(* ========================================================= *)
(* Preliminary library module for Gardens Point Modula       *)
(* ========================================================= *)

DEFINITION MODULE Types;

  (* this module supplies some traditional identifiers  *)
  (* subranges occupy as much storage space as needed   *)
  (* ************************************************** *)
  (* NOTE:  This is a definition icluding 64 bit        *)
  (*        representations on the DEC Alpha            *)
  (*        On 32 bit platforms (non Alpha) MIDINT and  *)
  (*        INTEGER map to 32 bits.                     *)
  (* ************************************************** *)
  

  (* Type Mapping Table
   * ==================
   *                                    Size
   *     Data Type         Alpha        Unix       PC
   *     ---------------+-----------+-----------+-----------+
   *     short int      |    16     |     16    |      8    |
   *     short unsigned |    16     |     16    |      8    |
   *                    |           |           |           |
   *     int            |    32     |     32    |     16    |
   *     unsigned int   |    32     |     32    |     16    |
   *                    |           |           |           |
   *     long int       |    64     |     32    |     32    |  
   *     unsigned long  |    64     |     32    |     32    |
   *     ---------------+-----------+-----------+-----------+
   *)

CONST
     maxInt32 = 2147483647;
     minInt32 = (-maxInt32 - 1); 
                (* avoids asymmetric nature of integers, and that an
                   explicit -2147483648 is out of range in 32 bits *)
     maxCrd32 = 4294967295;

TYPE 
    
(* INTEGER and CARDINAL Types *)

    (* Signed Types - Integers    *)    (* "c" type mapping      *)
    (* --------------------------------------------------------- *) 

    BYTEINT   = [-128 .. 127];		(* => signed char        *)
    SHORTINT  = [-32768 .. 32767];	(* => short int          *)
    MIDINT    = [minInt32 .. maxInt32]; (* => int                *)  
    LONGINT   = INTEGER;                (* => long int           *)

 
    (* Unsigned Types - Cardinals *)    (* "c" type mapping      *)
    (* --------------------------------------------------------- *)
 
    BYTECARD  = [0 .. 255];		(* => unsigned char      *)
    SHORTCARD = [0 .. 65535];		(* => short unsigned int *)
    MIDCARD   = [0 .. maxCrd32];        (* => unsigned int       *)
    LONGCARD  = CARDINAL;               (* => unsigned long int  *)

    (* Alternative Type Names    *)
    (* ----------------------    *)

    Int8   = BYTEINT;
    Card8  = BYTECARD;

    Int16  = SHORTINT;
    Card16 = SHORTCARD;

    Int32  = MIDINT;
    Card32 = MIDCARD;

END Types.