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Predefined C Macros


   EXTEND.H sets up several "parameter check" macros that can be used
   for parameter checking.  The following is a table of manifest
   constants and macros:


   Table: Manifest constants in EXTEND.H
   -----------------------------------------------------------------
    Type              Returns
   -----------------------------------------------------------------

    undefined      =  UNDEF
    character      =  CHARACTER
    numeric        =  NUMERIC
    logical        =  LOGICAL
    date           =  DATE
    by reference   =  MPTR   /* or'ed with type when passed
                                by reference */
    memo           =  MEMO
    array          =  ARRAY
   -----------------------------------------------------------------


   Table: C Interface Macros in EXTEND.H
   -----------------------------------------------------------------
    Macro               Defined as
   -----------------------------------------------------------------

    PCOUNT              (_parinfo(0))
    ISCHAR(order)       (_parinfo(order) & CHARACTER)
    ISNUM(order)        (_parinfo(order) & NUMERIC)
    ISLOG(order)        (_parinfo(order) & LOGICAL)
    ISDATE(order)       (_parinfo(order) & DATE)
    ISMEMO(order)       (_parinfo(order) & MEMO)
    ISBYREF(order)      (_parinfo(order) & MPTR)
    ISARRAY(order)      (_parinfo(order) & ARRAY)
    ALENGTH(order)      (_parinfa(order, 0))
   -----------------------------------------------------------------

   Within the user-defined function, you can use the PCOUNT macro and
   any of the IS-type macros to determine how many parameters were
   passed and their type.  This enables you to validate parameters
   ensuring the correct number and type passed.  It additionally allows
   you to pass variable numbers of parameters of various types.


--------------------------- Source code -- EXTEND.H ------------------------

   /***
   *    extend.h
   *
   *    DEFINEs and EXTERNs for interfacing with Clipper from C.
   *
   *    Large model C only (double word pointers to code and data)
   *
   *    Copyright (c) Nantucket Corporation 1987
   */

   #define CLIPPER      void pascal

   /* _parinfo types */
   #define UNDEF        0
   #define CHARACTER    1
   #define NUMERIC      2
   #define LOGICAL      4
   #define DATE         8
   #define ALIAS        16
   #define MPTR         32    /* or'ed with type when passed by reference */
   #define MEMO         65
   #define WORD         128
   #define ARRAY        512


   /* parameter count/type */
   extern int _parinfo(int);
   extern int _parinfa(int, int);


   /* parameter values */
   extern char *_parc(int, ...);
   extern int _parcsiz(int, ...);
   extern int _parclen(int, ...);
   extern int _parni(int, ...);
   extern long _parnl(int, ...);
   extern double _parnd(int, ...);
   extern int _parl(int, ...);
   extern char *_pards(int, ...);


   /* one and only one of the _ret?? functions must used */

   /* Clipper-function return values */
   extern void _retc(char *);
   extern void _retclen(char *, int);
   extern void _retni(int);
   extern void _retnl(long);
   extern void _retnd(double);
   extern void _retl(int);
   extern void _retds(char *);

   /* procedure (DO) return */
   extern void _ret(void);


   /* allocate memory */
   /* parameter:  requested size in bytes */
   /* returns:  far pointer to memory or NULL */
   extern unsigned char *_exmgrab(unsigned);

   /* free allocated memory */
   /* parameters:  pointer from _exmgrab(), same size passed to _exmgrab() */
   extern void _exmback(unsigned char *, unsigned);


   /* misc. */
   extern unsigned strlen(unsigned char *);


   /* parameter check macros */
   #define PCOUNT       (_parinfo(0))
   #define ISCHAR(n)    (_parinfo(n) & CHARACTER)
   #define ISNUM(n)     (_parinfo(n) & NUMERIC)
   #define ISLOG(n)     (_parinfo(n) & LOGICAL)
   #define ISDATE(n)    (_parinfo(n) & DATE)
   #define ISMEMO(n)    (_parinfo(n) & MEMO)
   #define ISBYREF(n)   (_parinfo(n) & MPTR)
   #define ISARRAY(n)   (_parinfo(n) & ARRAY)
   #define ALENGTH(n)   (_parinfa(n, 0))

   /* Header structure */
   typedef struct
   {
    byte signature;     /* 03 = dbf, 83 dbf+dbt */
    byte ymd[3];        /* y+1900 m d */
    long last_rec;
    quant data_off;
    quant rec_size;
    byte pad[20];
   } DBF_HEADER;


   extern DBF_HEADER *_dbfhead();
   extern int _dbfopen();


--------------------------- Source code -- NANDEF.H ------------------------

   /***
   *    nandef.h
   *
   *    Nantucket defines
   */

   #define FALSE    0
   #define TRUE 1

   #define NIL      '\0'
   #define NULL 0L

   typedef unsigned char byte;
   typedef unsigned int quant;
   typedef int Boolean;