segment.h

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#ifndef GRASS_SEGMENT_H
#define GRASS_SEGMENT_H
 
#include <grass/gis.h>
 
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
 
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
 
struct aq {                     /* age queue */
    int cur;                    /* segment number */
    struct aq *younger, *older; /* pointer to next younger and next older */
};
 
typedef struct SEGMENT {
    int open;      /* open flag */
    off_t nrows;   /* rows in original data */
    off_t ncols;   /* cols in original data */
    int len;       /* bytes per data value */
    int srows;     /* rows in segments */
    int scols;     /* cols in segments */
    int srowscols; /* rows x cols in segments */
    int size;      /* size in bytes of a segment */
    int spr;       /* segments per row */
    int spill;     /* cols in last segment in row */
 
    /* fast mode */
    int fast_adrs;  /* toggles fast address mode */
    off_t scolbits; /* column bitshift */
    off_t srowbits; /* row bitshift */
    off_t segbits;  /* segment bitshift */
    int fast_seek;  /* toggles fast seek mode */
    int lenbits;    /* data size bitshift */
    int sizebits;   /* segment size bitshift */
    int (*address)(const struct SEGMENT *, off_t, off_t, int *, int *);
    int (*seek)(const struct SEGMENT *S, int, int);
 
    char *fname; /* segment file name */
    int fd;      /* file descriptor to read/write segment */
    struct scb   /* control blocks */
    {
        char *buf;      /* data buffer */
        char dirty;     /* dirty flag */
        struct aq *age; /* pointer to position in age queue */
        int n;          /* segment number */
    } *scb;
    int *load_idx;       /* index of loaded segments */
    int nfreeslots;      /* number of free slots */
    int *freeslot;       /* array of free slots */
    struct aq *agequeue, /* queue of age for order of access */
        *youngest,       /* youngest in age queue */
        *oldest;         /* oldest in age queue */
    int nseg;            /* number of segments in memory */
    int cur;             /* last accessed segment */
    int offset;          /* offset of data past header */
 
    char *cache; /* all in memory cache */
} SEGMENT;
 
#include <grass/defs/segment.h>
 
#endif /* GRASS_SEGMENT_H */