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c00c310eac
In particular, remove the bit in the LICENCE file about contacting Red Hat for alternative arrangements. Their errant IS department broke that arrangement a long time ago -- the policy of collecting copyright assignments from contributors came to an end when the plug was pulled on the servers hosting the project, without notice or reason. We do still dual-license it for use with eCos, with the GPL+exception licence approved by the FSF as being GPL-compatible. It's just that nobody has the right to license it differently. Signed-off-by: David Woodhouse <dwmw2@infradead.org>
132 lines
2.8 KiB
C
132 lines
2.8 KiB
C
/*
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* JFFS2 -- Journalling Flash File System, Version 2.
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*
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* Copyright © 2001-2007 Red Hat, Inc.
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*
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* Created by Arjan van de Ven <arjanv@redhat.com>
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*
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* For licensing information, see the file 'LICENCE' in this directory.
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*
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*
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*
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* Very simple lz77-ish encoder.
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*
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* Theory of operation: Both encoder and decoder have a list of "last
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* occurrences" for every possible source-value; after sending the
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* first source-byte, the second byte indicated the "run" length of
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* matches
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*
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* The algorithm is intended to only send "whole bytes", no bit-messing.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/jffs2.h>
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#include "compr.h"
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/* _compress returns the compressed size, -1 if bigger */
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static int jffs2_rtime_compress(unsigned char *data_in,
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unsigned char *cpage_out,
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uint32_t *sourcelen, uint32_t *dstlen,
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void *model)
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{
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short positions[256];
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int outpos = 0;
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int pos=0;
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memset(positions,0,sizeof(positions));
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while (pos < (*sourcelen) && outpos <= (*dstlen)-2) {
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int backpos, runlen=0;
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unsigned char value;
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value = data_in[pos];
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cpage_out[outpos++] = data_in[pos++];
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backpos = positions[value];
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positions[value]=pos;
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while ((backpos < pos) && (pos < (*sourcelen)) &&
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(data_in[pos]==data_in[backpos++]) && (runlen<255)) {
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pos++;
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runlen++;
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}
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cpage_out[outpos++] = runlen;
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}
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if (outpos >= pos) {
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/* We failed */
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return -1;
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}
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/* Tell the caller how much we managed to compress, and how much space it took */
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*sourcelen = pos;
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*dstlen = outpos;
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return 0;
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}
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static int jffs2_rtime_decompress(unsigned char *data_in,
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unsigned char *cpage_out,
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uint32_t srclen, uint32_t destlen,
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void *model)
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{
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short positions[256];
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int outpos = 0;
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int pos=0;
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memset(positions,0,sizeof(positions));
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while (outpos<destlen) {
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unsigned char value;
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int backoffs;
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int repeat;
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value = data_in[pos++];
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cpage_out[outpos++] = value; /* first the verbatim copied byte */
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repeat = data_in[pos++];
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backoffs = positions[value];
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positions[value]=outpos;
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if (repeat) {
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if (backoffs + repeat >= outpos) {
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while(repeat) {
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cpage_out[outpos++] = cpage_out[backoffs++];
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repeat--;
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}
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} else {
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memcpy(&cpage_out[outpos],&cpage_out[backoffs],repeat);
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outpos+=repeat;
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}
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}
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}
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return 0;
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}
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static struct jffs2_compressor jffs2_rtime_comp = {
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.priority = JFFS2_RTIME_PRIORITY,
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.name = "rtime",
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.compr = JFFS2_COMPR_RTIME,
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.compress = &jffs2_rtime_compress,
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.decompress = &jffs2_rtime_decompress,
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#ifdef JFFS2_RTIME_DISABLED
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.disabled = 1,
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#else
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.disabled = 0,
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#endif
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};
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int jffs2_rtime_init(void)
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{
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return jffs2_register_compressor(&jffs2_rtime_comp);
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}
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void jffs2_rtime_exit(void)
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{
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jffs2_unregister_compressor(&jffs2_rtime_comp);
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}
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