Free Hero Mesh

  $  Class
  @  Global variable
  '  Key code
  :  Label
  %  Local variable
  #  User message
  !  User sound
  &  User function

Comments are also allowed; these start with a semicolon (outside of a
string literal) and end at the next line break.


=== Escapes ===

(@<name> <value>)
  Define a global variable and its initial value.

(@<name> Array <rows> <columns>)
  Define a global variable whose value is a reference to a new array, with
  the specified dimensions. The maximum number of rows is 64, and the
  maximum number of columns is 1024, and the maximum number of cells in
  all arrays in total is 65534. All elements are initialized to zero when
  the level starts.

(<message> <code...>)
  Defines a default message code for all classes which do not specify
  their own code for this message.

(&<name> <code...>)
  Define a user-defined function. User-defined functions may take any
  number of inputs from the stack and leave any number of outputs on the
  stack, but may not access user-defined local variables. (It may still
  access standard local variables, and all global variables, though.)


=== Class definitions ===

Within a class definition, the following definitions can be used. See also
the section about variables; many of these definitions are used to specify
the initial value for variables of objects of this class.

Some instructions are block instructions; see the next section.

Many instructions are state-changing instructions; these instructions are
marked with ** in the summary line. Such instructions are not allowed to be
used on the same turn as the IgnoreKey instruction.

<label>
  Define a label. Labels are local to the current class. (Label names
  always start with a colon.)

=<label>
  Go to a label. (Put the colon after the equal sign; this instruction,
  and the one below, are using a double sigil.)

,<label>
  Call a label as a subroutine; when it returns, comes back to here.

<function>
  Call a user-defined function.

.  ( x -- )

+  ( in1 in2 -- out )
  Add two numbers together.

-  ( in1 in2 -- out )
  Subtract in2 from in1.

    case OP_DUP: StackReq(1,2); t1=Pop(); Push(t1); Push(t1); break;
    case OP_EQ: StackReq(2,1); t2=Pop(); t1=Pop(); Push(NVALUE(v_equal(t1,t2)?1:0)); break;
    case OP_FLUSHCLASS: NoIgnore(); StackReq(1,0); t1=Pop(); if(t1.t==TY_CLASS) flush_class(t1.u); else if(t1.t==TY_NUMBER && t1.s==-1) flush_all(); else if(t1.t) Throw("Type mismatch"); break;
    case OP_FLUSHOBJ: NoIgnore(); flush_object(obj); break;
    case OP_FLUSHOBJ_C: NoIgnore(); StackReq(1,0); i=v_object(Pop()); if(i!=VOIDLINK) flush_object(i); break;
    case OP_FOR: NoIgnore(); StackReq(3,1); t3=Pop(); t2=Pop(); t1=Pop(); ptr=v_for(code,ptr,t1,t2,t3); break;
    case OP_FROM: StackReq(0,1); Push(OVALUE(msgvars.from)); break;
    case OP_FUNCTION: execute_program(classes[0]->codes,functions[code[ptr++]],obj); break;
    case OP_GE: StackReq(2,1); t2=Pop(); t1=Pop(); Push(NVALUE(v_unsigned_greater(t2,t1)?0:1)); break;
    case OP_GE_C: StackReq(2,1); t2=Pop(); t1=Pop(); Push(NVALUE(v_signed_greater(t2,t1)?0:1)); break;
    case OP_GETARRAY: StackReq(3,1); t3=Pop(); Numeric(t3); t2=Pop(); Numeric(t2); t1=Pop(); Push(v_get_array(t1,t2.u,t3.u)); break;
    case OP_GETINVENTORY: StackReq(2,2); t2=Pop(); t1=Pop(); v_get_inventory(t1,t2); break;
    case OP_GOTO: ptr=code[ptr]; break;
    case OP_GT: StackReq(2,1); t2=Pop(); t1=Pop(); Push(NVALUE(v_unsigned_greater(t1,t2)?1:0)); break;
    case OP_GT_C: StackReq(2,1); t2=Pop(); t1=Pop(); Push(NVALUE(v_signed_greater(t1,t2)?1:0)); break;