1 /* 2 * JFFS2 -- Journalling Flash File System, Version 2. 3 * 4 * Copyright (C) 2001 Red Hat, Inc. 5 * 6 * Created by Arjan van de Ven <arjanv@redhat.com> 7 * 8 * Heavily modified by Russ Dill <Russ.Dill@asu.edu> in an attempt at 9 * a little more speed. 10 * 11 * The original JFFS, from which the design for JFFS2 was derived, 12 * was designed and implemented by Axis Communications AB. 13 * 14 * The contents of this file are subject to the Red Hat eCos Public 15 * License Version 1.1 (the "Licence"); you may not use this file 16 * except in compliance with the Licence. You may obtain a copy of 17 * the Licence at http://www.redhat.com/ 18 * 19 * Software distributed under the Licence is distributed on an "AS IS" 20 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. 21 * See the Licence for the specific language governing rights and 22 * limitations under the Licence. 23 * 24 * The Original Code is JFFS2 - Journalling Flash File System, version 2 25 * 26 * Alternatively, the contents of this file may be used under the 27 * terms of the GNU General Public License version 2 (the "GPL"), in 28 * which case the provisions of the GPL are applicable instead of the 29 * above. If you wish to allow the use of your version of this file 30 * only under the terms of the GPL and not to allow others to use your 31 * version of this file under the RHEPL, indicate your decision by 32 * deleting the provisions above and replace them with the notice and 33 * other provisions required by the GPL. If you do not delete the 34 * provisions above, a recipient may use your version of this file 35 * under either the RHEPL or the GPL. 36 * 37 * $Id: compr_rubin.c,v 1.2 2002/01/24 22:58:42 rfeany Exp $ 38 * 39 */ 40 41 #include <config.h> 42 #include <jffs2/jffs2.h> 43 #include <jffs2/compr_rubin.h> 44 45 46 void rubin_do_decompress(unsigned char *bits, unsigned char *in, 47 unsigned char *page_out, __u32 destlen) 48 { 49 register char *curr = (char *)page_out; 50 char *end = (char *)(page_out + destlen); 51 register unsigned long temp; 52 register unsigned long result; 53 register unsigned long p; 54 register unsigned long q; 55 register unsigned long rec_q; 56 register unsigned long bit; 57 register long i0; 58 unsigned long i; 59 60 /* init_pushpull */ 61 temp = *(u32 *) in; 62 bit = 16; 63 64 /* init_rubin */ 65 q = 0; 66 p = (long) (2 * UPPER_BIT_RUBIN); 67 68 /* init_decode */ 69 rec_q = (in[0] << 8) | in[1]; 70 71 while (curr < end) { 72 /* in byte */ 73 74 result = 0; 75 for (i = 0; i < 8; i++) { 76 /* decode */ 77 78 while ((q & UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)) { 79 q &= ~UPPER_BIT_RUBIN; 80 q <<= 1; 81 p <<= 1; 82 rec_q &= ~UPPER_BIT_RUBIN; 83 rec_q <<= 1; 84 rec_q |= (temp >> (bit++ ^ 7)) & 1; 85 if (bit > 31) { 86 u32 *p = (u32 *)in; 87 bit = 0; 88 temp = *(++p); 89 in = (unsigned char *)p; 90 } 91 } 92 i0 = (bits[i] * p) >> 8; 93 94 if (i0 <= 0) i0 = 1; 95 /* if it fails, it fails, we have our crc 96 if (i0 >= p) i0 = p - 1; */ 97 98 result >>= 1; 99 if (rec_q < q + i0) { 100 /* result |= 0x00; */ 101 p = i0; 102 } else { 103 result |= 0x80; 104 p -= i0; 105 q += i0; 106 } 107 } 108 *(curr++) = result; 109 } 110 } 111 112 void dynrubin_decompress(unsigned char *data_in, unsigned char *cpage_out, 113 unsigned long sourcelen, unsigned long dstlen) 114 { 115 unsigned char bits[8]; 116 int c; 117 118 for (c=0; c<8; c++) 119 bits[c] = (256 - data_in[c]); 120 121 rubin_do_decompress(bits, data_in+8, cpage_out, dstlen); 122 } 123