Major upate of JFFS2 code; now in sync with snapshot of MTD CVS of
March 13, 2005); new configuration options CONFIG_JFFS2_LZO and
CONFIG_JFFS2_LZARI are added. Both are undefined by default.
diff --git a/fs/jffs2/compr_lzari.c b/fs/jffs2/compr_lzari.c
new file mode 100644
index 0000000..a6a708b
--- /dev/null
+++ b/fs/jffs2/compr_lzari.c
@@ -0,0 +1,262 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright (C) 2004 Patrik Kluba,
+ * University of Szeged, Hungary
+ *
+ * For licensing information, see the file 'LICENCE' in the
+ * jffs2 directory.
+ *
+ * $Id: compr_lzari.c,v 1.3 2004/06/23 16:34:39 havasi Exp $
+ *
+ */
+
+/*
+ Lempel-Ziv-Arithmetic coding compression module for jffs2
+ Based on the LZARI source included in LDS (lossless datacompression sources)
+*/
+
+/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 4; tab-width: 4 -*- */
+
+/*
+Original copyright follows:
+
+**************************************************************
+ LZARI.C -- A Data Compression Program
+ (tab = 4 spaces)
+**************************************************************
+ 4/7/1989 Haruhiko Okumura
+ Use, distribute, and modify this program freely.
+ Please send me your improved versions.
+ PC-VAN SCIENCE
+ NIFTY-Serve PAF01022
+ CompuServe 74050,1022
+**************************************************************
+
+LZARI.C (c)1989 by Haruyasu Yoshizaki, Haruhiko Okumura, and Kenji Rikitake.
+All rights reserved. Permission granted for non-commercial use.
+
+*/
+
+/*
+
+ 2004-02-18 pajko <pajko(AT)halom(DOT)u-szeged(DOT)hu>
+ Removed unused variables and fixed no return value
+
+ 2004-02-16 pajko <pajko(AT)halom(DOT)u-szeged(DOT)hu>
+ Initial release
+
+*/
+
+
+#include <config.h>
+#if ((CONFIG_COMMANDS & CFG_CMD_JFFS2) && defined(CONFIG_JFFS2_LZARI))
+
+#include <linux/stddef.h>
+#include <jffs2/jffs2.h>
+
+
+#define N 4096 /* size of ring buffer */
+#define F 60 /* upper limit for match_length */
+#define THRESHOLD 2 /* encode string into position and length
+ if match_length is greater than this */
+#define NIL N /* index for root of binary search trees */
+
+static unsigned char
+ text_buf[N + F - 1]; /* ring buffer of size N,
+ with extra F-1 bytes to facilitate string comparison */
+
+/********** Arithmetic Compression **********/
+
+/* If you are not familiar with arithmetic compression, you should read
+ I. E. Witten, R. M. Neal, and J. G. Cleary,
+ Communications of the ACM, Vol. 30, pp. 520-540 (1987),
+ from which much have been borrowed. */
+
+#define M 15
+
+/* Q1 (= 2 to the M) must be sufficiently large, but not so
+ large as the unsigned long 4 * Q1 * (Q1 - 1) overflows. */
+
+#define Q1 (1UL << M)
+#define Q2 (2 * Q1)
+#define Q3 (3 * Q1)
+#define Q4 (4 * Q1)
+#define MAX_CUM (Q1 - 1)
+
+#define N_CHAR (256 - THRESHOLD + F)
+ /* character code = 0, 1, ..., N_CHAR - 1 */
+
+static unsigned long char_to_sym[N_CHAR], sym_to_char[N_CHAR + 1];
+static unsigned long
+ sym_freq[N_CHAR + 1], /* frequency for symbols */
+ sym_cum[N_CHAR + 1], /* cumulative freq for symbols */
+ position_cum[N + 1]; /* cumulative freq for positions */
+
+static void StartModel(void) /* Initialize model */
+{
+ unsigned long ch, sym, i;
+
+ sym_cum[N_CHAR] = 0;
+ for (sym = N_CHAR; sym >= 1; sym--) {
+ ch = sym - 1;
+ char_to_sym[ch] = sym; sym_to_char[sym] = ch;
+ sym_freq[sym] = 1;
+ sym_cum[sym - 1] = sym_cum[sym] + sym_freq[sym];
+ }
+ sym_freq[0] = 0; /* sentinel (!= sym_freq[1]) */
+ position_cum[N] = 0;
+ for (i = N; i >= 1; i--)
+ position_cum[i - 1] = position_cum[i] + 10000 / (i + 200);
+ /* empirical distribution function (quite tentative) */
+ /* Please devise a better mechanism! */
+}
+
+static void UpdateModel(unsigned long sym)
+{
+ unsigned long c, ch_i, ch_sym;
+ unsigned long i;
+ if (sym_cum[0] >= MAX_CUM) {
+ c = 0;
+ for (i = N_CHAR; i > 0; i--) {
+ sym_cum[i] = c;
+ c += (sym_freq[i] = (sym_freq[i] + 1) >> 1);
+ }
+ sym_cum[0] = c;
+ }
+ for (i = sym; sym_freq[i] == sym_freq[i - 1]; i--) ;
+ if (i < sym) {
+ ch_i = sym_to_char[i]; ch_sym = sym_to_char[sym];
+ sym_to_char[i] = ch_sym; sym_to_char[sym] = ch_i;
+ char_to_sym[ch_i] = sym; char_to_sym[ch_sym] = i;
+ }
+ sym_freq[i]++;
+ while (--i > 0) sym_cum[i]++;
+ sym_cum[0]++;
+}
+
+static unsigned long BinarySearchSym(unsigned long x)
+ /* 1 if x >= sym_cum[1],
+ N_CHAR if sym_cum[N_CHAR] > x,
+ i such that sym_cum[i - 1] > x >= sym_cum[i] otherwise */
+{
+ unsigned long i, j, k;
+
+ i = 1; j = N_CHAR;
+ while (i < j) {
+ k = (i + j) / 2;
+ if (sym_cum[k] > x) i = k + 1; else j = k;
+ }
+ return i;
+}
+
+unsigned long BinarySearchPos(unsigned long x)
+ /* 0 if x >= position_cum[1],
+ N - 1 if position_cum[N] > x,
+ i such that position_cum[i] > x >= position_cum[i + 1] otherwise */
+{
+ unsigned long i, j, k;
+
+ i = 1; j = N;
+ while (i < j) {
+ k = (i + j) / 2;
+ if (position_cum[k] > x) i = k + 1; else j = k;
+ }
+ return i - 1;
+}
+
+static int Decode(unsigned char *srcbuf, unsigned char *dstbuf, unsigned long srclen,
+ unsigned long dstlen) /* Just the reverse of Encode(). */
+{
+ unsigned long i, r, j, k, c, range, sym;
+ unsigned char *ip, *op;
+ unsigned char *srcend = srcbuf + srclen;
+ unsigned char *dstend = dstbuf + dstlen;
+ unsigned char buffer = 0;
+ unsigned char mask = 0;
+ unsigned long low = 0;
+ unsigned long high = Q4;
+ unsigned long value = 0;
+
+ ip = srcbuf;
+ op = dstbuf;
+ for (i = 0; i < M + 2; i++) {
+ value *= 2;
+ if ((mask >>= 1) == 0) {
+ buffer = (ip >= srcend) ? 0 : *(ip++);
+ mask = 128;
+ }
+ value += ((buffer & mask) != 0);
+ }
+
+ StartModel();
+ for (i = 0; i < N - F; i++) text_buf[i] = ' ';
+ r = N - F;
+
+ while (op < dstend) {
+ range = high - low;
+ sym = BinarySearchSym((unsigned long)
+ (((value - low + 1) * sym_cum[0] - 1) / range));
+ high = low + (range * sym_cum[sym - 1]) / sym_cum[0];
+ low += (range * sym_cum[sym ]) / sym_cum[0];
+ for ( ; ; ) {
+ if (low >= Q2) {
+ value -= Q2; low -= Q2; high -= Q2;
+ } else if (low >= Q1 && high <= Q3) {
+ value -= Q1; low -= Q1; high -= Q1;
+ } else if (high > Q2) break;
+ low += low; high += high;
+ value *= 2;
+ if ((mask >>= 1) == 0) {
+ buffer = (ip >= srcend) ? 0 : *(ip++);
+ mask = 128;
+ }
+ value += ((buffer & mask) != 0);
+ }
+ c = sym_to_char[sym];
+ UpdateModel(sym);
+ if (c < 256) {
+ if (op >= dstend) return -1;
+ *(op++) = c;
+ text_buf[r++] = c;
+ r &= (N - 1);
+ } else {
+ j = c - 255 + THRESHOLD;
+ range = high - low;
+ i = BinarySearchPos((unsigned long)
+ (((value - low + 1) * position_cum[0] - 1) / range));
+ high = low + (range * position_cum[i ]) / position_cum[0];
+ low += (range * position_cum[i + 1]) / position_cum[0];
+ for ( ; ; ) {
+ if (low >= Q2) {
+ value -= Q2; low -= Q2; high -= Q2;
+ } else if (low >= Q1 && high <= Q3) {
+ value -= Q1; low -= Q1; high -= Q1;
+ } else if (high > Q2) break;
+ low += low; high += high;
+ value *= 2;
+ if ((mask >>= 1) == 0) {
+ buffer = (ip >= srcend) ? 0 : *(ip++);
+ mask = 128;
+ }
+ value += ((buffer & mask) != 0);
+ }
+ i = (r - i - 1) & (N - 1);
+ for (k = 0; k < j; k++) {
+ c = text_buf[(i + k) & (N - 1)];
+ if (op >= dstend) return -1;
+ *(op++) = c;
+ text_buf[r++] = c;
+ r &= (N - 1);
+ }
+ }
+ }
+ return 0;
+}
+
+int lzari_decompress(unsigned char *data_in, unsigned char *cpage_out,
+ u32 srclen, u32 destlen)
+{
+ return Decode(data_in, cpage_out, srclen, destlen);
+}
+#endif /* ((CONFIG_COMMANDS & CFG_CMD_JFFS2) && defined(CONFIG_JFFS2_LZARI)) */