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 #if (CONFIG_COMMANDS & CFG_CMD_JFFS2) || defined(CONFIG_CMD_JFFS2) 43 44 #include <jffs2/jffs2.h> 45 #include <jffs2/compr_rubin.h> 46 47 48 void rubin_do_decompress(unsigned char *bits, unsigned char *in, 49 unsigned char *page_out, __u32 destlen) 50 { 51 register char *curr = (char *)page_out; 52 char *end = (char *)(page_out + destlen); 53 register unsigned long temp; 54 register unsigned long result; 55 register unsigned long p; 56 register unsigned long q; 57 register unsigned long rec_q; 58 register unsigned long bit; 59 register long i0; 60 unsigned long i; 61 62 /* init_pushpull */ 63 temp = *(u32 *) in; 64 bit = 16; 65 66 /* init_rubin */ 67 q = 0; 68 p = (long) (2 * UPPER_BIT_RUBIN); 69 70 /* init_decode */ 71 rec_q = (in[0] << 8) | in[1]; 72 73 while (curr < end) { 74 /* in byte */ 75 76 result = 0; 77 for (i = 0; i < 8; i++) { 78 /* decode */ 79 80 while ((q & UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)) { 81 q &= ~UPPER_BIT_RUBIN; 82 q <<= 1; 83 p <<= 1; 84 rec_q &= ~UPPER_BIT_RUBIN; 85 rec_q <<= 1; 86 rec_q |= (temp >> (bit++ ^ 7)) & 1; 87 if (bit > 31) { 88 u32 *p = (u32 *)in; 89 bit = 0; 90 temp = *(++p); 91 in = (unsigned char *)p; 92 } 93 } 94 i0 = (bits[i] * p) >> 8; 95 96 if (i0 <= 0) i0 = 1; 97 /* if it fails, it fails, we have our crc 98 if (i0 >= p) i0 = p - 1; */ 99 100 result >>= 1; 101 if (rec_q < q + i0) { 102 /* result |= 0x00; */ 103 p = i0; 104 } else { 105 result |= 0x80; 106 p -= i0; 107 q += i0; 108 } 109 } 110 *(curr++) = result; 111 } 112 } 113 114 void dynrubin_decompress(unsigned char *data_in, unsigned char *cpage_out, 115 unsigned long sourcelen, unsigned long dstlen) 116 { 117 unsigned char bits[8]; 118 int c; 119 120 for (c=0; c<8; c++) 121 bits[c] = (256 - data_in[c]); 122 123 rubin_do_decompress(bits, data_in+8, cpage_out, dstlen); 124 } 125 126 #endif /* CFG_CMD_JFFS2 */ 127