.. topic:: limitations

  This file contains a collection of non-configurable limits:

  .. enumerate:: Program properties

    maximum program length: 1 MB (1048575 Bytes)
      This is defined by FUNSTART_MASK in exec.h, which is the maximum offset
      (address) of a functions code within the program block (relativ to the
      beginning). Changing it involves changing funflag_t and probably other
      stuff.

    maximum number of programs: 2^32-1
      The unique program ID number is a int32. It is incremented for each compiled
      program. If it reaches zero (after wrapping to negative values) the
      compiler or swapper calls renumber_programs(), which recycles numbers from
      old programs.
      (exec.h, prolang.y, swap.c, ...)

    maximum number of functions in a program: 65534
      The lookup table for function indexes holding the offsets of the function in
      the functions tables is unsigned short.
      The types of function arguments are stored in program_s.argument_types,
      which is index by the unsigned short programs_s.type_start. 65535 has a
      special meaning. Some code relies that this is unsigned short.
      (exec.h, ...)
      program_s.num_function_names and num_functions are unsigned short as well.

    maximum length of switch: 256k (262143 Bytes)
      Limited by BREAK_ADDRESS_MASK and CONTINUE_ADDRESS_MASK?

    maximum offset for branches: 32765 (0x7ffd)
      (prolang.y)

    number of virtual variables: 255
    number of global variables: 65536 (F_IDENTIFIER16)
    number of local variables: 256 (F_PUSH_LOCAL_VARIABLE_LVALUE)
    number of context variables: 256 (Should be consistent with local
      variables, MAX_LOCAL applies to both. 16 bit opcodes are not used yet.)

    max number of struct members: 255
      (exec.h, ...)

    max number of structs per program: usually 32767 (short)
      temporary text to keep this from stacking on below header


  .. enumerate:: Hash tables

    maximum size of the hash table for identifiers (ITABLE): 32768
      The hashes of identifiers are signed short which are in most cases 16 bit
      wide integers (lex.h, lex.c, ...)

    maximum size of the hash table for objects (OTABLE): 65536
    maximum size of the hash table for shared strings (HTABLE): 65536
      The hashes are of type unsigned short which are in most cases 16 bit
      wide integers.


  .. enumerate:: Objects

    maximum clone ID number: 2^32-1
      Not a real limitation, after that the driver starts checking if
      blueprint name + #cloneid are unique.


  .. enumerate:: Memory management

    max. size of single large block in slaballo.c and smalloc.c:
      0x07ffffff (134217727, defined by M_MASK)


  .. enumerate:: Language

    maximum number of simul-efuns: 2048
      Only values 0xf800-0xffff in .x.closure_type of
      a T_CLOSURE svalue are reserved for simul-efuns.
      F_SIMUL_EFUN however takes a short int, so there 65536
      simul-efuns would be possible.