cpu_6800.c

   1 #include <stdbool.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include "cpu_6800.h"
   5
   6 // initialization
   7 void cpu_6800_init(
   8   struct cpu_6800 *self,
   9   int (*read_byte)(void *context, int addr),
  10   void *read_byte_context,
  11   void (*write_byte)(void *context, int addr, int data),
  12   void *write_byte_context
  13 ) {
  14   memset(self, 0, sizeof(struct cpu_6800));
  15   self->regs.byte.p = 0xc0; // unused bits are hard coded to 1
  16   self->read_byte = read_byte;
  17   self->read_byte_context = read_byte_context;
  18   self->write_byte = write_byte;
  19   self->write_byte_context = write_byte_context;
  20 }
  21
  22 void cpu_6800_reset(struct cpu_6800 *self) {
  23   self->regs.word.pc = cpu_6800_read_word(self, CPU_6800_RESET_VECTOR);
  24   self->regs.byte.iflags = 0;
  25   self->regs.bit._if = true;
  26 }
  27
  28 // instruction decode
  29 void cpu_6800_execute(struct cpu_6800 *self) {
  30   if (self->regs.bit.nmi_pending) {
  31     self->regs.bit.nmi_pending = false;
  32     if (!self->regs.bit.wai_flag)
  33       cpu_6800_wai(self);
  34     self->regs.bit.wai_flag = false;
  35     self->regs.word.pc = cpu_6800_read_word(self, CPU_6800_NMI_VECTOR);
  36     self->regs.bit._if = true;
  37     return;
  38   }
  39
  40   if (self->regs.bit.irq_pending && !self->regs.bit._if) {
  41     self->regs.bit.irq_pending = false;
  42     if (!self->regs.bit.wai_flag)
  43       cpu_6800_wai(self);
  44     self->regs.bit.wai_flag = false;
  45     self->regs.word.pc = cpu_6800_read_word(self, CPU_6800_IRQ_VECTOR);
  46     self->regs.bit._if = true;
  47     return;
  48   }
  49
  50   if (self->regs.bit.wai_flag) {
  51     ++self->cycles;
  52     return;
  53   }
  54
  55   switch (cpu_6800_fetch_byte(self)) {
  56   case 0x00:
  57     cpu_6800_illegal_opcode(self);
  58     break;
  59   case 0x01:
  60     cpu_6800_nop(self);
  61     break;
  62   case 0x02:
  63     cpu_6800_illegal_opcode(self);
  64     break;
  65   case 0x03:
  66     cpu_6800_illegal_opcode(self);
  67     break;
  68   case 0x04:
  69     cpu_6800_illegal_opcode(self);
  70     break;
  71   case 0x05:
  72     cpu_6800_illegal_opcode(self);
  73     break;
  74   case 0x06:
  75     cpu_6800_tap(self);
  76     break;
  77   case 0x07:
  78     cpu_6800_tpa(self);
  79     break;
  80   case 0x08:
  81     cpu_6800_inc_word_zf(self, CPU_6800_EA_X);
  82     break;
  83   case 0x09:
  84     cpu_6800_dec_word_zf(self, CPU_6800_EA_X);
  85     break;
  86   case 0x0a:
  87     cpu_6800_cl(self, CPU_6800_REG_P_BIT_V);
  88     break;
  89   case 0x0b:
  90     cpu_6800_se(self, CPU_6800_REG_P_BIT_V);
  91     break;
  92   case 0x0c:
  93     cpu_6800_cl(self, CPU_6800_REG_P_BIT_C);
  94     break;
  95   case 0x0d:
  96     cpu_6800_se(self, CPU_6800_REG_P_BIT_C);
  97     break;
  98   case 0x0e:
  99     cpu_6800_cl(self, CPU_6800_REG_P_BIT_I);
 100     break;
 101   case 0x0f:
 102     cpu_6800_se(self, CPU_6800_REG_P_BIT_I);
 103     break;
 104   case 0x10:
 105     cpu_6800_sub(self, CPU_6800_EA_A, self->regs.byte.b);
 106     break;
 107   case 0x11:
 108     cpu_6800_cmp_byte(self, self->regs.byte.a, self->regs.byte.b);
 109     break;
 110   case 0x12:
 111     cpu_6800_illegal_opcode(self);
 112     break;
 113   case 0x13:
 114     cpu_6800_illegal_opcode(self);
 115     break;
 116   case 0x14:
 117     cpu_6800_illegal_opcode(self);
 118     break;
 119   case 0x15:
 120     cpu_6800_illegal_opcode(self);
 121     break;
 122   case 0x16:
 123     cpu_6800_ld_byte(self, CPU_6800_EA_B, self->regs.byte.a);
 124     break;
 125   case 0x17:
 126     cpu_6800_ld_byte(self, CPU_6800_EA_A, self->regs.byte.b);
 127     break;
 128   case 0x18:
 129     cpu_6800_illegal_opcode(self);
 130     break;
 131   case 0x19:
 132     cpu_6800_daa(self);
 133     break;
 134   case 0x1a:
 135     cpu_6800_illegal_opcode(self);
 136     break;
 137   case 0x1b:
 138     cpu_6800_add(self, CPU_6800_EA_A, self->regs.byte.b);
 139     break;
 140   case 0x1c:
 141     cpu_6800_illegal_opcode(self);
 142     break;
 143   case 0x1d:
 144     cpu_6800_illegal_opcode(self);
 145     break;
 146   case 0x1e:
 147     cpu_6800_illegal_opcode(self);
 148     break;
 149   case 0x1f:
 150     cpu_6800_illegal_opcode(self);
 151     break;
 152   case 0x20:
 153     cpu_6800_bra(self, true, cpu_6800_ea_relative(self));
 154     break;
 155   case 0x21:
 156     cpu_6800_illegal_opcode(self);
 157     break;
 158   case 0x22:
 159     cpu_6800_bra(self, !self->regs.bit.cf && !self->regs.bit.zf, cpu_6800_ea_relative(self));
 160     break;
 161   case 0x23:
 162     cpu_6800_bra(self, self->regs.bit.cf || self->regs.bit.zf, cpu_6800_ea_relative(self));
 163     break;
 164   case 0x24:
 165     cpu_6800_bra(self, !self->regs.bit.cf, cpu_6800_ea_relative(self));
 166     break;
 167   case 0x25:
 168     cpu_6800_bra(self, self->regs.bit.cf, cpu_6800_ea_relative(self));
 169     break;
 170   case 0x26:
 171     cpu_6800_bra(self, !self->regs.bit.zf, cpu_6800_ea_relative(self));
 172     break;
 173   case 0x27:
 174     cpu_6800_bra(self, self->regs.bit.zf, cpu_6800_ea_relative(self));
 175     break;
 176   case 0x28:
 177     cpu_6800_bra(self, !self->regs.bit.vf, cpu_6800_ea_relative(self));
 178     break;
 179   case 0x29:
 180     cpu_6800_bra(self, self->regs.bit.vf, cpu_6800_ea_relative(self));
 181     break;
 182   case 0x2a:
 183     cpu_6800_bra(self, !self->regs.bit.nf, cpu_6800_ea_relative(self));
 184     break;
 185   case 0x2b:
 186     cpu_6800_bra(self, self->regs.bit.nf, cpu_6800_ea_relative(self));
 187     break;
 188   case 0x2c:
 189     cpu_6800_bra(self, !self->regs.bit.nf && !self->regs.bit.vf, cpu_6800_ea_relative(self));
 190     break;
 191   case 0x2d:
 192     cpu_6800_bra(self, self->regs.bit.nf || self->regs.bit.vf, cpu_6800_ea_relative(self));
 193     break;
 194   case 0x2e:
 195     cpu_6800_bra(self, !self->regs.bit.nf && !self->regs.bit.vf && !self->regs.bit.zf, cpu_6800_ea_relative(self));
 196     break;
 197   case 0x2f:
 198     cpu_6800_bra(self, self->regs.bit.nf || self->regs.bit.vf || self->regs.bit.zf, cpu_6800_ea_relative(self));
 199     break;
 200   case 0x30:
 201     cpu_6800_tsx(self);
 202     break;
 203   case 0x31:
 204     cpu_6800_inc_word(self, CPU_6800_EA_S);
 205     break;
 206   case 0x32:
 207     cpu_6800_pul(self, CPU_6800_EA_A);
 208     break;
 209   case 0x33:
 210     cpu_6800_pul(self, CPU_6800_EA_B);
 211     break;
 212   case 0x34:
 213     cpu_6800_dec_word(self, CPU_6800_EA_S);
 214     break;
 215   case 0x35:
 216     cpu_6800_txs(self);
 217     break;
 218   case 0x36:
 219     cpu_6800_psh(self, self->regs.byte.a);
 220     break;
 221   case 0x37:
 222     cpu_6800_psh(self, self->regs.byte.b);
 223     break;
 224   case 0x38:
 225     cpu_6800_illegal_opcode(self);
 226     break;
 227   case 0x39:
 228     cpu_6800_rts(self);
 229     break;
 230   case 0x3a:
 231     cpu_6800_illegal_opcode(self);
 232     break;
 233   case 0x3b:
 234     cpu_6800_rti(self);
 235     break;
 236   case 0x3c:
 237     cpu_6800_illegal_opcode(self);
 238     break;
 239   case 0x3d:
 240     cpu_6800_illegal_opcode(self);
 241     break;
 242   case 0x3e:
 243     cpu_6800_wai(self);
 244     break;
 245   case 0x3f:
 246     cpu_6800_swi(self);
 247     break;
 248   case 0x40:
 249     cpu_6800_neg(self, CPU_6800_EA_A);
 250     break;
 251   case 0x41:
 252     cpu_6800_illegal_opcode(self);
 253     break;
 254   case 0x42:
 255     cpu_6800_illegal_opcode(self);
 256     break;
 257   case 0x43:
 258     cpu_6800_com(self, CPU_6800_EA_A);
 259     break;
 260   case 0x44:
 261     cpu_6800_lsr(self, CPU_6800_EA_A);
 262     break;
 263   case 0x45:
 264     cpu_6800_illegal_opcode(self);
 265     break;
 266   case 0x46:
 267     cpu_6800_ror(self, CPU_6800_EA_A);
 268     break;
 269   case 0x47:
 270     cpu_6800_asr(self, CPU_6800_EA_A);
 271     break;
 272   case 0x48:
 273     cpu_6800_asl(self, CPU_6800_EA_A);
 274     break;
 275   case 0x49:
 276     cpu_6800_rol(self, CPU_6800_EA_A);
 277     break;
 278   case 0x4a:
 279     cpu_6800_dec_byte(self, CPU_6800_EA_A);
 280     break;
 281   case 0x4b:
 282     cpu_6800_illegal_opcode(self);
 283     break;
 284   case 0x4c:
 285     cpu_6800_inc_byte(self, CPU_6800_EA_A);
 286     break;
 287   case 0x4d:
 288     cpu_6800_cmp_byte(self, self->regs.byte.a, 0);
 289     break;
 290   case 0x4e:
 291     cpu_6800_illegal_opcode(self);
 292     break;
 293   case 0x4f:
 294     cpu_6800_clr(self, CPU_6800_EA_A);
 295     break;
 296   case 0x50:
 297     cpu_6800_neg(self, CPU_6800_EA_B);
 298     break;
 299   case 0x51:
 300     cpu_6800_illegal_opcode(self);
 301     break;
 302   case 0x52:
 303     cpu_6800_illegal_opcode(self);
 304     break;
 305   case 0x53:
 306     cpu_6800_com(self, CPU_6800_EA_B);
 307     break;
 308   case 0x54:
 309     cpu_6800_lsr(self, CPU_6800_EA_B);
 310     break;
 311   case 0x55:
 312     cpu_6800_illegal_opcode(self);
 313     break;
 314   case 0x56:
 315     cpu_6800_ror(self, CPU_6800_EA_B);
 316     break;
 317   case 0x57:
 318     cpu_6800_asr(self, CPU_6800_EA_B);
 319     break;
 320   case 0x58:
 321     cpu_6800_asl(self, CPU_6800_EA_B);
 322     break;
 323   case 0x59:
 324     cpu_6800_rol(self, CPU_6800_EA_B);
 325     break;
 326   case 0x5a:
 327     cpu_6800_dec_byte(self, CPU_6800_EA_B);
 328     break;
 329   case 0x5b:
 330     cpu_6800_illegal_opcode(self);
 331     break;
 332   case 0x5c:
 333     cpu_6800_inc_byte(self, CPU_6800_EA_B);
 334     break;
 335   case 0x5d:
 336     cpu_6800_cmp_byte(self, self->regs.byte.b, 0);
 337     break;
 338   case 0x5e:
 339     cpu_6800_illegal_opcode(self);
 340     break;
 341   case 0x5f:
 342     cpu_6800_clr(self, CPU_6800_EA_B);
 343     break;
 344   case 0x60:
 345     cpu_6800_neg(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 346     break;
 347   case 0x61:
 348     cpu_6800_illegal_opcode(self);
 349     break;
 350   case 0x62:
 351     cpu_6800_illegal_opcode(self);
 352     break;
 353   case 0x63:
 354     cpu_6800_com(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 355     break;
 356   case 0x64:
 357     cpu_6800_lsr(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 358     break;
 359   case 0x65:
 360     cpu_6800_illegal_opcode(self);
 361     break;
 362   case 0x66:
 363     cpu_6800_ror(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 364     break;
 365   case 0x67:
 366     cpu_6800_asr(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 367     break;
 368   case 0x68:
 369     cpu_6800_asl(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 370     break;
 371   case 0x69:
 372     cpu_6800_rol(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 373     break;
 374   case 0x6a:
 375     cpu_6800_dec_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 376     break;
 377   case 0x6b:
 378     cpu_6800_illegal_opcode(self);
 379     break;
 380   case 0x6c:
 381     cpu_6800_inc_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 382     break;
 383   case 0x6d:
 384     cpu_6800_cmp_byte(self, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)), 0);
 385     break;
 386   case 0x6e:
 387     cpu_6800_jmp(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 388     break;
 389   case 0x6f:
 390     cpu_6800_clr(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 391     break;
 392   case 0x70:
 393     cpu_6800_neg(self, cpu_6800_ea_extended(self));
 394     break;
 395   case 0x71:
 396     cpu_6800_illegal_opcode(self);
 397     break;
 398   case 0x72:
 399     cpu_6800_illegal_opcode(self);
 400     break;
 401   case 0x73:
 402     cpu_6800_com(self, cpu_6800_ea_extended(self));
 403     break;
 404   case 0x74:
 405     cpu_6800_lsr(self, cpu_6800_ea_extended(self));
 406     break;
 407   case 0x75:
 408     cpu_6800_illegal_opcode(self);
 409     break;
 410   case 0x76:
 411     cpu_6800_ror(self, cpu_6800_ea_extended(self));
 412     break;
 413   case 0x77:
 414     cpu_6800_asr(self, cpu_6800_ea_extended(self));
 415     break;
 416   case 0x78:
 417     cpu_6800_asl(self, cpu_6800_ea_extended(self));
 418     break;
 419   case 0x79:
 420     cpu_6800_rol(self, cpu_6800_ea_extended(self));
 421     break;
 422   case 0x7a:
 423     cpu_6800_dec_byte(self, cpu_6800_ea_extended(self));
 424     break;
 425   case 0x7b:
 426     cpu_6800_illegal_opcode(self);
 427     break;
 428   case 0x7c:
 429     cpu_6800_inc_byte(self, cpu_6800_ea_extended(self));
 430     break;
 431   case 0x7d:
 432     cpu_6800_cmp_byte(self, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)), 0);
 433     break;
 434   case 0x7e:
 435     cpu_6800_jmp(self, cpu_6800_ea_extended(self));
 436     break;
 437   case 0x7f:
 438     cpu_6800_clr(self, cpu_6800_ea_extended(self));
 439     break;
 440   case 0x80:
 441     cpu_6800_sub(self, CPU_6800_EA_A, cpu_6800_fetch_byte(self));
 442     break;
 443   case 0x81:
 444     cpu_6800_cmp_byte(self, self->regs.byte.a, cpu_6800_fetch_byte(self));
 445     break;
 446   case 0x82:
 447     cpu_6800_sbc(self, CPU_6800_EA_A, cpu_6800_fetch_byte(self));
 448     break;
 449   case 0x83:
 450     cpu_6800_illegal_opcode(self);
 451     break;
 452   case 0x84:
 453     cpu_6800_and(self, CPU_6800_EA_A, cpu_6800_fetch_byte(self));
 454     break;
 455   case 0x85:
 456     cpu_6800_bit(self, self->regs.byte.a, cpu_6800_fetch_byte(self));
 457     break;
 458   case 0x86:
 459     cpu_6800_ld_byte(self, CPU_6800_EA_A, cpu_6800_fetch_byte(self));
 460     break;
 461   case 0x87:
 462     cpu_6800_illegal_opcode(self);
 463     break;
 464   case 0x88:
 465     cpu_6800_eor(self, CPU_6800_EA_A, cpu_6800_fetch_byte(self));
 466     break;
 467   case 0x89:
 468     cpu_6800_adc(self, CPU_6800_EA_A, cpu_6800_fetch_byte(self));
 469     break;
 470   case 0x8a:
 471     cpu_6800_ora(self, CPU_6800_EA_A, cpu_6800_fetch_byte(self));
 472     break;
 473   case 0x8b:
 474     cpu_6800_add(self, CPU_6800_EA_A, cpu_6800_fetch_byte(self));
 475     break;
 476   case 0x8c:
 477     cpu_6800_cmp_word(self, self->regs.word.x, cpu_6800_fetch_word(self));
 478     break;
 479   case 0x8d:
 480     cpu_6800_bsr(self, cpu_6800_ea_relative(self));
 481     break;
 482   case 0x8e:
 483     cpu_6800_ld_word(self, CPU_6800_EA_S, cpu_6800_fetch_word(self));
 484     break;
 485   case 0x8f:
 486     cpu_6800_illegal_opcode(self);
 487     break;
 488   case 0x90:
 489     cpu_6800_sub(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 490     break;
 491   case 0x91:
 492     cpu_6800_cmp_byte(self, self->regs.byte.a, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 493     break;
 494   case 0x92:
 495     cpu_6800_sbc(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 496     break;
 497   case 0x93:
 498     cpu_6800_illegal_opcode(self);
 499     break;
 500   case 0x94:
 501     cpu_6800_and(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 502     break;
 503   case 0x95:
 504     cpu_6800_bit(self, self->regs.byte.a, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 505     break;
 506   case 0x96:
 507     cpu_6800_ld_byte(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 508     break;
 509   case 0x97:
 510     cpu_6800_st_byte(self, self->regs.byte.a, cpu_6800_ea_direct(self));
 511     break;
 512   case 0x98:
 513     cpu_6800_eor(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 514     break;
 515   case 0x99:
 516     cpu_6800_adc(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 517     break;
 518   case 0x9a:
 519     cpu_6800_ora(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 520     break;
 521   case 0x9b:
 522     cpu_6800_add(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 523     break;
 524   case 0x9c:
 525     cpu_6800_cmp_word(self, self->regs.word.x, cpu_6800_read_word(self, cpu_6800_ea_direct(self)));
 526     break;
 527   case 0x9d:
 528     cpu_6800_illegal_opcode(self);
 529     break;
 530   case 0x9e:
 531     cpu_6800_ld_word(self, CPU_6800_EA_S, cpu_6800_read_word(self, cpu_6800_ea_direct(self)));
 532     break;
 533   case 0x9f:
 534     cpu_6800_st_word(self, self->regs.word.s, cpu_6800_ea_direct(self));
 535     break;
 536   case 0xa0:
 537     cpu_6800_sub(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 538     break;
 539   case 0xa1:
 540     cpu_6800_cmp_byte(self, self->regs.byte.a, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 541     break;
 542   case 0xa2:
 543     cpu_6800_sbc(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 544     break;
 545   case 0xa3:
 546     cpu_6800_illegal_opcode(self);
 547     break;
 548   case 0xa4:
 549     cpu_6800_and(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 550     break;
 551   case 0xa5:
 552     cpu_6800_bit(self, self->regs.byte.a, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 553     break;
 554   case 0xa6:
 555     cpu_6800_ld_byte(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 556     break;
 557   case 0xa7:
 558     cpu_6800_st_byte(self, self->regs.byte.a, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 559     break;
 560   case 0xa8:
 561     cpu_6800_eor(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 562     break;
 563   case 0xa9:
 564     cpu_6800_adc(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 565     break;
 566   case 0xaa:
 567     cpu_6800_ora(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 568     break;
 569   case 0xab:
 570     cpu_6800_add(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 571     break;
 572   case 0xac:
 573     cpu_6800_cmp_word(self, self->regs.word.x, cpu_6800_read_word(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 574     break;
 575   case 0xad:
 576     cpu_6800_jsr(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 577     break;
 578   case 0xae:
 579     cpu_6800_ld_word(self, CPU_6800_EA_S, cpu_6800_read_word(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 580     break;
 581   case 0xaf:
 582     cpu_6800_st_word(self, self->regs.word.s, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 583     break;
 584   case 0xb0:
 585     cpu_6800_sub(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 586     break;
 587   case 0xb1:
 588     cpu_6800_cmp_byte(self, self->regs.byte.a, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 589     break;
 590   case 0xb2:
 591     cpu_6800_sbc(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 592     break;
 593   case 0xb3:
 594     cpu_6800_illegal_opcode(self);
 595     break;
 596   case 0xb4:
 597     cpu_6800_and(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 598     break;
 599   case 0xb5:
 600     cpu_6800_bit(self, self->regs.byte.a, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 601     break;
 602   case 0xb6:
 603     cpu_6800_ld_byte(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 604     break;
 605   case 0xb7:
 606     cpu_6800_st_byte(self, self->regs.byte.a, cpu_6800_ea_extended(self));
 607     break;
 608   case 0xb8:
 609     cpu_6800_eor(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 610     break;
 611   case 0xb9:
 612     cpu_6800_adc(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 613     break;
 614   case 0xba:
 615     cpu_6800_ora(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 616     break;
 617   case 0xbb:
 618     cpu_6800_add(self, CPU_6800_EA_A, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 619     break;
 620   case 0xbc:
 621     cpu_6800_cmp_word(self, self->regs.word.x, cpu_6800_read_word(self, cpu_6800_ea_extended(self)));
 622     break;
 623   case 0xbd:
 624     cpu_6800_jsr(self, cpu_6800_ea_extended(self));
 625     break;
 626   case 0xbe:
 627     cpu_6800_ld_word(self, CPU_6800_EA_S, cpu_6800_read_word(self, cpu_6800_ea_extended(self)));
 628     break;
 629   case 0xbf:
 630     cpu_6800_st_word(self, self->regs.word.s, cpu_6800_ea_extended(self));
 631     break;
 632   case 0xc0:
 633     cpu_6800_sub(self, CPU_6800_EA_B, cpu_6800_fetch_byte(self));
 634     break;
 635   case 0xc1:
 636     cpu_6800_cmp_byte(self, self->regs.byte.b, cpu_6800_fetch_byte(self));
 637     break;
 638   case 0xc2:
 639     cpu_6800_sbc(self, CPU_6800_EA_B, cpu_6800_fetch_byte(self));
 640     break;
 641   case 0xc3:
 642     cpu_6800_illegal_opcode(self);
 643     break;
 644   case 0xc4:
 645     cpu_6800_and(self, CPU_6800_EA_B, cpu_6800_fetch_byte(self));
 646     break;
 647   case 0xc5:
 648     cpu_6800_bit(self, self->regs.byte.b, cpu_6800_fetch_byte(self));
 649     break;
 650   case 0xc6:
 651     cpu_6800_ld_byte(self, CPU_6800_EA_B, cpu_6800_fetch_byte(self));
 652     break;
 653   case 0xc7:
 654     cpu_6800_illegal_opcode(self);
 655     break;
 656   case 0xc8:
 657     cpu_6800_eor(self, CPU_6800_EA_B, cpu_6800_fetch_byte(self));
 658     break;
 659   case 0xc9:
 660     cpu_6800_adc(self, CPU_6800_EA_B, cpu_6800_fetch_byte(self));
 661     break;
 662   case 0xca:
 663     cpu_6800_ora(self, CPU_6800_EA_B, cpu_6800_fetch_byte(self));
 664     break;
 665   case 0xcb:
 666     cpu_6800_add(self, CPU_6800_EA_B, cpu_6800_fetch_byte(self));
 667     break;
 668   case 0xcc:
 669     cpu_6800_illegal_opcode(self);
 670     break;
 671   case 0xcd:
 672     cpu_6800_illegal_opcode(self);
 673     break;
 674   case 0xce:
 675     cpu_6800_ld_word(self, CPU_6800_EA_X, cpu_6800_fetch_word(self));
 676     break;
 677   case 0xcf:
 678     cpu_6800_illegal_opcode(self);
 679     break;
 680   case 0xd0:
 681     cpu_6800_sub(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 682     break;
 683   case 0xd1:
 684     cpu_6800_cmp_byte(self, self->regs.byte.b, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 685     break;
 686   case 0xd2:
 687     cpu_6800_sbc(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 688     break;
 689   case 0xd3:
 690     cpu_6800_illegal_opcode(self);
 691     break;
 692   case 0xd4:
 693     cpu_6800_and(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 694     break;
 695   case 0xd5:
 696     cpu_6800_bit(self, self->regs.byte.b, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 697     break;
 698   case 0xd6:
 699     cpu_6800_ld_byte(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 700     break;
 701   case 0xd7:
 702     cpu_6800_st_byte(self, self->regs.byte.b, cpu_6800_ea_direct(self));
 703     break;
 704   case 0xd8:
 705     cpu_6800_eor(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 706     break;
 707   case 0xd9:
 708     cpu_6800_adc(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 709     break;
 710   case 0xda:
 711     cpu_6800_ora(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 712     break;
 713   case 0xdb:
 714     cpu_6800_add(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct(self)));
 715     break;
 716   case 0xdc:
 717     cpu_6800_illegal_opcode(self);
 718     break;
 719   case 0xdd:
 720     cpu_6800_illegal_opcode(self);
 721     break;
 722   case 0xde:
 723     cpu_6800_ld_word(self, CPU_6800_EA_X, cpu_6800_read_word(self, cpu_6800_ea_direct(self)));
 724     break;
 725   case 0xdf:
 726     cpu_6800_st_word(self, self->regs.word.x, cpu_6800_ea_direct(self));
 727     break;
 728   case 0xe0:
 729     cpu_6800_sub(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 730     break;
 731   case 0xe1:
 732     cpu_6800_cmp_byte(self, self->regs.byte.b, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 733     break;
 734   case 0xe2:
 735     cpu_6800_sbc(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 736     break;
 737   case 0xe3:
 738     cpu_6800_illegal_opcode(self);
 739     break;
 740   case 0xe4:
 741     cpu_6800_and(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 742     break;
 743   case 0xe5:
 744     cpu_6800_bit(self, self->regs.byte.b, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 745     break;
 746   case 0xe6:
 747     cpu_6800_ld_byte(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 748     break;
 749   case 0xe7:
 750     cpu_6800_st_byte(self, self->regs.byte.b, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 751     break;
 752   case 0xe8:
 753     cpu_6800_eor(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 754     break;
 755   case 0xe9:
 756     cpu_6800_adc(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 757     break;
 758   case 0xea:
 759     cpu_6800_ora(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 760     break;
 761   case 0xeb:
 762     cpu_6800_add(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 763     break;
 764   case 0xec:
 765     cpu_6800_illegal_opcode(self);
 766     break;
 767   case 0xed:
 768     cpu_6800_illegal_opcode(self);
 769     break;
 770   case 0xee:
 771     cpu_6800_ld_word(self, CPU_6800_EA_X, cpu_6800_read_word(self, cpu_6800_ea_direct_indexed(self, self->regs.word.x)));
 772     break;
 773   case 0xef:
 774     cpu_6800_st_word(self, self->regs.word.x, cpu_6800_ea_direct_indexed(self, self->regs.word.x));
 775     break;
 776   case 0xf0:
 777     cpu_6800_sub(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 778     break;
 779   case 0xf1:
 780     cpu_6800_cmp_byte(self, self->regs.byte.b, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 781     break;
 782   case 0xf2:
 783     cpu_6800_sbc(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 784     break;
 785   case 0xf3:
 786     cpu_6800_illegal_opcode(self);
 787     break;
 788   case 0xf4:
 789     cpu_6800_and(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 790     break;
 791   case 0xf5:
 792     cpu_6800_bit(self, self->regs.byte.b, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 793     break;
 794   case 0xf6:
 795     cpu_6800_ld_byte(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 796     break;
 797   case 0xf7:
 798     cpu_6800_st_byte(self, self->regs.byte.b, cpu_6800_ea_extended(self));
 799     break;
 800   case 0xf8:
 801     cpu_6800_eor(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 802     break;
 803   case 0xf9:
 804     cpu_6800_adc(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 805     break;
 806   case 0xfa:
 807     cpu_6800_ora(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 808     break;
 809   case 0xfb:
 810     cpu_6800_add(self, CPU_6800_EA_B, cpu_6800_read_byte(self, cpu_6800_ea_extended(self)));
 811     break;
 812   case 0xfc:
 813     cpu_6800_illegal_opcode(self);
 814     break;
 815   case 0xfd:
 816     cpu_6800_illegal_opcode(self);
 817     break;
 818   case 0xfe:
 819     cpu_6800_ld_word(self, CPU_6800_EA_X, cpu_6800_read_word(self, cpu_6800_ea_extended(self)));
 820     break;
 821   case 0xff:
 822     cpu_6800_st_word(self, self->regs.word.x, cpu_6800_ea_extended(self));
 823     break;
 824   }
 825 }