the addresses of the saved registers of frame described by FRAME_INFO.
 127    This includes special registers such as pc and fp saved in special
 128    ways in the stack frame.  sp is even more special:
 129    the address we return for it IS the sp for the next frame.
 130
 131    We cache the result of doing this in the frame_cache_obstack, since
 132    it is fairly expensive.  */
 133
 134 void
 135 frame_find_saved_regs (fi, fsr)
 136      struct frame_info *fi;
 137      struct frame_saved_regs *fsr;
 138 {
 139   register CORE_ADDR next_addr;
 140   register CORE_ADDR *saved_regs;
 141   register int regnum;
 142   register struct frame_saved_regs *cache_fsr;
 143   extern struct obstack frame_cache_obstack;
 144   CORE_ADDR ip;
 145   struct symtab_and_line sal;
 146   CORE_ADDR limit;
 147
 148   if (!fi->fsr)
 149     {
 150       cache_fsr = (struct frame_saved_regs *)
 151         obstack_alloc (&frame_cache_obstack,
 152                        sizeof (struct frame_saved_regs));
 153       bzero (cache_fsr, sizeof (struct frame_saved_regs));
 154
 155       fi->fsr = cache_fsr;
 156
 157       /* Find the start and end of the function prologue.  If the PC
 158          is in the function prologue, we only consider the part that
 159          has executed already.  */
 160
 161       ip = get_pc_function_start (fi->pc);
 162       sal = find_pc_line (ip, 0);
 163       limit = (sal.end && sal.end < fi->pc) ? sal.end : fi->pc;
 164
 165       /* This will fill in fields in *fi as well as in cache_fsr.  */
 166       examine_prologue (ip, limit, fi->frame, cache_fsr, fi);
 167     }
 168
 169   if (fsr)
 170     *fsr = *fi->fsr;
 171 }
 172
 173 /* Fetch the instruction at ADDR, returning 0 if ADDR is beyond LIM or
 174    is not the address of a valid instruction, the address of the next
 175    instruction beyond ADDR otherwise.  *PWORD1 receives the first word
 176    of the instruction.*/
 177
 178 CORE_ADDR
 179 NEXT_PROLOGUE_INSN (addr, lim, pword1)
 180      CORE_ADDR addr;
 181      CORE_ADDR lim;
 182      INSN_WORD *pword1;
 183 {
 184   char buf[2];
 185   if (addr < lim + 8)
 186     {
 187       read_memory (addr, buf, 2);
 188       *pword1 = extract_signed_integer (buf, 2);
 189
 190       return addr + 2;
 191     }
 192   return 0;
 193 }
 194
 195 /* Examine the prologue of a function.  `ip' points to the first instruction.
 196    `limit' is the limit of the prologue (e.g. the addr of the first
 197    linenumber, or perhaps the program counter if we're stepping through).
 198    `frame_sp' is the stack pointer value in use in this frame.
 199    `fsr' is a pointer to a frame_saved_regs structure into which we put
 200    info about the registers saved by this frame.
 201    `fi' is a struct frame_info pointer; we fill in various fields in it
 202    to reflect the offsets of the arg pointer and the locals pointer.  */
 203
 204 static CORE_ADDR
 205 examine_prologue (ip, limit, after_prolog_fp, fsr, fi)
 206      register CORE_ADDR ip;
 207      register CORE_ADDR limit;
 208      FRAME_ADDR after_prolog_fp;
 209      struct frame_saved_regs *fsr;
 210      struct frame_info *fi;
 211 {
 212   register CORE_ADDR next_ip;
 213   int r;
 214   int i;
 215   int have_fp = 0;
 216   register int src;
 217   register struct pic_prologue_code *pcode;
 218   INSN_WORD insn_word;
 219   int size, offset;
 220   /* Number of things pushed onto stack, starts at 2/4, 'cause the
 221      PC is already there */
 222   unsigned int reg_save_depth = HMODE ? 4 : 2;
 223
 224   unsigned int auto_depth = 0;  /* Number of bytes of autos */
 225
 226   char in_frame[11];            /* One for each reg */
 227
 228   memset (in_frame, 1, 11);
 229   for (r = 0; r < 8; r++)
 230     {
 231       fsr->regs[r] = 0;
 232     }
 233   if (after_prolog_fp == 0)
 234     {
 235       after_prolog_fp = read_register (SP_REGNUM);
 236     }
 237   if (ip == 0 || ip & (HMODE ? ~0xffff : ~0xffff))
 238     return 0;
 239
 240   next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 241
 242   /* Skip over any fp push instructions */
 243   fsr->regs[6] = after_prolog_fp;
 244   while (next_ip && IS_PUSH_FP (insn_word))
 245     {
 246       ip = next_ip;
 247
 248       in_frame[insn_word & 0x7] = reg_save_depth;
 249       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 250       reg_save_depth += 2;
 251     }
 252
 253   /* Is this a move into the fp */
 254   if (next_ip && IS_MOV_SP_FP (insn_word))
 255     {
 256       ip = next_ip;
 257       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 258       have_fp = 1;
 259     }
 260
 261   /* Skip over any stack adjustment, happens either with a number of
 262      sub#2,sp or a mov #x,r5 sub r5,sp */
 263
 264   if (next_ip && IS_SUB2_SP (insn_word))
 265     {
 266       while (next_ip && IS_SUB2_SP (insn_word))
 267         {
 268           auto_depth += 2;
 269           ip = next_ip;
 270           next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 271         }
 272     }
 273   else
 274     {
 275       if (next_ip && IS_MOVK_R5 (insn_word))
 276         {
 277           ip = next_ip;
 278           next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 279           auto_depth += insn_word;
 280
 281           next_ip = NEXT_PROLOGUE_INSN (next_ip, limit, &insn_word);
 282           auto_depth += insn_word;
 283         }
 284     }
 285   /* Work out which regs are stored where */
 286   while (next_ip && IS_PUSH (insn_word))
 287     {
 288       ip = next_ip;
 289       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 290       fsr->regs[r] = after_prolog_fp + auto_depth;
 291       auto_depth += 2;
 292     }
 293
 294   /* The args are always reffed based from the stack pointer */
 295   fi->args_pointer = after_prolog_fp;
 296   /* Locals are always reffed based from the fp */
 297   fi->locals_pointer = after_prolog_fp;
 298   /* The PC is at a known place */
 299   fi->from_pc = read_memory_unsigned_integer (after_prolog_fp + 2, BINWORD);
 300
 301   /* Rememeber any others too */
 302   in_frame[PC_REGNUM] = 0;
 303
 304   if (have_fp)
 305     /* We keep the old FP in the SP spot */
 306     fsr->regs[SP_REGNUM] = read_memory_unsigned_integer (fsr->regs[6], BINWORD);
 307   else
 308     fsr->regs[SP_REGNUM] = after_prolog_fp + auto_depth;
 309
 310   return (ip);
 311 }
 312
 313 void
 314 init_extra_frame_info (fromleaf, fi)
 315      int fromleaf;
 316      struct frame_info *fi;
 317 {
 318   fi->fsr = 0;                  /* Not yet allocated */
 319   fi->args_pointer = 0;         /* Unknown */
 320   fi->locals_pointer = 0;       /* Unknown */
 321   fi->from_pc = 0;
 322 }
 323
 324 /* Return the saved PC from this frame.
 325
 326    If the frame has a memory copy of SRP_REGNUM, use that.  If not,
 327    just use the register SRP_REGNUM itself.  */
 328
 329 CORE_ADDR
 330 frame_saved_pc (frame)
 331      FRAME frame;
 332 {
 333   return frame->from_pc;
 334 }
 335
 336 CORE_ADDR
 337 frame_locals_address (fi)
 338      struct frame_info *fi;
 339 {
 340   if (!fi->locals_pointer)
 341     {
 342       struct frame_saved_regs ignore;
 343
 344       get_frame_saved_regs (fi, &ignore);
 345
 346     }
 347   return fi->locals_pointer;
 348 }
 349
 350 /* Return the address of the argument block for the frame
 351    described by FI.  Returns 0 if the address is unknown.  */
 352
 353 CORE_ADDR
 354 frame_args_address (fi)
 355      struct frame_info *fi;
 356 {
 357   if (!fi->args_pointer)
 358     {
 359       struct frame_saved_regs ignore;
 360
 361       get_frame_saved_regs (fi, &ignore);
 362
 363     }
 364
 365   return fi->args_pointer;
 366 }
 367
 368 void
 369 h8300_pop_frame ()
 370 {
 371   unsigned regnum;
 372   struct frame_saved_regs fsr;
 373   struct frame_info *fi;
 374
 375   FRAME frame = get_current_frame ();
 376
 377   fi = get_frame_info (frame);
 378   get_frame_saved_regs (fi, &fsr);
 379
 380   for (regnum = 0; regnum < 8; regnum++)
 381     {
 382       if (fsr.regs[regnum])
 383         {
 384           write_register (regnum, read_memory_integer(fsr.regs[regnum]), BINWORD);
 385         }
 386
 387       flush_cached_frames ();
 388       set_current_frame (create_new_frame (read_register (FP_REGNUM),
 389                                            read_pc ()));
 390     }
 391 }
 392
 393 void
 394 print_register_hook (regno)
 395 {
 396   if (regno == 8)
 397     {
 398       /* CCR register */
 399
 400       int C, Z, N, V;
 401       unsigned char b[2];
 402       unsigned char l;
 403
 404       read_relative_register_raw_bytes (regno, b);
 405       l = b[1];
 406       printf ("\t");
 407       printf ("I-%d - ", (l & 0x80) != 0);
 408       printf ("H-%d - ", (l & 0x20) != 0);
 409       N = (l & 0x8) != 0;
 410       Z = (l & 0x4) != 0;
 411       V = (l & 0x2) != 0;
 412       C = (l & 0x1) != 0;
 413       printf ("N-%d ", N);
 414       printf ("Z-%d ", Z);
 415       printf ("V-%d ", V);
 416       printf ("C-%d ", C);
 417       if ((C | Z) == 0)
 418         printf ("u> ");
 419       if ((C | Z) == 1)
 420         printf ("u<= ");
 421       if ((C == 0))
 422         printf ("u>= ");
 423       if (C == 1)
 424         printf ("u< ");
 425       if (Z == 0)
 426         printf ("!= ");
 427       if (Z == 1)
 428         printf ("== ");
 429       if ((N ^ V) == 0)
 430         printf (">= ");
 431       if ((N ^ V) == 1)
 432         printf ("< ");
 433       if ((Z | (N ^ V)) == 0)
 434         printf ("> ");
 435       if ((Z | (N ^ V)) == 1)
 436         printf ("<= ");
 437     }
 438 }