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 #define UNSIGNED_SHORT(X) ((X) & 0xffff)
  30
  31 /* an easy to debug H8 stack frame looks like:
  32 0x6df6          push    r6
  33 0x0d76          mov.w   r7,r6
  34 0x6dfn          push    reg
  35 0x7905 nnnn     mov.w  #n,r5    or   0x1b87  subs #2,sp
  36 0x1957          sub.w  r5,sp
  37
  38  */
  39
  40 #define IS_PUSH(x) ((x & 0xff00)==0x6d00)
  41 #define IS_PUSH_FP(x) (x == 0x6df6)
  42 #define IS_MOVE_FP(x) (x == 0x0d76)
  43 #define IS_MOV_SP_FP(x) (x == 0x0d76)
  44 #define IS_SUB2_SP(x) (x==0x1b87)
  45 #define IS_MOVK_R5(x) (x==0x7905)
  46 #define IS_SUB_R5SP(x) (x==0x1957)
  47 CORE_ADDR examine_prologue ();
  48
  49 void frame_find_saved_regs ();
  50 CORE_ADDR
  51 h8300_skip_prologue (start_pc)
  52      CORE_ADDR start_pc;
  53
  54 {
  55   short int w;
  56
  57   w = read_memory_short (start_pc);
  58   /* Skip past all push insns */
  59   while (IS_PUSH_FP (w))
  60     {
  61       start_pc += 2;
  62       w = read_memory_short (start_pc);
  63     }
  64
  65   /* Skip past a move to FP */
  66   if (IS_MOVE_FP (w))
  67     {
  68       start_pc += 2;
  69       w = read_memory_short (start_pc);
  70     }
  71
  72   /* Skip the stack adjust */
  73
  74   if (IS_MOVK_R5 (w))
  75     {
  76       start_pc += 2;
  77       w = read_memory_short (start_pc);
  78     }
  79   if (IS_SUB_R5SP (w))
  80     {
  81       start_pc += 2;
  82       w = read_memory_short (start_pc);
  83     }
  84   while (IS_SUB2_SP (w))
  85     {
  86       start_pc += 2;
  87       w = read_memory_short (start_pc);
  88     }
  89
  90   return start_pc;
  91
  92 }
  93
  94 int
  95 print_insn (memaddr, stream)
  96      CORE_ADDR memaddr;
  97      FILE *stream;
  98 {
  99   /* Nothing is bigger than 8 bytes */
 100   char data[8];
 101
 102   read_memory (memaddr, data, sizeof (data));
 103   return print_insn_h8300 (memaddr, data, stream);
 104 }
 105
 106 /* Given a GDB frame, determine the address of the calling function's frame.
 107    This will be used to create a new GDB frame struct, and then
 108    INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame.
 109
 110    For us, the frame address is its stack pointer value, so we look up
 111    the function prologue to determine the caller's sp value, and return it.  */
 112
 113 FRAME_ADDR
 114 FRAME_CHAIN (thisframe)
 115      FRAME thisframe;
 116 {
 117
 118   frame_find_saved_regs (thisframe, (struct frame_saved_regs *) 0);
 119   return thisframe->fsr->regs[SP_REGNUM];
 120 }
 121
 122 /* Put here the code to store, into a struct frame_saved_regs,
 123    the addresses of the saved registers of frame described by FRAME_INFO.
 124    This includes special registers such as pc and fp saved in special
 125    ways in the stack frame.  sp is even more special:
 126    the address we return for it IS the sp for the next frame.
 127
 128    We cache the result of doing this in the frame_cache_obstack, since
 129    it is fairly expensive.  */
 130
 131 void
 132 frame_find_saved_regs (fi, fsr)
 133      struct frame_info *fi;
 134      struct frame_saved_regs *fsr;
 135 {
 136   register CORE_ADDR next_addr;
 137   register CORE_ADDR *saved_regs;
 138   register int regnum;
 139   register struct frame_saved_regs *cache_fsr;
 140   extern struct obstack frame_cache_obstack;
 141   CORE_ADDR ip;
 142   struct symtab_and_line sal;
 143   CORE_ADDR limit;
 144
 145   if (!fi->fsr)
 146     {
 147       cache_fsr = (struct frame_saved_regs *)
 148         obstack_alloc (&frame_cache_obstack,
 149                        sizeof (struct frame_saved_regs));
 150       bzero (cache_fsr, sizeof (struct frame_saved_regs));
 151
 152       fi->fsr = cache_fsr;
 153
 154       /* Find the start and end of the function prologue.  If the PC
 155          is in the function prologue, we only consider the part that
 156          has executed already.  */
 157
 158       ip = get_pc_function_start (fi->pc);
 159       sal = find_pc_line (ip, 0);
 160       limit = (sal.end && sal.end < fi->pc) ? sal.end : fi->pc;
 161
 162       /* This will fill in fields in *fi as well as in cache_fsr.  */
 163       examine_prologue (ip, limit, fi->frame, cache_fsr, fi);
 164     }
 165
 166   if (fsr)
 167     *fsr = *fi->fsr;
 168 }
 169
 170 /* Fetch the instruction at ADDR, returning 0 if ADDR is beyond LIM or
 171    is not the address of a valid instruction, the address of the next
 172    instruction beyond ADDR otherwise.  *PWORD1 receives the first word
 173    of the instruction.*/
 174
 175 CORE_ADDR
 176 NEXT_PROLOGUE_INSN (addr, lim, pword1)
 177      CORE_ADDR addr;
 178      CORE_ADDR lim;
 179      short *pword1;
 180 {
 181   if (addr < lim + 8)
 182     {
 183       read_memory (addr, pword1, sizeof (*pword1));
 184       SWAP_TARGET_AND_HOST (pword1, sizeof (short));
 185
 186       return addr + 2;
 187     }
 188   return 0;
 189 }
 190
 191 /* Examine the prologue of a function.  `ip' points to the first instruction.
 192    `limit' is the limit of the prologue (e.g. the addr of the first
 193    linenumber, or perhaps the program counter if we're stepping through).
 194    `frame_sp' is the stack pointer value in use in this frame.
 195    `fsr' is a pointer to a frame_saved_regs structure into which we put
 196    info about the registers saved by this frame.
 197    `fi' is a struct frame_info pointer; we fill in various fields in it
 198    to reflect the offsets of the arg pointer and the locals pointer.  */
 199
 200 static CORE_ADDR
 201 examine_prologue (ip, limit, after_prolog_fp, fsr, fi)
 202      register CORE_ADDR ip;
 203      register CORE_ADDR limit;
 204      FRAME_ADDR after_prolog_fp;
 205      struct frame_saved_regs *fsr;
 206      struct frame_info *fi;
 207 {
 208   register CORE_ADDR next_ip;
 209   int r;
 210   int i;
 211   int have_fp = 0;
 212
 213   register int src;
 214   register struct pic_prologue_code *pcode;
 215   INSN_WORD insn_word;
 216   int size, offset;
 217   unsigned int reg_save_depth = 2;      /* Number of things pushed onto
 218                                       stack, starts at 2, 'cause the
 219                                       PC is already there */
 220
 221   unsigned int auto_depth = 0;  /* Number of bytes of autos */
 222
 223   char in_frame[NUM_REGS];      /* One for each reg */
 224
 225   memset (in_frame, 1, NUM_REGS);
 226   for (r = 0; r < NUM_REGS; r++)
 227     {
 228       fsr->regs[r] = 0;
 229     }
 230   if (after_prolog_fp == 0)
 231     {
 232       after_prolog_fp = read_register (SP_REGNUM);
 233     }
 234   if (ip == 0 || ip & ~0xffff)
 235     return 0;
 236
 237   next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 238
 239   /* Skip over any fp push instructions */
 240   fsr->regs[6] = after_prolog_fp;
 241   while (next_ip && IS_PUSH_FP (insn_word))
 242     {
 243       ip = next_ip;
 244
 245       in_frame[insn_word & 0x7] = reg_save_depth;
 246       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 247       reg_save_depth += 2;
 248     }
 249
 250   /* Is this a move into the fp */
 251   if (next_ip && IS_MOV_SP_FP (insn_word))
 252     {
 253       ip = next_ip;
 254       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 255       have_fp = 1;
 256     }
 257
 258   /* Skip over any stack adjustment, happens either with a number of
 259      sub#2,sp or a mov #x,r5 sub r5,sp */
 260
 261   if (next_ip && IS_SUB2_SP (insn_word))
 262     {
 263       while (next_ip && IS_SUB2_SP (insn_word))
 264         {
 265           auto_depth += 2;
 266           ip = next_ip;
 267           next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 268         }
 269     }
 270   else
 271     {
 272       if (next_ip && IS_MOVK_R5 (insn_word))
 273         {
 274           ip = next_ip;
 275           next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 276           auto_depth += insn_word;
 277
 278           next_ip = NEXT_PROLOGUE_INSN (next_ip, limit, &insn_word);
 279           auto_depth += insn_word;
 280
 281         }
 282     }
 283   /* Work out which regs are stored where */
 284   while (next_ip && IS_PUSH (insn_word))
 285     {
 286       ip = next_ip;
 287       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 288       fsr->regs[r] = after_prolog_fp + auto_depth;
 289       auto_depth += 2;
 290     }
 291
 292   /* The args are always reffed based from the stack pointer */
 293   fi->args_pointer = after_prolog_fp;
 294   /* Locals are always reffed based from the fp */
 295   fi->locals_pointer = after_prolog_fp;
 296   /* The PC is at a known place */
 297   fi->from_pc = read_memory_short (after_prolog_fp + 2);
 298
 299   /* Rememeber any others too */
 300   in_frame[PC_REGNUM] = 0;
 301
 302   if (have_fp)
 303     /* We keep the old FP in the SP spot */
 304     fsr->regs[SP_REGNUM] = (read_memory_short (fsr->regs[6]));
 305   else
 306     fsr->regs[SP_REGNUM] = after_prolog_fp + auto_depth;
 307
 308   return (ip);
 309 }
 310
 311 void
 312 init_extra_frame_info (fromleaf, fi)
 313      int fromleaf;
 314      struct frame_info *fi;
 315 {
 316   fi->fsr = 0;                  /* Not yet allocated */
 317   fi->args_pointer = 0;         /* Unknown */
 318   fi->locals_pointer = 0;       /* Unknown */
 319   fi->from_pc = 0;
 320
 321 }
 322
 323 /* Return the saved PC from this frame.
 324
 325    If the frame has a memory copy of SRP_REGNUM, use that.  If not,
 326    just use the register SRP_REGNUM itself.  */
 327
 328 CORE_ADDR
 329 frame_saved_pc (frame)
 330      FRAME frame;
 331
 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 < NUM_REGS; regnum++)
 381     {
 382       if (fsr.regs[regnum])
 383         {
 384           write_register (regnum, read_memory_short (fsr.regs[regnum]));
 385         }
 386
 387       flush_cached_frames ();
 388       set_current_frame (create_new_frame (read_register (FP_REGNUM),
 389                                            read_pc ()));
 390
 391     }
 392
 393 }
 394
 395 void
 396 print_register_hook (regno)
 397 {
 398   if (regno == 8)
 399     {
 400       /* CCR register */
 401
 402       int C, Z, N, V;
 403       unsigned char b[2];
 404       unsigned char l;
 405
 406       read_relative_register_raw_bytes (regno, b);
 407       l = b[1];
 408       printf ("\t");
 409       printf ("I-%d - ", (l & 0x80) != 0);
 410       printf ("H-%d - ", (l & 0x20) != 0);
 411       N = (l & 0x8) != 0;
 412       Z = (l & 0x4) != 0;
 413       V = (l & 0x2) != 0;
 414       C = (l & 0x1) != 0;
 415       printf ("N-%d ", N);
 416       printf ("Z-%d ", Z);
 417       printf ("V-%d ", V);
 418       printf ("C-%d ", C);
 419       if ((C | Z) == 0)
 420         printf ("u> ");
 421       if ((C | Z) == 1)
 422         printf ("u<= ");
 423       if ((C == 0))
 424         printf ("u>= ");
 425       if (C == 1)
 426         printf ("u< ");
 427       if (Z == 0)
 428         printf ("!= ");
 429       if (Z == 1)
 430         printf ("== ");
 431       if ((N ^ V) == 0)
 432         printf (">= ");
 433       if ((N ^ V) == 1)
 434         printf ("< ");
 435       if ((Z | (N ^ V)) == 0)
 436         printf ("> ");
 437       if ((Z | (N ^ V)) == 1)
 438         printf ("<= ");
 439     }
 440 }