base91-0.6.0/base91.c

   1 /*
   2  * basE91 encoding/decoding routines
   3  *
   4  * Copyright (c) 2000-2006 Joachim Henke
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions are met:
   9  *
  10  *  - Redistributions of source code must retain the above copyright notice,
  11  *    this list of conditions and the following disclaimer.
  12  *  - Redistributions in binary form must reproduce the above copyright notice,
  13  *    this list of conditions and the following disclaimer in the documentation
  14  *    and/or other materials provided with the distribution.
  15  *  - Neither the name of Joachim Henke nor the names of his contributors may
  16  *    be used to endorse or promote products derived from this software without
  17  *    specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  20  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  23  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include "base91.h"
  33
  34 const unsigned char enctab[91] = {
  35         'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
  36         'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
  37         'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
  38         'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
  39         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '!', '#', '$',
  40         '%', '&', '(', ')', '*', '+', ',', '.', '/', ':', ';', '<', '=',
  41         '>', '?', '@', '[', ']', '^', '_', '`', '{', '|', '}', '~', '"'
  42 };
  43 const unsigned char dectab[256] = {
  44         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91,
  45         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91,
  46         91, 62, 90, 63, 64, 65, 66, 91, 67, 68, 69, 70, 71, 91, 72, 73,
  47         52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 74, 75, 76, 77, 78, 79,
  48         80,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
  49         15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 81, 91, 82, 83, 84,
  50         85, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
  51         41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 86, 87, 88, 89, 91,
  52         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91,
  53         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91,
  54         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91,
  55         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91,
  56         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91,
  57         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91,
  58         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91,
  59         91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91
  60 };
  61
  62 void basE91_init(struct basE91 *b)
  63 {
  64         b->queue = 0;
  65         b->nbits = 0;
  66         b->val = -1;
  67 }
  68
  69 size_t basE91_encode(struct basE91 *b, const void *i, size_t len, void *o)
  70 {
  71         const unsigned char *ib = i;
  72         unsigned char *ob = o;
  73         size_t n = 0;
  74
  75         while (len--) {
  76                 b->queue |= *ib++ << b->nbits;
  77                 b->nbits += 8;
  78                 if (b->nbits > 13) {    /* enough bits in queue */
  79                         unsigned int val = b->queue & 8191;
  80
  81                         if (val > 88) {
  82                                 b->queue >>= 13;
  83                                 b->nbits -= 13;
  84                         } else {        /* we can take 14 bits */
  85                                 val = b->queue & 16383;
  86                                 b->queue >>= 14;
  87                                 b->nbits -= 14;
  88                         }
  89                         ob[n++] = enctab[val % 91];
  90                         ob[n++] = enctab[val / 91];
  91                 }
  92         }
  93
  94         return n;
  95 }
  96
  97 /* process remaining bits from bit queue; write up to 2 bytes */
  98
  99 size_t basE91_encode_end(struct basE91 *b, void *o)
 100 {
 101         unsigned char *ob = o;
 102         size_t n = 0;
 103
 104         if (b->nbits) {
 105                 ob[n++] = enctab[b->queue % 91];
 106                 if (b->nbits > 7 || b->queue > 90)
 107                         ob[n++] = enctab[b->queue / 91];
 108         }
 109         b->queue = 0;
 110         b->nbits = 0;
 111         b->val = -1;
 112
 113         return n;
 114 }
 115
 116 size_t basE91_decode(struct basE91 *b, const void *i, size_t len, void *o)
 117 {
 118         const unsigned char *ib = i;
 119         unsigned char *ob = o;
 120         size_t n = 0;
 121         unsigned int d;
 122
 123         while (len--) {
 124                 d = dectab[*ib++];
 125                 if (d == 91)
 126                         continue;       /* ignore non-alphabet chars */
 127                 if (b->val == -1)
 128                         b->val = d;     /* start next value */
 129                 else {
 130                         b->val += d * 91;
 131                         b->queue |= b->val << b->nbits;
 132                         b->nbits += (b->val & 8191) > 88 ? 13 : 14;
 133                         do {
 134                                 ob[n++] = b->queue;
 135                                 b->queue >>= 8;
 136                                 b->nbits -= 8;
 137                         } while (b->nbits > 7);
 138                         b->val = -1;    /* mark value complete */
 139                 }
 140         }
 141
 142         return n;
 143 }
 144
 145 /* process remaining bits; write at most 1 byte */
 146
 147 size_t basE91_decode_end(struct basE91 *b, void *o)
 148 {
 149         unsigned char *ob = o;
 150         size_t n = 0;
 151
 152         if (b->val != -1)
 153                 ob[n++] = b->queue | b->val << b->nbits;
 154         b->queue = 0;
 155         b->nbits = 0;
 156         b->val = -1;
 157
 158         return n;
 159 }