mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-21 11:44:01 +08:00
088bd455c9
The jffs2 compression framework provides a "model" argument when compressing and decompressing, but the caller always passes in NULL and the callees never use it. So punt this useless overhead. Signed-off-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
131 lines
2.8 KiB
C
131 lines
2.8 KiB
C
/*
|
|
* JFFS2 -- Journalling Flash File System, Version 2.
|
|
*
|
|
* Copyright © 2001-2007 Red Hat, Inc.
|
|
* Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
|
|
*
|
|
* Created by Arjan van de Ven <arjanv@redhat.com>
|
|
*
|
|
* For licensing information, see the file 'LICENCE' in this directory.
|
|
*
|
|
*
|
|
*
|
|
* Very simple lz77-ish encoder.
|
|
*
|
|
* Theory of operation: Both encoder and decoder have a list of "last
|
|
* occurrences" for every possible source-value; after sending the
|
|
* first source-byte, the second byte indicated the "run" length of
|
|
* matches
|
|
*
|
|
* The algorithm is intended to only send "whole bytes", no bit-messing.
|
|
*
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/types.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/string.h>
|
|
#include <linux/jffs2.h>
|
|
#include "compr.h"
|
|
|
|
/* _compress returns the compressed size, -1 if bigger */
|
|
static int jffs2_rtime_compress(unsigned char *data_in,
|
|
unsigned char *cpage_out,
|
|
uint32_t *sourcelen, uint32_t *dstlen)
|
|
{
|
|
short positions[256];
|
|
int outpos = 0;
|
|
int pos=0;
|
|
|
|
memset(positions,0,sizeof(positions));
|
|
|
|
while (pos < (*sourcelen) && outpos <= (*dstlen)-2) {
|
|
int backpos, runlen=0;
|
|
unsigned char value;
|
|
|
|
value = data_in[pos];
|
|
|
|
cpage_out[outpos++] = data_in[pos++];
|
|
|
|
backpos = positions[value];
|
|
positions[value]=pos;
|
|
|
|
while ((backpos < pos) && (pos < (*sourcelen)) &&
|
|
(data_in[pos]==data_in[backpos++]) && (runlen<255)) {
|
|
pos++;
|
|
runlen++;
|
|
}
|
|
cpage_out[outpos++] = runlen;
|
|
}
|
|
|
|
if (outpos >= pos) {
|
|
/* We failed */
|
|
return -1;
|
|
}
|
|
|
|
/* Tell the caller how much we managed to compress, and how much space it took */
|
|
*sourcelen = pos;
|
|
*dstlen = outpos;
|
|
return 0;
|
|
}
|
|
|
|
|
|
static int jffs2_rtime_decompress(unsigned char *data_in,
|
|
unsigned char *cpage_out,
|
|
uint32_t srclen, uint32_t destlen)
|
|
{
|
|
short positions[256];
|
|
int outpos = 0;
|
|
int pos=0;
|
|
|
|
memset(positions,0,sizeof(positions));
|
|
|
|
while (outpos<destlen) {
|
|
unsigned char value;
|
|
int backoffs;
|
|
int repeat;
|
|
|
|
value = data_in[pos++];
|
|
cpage_out[outpos++] = value; /* first the verbatim copied byte */
|
|
repeat = data_in[pos++];
|
|
backoffs = positions[value];
|
|
|
|
positions[value]=outpos;
|
|
if (repeat) {
|
|
if (backoffs + repeat >= outpos) {
|
|
while(repeat) {
|
|
cpage_out[outpos++] = cpage_out[backoffs++];
|
|
repeat--;
|
|
}
|
|
} else {
|
|
memcpy(&cpage_out[outpos],&cpage_out[backoffs],repeat);
|
|
outpos+=repeat;
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static struct jffs2_compressor jffs2_rtime_comp = {
|
|
.priority = JFFS2_RTIME_PRIORITY,
|
|
.name = "rtime",
|
|
.compr = JFFS2_COMPR_RTIME,
|
|
.compress = &jffs2_rtime_compress,
|
|
.decompress = &jffs2_rtime_decompress,
|
|
#ifdef JFFS2_RTIME_DISABLED
|
|
.disabled = 1,
|
|
#else
|
|
.disabled = 0,
|
|
#endif
|
|
};
|
|
|
|
int jffs2_rtime_init(void)
|
|
{
|
|
return jffs2_register_compressor(&jffs2_rtime_comp);
|
|
}
|
|
|
|
void jffs2_rtime_exit(void)
|
|
{
|
|
jffs2_unregister_compressor(&jffs2_rtime_comp);
|
|
}
|