File: sum_p.h

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/*				       	-*- c-file-style: "bsd" -*-
 * rproxy -- dynamic caching and delta update in HTTP
 * $Id: sum_p.h,v 1.3 2000/08/06 12:50:36 mbp Exp $
 * 
 * Copyright (C) 1999, 2000 by Martin Pool <mbp@humbug.org.au>
 * Copyright (C) 1999 by Andrew Tridgell
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */


typedef unsigned short tag;

struct target {
    tag             t;
    int             i;
};


/* TODO: Include length of strong checksums in case it varies between
 * files. */

typedef struct hs_sum_buf hs_sum_buf_t;

/*
 * This structure describes all the sums generated for an instance of
 * a file.  It incorporates some redundancy to make it easier to
 * search.
 */
struct hs_sumset {
    off_t        flength;	/* total file length */
    int             count;	/* how many chunks */
    int             remainder;	/* flength % block_length */
    int             block_len;	/* block_length */
    hs_sum_buf_t   *block_sums; /* points to info for each chunk */
    int            *tag_table;
    struct target  *targets;
};


/*
 * All blocks are the same length in the current algorithm except for
 * the last block which may be short.
 */
struct hs_sum_buf {
    int             i;		/* index of this chunk */
    hs_weak_sum_t   weak_sum;	/* simple checksum */
    hs_strong_sum_t strong_sum;	/* checksum  */
};