1 files changed, 452 insertions, 0 deletions
diff --git a/fs/jffs2/compr_rubin.c b/fs/jffs2/compr_rubin.c
new file mode 100644
index 000000000..556de100e
--- /dev/null
+++ b/fs/jffs2/compr_rubin.c
@@ -0,0 +1,452 @@
+/*
+ * 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);
+}