decoder.c

linux下的MPEG1

      break;
    case 6: /*  Set system reg 8 (Highlighted button) */
      data = eval_reg_or_data(command, vm_getbits(command, 60, 1), 31); /*  Not system reg!! */
      if(cond) {
	command->registers->SPRM[8] = data;
      }
      break;
  }
  if(vm_getbits(command, 51, 4)) {
    return eval_link_instruction(command, cond, return_values);
  }
  return 0;
}


/* Evaluate set operation
   Sets the register given to the value indicated by op and data.
   For the swap case the contents of reg is stored in reg2.
*/
static void eval_set_op(command_t* command, int32_t op, int32_t reg, int32_t reg2, int32_t data) {
  const int32_t shortmax = 0xffff;
  int32_t     tmp; 
  switch(op) {
    case 1:
      set_GPRM(command->registers, reg, data);
      break;
    case 2: /* SPECIAL CASE - SWAP! */
      set_GPRM(command->registers, reg2, get_GPRM(command->registers, reg));
      set_GPRM(command->registers, reg, data);
      break;
    case 3:
      tmp = get_GPRM(command->registers, reg) + data;
      if(tmp > shortmax) tmp = shortmax;
      set_GPRM(command->registers, reg, (uint16_t)tmp);
      break;
    case 4:
      tmp = get_GPRM(command->registers, reg) - data;
      if(tmp < 0) tmp = 0;
      set_GPRM(command->registers, reg, (uint16_t)tmp);
      break;
    case 5:
      tmp = get_GPRM(command->registers, reg) * data;
      if(tmp > shortmax) tmp = shortmax;
      set_GPRM(command->registers, reg, (uint16_t)tmp);
      break;
    case 6:
      if (data != 0) {
        set_GPRM(command->registers, reg, (get_GPRM(command->registers, reg) / data) );
      } else {
        set_GPRM(command->registers, reg, 0xffff); /* Avoid that divide by zero! */
      }
      break;
    case 7:
      if (data != 0) {
        set_GPRM(command->registers, reg, (get_GPRM(command->registers, reg) % data) );
      } else {
        set_GPRM(command->registers, reg, 0xffff); /* Avoid that divide by zero! */
      }
      break;
    case 8: /* SPECIAL CASE - RND! Return numbers between 1 and data. */
      set_GPRM(command->registers, reg, 1 + ((uint16_t) ((float) data * rand()/(RAND_MAX+1.0))) );
      break;
    case 9:
      set_GPRM(command->registers, reg, (get_GPRM(command->registers, reg) & data) );
      break;
    case 10:
      set_GPRM(command->registers, reg, (get_GPRM(command->registers, reg) | data) );
      break;
    case 11:
      set_GPRM(command->registers, reg, (get_GPRM(command->registers, reg) ^ data) );
      break;
  }
}

/* Evaluate set instruction, combined with either Link or Compare. */
static void eval_set_version_1(command_t* command, int32_t cond) {
  uint8_t  op   = vm_getbits(command, 59, 4);
  uint8_t  reg  = vm_getbits(command, 35, 4); /* FIXME: This is different from vmcmd.c!!! */
  uint8_t  reg2 = vm_getbits(command, 19, 4);
  uint16_t data = eval_reg_or_data(command, vm_getbits(command, 60, 1), 31);

  if(cond) {
    eval_set_op(command, op, reg, reg2, data);
  }
}


/* Evaluate set instruction, combined with both Link and Compare. */
static void eval_set_version_2(command_t* command, int32_t cond) {
  uint8_t  op   = vm_getbits(command, 59, 4);
  uint8_t  reg  = vm_getbits(command, 51, 4);
  uint8_t  reg2 = vm_getbits(command, 35, 4); /* FIXME: This is different from vmcmd.c!!! */
  uint16_t data = eval_reg_or_data(command, vm_getbits(command, 60, 1), 47);

  if(cond) {
    eval_set_op(command, op, reg, reg2, data);
  }
}


/* Evaluate a command
   returns row number of goto, 0 if no goto, -1 if link.
   Link command in return_values */
static int32_t eval_command(uint8_t *bytes, registers_t* registers, link_t *return_values) {
  int32_t cond, res = 0;
  command_t command;
  command.instruction =( (uint64_t) bytes[0] << 56 ) |
        ( (uint64_t) bytes[1] << 48 ) |
        ( (uint64_t) bytes[2] << 40 ) |
        ( (uint64_t) bytes[3] << 32 ) |
        ( (uint64_t) bytes[4] << 24 ) |
        ( (uint64_t) bytes[5] << 16 ) |
        ( (uint64_t) bytes[6] <<  8 ) |
          (uint64_t) bytes[7] ;
  command.examined = 0;
  command.registers = registers;
  memset(return_values, 0, sizeof(link_t));

  switch(vm_getbits(&command, 63, 3)) { /* three first old_bits */
    case 0: /*  Special instructions */
      cond = eval_if_version_1(&command);
      res = eval_special_instruction(&command, cond);
      if(res == -1) {
	fprintf(MSG_OUT, "libdvdnav: Unknown Instruction!\n");
	abort();
      }
      break;
    case 1: /*  Link/jump instructions */
      if(vm_getbits(&command, 60, 1)) {
        cond = eval_if_version_2(&command);
        res = eval_jump_instruction(&command, cond, return_values);
      } else {
        cond = eval_if_version_1(&command);
        res = eval_link_instruction(&command, cond, return_values);
      }
      if(res)
	res = -1;
      break;
    case 2: /*  System set instructions */
      cond = eval_if_version_2(&command);
      res = eval_system_set(&command, cond, return_values);
      if(res)
	res = -1;
      break;
    case 3: /*  Set instructions, either Compare or Link may be used */
      cond = eval_if_version_3(&command);
      eval_set_version_1(&command, cond);
      if(vm_getbits(&command, 51, 4)) {
	res = eval_link_instruction(&command, cond, return_values);
      }
      if(res)
	res = -1;
      break;
    case 4: /*  Set, Compare -> Link Sub-Instruction */
      eval_set_version_2(&command, /*True*/ 1);
      cond = eval_if_version_4(&command);
      res = eval_link_subins(&command, cond, return_values);
      if(res)
	res = -1;
      break;
    case 5: /*  Compare -> (Set and Link Sub-Instruction) */
      /* FIXME: These are wrong. Need to be updated from vmcmd.c */
      cond = eval_if_version_4(&command);
      eval_set_version_2(&command, cond);
      res = eval_link_subins(&command, cond, return_values);
      if(res)
	res = -1;
      break;
    case 6: /*  Compare -> Set, allways Link Sub-Instruction */
      /* FIXME: These are wrong. Need to be updated from vmcmd.c */
      cond = eval_if_version_4(&command);
      eval_set_version_2(&command, cond);
      res = eval_link_subins(&command, /*True*/ 1, return_values);
      if(res)
	res = -1;
      break;
    default: /* Unknown command */
      fprintf(MSG_OUT, "libdvdnav: WARNING: Unknown Command=%x\n", vm_getbits(&command, 63, 3));
      abort();
  }
  /*  Check if there are bits not yet examined */

  if(command.instruction & ~ command.examined) {
    fprintf(MSG_OUT, "libdvdnav: decoder.c: [WARNING, unknown bits:");
    fprintf(MSG_OUT, " %08llx", (command.instruction & ~ command.examined) );
    fprintf(MSG_OUT, "]\n");
  }

  return res;
}

/* Evaluate a set of commands in the given register set (which is modified) */
int32_t vmEval_CMD(vm_cmd_t commands[], int32_t num_commands, 
	       registers_t *registers, link_t *return_values) {
  int32_t i = 0;
  int32_t total = 0;
  
#ifdef TRACE
  /*  DEBUG */
  fprintf(MSG_OUT, "libdvdnav: Registers before transaction\n");
  vm_print_registers( registers );
  fprintf(MSG_OUT, "libdvdnav: Full list of commands to execute\n");
  for(i = 0; i < num_commands; i++)
    vm_print_cmd(i, &commands[i]);
  fprintf(MSG_OUT, "libdvdnav: --------------------------------------------\n");
  fprintf(MSG_OUT, "libdvdnav: Single stepping commands\n");
#endif

  i = 0; 
  while(i < num_commands && total < 100000) {
    int32_t line;
    
#ifdef TRACE
    vm_print_cmd(i, &commands[i]);
#endif

    line = eval_command(&commands[i].bytes[0], registers, return_values);
    
    if (line < 0) { /*  Link command */
#ifdef TRACE
      fprintf(MSG_OUT, "libdvdnav: Registers after transaction\n");
      vm_print_registers( registers );
      fprintf(MSG_OUT, "libdvdnav: eval: Doing Link/Jump/Call\n"); 
#endif
      return 1;
    }
    
    if (line > 0) /*  Goto command */
      i = line - 1;
    else /*  Just continue on the next line */
      i++;

    total++;
  }
  
  memset(return_values, 0, sizeof(link_t));
#ifdef TRACE
  fprintf(MSG_OUT, "libdvdnav: Registers after transaction\n");
  vm_print_registers( registers );
#endif
  return 0;
}

#ifdef TRACE

static char *linkcmd2str(link_cmd_t cmd) {
  switch(cmd) {
  case LinkNoLink:
    return "LinkNoLink";
  case LinkTopC:
    return "LinkTopC";
  case LinkNextC:
    return "LinkNextC";
  case LinkPrevC:
    return "LinkPrevC";
  case LinkTopPG:
    return "LinkTopPG";
  case LinkNextPG:
    return "LinkNextPG";
  case LinkPrevPG:
    return "LinkPrevPG";
  case LinkTopPGC:
    return "LinkTopPGC";
  case LinkNextPGC:
    return "LinkNextPGC";
  case LinkPrevPGC:
    return "LinkPrevPGC";
  case LinkGoUpPGC:
    return "LinkGoUpPGC";
  case LinkTailPGC:
    return "LinkTailPGC";
  case LinkRSM:
    return "LinkRSM";
  case LinkPGCN:
    return "LinkPGCN";
  case LinkPTTN:
    return "LinkPTTN";
  case LinkPGN:
    return "LinkPGN";
  case LinkCN:
    return "LinkCN";
  case Exit:
    return "Exit";
  case JumpTT:
    return "JumpTT";
  case JumpVTS_TT:
    return "JumpVTS_TT";
  case JumpVTS_PTT:
    return "JumpVTS_PTT";
  case JumpSS_FP:
    return "JumpSS_FP";
  case JumpSS_VMGM_MENU:
    return "JumpSS_VMGM_MENU";
  case JumpSS_VTSM:
    return "JumpSS_VTSM";
  case JumpSS_VMGM_PGC:
    return "JumpSS_VMGM_PGC";
  case CallSS_FP:
    return "CallSS_FP";
  case CallSS_VMGM_MENU:
    return "CallSS_VMGM_MENU";
  case CallSS_VTSM:
    return "CallSS_VTSM";
  case CallSS_VMGM_PGC:
    return "CallSS_VMGM_PGC";
  case PlayThis:
    return "PlayThis";
  }
  return "*** (bug)";
}

void vm_print_link(link_t value) {
  char *cmd = linkcmd2str(value.command);
    
  switch(value.command) {
  case LinkNoLink:
  case LinkTopC:
  case LinkNextC:
  case LinkPrevC:
  case LinkTopPG:
  case LinkNextPG:
  case LinkPrevPG:
  case LinkTopPGC:
  case LinkNextPGC:
  case LinkPrevPGC:
  case LinkGoUpPGC:
  case LinkTailPGC:
  case LinkRSM:
    fprintf(MSG_OUT, "libdvdnav: %s (button %d)\n", cmd, value.data1);
    break;
  case LinkPGCN:
  case JumpTT:
  case JumpVTS_TT:
  case JumpSS_VMGM_MENU: /*  == 2 -> Title Menu */
  case JumpSS_VMGM_PGC:
    fprintf(MSG_OUT, "libdvdnav: %s %d\n", cmd, value.data1);
    break;
  case LinkPTTN:
  case LinkPGN:
  case LinkCN:
    fprintf(MSG_OUT, "libdvdnav: %s %d (button %d)\n", cmd, value.data1, value.data2);
    break;
  case Exit:
  case JumpSS_FP:
  case PlayThis: /*  Humm.. should we have this at all.. */
    fprintf(MSG_OUT, "libdvdnav: %s\n", cmd);
    break;
  case JumpVTS_PTT:
    fprintf(MSG_OUT, "libdvdnav: %s %d:%d\n", cmd, value.data1, value.data2);
    break;
  case JumpSS_VTSM:
    fprintf(MSG_OUT, "libdvdnav: %s vts %d title %d menu %d\n", 
	    cmd, value.data1, value.data2, value.data3);
    break;
  case CallSS_FP:
    fprintf(MSG_OUT, "libdvdnav: %s resume cell %d\n", cmd, value.data1);
    break;
  case CallSS_VMGM_MENU: /*  == 2 -> Title Menu */
  case CallSS_VTSM:
    fprintf(MSG_OUT, "libdvdnav: %s %d resume cell %d\n", cmd, value.data1, value.data2);
    break;
  case CallSS_VMGM_PGC:
    fprintf(MSG_OUT, "libdvdnav: %s %d resume cell %d\n", cmd, value.data1, value.data2);
    break;
  }
 }

void vm_print_registers( registers_t *registers ) {
  int32_t i;
  fprintf(MSG_OUT, "libdvdnav:    #   ");
  for(i = 0; i < 24; i++)
    fprintf(MSG_OUT, " %2d |", i);
  fprintf(MSG_OUT, "\nlibdvdnav: SRPMS: ");
  for(i = 0; i < 24; i++)
    fprintf(MSG_OUT, "%04x|", registers->SPRM[i]);
  fprintf(MSG_OUT, "\nlibdvdnav: GRPMS: ");
  for(i = 0; i < 16; i++)
    fprintf(MSG_OUT, "%04x|", get_GPRM(registers, i) );
  fprintf(MSG_OUT, "\nlibdvdnav: Gmode: ");
  for(i = 0; i < 16; i++)
    fprintf(MSG_OUT, "%04x|", registers->GPRM_mode[i]);
  fprintf(MSG_OUT, "\nlibdvdnav: Gtime: ");
  for(i = 0; i < 16; i++)
    fprintf(MSG_OUT, "%04lx|", registers->GPRM_time[i].tv_sec & 0xffff);
  fprintf(MSG_OUT, "\n");
}

#endif