FreeBSD/Linux Kernel Cross Reference
sys/fs/jffs2/compr.c

     /*
      * JFFS2 -- Journalling Flash File System, Version 2.
      *
      * Copyright (C) 2001 Red Hat, Inc.
      *
      * Created by Arjan van de Ven <arjanv@redhat.com>
      *
      * The original JFFS, from which the design for JFFS2 was derived,
      * was designed and implemented by Axis Communications AB.
     *
     * The contents of this file are subject to the Red Hat eCos Public
     * License Version 1.1 (the "Licence"); you may not use this file
     * except in compliance with the Licence.  You may obtain a copy of
     * the Licence at http://www.redhat.com/
     *
     * Software distributed under the Licence is distributed on an "AS IS"
     * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
     * See the Licence for the specific language governing rights and
     * limitations under the Licence.
     *
     * The Original Code is JFFS2 - Journalling Flash File System, version 2
     *
     * Alternatively, the contents of this file may be used under the
     * terms of the GNU General Public License version 2 (the "GPL"), in
     * which case the provisions of the GPL are applicable instead of the
     * above.  If you wish to allow the use of your version of this file
     * only under the terms of the GPL and not to allow others to use your
     * version of this file under the RHEPL, indicate your decision by
     * deleting the provisions above and replace them with the notice and
     * other provisions required by the GPL.  If you do not delete the
     * provisions above, a recipient may use your version of this file
     * under either the RHEPL or the GPL.
     *
     * $Id: compr.c,v 1.17 2001/09/23 09:56:46 dwmw2 Exp $
     *
     */
    
    #include <linux/kernel.h>
    #include <linux/string.h>
    #include <linux/types.h>
    #include <linux/errno.h>
    #include <linux/jffs2.h>
    
    int zlib_compress(unsigned char *data_in, unsigned char *cpage_out, __u32 *sourcelen, __u32 *dstlen);
    void zlib_decompress(unsigned char *data_in, unsigned char *cpage_out, __u32 srclen, __u32 destlen);
    int rtime_compress(unsigned char *data_in, unsigned char *cpage_out, __u32 *sourcelen, __u32 *dstlen);
    void rtime_decompress(unsigned char *data_in, unsigned char *cpage_out, __u32 srclen, __u32 destlen);
    int rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out, __u32 *sourcelen, __u32 *dstlen);
    void rubinmips_decompress(unsigned char *data_in, unsigned char *cpage_out, __u32 srclen, __u32 destlen);
    int dynrubin_compress(unsigned char *data_in, unsigned char *cpage_out, __u32 *sourcelen, __u32 *dstlen);
    void dynrubin_decompress(unsigned char *data_in, unsigned char *cpage_out, __u32 srclen, __u32 destlen);
    
    
    /* jffs2_compress:
     * @data: Pointer to uncompressed data
     * @cdata: Pointer to buffer for compressed data
     * @datalen: On entry, holds the amount of data available for compression.
     *      On exit, expected to hold the amount of data actually compressed.
     * @cdatalen: On entry, holds the amount of space available for compressed
     *      data. On exit, expected to hold the actual size of the compressed
     *      data.
     *
     * Returns: Byte to be stored with data indicating compression type used.
     * Zero is used to show that the data could not be compressed - the 
     * compressed version was actually larger than the original.
     *
     * If the cdata buffer isn't large enough to hold all the uncompressed data,
     * jffs2_compress should compress as much as will fit, and should set 
     * *datalen accordingly to show the amount of data which were compressed.
     */
    unsigned char jffs2_compress(unsigned char *data_in, unsigned char *cpage_out, 
                        __u32 *datalen, __u32 *cdatalen)
    {
            int ret;
    
            ret = zlib_compress(data_in, cpage_out, datalen, cdatalen);
            if (!ret) {
                    return JFFS2_COMPR_ZLIB;
            }
    #if 0 /* Disabled 23/9/1. With zlib it hardly ever gets a look in */
            ret = dynrubin_compress(data_in, cpage_out, datalen, cdatalen);
            if (!ret) {
                    return JFFS2_COMPR_DYNRUBIN;
            }
    #endif
    #if 0 /* Disabled 26/2/1. Obsoleted by dynrubin */
            ret = rubinmips_compress(data_in, cpage_out, datalen, cdatalen);
            if (!ret) {
                    return JFFS2_COMPR_RUBINMIPS;
            }
    #endif
            /* rtime does manage to recompress already-compressed data */
            ret = rtime_compress(data_in, cpage_out, datalen, cdatalen);
            if (!ret) {
                    return JFFS2_COMPR_RTIME;
            }
    #if 0
            /* We don't need to copy. Let the caller special-case the COMPR_NONE case. */
            /* If we get here, no compression is going to work */
           /* But we might want to use the fragmentation part -- Arjan */
           memcpy(cpage_out,data_in,min(*datalen,*cdatalen));
           if (*datalen > *cdatalen)
                   *datalen = *cdatalen;
   #endif          
           return JFFS2_COMPR_NONE; /* We failed to compress */
   
   }
   
   
   int jffs2_decompress(unsigned char comprtype, unsigned char *cdata_in, 
                        unsigned char *data_out, __u32 cdatalen, __u32 datalen)
   {
           switch (comprtype) {
           case JFFS2_COMPR_NONE:
                   /* This should be special-cased elsewhere, but we might as well deal with it */
                   memcpy(data_out, cdata_in, datalen);
                   break;
   
           case JFFS2_COMPR_ZERO:
                   memset(data_out, 0, datalen);
                   break;
   
           case JFFS2_COMPR_ZLIB:
                   zlib_decompress(cdata_in, data_out, cdatalen, datalen);
                   break;
   
           case JFFS2_COMPR_RTIME:
                   rtime_decompress(cdata_in, data_out, cdatalen, datalen);
                   break;
   
           case JFFS2_COMPR_RUBINMIPS:
   #if 0 /* Disabled 23/9/1 */
                   rubinmips_decompress(cdata_in, data_out, cdatalen, datalen);
   #else
                   printk(KERN_WARNING "JFFS2: Rubinmips compression encountered but support not compiled in!\n");
   #endif
                   break;
           case JFFS2_COMPR_DYNRUBIN:
   #if 1 /* Phase this one out */
                   dynrubin_decompress(cdata_in, data_out, cdatalen, datalen);
   #else
                   printk(KERN_WARNING "JFFS2: Dynrubin compression encountered but support not compiled in!\n");
   #endif
                   break;
   
           default:
                   printk(KERN_NOTICE "Unknown JFFS2 compression type 0x%02x\n", comprtype);
                   return -EIO;
           }
           return 0;
   }

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