patch-2.4.10 linux/fs/jffs2/compr_rubin.c

• Lines: 327
• Date: Fri Sep 14 14:04:07 2001
• Orig file: v2.4.9/linux/fs/jffs2/compr_rubin.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.9/linux/fs/jffs2/compr_rubin.c linux/fs/jffs2/compr_rubin.c
@@ -0,0 +1,326 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright (C) 2001 Red Hat, Inc.
+ *
+ * Created by Arjan van de Ven <arjanv@redhat.com>
+ *
+ * The original JFFS, from which the design for JFFS2 was derived,
+ * was designed and implemented by Axis Communications AB.
+ *
+ * The contents of this file are subject to the Red Hat eCos Public
+ * License Version 1.1 (the "Licence"); you may not use this file
+ * except in compliance with the Licence.  You may obtain a copy of
+ * the Licence at http://www.redhat.com/
+ *
+ * Software distributed under the Licence is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
+ * See the Licence for the specific language governing rights and
+ * limitations under the Licence.
+ *
+ * The Original Code is JFFS2 - Journalling Flash File System, version 2
+ *
+ * Alternatively, the contents of this file may be used under the
+ * terms of the GNU General Public License version 2 (the "GPL"), in
+ * which case the provisions of the GPL are applicable instead of the
+ * above.  If you wish to allow the use of your version of this file
+ * only under the terms of the GPL and not to allow others to use your
+ * version of this file under the RHEPL, indicate your decision by
+ * deleting the provisions above and replace them with the notice and
+ * other provisions required by the GPL.  If you do not delete the
+ * provisions above, a recipient may use your version of this file
+ * under either the RHEPL or the GPL.
+ *
+ * $Id: compr_rubin.c,v 1.11 2001/03/21 16:20:48 dwmw2 Exp $
+ *
+ */
+
+ 
+#include <linux/string.h>
+#include "compr_rubin.h"
+#include "histo_mips.h"
+
+
+
+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];
+}
+
+
+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;
+}
+
+
+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;
+	}
+}
+
+
+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)))
+		;
+}
+
+
+
+int decode(struct rubin_state *rs, long A, long B)
+{
+
+	char c;
+	long i0, i1, threshold;
+	int symbol;
+	
+
+	while ((rs->q >= UPPER_BIT_RUBIN) || ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
+		c = pullbit(&rs->pp);
+		rs->bit_number++;
+		rs->q &= LOWER_BITS_RUBIN;
+		rs->q <<= 1;
+		rs->p <<= 1;
+		rs->rec_q &= LOWER_BITS_RUBIN;
+		rs->rec_q <<= 1;
+		rs->rec_q += c;
+	};
+	i0 = A * rs->p / (A + B);
+	if (i0 <= 0) {
+		i0 = 1;
+	}
+	if (i0 >= rs->p) {
+		i0 = rs->p - 1;
+	}
+	i1 = rs->p - i0;
+
+
+	threshold = rs->q + i0;
+	if (rs->rec_q < threshold) {
+		symbol = 0;
+		rs->p = i0;
+	} else {
+		symbol = 1;
+		rs->p = i1;
+		rs->q += 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=byte>>1;
+	}
+	return 0;
+}
+
+static int in_byte(struct rubin_state *rs)
+{
+	int i;
+	int result=0;
+	for (i=0;i<8;i++) {
+		result |=  decode(rs, rs->bit_divider-rs->bits[i],rs->bits[i])<<i;
+	}
+	return result;
+}
+
+
+
+int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in, 
+		      unsigned char *cpage_out, __u32 *sourcelen, __u32 *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 rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out, 
+		   __u32 *sourcelen, __u32 *dstlen)
+{
+	return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen);
+}
+#endif
+int dynrubin_compress(unsigned char *data_in, unsigned char *cpage_out, 
+		   __u32 *sourcelen, __u32 *dstlen)
+{
+	int bits[8];
+	unsigned char histo[256];
+	int i;
+	int ret;
+	__u32 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;
+}
+
+void rubin_do_decompress(int bit_divider, int *bits, unsigned char *cdata_in, 
+			 unsigned char *page_out, __u32 srclen, __u32 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);
+	}
+}		   
+
+
+void rubinmips_decompress(unsigned char *data_in, unsigned char *cpage_out, 
+		   __u32 sourcelen, __u32 dstlen)
+{
+	rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, cpage_out, sourcelen, dstlen);
+}
+
+void dynrubin_decompress(unsigned char *data_in, unsigned char *cpage_out, 
+		   __u32 sourcelen, __u32 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);
+}