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   short int w;
  59
  60   w = read_memory_unsigned_integer (start_pc, 2);
  61   /* Skip past all push insns */
  62   while (IS_PUSH_FP (w))
  63     {
  64       start_pc += 2;
  65       w = read_memory_unsigned_integer (start_pc, 2);
  66     }
  67
  68   /* Skip past a move to FP */
  69   if (IS_MOVE_FP (w))
  70     {
  71       start_pc += 2;
  72       w = read_memory_unsigned_integer (start_pc, 2);
  73     }
  74
  75   /* Skip the stack adjust */
  76
  77   if (IS_MOVK_R5 (w))
  78     {
  79       start_pc += 2;
  80       w = read_memory_unsigned_integer (start_pc, 2);
  81     }
  82   if (IS_SUB_R5SP (w))
  83     {
  84       start_pc += 2;
  85       w = read_memory_unsigned_integer (start_pc, 2);
  86     }
  87   while (IS_SUB2_SP (w))
  88     {
  89       start_pc += 2;
  90       w = read_memory_unsigned_integer (start_pc, 2);
  91     }
  92
  93   return start_pc;
  94 }
  95
  96 int
  97 print_insn (memaddr, stream)
  98      CORE_ADDR memaddr;
  99      FILE *stream;
 100 {
 101   disassemble_info info;
 102   GDB_INIT_DISASSEMBLE_INFO(info, stream);
 103   if (HMODE)
 104     return print_insn_h8300h (memaddr, &info);
 105   else
 106     return print_insn_h8300 (memaddr, &info);
 107 }
 108
 109 /* Given a GDB frame, determine the address of the calling function's frame.
 110    This will be used to create a new GDB frame struct, and then
 111    INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame.
 112
 113    For us, the frame address is its stack pointer value, so we look up
 114    the function prologue to determine the caller's sp value, and return it.  */
 115
 116 FRAME_ADDR
 117 FRAME_CHAIN (thisframe)
 118      FRAME thisframe;
 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   register int src;
 215   register struct pic_prologue_code *pcode;
 216   INSN_WORD insn_word;
 217   int size, offset;
 218   /* Number of things pushed onto stack, starts at 2/4, 'cause the
 219      PC is already there */
 220   unsigned int reg_save_depth = HMODE ? 4 : 2;
 221
 222   unsigned int auto_depth = 0;  /* Number of bytes of autos */
 223
 224   char in_frame[11];            /* One for each reg */
 225
 226   memset (in_frame, 1, 11);
 227   for (r = 0; r < 8; r++)
 228     {
 229       fsr->regs[r] = 0;
 230     }
 231   if (after_prolog_fp == 0)
 232     {
 233       after_prolog_fp = read_register (SP_REGNUM);
 234     }
 235   if (ip == 0 || ip & (HMODE ? ~0xffff : ~0xffff))
 236     return 0;
 237
 238   next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 239
 240   /* Skip over any fp push instructions */
 241   fsr->regs[6] = after_prolog_fp;
 242   while (next_ip && IS_PUSH_FP (insn_word))
 243     {
 244       ip = next_ip;
 245
 246       in_frame[insn_word & 0x7] = reg_save_depth;
 247       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 248       reg_save_depth += 2;
 249     }
 250
 251   /* Is this a move into the fp */
 252   if (next_ip && IS_MOV_SP_FP (insn_word))
 253     {
 254       ip = next_ip;
 255       next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 256       have_fp = 1;
 257     }
 258
 259   /* Skip over any stack adjustment, happens either with a number of
 260      sub#2,sp or a mov #x,r5 sub r5,sp */
 261
 262   if (next_ip && IS_SUB2_SP (insn_word))
 263     {
 264       while (next_ip && IS_SUB2_SP (insn_word))
 265         {
 266           auto_depth += 2;
 267           ip = next_ip;
 268           next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 269         }
 270     }
 271   else
 272     {
 273       if (next_ip && IS_MOVK_R5 (insn_word))
 274         {
 275           ip = next_ip;
 276           next_ip = NEXT_PROLOGUE_INSN (ip, limit, &insn_word);
 277           auto_depth += insn_word;
 278
 279           next_ip = NEXT_PROLOGUE_INSN (next_ip, limit, &insn_word);
 280           auto_depth += insn_word;
 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_unsigned_integer (after_prolog_fp + 2, BINWORD);
 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_unsigned_integer (fsr->regs[6], BINWORD);
 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 /* Return the saved PC from this frame.
 323
 324    If the frame has a memory copy of SRP_REGNUM, use that.  If not,
 325    just use the register SRP_REGNUM itself.  */
 326
 327 CORE_ADDR
 328 frame_saved_pc (frame)
 329      FRAME frame;
 330 {
 331   return frame->from_pc;
 332 }
 333
 334 CORE_ADDR
 335 frame_locals_address (fi)
 336      struct frame_info *fi;
 337 {
 338   if (!fi->locals_pointer)
 339     {
 340       struct frame_saved_regs ignore;
 341
 342       get_frame_saved_regs (fi, &ignore);
 343
 344     }
 345   return fi->locals_pointer;
 346 }
 347
 348 /* Return the address of the argument block for the frame
 349    described by FI.  Returns 0 if the address is unknown.  */
 350
 351 CORE_ADDR
 352 frame_args_address (fi)
 353      struct frame_info *fi;
 354 {
 355   if (!fi->args_pointer)
 356     {
 357       struct frame_saved_regs ignore;
 358
 359       get_frame_saved_regs (fi, &ignore);
 360
 361     }
 362
 363   return fi->args_pointer;
 364 }
 365
 366 void
 367 h8300_pop_frame ()
 368 {
 369   unsigned regnum;
 370   struct frame_saved_regs fsr;
 371   struct frame_info *fi;
 372
 373   FRAME frame = get_current_frame ();
 374
 375   fi = get_frame_info (frame);
 376   get_frame_saved_regs (fi, &fsr);
 377
 378   for (regnum = 0; regnum < 8; regnum++)
 379     {
 380       if (fsr.regs[regnum])
 381         {
 382           write_register (regnum, read_memory_integer(fsr.regs[regnum]), BINWORD);
 383         }
 384
 385       flush_cached_frames ();
 386       set_current_frame (create_new_frame (read_register (FP_REGNUM),
 387                                            read_pc ()));
 388     }
 389 }
 390
 391 void
 392 print_register_hook (regno)
 393 {
 394   if (regno == 8)
 395     {
 396       /* CCR register */
 397
 398       int C, Z, N, V;
 399       unsigned char b[2];
 400       unsigned char l;
 401
 402       read_relative_register_raw_bytes (regno, b);
 403       l = b[1];
 404       printf ("\t");
 405       printf ("I-%d - ", (l & 0x80) != 0);
 406       printf ("H-%d - ", (l & 0x20) != 0);
 407       N = (l & 0x8) != 0;
 408       Z = (l & 0x4) != 0;
 409       V = (l & 0x2) != 0;
 410       C = (l & 0x1) != 0;
 411       printf ("N-%d ", N);
 412       printf ("Z-%d ", Z);
 413       printf ("V-%d ", V);
 414       printf ("C-%d ", C);
 415       if ((C | Z) == 0)
 416         printf ("u> ");
 417       if ((C | Z) == 1)
 418         printf ("u<= ");
 419       if ((C == 0))
 420         printf ("u>= ");
 421       if (C == 1)
 422         printf ("u< ");
 423       if (Z == 0)
 424         printf ("!= ");
 425       if (Z == 1)
 426         printf ("== ");
 427       if ((N ^ V) == 0)
 428         printf (">= ");
 429       if ((N ^ V) == 1)
 430         printf ("< ");
 431       if ((Z | (N ^ V)) == 0)
 432         printf ("> ");
 433       if ((Z | (N ^ V)) == 1)
 434         printf ("<= ");
 435     }
 436 }