[mirror_ubuntu-zesty-kernel.git] / fs / jffs2 / compr_rubin.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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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 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++) {
		ret = encode(rs, rs->bit_divider-rs->bits[i],
			     rs->bits[i], byte & 1);
		if (ret) {
			/* Failed. Restore old state */
			*rs = rs_copy;
			return ret;
		}
		byte >>= 1 ;
	}
	return 0;
}

static int in_byte(struct rubin_state *rs)
{
	int i, result = 0, bit_divider = rs->bit_divider;

	for (i = 0; i < 8; i++)
		result |= decode(rs, bit_divider - rs->bits[i],
				 rs->bits[i]) << i;

	return result;
}


static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in,
			     unsigned char *cpage_out, uint32_t *sourcelen,
			     uint32_t *dstlen)
	{
	int outpos = 0;
	int pos=0;
	struct rubin_state rs;

	init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32);

	init_rubin(&rs, bit_divider, bits);

	while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
		pos++;

	end_rubin(&rs);

	if (outpos > pos) {
		/* We failed */
		return -1;
	}

	/* Tell the caller how much we managed to compress,
	 * and how much space it took */

	outpos = (pushedbits(&rs.pp)+7)/8;

	if (outpos >= pos)
		return -1; /* We didn't actually compress */
	*sourcelen = pos;
	*dstlen = outpos;
	return 0;
}
#if 0
/* _compress returns the compressed size, -1 if bigger */
int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out,
		   uint32_t *sourcelen, uint32_t *dstlen)
{
	return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in,
				 cpage_out, sourcelen, dstlen);
}
#endif
static int jffs2_dynrubin_compress(unsigned char *data_in,
				   unsigned char *cpage_out,
				   uint32_t *sourcelen, uint32_t *dstlen)
{
	int bits[8];
	unsigned char histo[256];
	int i;
	int ret;
	uint32_t mysrclen, mydstlen;

	mysrclen = *sourcelen;
	mydstlen = *dstlen - 8;

	if (*dstlen <= 12)
		return -1;

	memset(histo, 0, 256);
	for (i=0; i<mysrclen; i++)
		histo[data_in[i]]++;
	memset(bits, 0, sizeof(int)*8);
	for (i=0; i<256; i++) {
		if (i&128)
			bits[7] += histo[i];
		if (i&64)
			bits[6] += histo[i];
		if (i&32)
			bits[5] += histo[i];
		if (i&16)
			bits[4] += histo[i];
		if (i&8)
			bits[3] += histo[i];
		if (i&4)
			bits[2] += histo[i];
		if (i&2)
			bits[1] += histo[i];
		if (i&1)
			bits[0] += histo[i];
	}

	for (i=0; i<8; i++) {
		bits[i] = (bits[i] * 256) / mysrclen;
		if (!bits[i]) bits[i] = 1;
		if (bits[i] > 255) bits[i] = 255;
		cpage_out[i] = bits[i];
	}

	ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen,
				&mydstlen);
	if (ret)
		return ret;

	/* Add back the 8 bytes we took for the probabilities */
	mydstlen += 8;

	if (mysrclen <= mydstlen) {
		/* We compressed */
		return -1;
	}

	*sourcelen = mysrclen;
	*dstlen = mydstlen;
	return 0;
}

static void rubin_do_decompress(int bit_divider, int *bits,
				unsigned char *cdata_in, 
				unsigned char *page_out, uint32_t srclen,
				uint32_t destlen)
{
	int outpos = 0;
	struct rubin_state rs;

	init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
	init_decode(&rs, bit_divider, bits);

	while (outpos < destlen)
		page_out[outpos++] = in_byte(&rs);
}


static int jffs2_rubinmips_decompress(unsigned char *data_in,
				      unsigned char *cpage_out,
				      uint32_t sourcelen, uint32_t dstlen)
{
	rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in,
			    cpage_out, sourcelen, dstlen);
	return 0;
}

static int jffs2_dynrubin_decompress(unsigned char *data_in,
				     unsigned char *cpage_out,
				     uint32_t sourcelen, uint32_t dstlen)
{
	int bits[8];
	int c;

	for (c=0; c<8; c++)
		bits[c] = data_in[c];

	rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8,
			    dstlen);
	return 0;
}

static struct jffs2_compressor jffs2_rubinmips_comp = {
	.priority = JFFS2_RUBINMIPS_PRIORITY,
	.name = "rubinmips",
	.compr = JFFS2_COMPR_DYNRUBIN,
	.compress = NULL, /*&jffs2_rubinmips_compress,*/
	.decompress = &jffs2_rubinmips_decompress,
#ifdef JFFS2_RUBINMIPS_DISABLED
	.disabled = 1,
#else
	.disabled = 0,
#endif
};

int jffs2_rubinmips_init(void)
{
	return jffs2_register_compressor(&jffs2_rubinmips_comp);
}

void jffs2_rubinmips_exit(void)
{
	jffs2_unregister_compressor(&jffs2_rubinmips_comp);
}

static struct jffs2_compressor jffs2_dynrubin_comp = {
	.priority = JFFS2_DYNRUBIN_PRIORITY,
	.name = "dynrubin",
	.compr = JFFS2_COMPR_RUBINMIPS,
	.compress = jffs2_dynrubin_compress,
	.decompress = &jffs2_dynrubin_decompress,
#ifdef JFFS2_DYNRUBIN_DISABLED
	.disabled = 1,
#else
	.disabled = 0,
#endif
};

int jffs2_dynrubin_init(void)
{
	return jffs2_register_compressor(&jffs2_dynrubin_comp);
}

void jffs2_dynrubin_exit(void)
{
	jffs2_unregister_compressor(&jffs2_dynrubin_comp);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* JFFS2 -- Journalling Flash File System, Version 2.
	3	*
c00c310e	4	* Copyright © 2001-2007 Red Hat, Inc.
6088c058	5	* Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
1da177e4 LT	6	*
	7	* Created by Arjan van de Ven <arjanv@redhat.com>
	8	*
	9	* For licensing information, see the file 'LICENCE' in this directory.
	10	*
1da177e4 LT	11	*/
1da177e4 LT	12
5a528957 JP	13	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
5a528957 JP	14
1da177e4 LT	15	#include <linux/string.h>
	16	#include <linux/types.h>
	17	#include <linux/jffs2.h>
c00c310e	18	#include <linux/errno.h>
1da177e4 LT	19	#include "compr.h"
1da177e4 LT	20
c00c310e DW	21
	22	#define RUBIN_REG_SIZE 16
	23	#define UPPER_BIT_RUBIN (((long) 1)<<(RUBIN_REG_SIZE-1))
	24	#define LOWER_BITS_RUBIN ((((long) 1)<<(RUBIN_REG_SIZE-1))-1)
	25
	26
c00c310e	27	#define BIT_DIVIDER_MIPS 1043
0bc4382a	28	static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241};
c00c310e DW	29
	30	struct pushpull {
	31	unsigned char *buf;
	32	unsigned int buflen;
	33	unsigned int ofs;
	34	unsigned int reserve;
	35	};
	36
f6449f4e AM	37	struct rubin_state {
	38	unsigned long p;
	39	unsigned long q;
	40	unsigned long rec_q;
	41	long bit_number;
	42	struct pushpull pp;
	43	int bit_divider;
	44	int bits[8];
	45	};
c00c310e	46
0bc4382a DW	47	static inline void init_pushpull(struct pushpull pp, char buf,
	48	unsigned buflen, unsigned ofs,
	49	unsigned reserve)
c00c310e DW	50	{
	51	pp->buf = buf;
	52	pp->buflen = buflen;
	53	pp->ofs = ofs;
	54	pp->reserve = reserve;
	55	}
	56
	57	static inline int pushbit(struct pushpull *pp, int bit, int use_reserved)
	58	{
0bc4382a	59	if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve))
c00c310e	60	return -ENOSPC;
c00c310e	61
0bc4382a DW	62	if (bit)
	63	pp->buf[pp->ofs >> 3] \|= (1<<(7-(pp->ofs & 7)));
	64	else
	65	pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs & 7)));
	66
c00c310e DW	67	pp->ofs++;
	68
	69	return 0;
	70	}
	71
	72	static inline int pushedbits(struct pushpull *pp)
	73	{
	74	return pp->ofs;
	75	}
	76
	77	static inline int pullbit(struct pushpull *pp)
	78	{
	79	int bit;
	80
	81	bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1;
	82
	83	pp->ofs++;
	84	return bit;
	85	}
	86
c00c310e	87
1da177e4	88	static void init_rubin(struct rubin_state rs, int div, int bits)
182ec4ee	89	{
1da177e4 LT	90	int c;
	91
	92	rs->q = 0;
	93	rs->p = (long) (2 * UPPER_BIT_RUBIN);
	94	rs->bit_number = (long) 0;
	95	rs->bit_divider = div;
0bc4382a	96
1da177e4 LT	97	for (c=0; c<8; c++)
	98	rs->bits[c] = bits[c];
	99	}
	100
	101
	102	static int encode(struct rubin_state *rs, long A, long B, int symbol)
	103	{
	104
	105	long i0, i1;
	106	int ret;
	107
0bc4382a DW	108	while ((rs->q >= UPPER_BIT_RUBIN) \|\|
0bc4382a DW	109	((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
1da177e4	110	rs->bit_number++;
182ec4ee	111
1da177e4 LT	112	ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0);
	113	if (ret)
	114	return ret;
	115	rs->q &= LOWER_BITS_RUBIN;
	116	rs->q <<= 1;
	117	rs->p <<= 1;
	118	}
	119	i0 = A * rs->p / (A + B);
0bc4382a	120	if (i0 <= 0)
1da177e4	121	i0 = 1;
0bc4382a DW	122
0bc4382a DW	123	if (i0 >= rs->p)
1da177e4	124	i0 = rs->p - 1;
0bc4382a	125
1da177e4 LT	126	i1 = rs->p - i0;
	127
	128	if (symbol == 0)
	129	rs->p = i0;
	130	else {
	131	rs->p = i1;
	132	rs->q += i0;
	133	}
	134	return 0;
	135	}
	136
	137
	138	static void end_rubin(struct rubin_state *rs)
182ec4ee	139	{
1da177e4 LT	140
	141	int i;
	142
	143	for (i = 0; i < RUBIN_REG_SIZE; i++) {
	144	pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1);
	145	rs->q &= LOWER_BITS_RUBIN;
	146	rs->q <<= 1;
	147	}
	148	}
	149
	150
	151	static void init_decode(struct rubin_state rs, int div, int bits)
	152	{
182ec4ee	153	init_rubin(rs, div, bits);
1da177e4 LT	154
	155	/* behalve lower */
	156	rs->rec_q = 0;
	157
0bc4382a DW	158	for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE;
0bc4382a DW	159	rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp)))
1da177e4 LT	160	;
	161	}
	162
0bc4382a DW	163	static void __do_decode(struct rubin_state *rs, unsigned long p,
0bc4382a DW	164	unsigned long q)
1da177e4 LT	165	{
	166	register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN;
	167	unsigned long rec_q;
	168	int c, bits = 0;
	169
	170	/*
	171	* First, work out how many bits we need from the input stream.
	172	* Note that we have already done the initial check on this
	173	* loop prior to calling this function.
	174	*/
	175	do {
	176	bits++;
	177	q &= lower_bits_rubin;
	178	q <<= 1;
	179	p <<= 1;
	180	} while ((q >= UPPER_BIT_RUBIN) \|\| ((p + q) <= UPPER_BIT_RUBIN));
	181
	182	rs->p = p;
	183	rs->q = q;
	184
	185	rs->bit_number += bits;
	186
	187	/*
	188	* Now get the bits. We really want this to be "get n bits".
	189	*/
	190	rec_q = rs->rec_q;
	191	do {
	192	c = pullbit(&rs->pp);
	193	rec_q &= lower_bits_rubin;
	194	rec_q <<= 1;
	195	rec_q += c;
	196	} while (--bits);
	197	rs->rec_q = rec_q;
	198	}
	199
	200	static int decode(struct rubin_state *rs, long A, long B)
	201	{
	202	unsigned long p = rs->p, q = rs->q;
	203	long i0, threshold;
	204	int symbol;
	205
	206	if (q >= UPPER_BIT_RUBIN \|\| ((p + q) <= UPPER_BIT_RUBIN))
	207	__do_decode(rs, p, q);
	208
	209	i0 = A * rs->p / (A + B);
0bc4382a	210	if (i0 <= 0)
1da177e4	211	i0 = 1;
0bc4382a DW	212
0bc4382a DW	213	if (i0 >= rs->p)
1da177e4	214	i0 = rs->p - 1;
1da177e4 LT	215
	216	threshold = rs->q + i0;
	217	symbol = rs->rec_q >= threshold;
	218	if (rs->rec_q >= threshold) {
	219	rs->q += i0;
	220	i0 = rs->p - i0;
	221	}
	222
	223	rs->p = i0;
	224
	225	return symbol;
	226	}
	227
	228
	229
	230	static int out_byte(struct rubin_state *rs, unsigned char byte)
	231	{
	232	int i, ret;
	233	struct rubin_state rs_copy;
	234	rs_copy = *rs;
	235
0bc4382a DW	236	for (i=0; i<8; i++) {
	237	ret = encode(rs, rs->bit_divider-rs->bits[i],
	238	rs->bits[i], byte & 1);
1da177e4 LT	239	if (ret) {
	240	/* Failed. Restore old state */
	241	*rs = rs_copy;
	242	return ret;
	243	}
0bc4382a	244	byte >>= 1 ;
1da177e4 LT	245	}
	246	return 0;
	247	}
	248
	249	static int in_byte(struct rubin_state *rs)
	250	{
	251	int i, result = 0, bit_divider = rs->bit_divider;
	252
	253	for (i = 0; i < 8; i++)
0bc4382a DW	254	result \|= decode(rs, bit_divider - rs->bits[i],
0bc4382a DW	255	rs->bits[i]) << i;
1da177e4 LT	256
	257	return result;
	258	}
	259
	260
	261
182ec4ee	262	static int rubin_do_compress(int bit_divider, int bits, unsigned char data_in,
0bc4382a DW	263	unsigned char cpage_out, uint32_t sourcelen,
0bc4382a DW	264	uint32_t *dstlen)
1da177e4 LT	265	{
	266	int outpos = 0;
	267	int pos=0;
	268	struct rubin_state rs;
	269
	270	init_pushpull(&rs.pp, cpage_out, dstlen 8, 0, 32);
	271
	272	init_rubin(&rs, bit_divider, bits);
182ec4ee	273
1da177e4 LT	274	while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
1da177e4 LT	275	pos++;
182ec4ee	276
1da177e4 LT	277	end_rubin(&rs);
	278
	279	if (outpos > pos) {
	280	/* We failed */
	281	return -1;
	282	}
182ec4ee TG	283
182ec4ee TG	284	/* Tell the caller how much we managed to compress,
1da177e4	285	* and how much space it took */
182ec4ee	286
1da177e4	287	outpos = (pushedbits(&rs.pp)+7)/8;
182ec4ee	288
1da177e4 LT	289	if (outpos >= pos)
	290	return -1; /* We didn't actually compress */
	291	*sourcelen = pos;
	292	*dstlen = outpos;
	293	return 0;
182ec4ee	294	}
1da177e4 LT	295	#if 0
1da177e4 LT	296	/* _compress returns the compressed size, -1 if bigger */
182ec4ee	297	int jffs2_rubinmips_compress(unsigned char data_in, unsigned char cpage_out,
088bd455	298	uint32_t sourcelen, uint32_t dstlen)
1da177e4	299	{
0bc4382a DW	300	return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in,
0bc4382a DW	301	cpage_out, sourcelen, dstlen);
1da177e4 LT	302	}
1da177e4 LT	303	#endif
75c96f85 AB	304	static int jffs2_dynrubin_compress(unsigned char *data_in,
75c96f85 AB	305	unsigned char *cpage_out,
088bd455	306	uint32_t sourcelen, uint32_t dstlen)
1da177e4 LT	307	{
	308	int bits[8];
	309	unsigned char histo[256];
	310	int i;
	311	int ret;
	312	uint32_t mysrclen, mydstlen;
	313
	314	mysrclen = *sourcelen;
	315	mydstlen = *dstlen - 8;
	316
	317	if (*dstlen <= 12)
	318	return -1;
	319
	320	memset(histo, 0, 256);
0bc4382a	321	for (i=0; i<mysrclen; i++)
1da177e4	322	histo[data_in[i]]++;
1da177e4 LT	323	memset(bits, 0, sizeof(int)*8);
	324	for (i=0; i<256; i++) {
	325	if (i&128)
	326	bits[7] += histo[i];
	327	if (i&64)
	328	bits[6] += histo[i];
	329	if (i&32)
	330	bits[5] += histo[i];
	331	if (i&16)
	332	bits[4] += histo[i];
	333	if (i&8)
	334	bits[3] += histo[i];
	335	if (i&4)
	336	bits[2] += histo[i];
	337	if (i&2)
	338	bits[1] += histo[i];
	339	if (i&1)
	340	bits[0] += histo[i];
	341	}
	342
	343	for (i=0; i<8; i++) {
	344	bits[i] = (bits[i] * 256) / mysrclen;
	345	if (!bits[i]) bits[i] = 1;
	346	if (bits[i] > 255) bits[i] = 255;
	347	cpage_out[i] = bits[i];
	348	}
	349
0bc4382a DW	350	ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen,
0bc4382a DW	351	&mydstlen);
182ec4ee	352	if (ret)
1da177e4 LT	353	return ret;
	354
	355	/* Add back the 8 bytes we took for the probabilities */
	356	mydstlen += 8;
	357
	358	if (mysrclen <= mydstlen) {
	359	/* We compressed */
	360	return -1;
	361	}
	362
	363	*sourcelen = mysrclen;
	364	*dstlen = mydstlen;
	365	return 0;
	366	}
	367
0bc4382a DW	368	static void rubin_do_decompress(int bit_divider, int *bits,
	369	unsigned char *cdata_in,
	370	unsigned char *page_out, uint32_t srclen,
	371	uint32_t destlen)
1da177e4 LT	372	{
	373	int outpos = 0;
	374	struct rubin_state rs;
182ec4ee	375
1da177e4 LT	376	init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
1da177e4 LT	377	init_decode(&rs, bit_divider, bits);
182ec4ee	378
0bc4382a	379	while (outpos < destlen)
1da177e4	380	page_out[outpos++] = in_byte(&rs);
182ec4ee	381	}
1da177e4 LT	382
1da177e4 LT	383
75c96f85 AB	384	static int jffs2_rubinmips_decompress(unsigned char *data_in,
75c96f85 AB	385	unsigned char *cpage_out,
088bd455	386	uint32_t sourcelen, uint32_t dstlen)
1da177e4	387	{
0bc4382a DW	388	rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in,
0bc4382a DW	389	cpage_out, sourcelen, dstlen);
ef53cb02	390	return 0;
1da177e4 LT	391	}
1da177e4 LT	392
75c96f85 AB	393	static int jffs2_dynrubin_decompress(unsigned char *data_in,
75c96f85 AB	394	unsigned char *cpage_out,
088bd455	395	uint32_t sourcelen, uint32_t dstlen)
1da177e4 LT	396	{
	397	int bits[8];
	398	int c;
	399
	400	for (c=0; c<8; c++)
	401	bits[c] = data_in[c];
	402
0bc4382a DW	403	rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8,
0bc4382a DW	404	dstlen);
ef53cb02	405	return 0;
1da177e4 LT	406	}
	407
	408	static struct jffs2_compressor jffs2_rubinmips_comp = {
0bc4382a DW	409	.priority = JFFS2_RUBINMIPS_PRIORITY,
	410	.name = "rubinmips",
	411	.compr = JFFS2_COMPR_DYNRUBIN,
	412	.compress = NULL, /&jffs2_rubinmips_compress,/
	413	.decompress = &jffs2_rubinmips_decompress,
1da177e4	414	#ifdef JFFS2_RUBINMIPS_DISABLED
0bc4382a	415	.disabled = 1,
1da177e4	416	#else
0bc4382a	417	.disabled = 0,
1da177e4 LT	418	#endif
	419	};
	420
	421	int jffs2_rubinmips_init(void)
	422	{
0bc4382a	423	return jffs2_register_compressor(&jffs2_rubinmips_comp);
1da177e4 LT	424	}
	425
	426	void jffs2_rubinmips_exit(void)
	427	{
0bc4382a	428	jffs2_unregister_compressor(&jffs2_rubinmips_comp);
1da177e4 LT	429	}
	430
	431	static struct jffs2_compressor jffs2_dynrubin_comp = {
0bc4382a DW	432	.priority = JFFS2_DYNRUBIN_PRIORITY,
	433	.name = "dynrubin",
	434	.compr = JFFS2_COMPR_RUBINMIPS,
	435	.compress = jffs2_dynrubin_compress,
	436	.decompress = &jffs2_dynrubin_decompress,
1da177e4	437	#ifdef JFFS2_DYNRUBIN_DISABLED
0bc4382a	438	.disabled = 1,
1da177e4	439	#else
0bc4382a	440	.disabled = 0,
1da177e4 LT	441	#endif
	442	};
	443
	444	int jffs2_dynrubin_init(void)
	445	{
0bc4382a	446	return jffs2_register_compressor(&jffs2_dynrubin_comp);
1da177e4 LT	447	}
	448
	449	void jffs2_dynrubin_exit(void)
	450	{
0bc4382a	451	jffs2_unregister_compressor(&jffs2_dynrubin_comp);
1da177e4	452	}