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   1 /* z80mch.c
   2
   3    Copyright (C) 1989-1995 Alan R. Baldwin
   4    721 Berkeley St., Kent, Ohio 44240
   5
   6 This program is free software; you can redistribute it and/or modify it
   7 under the terms of the GNU General Public License as published by the
   8 Free Software Foundation; either version 3, or (at your option) any
   9 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, see <http://www.gnu.org/licenses/>. */
  18
  19 /*
  20  * Extensions: P. Felber
  21  */
  22
  23 #include <stdio.h>
  24 #include <setjmp.h>
  25 #include "asm.h"
  26 #include "z80.h"
  27
  28 char    imtab[3] = { 0x46, 0x56, 0x5E };
  29 #ifndef GAMEBOY
  30 int     hd64;
  31 #endif /* GAMEBOY */
  32
  33 /*
  34  * Process a machine op.
  35  */
  36 VOID
  37 machine(mp)
  38 struct mne *mp;
  39 {
  40         register int op, t1, t2;
  41         struct expr e1, e2;
  42         int rf, v1, v2;
  43
  44         clrexpr(&e1);
  45         clrexpr(&e2);
  46         op = mp->m_valu;
  47         rf = mp->m_type;
  48 #ifndef GAMEBOY
  49         if (!hd64 && rf>X_HD64)
  50                 rf = 0;
  51 #endif /* GAMEBOY */
  52         switch (rf) {
  53
  54         case S_INH1:
  55                 outab(op);
  56                 break;
  57
  58 #ifndef GAMEBOY
  59         case S_INH2:
  60                 outab(0xED);
  61                 outab(op);
  62                 break;
  63 #endif /* GAMEBOY */
  64
  65         case S_RET:
  66                 if (more()) {
  67                         if ((v1 = admode(CND)) != 0) {
  68                                 outab(op | v1<<3);
  69                         } else {
  70                                 qerr();
  71                         }
  72                 } else {
  73                         outab(0xC9);
  74                 }
  75                 break;
  76
  77         case S_PUSH:
  78                 if (admode(R16X)) {
  79                         outab(op+0x30);
  80                         break;
  81                 } else
  82                 if ((v1 = admode(R16)) != 0 && (v1 &= 0xFF) != SP) {
  83                         if (v1 != gixiy(v1)) {
  84                                 outab(op+0x20);
  85                                 break;
  86                         }
  87                         outab(op | v1<<4);
  88                         break;
  89                 }
  90                 aerr();
  91                 break;
  92
  93         case S_RST:
  94                 v1 = absexpr();
  95                 if (v1 & ~0x38) {
  96                         aerr();
  97                         v1 = 0;
  98                 }
  99                 outab(op|v1);
 100                 break;
 101
 102         case S_IM:
 103                 expr(&e1, 0);
 104                 abscheck(&e1);
 105                 if (e1.e_addr > 2) {
 106                         aerr();
 107                         e1.e_addr = 0;
 108                 }
 109                 outab(op);
 110                 outab(imtab[e1.e_addr]);
 111                 break;
 112
 113         case S_BIT:
 114                 expr(&e1, 0);
 115                 t1 = 0;
 116                 v1 = e1.e_addr;
 117                 if (v1 > 7) {
 118                         ++t1;
 119                         v1 &= 0x07;
 120                 }
 121                 op |= (v1<<3);
 122                 comma();
 123                 addr(&e2);
 124                 abscheck(&e1);
 125                 if (genop(0xCB, op, &e2, 0) || t1)
 126                         aerr();
 127                 break;
 128
 129         case S_RL:
 130                 t1 = 0;
 131                 t2 = addr(&e2);
 132                 if (more()) {
 133                         if ((t2 != S_R8) || (e2.e_addr != A))
 134                                 ++t1;
 135                         comma();
 136                         clrexpr(&e2);
 137                         t2 = addr(&e2);
 138                 }
 139                 if (genop(0xCB, op, &e2, 0) || t1)
 140                         aerr();
 141                 break;
 142
 143         case S_AND:
 144         case S_SUB:
 145                 t1 = 0;
 146                 t2 = addr(&e2);
 147                 if (more()) {
 148                         if ((t2 != S_R8) || (e2.e_addr != A))
 149                                 ++t1;
 150                         comma();
 151                         clrexpr(&e2);
 152                         t2 = addr(&e2);
 153                 }
 154                 if (genop(0, op, &e2, 1) || t1)
 155                         aerr();
 156                 break;
 157
 158         case S_ADD:
 159         case S_ADC:
 160         case S_SBC:
 161                 t1 = addr(&e1);
 162                 t2 = 0;
 163                 if (more()) {
 164                         comma();
 165                         t2 = addr(&e2);
 166                 }
 167                 if (t2 == 0) {
 168                         if (genop(0, op, &e1, 1))
 169                                 aerr();
 170                         break;
 171                 }
 172                 if ((t1 == S_R8) && (e1.e_addr == A)) {
 173                         if (genop(0, op, &e2, 1))
 174                                 aerr();
 175                         break;
 176                 }
 177                 if ((t1 == S_R16) && (t2 == S_R16)) {
 178 #ifndef GAMEBOY
 179                         if (rf == S_ADD)
 180                                 op = 0x09;
 181                         if (rf == S_ADC)
 182                                 op = 0x4A;
 183                         if (rf == S_SBC)
 184                                 op = 0x42;
 185                         v1 = e1.e_addr;
 186                         v2 = e2.e_addr;
 187                         if ((v1 == HL) && (v2 <= SP)) {
 188                                 if (rf != S_ADD)
 189                                         outab(0xED);
 190                                 outab(op | (v2<<4));
 191                                 break;
 192                         }
 193                         if (rf != S_ADD) {
 194                                 aerr();
 195                                 break;
 196                         }
 197                         if ((v1 == IX) && (v2 != HL) && (v2 != IY)) {
 198                                 if (v2 == IX)
 199                                         v2 = HL;
 200                                 outab(0xDD);
 201                                 outab(op | (v2<<4));
 202                                 break;
 203                         }
 204                         if ((v1 == IY) && (v2 != HL) && (v2 != IX)) {
 205                                 if (v2 == IY)
 206                                         v2 = HL;
 207                                 outab(0xFD);
 208                                 outab(op | (v2<<4));
 209                                 break;
 210                         }
 211                 }
 212 #else /* GAMEBOY */
 213                         v1 = e1.e_addr;
 214                         v2 = e2.e_addr;
 215                         if ((v1 == HL) && (v2 <= SP) && (rf == S_ADD)) {
 216                                 outab(0x09 | (v2<<4));
 217                                 break;
 218                         }
 219                 }
 220                 /*
 221                  * 0xE8 : ADD SP,#n
 222                  */
 223                 if ((rf == S_ADD) && (t1 == S_R16) && (e1.e_addr == SP) && (t2 == S_IMMED)) {
 224                         outab(0xE8);
 225                         outrb(&e2,0);
 226                         break;
 227                 }
 228 #endif /* GAMEBOY */
 229                 aerr();
 230                 break;
 231
 232         case S_LD:
 233                 t1 = addr(&e1);
 234                 comma();
 235                 t2 = addr(&e2);
 236                 if (t1 == S_R8) {
 237                         v1 = op | e1.e_addr<<3;
 238                         if (genop(0, v1, &e2, 0) == 0)
 239                                 break;
 240                         if (t2 == S_IMMED) {
 241                                 outab(e1.e_addr<<3 | 0x06);
 242                                 outrb(&e2,0);
 243                                 break;
 244                         }
 245                 }
 246                 v1 = e1.e_addr;
 247                 v2 = e2.e_addr;
 248                 if ((t1 == S_R16) && (t2 == S_IMMED)) {
 249                         v1 = gixiy(v1);
 250                         outab(0x01|v1<<4);
 251                         outrw(&e2, 0);
 252                         break;
 253                 }
 254 #ifndef GAMEBOY
 255                 if ((t1 == S_R16) && (t2 == S_INDM)) {
 256                         if (gixiy(v1) == HL) {
 257                                 outab(0x2A);
 258                         } else {
 259                                 outab(0xED);
 260                                 outab(0x4B | v1<<4);
 261                         }
 262                         outrw(&e2, 0);
 263                         break;
 264                 }
 265                 if ((t1 == S_INDM) && (t2 == S_R16)) {
 266                         if (gixiy(v2) == HL) {
 267                                 outab(0x22);
 268                         } else {
 269                                 outab(0xED);
 270                                 outab(0x43 | v2<<4);
 271                         }
 272                         outrw(&e1, 0);
 273                         break;
 274                 }
 275                 if ((t1 == S_R8) && (v1 == A) && (t2 == S_INDM)) {
 276                         outab(0x3A);
 277                         outrw(&e2, 0);
 278                         break;
 279                 }
 280                 if ((t1 == S_INDM) && (t2 == S_R8) && (v2 == A)) {
 281                         outab(0x32);
 282                         outrw(&e1, 0);
 283                         break;
 284                 }
 285 #endif /* GAMEBOY */
 286                 if ((t2 == S_R8) && (gixiy(t1) == S_IDHL)) {
 287                         outab(0x70|v2);
 288                         if (t1 != S_IDHL)
 289                                 outrb(&e1, 0);
 290                         break;
 291                 }
 292                 if ((t2 == S_IMMED) && (gixiy(t1) == S_IDHL)) {
 293                         outab(0x36);
 294                         if (t1 != S_IDHL)
 295                                 outrb(&e1, 0);
 296                         outrb(&e2, 0);
 297                         break;
 298                 }
 299 #ifndef GAMEBOY
 300                 if ((t1 == S_R8X) && (t2 == S_R8) && (v2 == A)) {
 301                         outab(0xED);
 302                         outab(v1);
 303                         break;
 304                 }
 305                 if ((t1 == S_R8) && (v1 == A) && (t2 == S_R8X)) {
 306                         outab(0xED);
 307                         outab(v2|0x10);
 308                         break;
 309                 }
 310 #endif /* GAMEBOY */
 311                 if ((t1 == S_R16) && (v1 == SP)) {
 312                         if ((t2 == S_R16) && (gixiy(v2) == HL)) {
 313                                 outab(0xF9);
 314                                 break;
 315                         }
 316                 }
 317                 if ((t1 == S_R8) && (v1 == A)) {
 318                         if ((t2 == S_IDBC) || (t2 == S_IDDE)) {
 319                                 outab(0x0A | (t2-S_INDR)<<4);
 320                                 break;
 321                         }
 322                 }
 323                 if ((t2 == S_R8) && (v2 == A)) {
 324                         if ((t1 == S_IDBC) || (t1 == S_IDDE)) {
 325                                 outab(0x02 | (t1-S_INDR)<<4);
 326                                 break;
 327                         }
 328                 }
 329 #ifdef GAMEBOY
 330                 /*
 331                  * 0x08 : LD (nn),SP
 332                  */
 333                 if ((t1 == S_INDM) && (t2 == S_R16) && (v2 == SP)) {
 334                         outab(0x08);
 335                         outrw(&e1, 0);
 336                         break;
 337                 }
 338                 /*
 339                  * 0xEA : LD (nn),A
 340                  * 0xFA : LD A,(nn)
 341                  */
 342                 if ((t1 == S_INDM) && (t2 == S_R8) && (v2 == A)) {
 343                         outab(0xEA);
 344                         outrw(&e1, 0);
 345                         break;
 346                 }
 347                 if ((t2 == S_INDM) && (t1 == S_R8) && (v1 == A)) {
 348                         outab(0xFA);
 349                         outrw(&e2, 0);
 350                         break;
 351                 }
 352                 /*
 353                  * 0x32 : LD (HL-),A
 354                  * 0x3A : LD A,(HL-)
 355                  */
 356                 if ((t1 == S_R8) && (v1 == A) && (t2 == S_IDHLD)) {
 357                         outab(0x3A);
 358                         break;
 359                 }
 360                 if ((t2 == S_R8) && (v2 == A) && (t1 == S_IDHLD)) {
 361                         outab(0x32);
 362                         break;
 363                 }
 364                 /*
 365                  * 0x22 : LD (HL+),A
 366                  * 0x2A : LD A,(HL+)
 367                  */
 368                 if ((t1 == S_R8) && (v1 == A) && (t2 == S_IDHLI)) {
 369                         outab(0x2A);
 370                         break;
 371                 }
 372                 if ((t2 == S_R8) && (v2 == A) && (t1 == S_IDHLI)) {
 373                         outab(0x22);
 374                         break;
 375                 }
 376 #endif /* GAMEBOY */
 377                 aerr();
 378                 break;
 379
 380
 381 #ifdef GAMEBOY
 382         case S_STOP:    /* 0x10 */
 383                 /*
 384                  * 0x10 : STOP
 385                  */
 386                 outab(op);
 387                 outab(0x00);
 388                 break;
 389
 390
 391         case S_LDH:     /* 0xE0 */
 392                 /*
 393                  * 0xE0 : LDH (n),A = LD ($FF00+n),A
 394                  * 0xE2 : LDH (C),A = LD ($FF00+C),A
 395                  * 0xF0 : LDH A,(n) = LD A,($FF00+n)
 396                  * 0xF2 : LDH A,(C) = LD A,($FF00+C)
 397                  */
 398                 t1 = addr(&e1);
 399                 comma();
 400                 t2 = addr(&e2);
 401                 if ((t1 == S_INDM) && (t2 == S_R8) && (e2.e_addr == A)) {
 402                         outab(0xE0);
 403                         outrb(&e1, 0);
 404                         break;
 405                 }
 406                 if ((t1 == S_IDC) && (t2 == S_R8) && (e2.e_addr == A)) {
 407                         outab(0xE2);
 408                         break;
 409                 }
 410                 if ((t2 == S_INDM) && (t1 == S_R8) && (e1.e_addr == A)) {
 411                         outab(0xF0);
 412                         outrb(&e2, 0);
 413                         break;
 414                 }
 415                 if ((t2 == S_IDC) && (t1 == S_R8) && (e1.e_addr == A)) {
 416                         outab(0xF2);
 417                         break;
 418                 }
 419                 aerr();
 420                 break;
 421
 422
 423         case S_LDA:     /* 0xE8 */
 424                 /*
 425                  * 0xE8 : LDA SP,#n(SP)
 426                  * 0xF8 : LDA HL,#n(SP)
 427                  */
 428                 t1 = addr(&e1);
 429                 comma();
 430                 t2 = addr(&e2);
 431                 if ((t1 == S_R16) && (e1.e_addr == SP) && (t2 == S_INDR+SP)) {
 432                         outab(0xE8);
 433                         outrb(&e2,0);
 434                         break;
 435                 }
 436                 if ((t1 == S_R16) && (e1.e_addr == HL) && (t2 == S_INDR+SP)) {
 437                         outab(0xF8);
 438                         outrb(&e2,0);
 439                         break;
 440                 }
 441                 aerr();
 442                 break;
 443
 444
 445         case S_LDHL:    /* 0xF8 */
 446                 /*
 447                  * 0xF8 : LDHL SP,#n
 448                  */
 449                 t1 = addr(&e1);
 450                 comma();
 451                 t2 = addr(&e2);
 452                 if ((t1 == S_R16) && (e1.e_addr == SP) && (t2 == S_IMMED)) {
 453                         outab(0xF8);
 454                         outrb(&e2,0);
 455                         break;
 456                 }
 457                 aerr();
 458                 break;
 459 #endif /* GAMEBOY */
 460
 461
 462 #ifndef GAMEBOY
 463         case S_EX:
 464                 t1 = addr(&e1);
 465                 comma();
 466                 t2 = addr(&e2);
 467                 if (t2 == S_R16) {
 468                         v1 = e1.e_addr;
 469                         v2 = e2.e_addr;
 470                         if ((t1 == S_IDSP) && (v1 == 0)) {
 471                                 if (gixiy(v2) == HL) {
 472                                         outab(op);
 473                                         break;
 474                                 }
 475                         }
 476                         if (t1 == S_R16) {
 477                                 if ((v1 == DE) && (v2 == HL)) {
 478                                         outab(0xEB);
 479                                         break;
 480                                 }
 481                         }
 482                 }
 483                 if ((t1 == S_R16X) && (t2 == S_R16X)) {
 484                         outab(0x08);
 485                         break;
 486                 }
 487                 aerr();
 488                 break;
 489
 490         case S_IN:
 491         case S_OUT:
 492                 if (rf == S_IN) {
 493                         t1 = addr(&e1);
 494                         comma();
 495                         t2 = addr(&e2);
 496                 } else {
 497                         t2 = addr(&e2);
 498                         comma();
 499                         t1 = addr(&e1);
 500                 }
 501                 v1 = e1.e_addr;
 502                 v2 = e2.e_addr;
 503                 if (t1 == S_R8) {
 504                         if ((v1 == A) && (t2 == S_INDM)) {
 505                                 outab(op);
 506                                 outab(v2);
 507                                 break;
 508                         }
 509                         if (t2 == S_IDC) {
 510                                 outab(0xED);
 511                                 outab(((rf == S_IN) ? 0x40 : 0x41) + (v1<<3));
 512                                 break;
 513                         }
 514                 }
 515                 aerr();
 516                 break;
 517 #endif /* GAMEBOY */
 518
 519         case S_DEC:
 520         case S_INC:
 521                 t1 = addr(&e1);
 522                 v1 = e1.e_addr;
 523                 if (t1 == S_R8) {
 524                         outab(op|(v1<<3));
 525                         break;
 526                 }
 527                 if (t1 == S_IDHL) {
 528                         outab(op|0x30);
 529                         break;
 530                 }
 531                 if (t1 != gixiy(t1)) {
 532                         outab(op|0x30);
 533                         outrb(&e1,0);
 534                         break;
 535                 }
 536                 if (t1 == S_R16) {
 537                         v1 = gixiy(v1);
 538                         if (rf == S_INC) {
 539                                 outab(0x03|(v1<<4));
 540                                 break;
 541                         }
 542                         if (rf == S_DEC) {
 543                                 outab(0x0B|(v1<<4));
 544                                 break;
 545                         }
 546                 }
 547                 aerr();
 548                 break;
 549
 550 #ifndef GAMEBOY
 551         case S_DJNZ:
 552         case S_JR:
 553                 if ((v1 = admode(CND)) != 0 && rf != S_DJNZ) {
 554                         if ((v1 &= 0xFF) <= 0x03) {
 555                                 op += (v1+1)<<3;
 556                         } else {
 557                                 aerr();
 558                         }
 559                         comma();
 560                 }
 561 #else /* GAMEBOY */
 562         case S_JR:
 563                 if ((v1 = admode(CND)) != 0) {
 564                         if ((v1 &= 0xFF) <= 0x18) {
 565                                 op += (v1+1)<<3;
 566                         } else {
 567                                 aerr();
 568                         }
 569                         comma();
 570                 }
 571 #endif /* GAMEBOY */
 572                 expr(&e2, 0);
 573                 outab(op);
 574                 if (e2.e_base.e_ap == NULL || e2.e_base.e_ap == dot.s_area) {
 575                         v2 = e2.e_addr - dot.s_addr - 1;
 576                         if (pass == 2 && ((v2 < -128) || (v2 > 127)))
 577                                 aerr();
 578                         outab(v2);
 579                 } else {
 580                         outrb(&e2, R_PCR);
 581                 }
 582                 if (e2.e_mode != S_USER)
 583                         rerr();
 584                 break;
 585
 586         case S_CALL:
 587                 if ((v1 = admode(CND)) != 0) {
 588                         op |= (v1&0xFF)<<3;
 589                         comma();
 590                 } else {
 591                         op = 0xCD;
 592                 }
 593                 expr(&e1, 0);
 594                 outab(op);
 595                 outrw(&e1, 0);
 596                 break;
 597
 598         case S_JP:
 599                 if ((v1 = admode(CND)) != 0) {
 600                         op |= (v1&0xFF)<<3;
 601                         comma();
 602                         expr(&e1, 0);
 603                         outab(op);
 604                         outrw(&e1, 0);
 605                         break;
 606                 }
 607                 t1 = addr(&e1);
 608                 if (t1 == S_USER) {
 609                         outab(0xC3);
 610                         outrw(&e1, 0);
 611                         break;
 612                 }
 613                 if ((e1.e_addr == 0) && (gixiy(t1) == S_IDHL)) {
 614                         outab(0xE9);
 615                         break;
 616                 }
 617                 aerr();
 618                 break;
 619
 620 #ifndef GAMEBOY
 621         case X_HD64:
 622                 ++hd64;
 623                 break;
 624
 625         case X_INH2:
 626                 outab(0xED);
 627                 outab(op);
 628                 break;
 629
 630         case X_IN:
 631         case X_OUT:
 632                 if (rf == X_IN) {
 633                         t1 = addr(&e1);
 634                         comma();
 635                         t2 = addr(&e2);
 636                 } else {
 637                         t2 = addr(&e2);
 638                         comma();
 639                         t1 = addr(&e1);
 640                 }
 641                 if ((t1 == S_R8) && (t2 == S_INDM)) {
 642                         outab(0xED);
 643                         outab(op | e1.e_addr<<3);
 644                         outrb(&e2, 0);
 645                         break;
 646                 }
 647                 aerr();
 648                 break;
 649
 650         case X_MLT:
 651                 t1 = addr(&e1);
 652                 if ((t1 == S_R16) && ((v1 = e1.e_addr) <= SP)) {
 653                         outab(0xED);
 654                         outab(op | v1<<4);
 655                         break;
 656                 }
 657                 aerr();
 658                 break;
 659
 660         case X_TST:
 661                 t1 = addr(&e1);
 662                 if (t1 == S_R8) {
 663                         outab(0xED);
 664                         outab(op | e1.e_addr<<3);
 665                         break;
 666                 }
 667                 if (t1 == S_IDHL) {
 668                         outab(0xED);
 669                         outab(0x34);
 670                         break;
 671                 }
 672                 if (t1 == S_IMMED) {
 673                         outab(0xED);
 674                         outab(0x64);
 675                         outrb(&e1, 0);
 676                         break;
 677                 }
 678                 aerr();
 679                 break;
 680
 681         case X_TSTIO:
 682                 t1 = addr(&e1);
 683                 if (t1 == S_IMMED) {
 684                         outab(0xED);
 685                         outab(op);
 686                         outrb(&e1, 0);
 687                         break;
 688                 }
 689                 aerr();
 690                 break;
 691 #endif /* GAMEBOY */
 692
 693         default:
 694                 err('o');
 695         }
 696 }
 697
 698 /*
 699  * general addressing evaluation
 700  * return(0) if general addressing mode output, else
 701  * return(esp->e_mode)
 702  */
 703 int
 704 genop(pop, op, esp, f)
 705 register int pop, op;
 706 register struct expr *esp;
 707 int f;
 708 {
 709         register int t1;
 710         if ((t1 = esp->e_mode) == S_R8) {
 711                 if (pop)
 712                         outab(pop);
 713                 outab(op|esp->e_addr);
 714                 return(0);
 715         }
 716         if (t1 == S_IDHL) {
 717                 if (pop)
 718                         outab(pop);
 719                 outab(op|0x06);
 720                 return(0);
 721         }
 722         if (gixiy(t1) == S_IDHL) {
 723                 if (pop) {
 724                         outab(pop);
 725                         outrb(esp,0);
 726                         outab(op|0x06);
 727                 } else {
 728                         outab(op|0x06);
 729                         outrb(esp,0);
 730                 }
 731                 return(0);
 732         }
 733         if ((t1 == S_IMMED) && (f)) {
 734                 if (pop)
 735                         outab(pop);
 736                 outab(op|0x46);
 737                 outrb(esp,0);
 738                 return(0);
 739         }
 740         return(t1);
 741 }
 742
 743 /*
 744  * IX and IY prebyte check
 745  */
 746 int
 747 gixiy(v)
 748 int v;
 749 {
 750 #ifndef GAMEBOY
 751         if (v == IX) {
 752                 v = HL;
 753                 outab(0xDD);
 754         } else if (v == IY) {
 755                 v = HL;
 756                 outab(0xFD);
 757         } else if (v == S_IDIX) {
 758                 v = S_IDHL;
 759                 outab(0xDD);
 760         } else if (v == S_IDIY) {
 761                 v = S_IDHL;
 762                 outab(0xFD);
 763         }
 764 #endif /* GAMEBOY */
 765         return(v);
 766 }
 767
 768 /*
 769  * The next character must be a
 770  * comma.
 771  */
 772 int
 773 comma()
 774 {
 775         if (getnb() != ',')
 776                 qerr();
 777         return(1);
 778 }
 779
 780 /*
 781  * Machine dependent initialization
 782  */
 783 VOID
 784 minit()
 785 {
 786 #ifndef GAMEBOY
 787         hd64 = 0;
 788 #endif /* GAMEBOY */
 789 }