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/*
* 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.
*
*/
#include <linux/string.h>
#include <linux/types.h>
#include <linux/jffs2.h>
#include <linux/errno.h>
#include "compr.h"
#define RUBIN_REG_SIZE 16
#define UPPER_BIT_RUBIN (((long) 1)<<(RUBIN_REG_SIZE-1))
#define LOWER_BITS_RUBIN ((((long) 1)<<(RUBIN_REG_SIZE-1))-1)
#define BIT_DIVIDER_MIPS 1043
static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241};
struct pushpull {
unsigned char *buf;
unsigned int buflen;
unsigned int ofs;
unsigned int reserve;
};
struct rubin_state {
unsigned long p;
unsigned long q;
unsigned long rec_q;
long bit_number;
struct pushpull pp;
int bit_divider;
int bits[8];
};
static inline void init_pushpull(struct pushpull *pp, char *buf,
unsigned buflen, unsigned ofs,
unsigned reserve)
{
pp->buf = buf;
pp->buflen = buflen;
pp->ofs = ofs;
pp->reserve = reserve;
}
static inline int pushbit(struct pushpull *pp, int bit, int use_reserved)
{
if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve))
return -ENOSPC;
if (bit)
pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs & 7)));
else
pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs & 7)));
pp->ofs++;
return 0;
}
static inline int pushedbits(struct pushpull *pp)
{
return pp->ofs;
}
static inline int pullbit(struct pushpull *pp)
{
int bit;
bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1;
pp->ofs++;
return bit;
}
static inline int pulledbits(struct pushpull *pp)
{
return pp->ofs;
}
static void init_rubin(struct rubin_state *rs, int div, int *bits)
{
int c;
rs->q = 0;
rs->p = (long) (2 * UPPER_BIT_RUBIN);
rs->bit_number = (long) 0;
rs->bit_divider = div;
for (c=0; c<8; c++)
rs->bits[c] = bits[c];
}
static int encode(struct rubin_state *rs, long A, long B, int symbol)
{
long i0, i1;
int ret;
while ((rs->q >= UPPER_BIT_RUBIN) ||
((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
rs->bit_number++;
ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0);
if (ret)
return ret;
rs->q &= LOWER_BITS_RUBIN;
rs->q <<= 1;
rs->p <<= 1;
}
i0 = A * rs->p / (A + B);
if (i0 <= 0)
i0 = 1;
if (i0 >= rs->p)
i0 = rs->p - 1;
i1 = rs->p - i0;
if (symbol == 0)
rs->p = i0;
else {
rs->p = i1;
rs->q += i0;
}
return 0;
}
static void end_rubin(struct rubin_state *rs)
{
int i;
for (i = 0; i < RUBIN_REG_SIZE; i++) {
pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1);
rs->q &= LOWER_BITS_RUBIN;
rs->q <<= 1;
}
}
static void init_decode(struct rubin_state *rs, int div, int *bits)
{
init_rubin(rs, div, bits);
/* behalve lower */
rs->rec_q = 0;
for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE;
rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp)))
;
}
static void __do_decode(struct rubin_state *rs, unsigned long p,
unsigned long q)
{
register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN;
unsigned long rec_q;
int c, bits = 0;
/*
* First, work out how many bits we need from the input stream.
* Note that we have already done the initial check on this
* loop prior to calling this function.
*/
do {
bits++;
q &= lower_bits_rubin;
q <<= 1;
p <<= 1;
} while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN));
rs->p = p;
rs->q = q;
rs->bit_number += bits;
/*
* Now get the bits. We really want this to be "get n bits".
*/
rec_q = rs->rec_q;
do {
c = pullbit(&rs->pp);
rec_q &= lower_bits_rubin;
rec_q <<= 1;
rec_q += c;
} while (--bits);
rs->rec_q = rec_q;
}
static int decode(struct rubin_state *rs, long A, long B)
{
unsigned long p = rs->p, q = rs->q;
long i0, threshold;
int symbol;
if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN))
__do_decode(rs, p, q);
i0 = A * rs->p / (A + B);
if (i0 <= 0)
i0 = 1;
if (i0 >= rs->p)
i0 = rs->p - 1;
threshold = rs->q + i0;
symbol = rs->rec_q >= threshold;
if (rs->rec_q >= threshold) {
rs->q += i0;
i0 = rs->p - i0;
}
rs->p = i0;
return symbol;
}
static int out_byte(struct rubin_state *rs, unsigned char byte)
{
int i, ret;
struct rubin_state rs_copy;
rs_copy = *rs;
for (i=0; i<8; i++
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