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 CORE_ADDR examine_prologue ();
  52
  53 void frame_find_saved_regs ();
  54 CORE_ADDR
  55 h8300_skip_prologue (start_pc)
  56      CORE_ADDR start_pc;
  57
  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
  98 int
  99 print_insn (memaddr, stream)
 100      CORE_ADDR memaddr;
 101      FILE *stream;
 102 {
 103   disassemble_info info;
 104   GDB_INIT_DISASSEMBLE_INFO(info, stream);
 105   return print_insn_h8300 (memaddr, &info);
 106 }
 107
 108 /* Given a GDB frame, determine the address of the calling function's frame.
 109    This will be used to create a new GDB frame struct, and then
 110    INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame.
 111
 112    For us, the frame address is its stack pointer value, so we look up
 113    the function prologue to determine the caller's sp value, and return it.  */
 114
 115 FRAME_ADDR
 116 FRAME_CHAIN (thisframe)
 117      FRAME thisframe;
 118 {
 119
 120   frame_find_saved_regs (thisframe, (struct frame_saved_regs *) 0);
 121   return thisframe->fsr->regs[SP_REGNUM];
 122 }
 123
 124 /* Put here the code to store, into a struct frame_saved_regs,
 125    the addresses of the saved registers of frame described by FRAME_INFO.
 126    This includes special registers such as pc and fp saved in special
 127    ways in the stack frame.  sp is even more special:
 128    the address we return for it IS the sp for the next frame.
 129
 130    We cache the result of doing this in the frame_cache_obstack, since
 131    it is fairly expensive.  */
 132
 133 void
 134 frame_find_saved_regs (fi, fsr)
 135      struct frame_info *fi;
 136      struct frame_saved_regs *fsr;
 137 {
 138   register CORE_ADDR next_addr;
 139   register CORE_ADDR *saved_regs;
 140   register int regnum;
 141   register struct frame_saved_regs *cache_fsr;
 142   extern struct obstack frame_cache_obstack;
 143   CORE_ADDR ip;
 144   struct symtab_and_line sal;
 145   CORE_ADDR limit;
 146
 147   if (!fi->fsr)
 148     {
 149       cache_fsr = (struct frame_saved_regs *)
 150         obstack_alloc (&frame_cache_obstack,
 151                        sizeof (struct frame_saved_regs));
 152       bzero (cache_fsr, sizeof (struct frame_saved_regs));
 153
 154       fi->fsr = cache_fsr;
 155
 156       /* Find the start and end of the function prologue.  If the PC
 157          is in the function prologue, we only consider the part that
 158          has executed already.  */
 159
 160       ip = get_pc_function_start (fi->pc);
 161       sal = find_pc_line (ip, 0);
 162       limit = (sal.end && sal.end < fi->pc) ? sal.end : fi->pc;
 163
 164       /* This will fill in fields in *fi as well as in cache_fsr.  */
 165       examine_prologue (ip, limit, fi->frame, cache_fsr, fi);
 166     }
 167
 168   if (fsr)
 169     *fsr = *fi->fsr;
 170 }
 171
 172 /* Fetch the instruction at ADDR, returning 0 if ADDR is beyond LIM or
 173    is not the address of a valid instruction, the address of the next
 174    instruction beyond ADDR otherwise.  *PWORD1 receives the first word
 175    of the instruction.*/
 176
 177 CORE_ADDR
 178 NEXT_PROLOGUE_INSN (addr, lim, pword1)
 179      CORE_ADDR addr;
 180      CORE_ADDR lim;
 181      short *pword1;
 182 {
 183   if (addr < lim + 8)
 184     {
 185       read_memory (addr, pword1, sizeof (*pword1));
 186       SWAP_TARGET_AND_HOST (pword1, sizeof (short));
 187
 188       return addr + 2;
 189     }
 190   return 0;
 191 }
 192
 193 /* Examine the prologue of a function.  `ip' points to the first instruction.
 194    `limit' is the limit of the prologue (e.g. the addr of the first
 195    linenumber, or perhaps the program counter if we're stepping through).
 196    `frame_sp' is the stack pointer value in use in this frame.
 197    `fsr' is a pointer to a frame_saved_regs structure into which we put
 198    info about the registers saved by this frame.
 199    `fi' is a struct frame_info pointer; we fill in various fields in it
 200    to reflect the offsets of the arg pointer and the locals pointer.  */
 201
 202 static CORE_ADDR
 203 examine_prologue (ip, limit, after_prolog_fp, fsr, fi)
 204      register CORE_ADDR ip;
 205      register CORE_ADDR limit;
 206      FRAME_ADDR after_prolog_fp;
 207      struct frame_saved_regs *fsr;
 208      struct frame_info *fi;
 209 {
 210   register CORE_ADDR next_ip;
 211   int r;
 212   int i;
 213   int have_fp = 0;
 214
 215   register int src;
 216   register struct pic_prologue_code *pcode;
 217   INSN_WORD insn_word;
 218   int size, offset;
 219   unsigned int reg_save_depth = 2; /* Number of things pushed onto
 220                                       stack, starts at 2, 'cause the
 221                                       PC is already there */
 222
 223   unsigned int auto_depth = 0;  /* Number of bytes of autos */
 224
 225   char in_frame[11];            /* One for each reg */
 226
 227   memset (in_frame, 1, 11);
 228   for (r = 0; r < 8; r++)
 229     {
 230       fsr->regs[r] = 0;
 231     }
 232   if (after_prolog_fp == 0)
 233     {
 234       after_prolog_fp = read_register (SP_REGNUM);
 235     }
 236   if (ip == 0 || ip & ~0xffff)
 237     return 0;
 238
 239   next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 240
 241   /* Skip over any fp push instructions */
 242   fsr->regs[6] = after_prolog_fp;
 243   while (next_ip && IS_PUSH_FP (insn_word))
 244     {
 245       ip = next_ip;
 246
 247       in_frame[insn_word & 0x7] = reg_save_depth;
 248       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 249       reg_save_depth += 2;
 250     }
 251
 252   /* Is this a move into the fp */
 253   if (next_ip && IS_MOV_SP_FP (insn_word))
 254     {
 255       ip = next_ip;
 256       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 257       have_fp = 1;
 258     }
 259
 260   /* Skip over any stack adjustment, happens either with a number of
 261      sub#2,sp or a mov #x,r5 sub r5,sp */
 262
 263   if (next_ip && IS_SUB2_SP (insn_word))
 264     {
 265       while (next_ip && IS_SUB2_SP (insn_word))
 266         {
 267           auto_depth += 2;
 268           ip = next_ip;
 269           next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 270         }
 271     }
 272   else
 273     {
 274       if (next_ip && IS_MOVK_R5 (insn_word))
 275         {
 276           ip = next_ip;
 277           next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 278           auto_depth += insn_word;
 279
 280           next_ip = NEXT_PROLOGUE_INSN (next_ip, limit, &insn_word);
 281           auto_depth += insn_word;
 282
 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
 325 /* Return the saved PC from this frame.
 326
 327    If the frame has a memory copy of SRP_REGNUM, use that.  If not,
 328    just use the register SRP_REGNUM itself.  */
 329
 330 CORE_ADDR
 331 frame_saved_pc (frame)
 332      FRAME frame;
 333
 334 {
 335   return frame->from_pc;
 336 }
 337
 338 CORE_ADDR
 339 frame_locals_address (fi)
 340      struct frame_info *fi;
 341 {
 342   if (!fi->locals_pointer)
 343     {
 344       struct frame_saved_regs ignore;
 345
 346       get_frame_saved_regs (fi, &ignore);
 347
 348     }
 349   return fi->locals_pointer;
 350 }
 351
 352 /* Return the address of the argument block for the frame
 353    described by FI.  Returns 0 if the address is unknown.  */
 354
 355 CORE_ADDR
 356 frame_args_address (fi)
 357      struct frame_info *fi;
 358 {
 359   if (!fi->args_pointer)
 360     {
 361       struct frame_saved_regs ignore;
 362
 363       get_frame_saved_regs (fi, &ignore);
 364
 365     }
 366
 367   return fi->args_pointer;
 368 }
 369
 370 void
 371 h8300_pop_frame ()
 372 {
 373   unsigned regnum;
 374   struct frame_saved_regs fsr;
 375   struct frame_info *fi;
 376
 377   FRAME frame = get_current_frame ();
 378
 379   fi = get_frame_info (frame);
 380   get_frame_saved_regs (fi, &fsr);
 381
 382   for (regnum = 0; regnum < 8; regnum++)
 383     {
 384       if (fsr.regs[regnum])
 385         {
 386           write_register (regnum, read_memory_integer(fsr.regs[regnum]), BINWORD);
 387         }
 388
 389       flush_cached_frames ();
 390       set_current_frame (create_new_frame (read_register (FP_REGNUM),
 391                                            read_pc ()));
 392
 393     }
 394
 395 }
 396
 397 void
 398 print_register_hook (regno)
 399 {
 400   if (regno == 8)
 401     {
 402       /* CCR register */
 403
 404       int C, Z, N, V;
 405       unsigned char b[2];
 406       unsigned char l;
 407
 408       read_relative_register_raw_bytes (regno, b);
 409       l = b[1];
 410       printf ("\t");
 411       printf ("I-%d - ", (l & 0x80) != 0);
 412       printf ("H-%d - ", (l & 0x20) != 0);
 413       N = (l & 0x8) != 0;
 414       Z = (l & 0x4) != 0;
 415       V = (l & 0x2) != 0;
 416       C = (l & 0x1) != 0;
 417       printf ("N-%d ", N);
 418       printf ("Z-%d ", Z);
 419       printf ("V-%d ", V);
 420       printf ("C-%d ", C);
 421       if ((C | Z) == 0)
 422         printf ("u> ");
 423       if ((C | Z) == 1)
 424         printf ("u<= ");
 425       if ((C == 0))
 426         printf ("u>= ");
 427       if (C == 1)
 428         printf ("u< ");
 429       if (Z == 0)
 430         printf ("!= ");
 431       if (Z == 1)
 432         printf ("== ");
 433       if ((N ^ V) == 0)
 434         printf (">= ");
 435       if ((N ^ V) == 1)
 436         printf ("< ");
 437       if ((Z | (N ^ V)) == 0)
 438         printf ("> ");
 439       if ((Z | (N ^ V)) == 1)
 440         printf ("<= ");
 441     }
 442 }