ext/sdbm/sdbm.h

   1 /*
   2  * sdbm - ndbm work-alike hashed database library
   3  * based on Per-Ake Larson's Dynamic Hashing algorithms. BIT 18 (1978).
   4  * author: oz@nexus.yorku.ca
   5  * status: public domain.
   6  */
   7 #ifndef _SDBM_H_
   8 #define _SDBM_H_
   9
  10 #define DBLKSIZ 4096
  11 #define PBLKSIZ 1024
  12 #define PAIRMAX 1008                    /* arbitrary on PBLKSIZ-N */
  13 #define SPLTMAX 10                      /* maximum allowed splits */
  14                                         /* for a single insertion */
  15 #define DIRFEXT ".dir"
  16 #define PAGFEXT ".pag"
  17
  18 typedef struct {
  19         int dirf;                      /* directory file descriptor */
  20         int pagf;                      /* page file descriptor */
  21         int flags;                     /* status/error flags, see below */
  22         long maxbno;                   /* size of dirfile in bits */
  23         long curbit;                   /* current bit number */
  24         long hmask;                    /* current hash mask */
  25         long blkptr;                   /* current block for nextkey */
  26         int keyptr;                    /* current key for nextkey */
  27         long blkno;                    /* current page to read/write */
  28         long pagbno;                   /* current page in pagbuf */
  29         char pagbuf[PBLKSIZ];          /* page file block buffer */
  30         long dirbno;                   /* current block in dirbuf */
  31         char dirbuf[DBLKSIZ];          /* directory file block buffer */
  32 } DBM;
  33
  34 #define DBM_RDONLY      0x1            /* data base open read-only */
  35 #define DBM_IOERR       0x2            /* data base I/O error */
  36
  37 /*
  38  * utility macros
  39  */
  40 #define sdbm_rdonly(db)         ((db)->flags & DBM_RDONLY)
  41 #define sdbm_error(db)          ((db)->flags & DBM_IOERR)
  42
  43 #define sdbm_clearerr(db)       ((db)->flags &= ~DBM_IOERR)  /* ouch */
  44
  45 #define sdbm_dirfno(db) ((db)->dirf)
  46 #define sdbm_pagfno(db) ((db)->pagf)
  47
  48 typedef struct {
  49         char *dptr;
  50         int dsize;
  51 } datum;
  52
  53 extern datum nullitem;
  54
  55 #if defined(__STDC__) || defined(MSDOS)
  56 #define proto(p) p
  57 #else
  58 #define proto(p) ()
  59 #endif
  60
  61 /*
  62  * flags to sdbm_store
  63  */
  64 #define DBM_INSERT      0
  65 #define DBM_REPLACE     1
  66
  67 /*
  68  * ndbm interface
  69  */
  70 extern DBM *sdbm_open proto((char *, int, int));
  71 extern void sdbm_close proto((DBM *));
  72 extern datum sdbm_fetch proto((DBM *, datum));
  73 extern int sdbm_delete proto((DBM *, datum));
  74 extern int sdbm_store proto((DBM *, datum, datum, int));
  75 extern datum sdbm_firstkey proto((DBM *));
  76 extern datum sdbm_nextkey proto((DBM *));
  77
  78 /*
  79  * other
  80  */
  81 extern DBM *sdbm_prep proto((char *, char *, int, int));
  82 extern long sdbm_hash proto((char *, int));
  83
  84 #endif  /* _SDBM_H_ */