root/ext/dbase/dbf_ndx.h

INCLUDED FROM

/*
 * Copyright (c) 1993 Brad Eacker,
 *              (Music, Intuition, Software, and Computers)
 * All Rights Reserved
 */

/*
 * dbf .ndx header structure on disk and in memory
 *
 *  Basic info taken from:
 *      "Clipper Programming Guide, 3rd Edition, Version 5.01"
 *      by Rick Spence
 */

#ifndef DBF_NDX_H_
#define  DBF_NDX_H_

#include "dbf.h"

#define NDX_PAGE_SZ     512

/* on disk ndx header */
struct dndx_header {
        char    dndx_st_pg[4];          /* starting page number */
        char    dndx_tot_pg[4];         /* total number of pages */
        char    dndx_filler1[4];        /* space */
        char    dndx_key_len[2];        /* key length */
        char    dndx_keys_ppg[2];       /* number of keys per page */
        char    dndx_key_type[2];       /* key type */
        char    dndx_size_key[4];       /* size of the key record */
        char    dndx_filler2;           /* space */
        char    dndx_unique;            /* whether or not done with unique */
        char    dndx_key_name[488];     /* string defining the key */
};
typedef struct dndx_header dndx_header_t;

/* in memory ndx header */
struct ndx_header {
        long    ndx_start_pg;
        long    ndx_total_pgs;
        unsigned short  ndx_key_len;
        unsigned short  ndx_keys_ppg;
        unsigned short  ndx_key_type;
        char    ndx_unique;
        long    ndx_key_size;
        char    *ndx_key_name;
        int     ndx_fd;
        struct ndx_page *ndx_fp;
        dndx_header_t *ndx_hpage;
        struct ndx_record *ndx_cur_rec;
};
typedef struct ndx_header ndx_header_t;

/* these are the possible values in the key type field */
#define NDX_CHAR_TYPE   00
#define NDX_NUM_TYPE    01

/* on disk key record */
struct dndx_record {
        char    dndx_left_pg[4];        /* number of left page */
        char    dndx_dbf_rec[4];        /* dbf record number */
        char    dndx_key_data;          /* key data */
};
typedef struct dndx_record dndx_record_t;

struct ndx_record {
        long    ndxr_left;
        long    ndxr_rec;
        char    *ndxr_key_data;
        struct ndx_page *ndxr_page;     /* page pointer to where we are from*/
        int     ndxr_p_nrec;            /* number of the record within page */
};
typedef struct ndx_record ndx_record_t;

struct dndx_page {
        char    dndxp_num_keys[4];      /* number of keys on this page */
        struct dndx_record dndx_rp;
};
typedef struct dndx_page dndx_page_t;

struct ndx_page {
        long            ndxp_page_no;
        long            ndxp_num_keys;
        dndx_page_t     *ndxp_page_data;
        ndx_header_t    *ndxp_header_p;
        long            ndxp_last_key;
        struct ndx_page *ndxp_parent;   /* parent page */
        int             ndxp_par_rno;   /* record number within parent */
        struct ndx_record *ndxp_records;
};
typedef struct ndx_page ndx_page_t;

extern ndx_header_t *ndx_get_header(int);

extern ndx_record_t *ndx_get_first_rec(ndx_header_t *);
extern ndx_record_t *ndx_get_next_rec(ndx_header_t *, ndx_record_t *);

#endif /* DBF_NDX_H_ */