Free Hero Mesh

    case OP_OBJBOTTOMAT:
      n=obj_bottom_at(x,y);
      break;
    case OP_OBJTOPAT:
      n=obj_top_at(x,y);
      break;
    case OP_RET:
      if(all) {
        if(vstackptr>=VSTACKSIZE-1) Throw("Stack overflow");
        if(n==VOIDLINK) n=obj_bottom_at(x,y);
        Push(OVALUE(n));
        goto fail;
      } else {
        return n==VOIDLINK?obj_bottom_at(x,y):n;
      }
      break;
    case OP_SUB:
      if(vstackptr>=VSTACKSIZE-1) Throw("Stack overflow");
      Push(NVALUE(0));
      break;
    case OP_THEN:
      // This opcode does nothing
      break;
    case OP_TRACE:
      if(main_options['t']) {
        printf("ptr=%d cpi=%d x=%d y=%d dir=%d obj=%lu ",ptr,cpi,x,y,d,(long)n);
        printf("[ptr=%d x=%d y=%d dir=%d]\n",cp[cpi].ptr,cp[cpi].x,cp[cpi].y,cp[cpi].dir);
      }
      break;
    default: Throw("Unimplemented opcode in pattern");
  }
  goto again;
  fail:
  if(!all) {
    if(vstackptr<cp->depth) Throw("Stack underflow in pattern matching");
    vstackptr=cp[cpi].depth;
  }
  if(!cpi) return VOIDLINK;
  x=cp[cpi].x;
  y=cp[cpi].y;
  d=cp[cpi].dir;
  ptr=cp[cpi].ptr;
  n=VOIDLINK;
  cpi--;
  goto again;
}

static Uint32 v_pattern_anywhere(Uint16*code,int ptr,char all) {
  int i;
  Uint32 n;
  for(i=0;i<pfheight*64;i++) {
    n=playfield[i];
    if(n!=VOIDLINK) {
      n=v_pattern(code,ptr,n,all);
      if(n!=VOIDLINK && !all) return n;
    }
  }
  return VOIDLINK;
}

// Here is where the execution of a Free Hero Mesh bytecode subroutine is executed.
#define NoIgnore() do{ changed=1; }while(0)
#define GetVariableOf(a,b) (i=v_object(Pop()),i==VOIDLINK?NVALUE(0):b(objects[i]->a))
#define GetVariableOrAttributeOf(a,b) (t2=Pop(),t2.t==TY_CLASS?NVALUE(classes[t2.u]->a):(i=v_object(t2),i==VOIDLINK?NVALUE(0):b(objects[i]->a)))
#define Numeric(a) do{ if((a).t!=TY_NUMBER) Throw("Type mismatch"); }while(0)
#define DivideBy(a) do{ Numeric(a); if(!(a).u) Throw("Division by zero"); }while(0)

    case OP_OBJDIR_C: StackReq(2,1); t2=Pop(); Numeric(t2); i=obj_dir(v_object(Pop()),t2.u); Push(OVALUE(i)); break;
    case OP_OBJLAYERAT: StackReq(3,1); t3=Pop(); Numeric(t3); t2=Pop(); Numeric(t2); t1=Pop(); Numeric(t1); i=obj_layer_at(t1.u,t2.u,t3.u); Push(OVALUE(i)); break;
    case OP_OBJMOVINGTO: StackReq(2,0); t2=Pop(); Numeric(t2); t1=Pop(); Numeric(t1); v_obj_moving_to(t1.u,t2.u); break;
    case OP_OBJTOPAT: StackReq(2,1); t2=Pop(); Numeric(t2); t1=Pop(); Numeric(t1); i=obj_top_at(t1.u,t2.u); Push(OVALUE(i)); break;
    case OP_OVER: StackReq(2,3); t2=Pop(); t1=Pop(); Push(t1); Push(t2); Push(t1); break;
    case OP_PATTERN: StackReq(0,1); i=code[ptr++]; j=v_pattern(code,ptr,obj,0); ptr=i; Push(OVALUE(j)); break;
    case OP_PATTERN_C: StackReq(1,1); i=code[ptr++]; j=v_object(Pop()); if(j!=VOIDLINK) j=v_pattern(code,ptr,j,0); ptr=i; Push(OVALUE(j)); break;
    case OP_PATTERN_E: StackReq(0,1); i=code[ptr++]; j=v_pattern_anywhere(code,ptr,0); ptr=i; Push(OVALUE(j)); break;
    case OP_PATTERNS: StackReq(0,1); i=code[ptr++]; v_pattern(code,ptr,obj,1); ptr=i; break;
    case OP_PATTERNS_C: StackReq(1,1); i=code[ptr++]; j=v_object(Pop()); if(j!=VOIDLINK) v_pattern(code,ptr,j,1); ptr=i; break;
    case OP_PATTERNS_E: StackReq(0,1); i=code[ptr++]; v_pattern_anywhere(code,ptr,1); ptr=i; break;
    case OP_PICK: StackReq(0,1); t1=Pop(); Numeric(t1); if(t1.u>=vstackptr) Throw("Stack index out of range"); t1=vstack[vstackptr-t1.u-1]; Push(t1); break;
    case OP_PLAYER: StackReq(0,1); if(classes[o->class]->cflags&CF_PLAYER) Push(NVALUE(1)); else Push(NVALUE(0)); break;
    case OP_PLAYER_C: StackReq(1,1); GetClassFlagOf(CF_PLAYER); break;
    case OP_PLUSMOVE: StackReq(1,1); t1=Pop(); Numeric(t1); i=defer_move(obj,t1.u,1); Push(NVALUE(i)); break;
    case OP_PLUSMOVE_C: StackReq(2,1); t1=Pop(); Numeric(t1); i=v_object(Pop()); i=defer_move(i,t1.u,1); Push(NVALUE(i)); break;
    case OP_PLUSMOVE_D: StackReq(1,0); t1=Pop(); Numeric(t1); defer_move(obj,t1.u,1); break;
    case OP_PLUSMOVE_CD: StackReq(2,1); t1=Pop(); Numeric(t1); i=v_object(Pop()); defer_move(i,t1.u,1); break;