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October 13, 2012 10:49
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/* | |
* basE91 encoding/decoding routines | |
* | |
* Copyright (c) 2000-2006 Joachim Henke | |
* All rights reserved. | |
* | |
* Redistribution and use in source and binary forms, with or without | |
* modification, are permitted provided that the following conditions are met: | |
* | |
* - Redistributions of source code must retain the above copyright notice, | |
* this list of conditions and the following disclaimer. | |
* - Redistributions in binary form must reproduce the above copyright notice, | |
* this list of conditions and the following disclaimer in the documentation | |
* and/or other materials provided with the distribution. | |
* - Neither the name of Joachim Henke nor the names of his contributors may | |
* be used to endorse or promote products derived from this software without | |
* specific prior written permission. | |
* | |
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE | |
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
* POSSIBILITY OF SUCH DAMAGE. | |
*/ | |
#include "base91.h" | |
const unsigned char enctab[91] = { | |
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', | |
'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', | |
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', | |
'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', | |
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '!', '#', '$', | |
'%', '&', '(', ')', '*', '+', ',', '.', '/', ':', ';', '<', '=', | |
'>', '?', '@', '[', ']', '^', '_', '`', '{', '|', '}', '~', '"' | |
}; | |
const unsigned char dectab[256] = { | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, | |
91, 62, 90, 63, 64, 65, 66, 91, 67, 68, 69, 70, 71, 91, 72, 73, | |
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 74, 75, 76, 77, 78, 79, | |
80, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, | |
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 81, 91, 82, 83, 84, | |
85, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, | |
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 86, 87, 88, 89, 91, | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, | |
91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91 | |
}; | |
void basE91_init(struct basE91 *b) | |
{ | |
b->queue = 0; | |
b->nbits = 0; | |
b->val = -1; | |
} | |
size_t basE91_encode(struct basE91 *b, const void *i, size_t len, void *o) | |
{ | |
const unsigned char *ib = i; | |
unsigned char *ob = o; | |
size_t n = 0; | |
while (len--) { | |
b->queue |= *ib++ << b->nbits; | |
b->nbits += 8; | |
if (b->nbits > 13) { /* enough bits in queue */ | |
unsigned int val = b->queue & 8191; | |
if (val > 88) { | |
b->queue >>= 13; | |
b->nbits -= 13; | |
} else { /* we can take 14 bits */ | |
val = b->queue & 16383; | |
b->queue >>= 14; | |
b->nbits -= 14; | |
} | |
ob[n++] = enctab[val % 91]; | |
ob[n++] = enctab[val / 91]; | |
} | |
} | |
return n; | |
} | |
/* process remaining bits from bit queue; write up to 2 bytes */ | |
size_t basE91_encode_end(struct basE91 *b, void *o) | |
{ | |
unsigned char *ob = o; | |
size_t n = 0; | |
if (b->nbits) { | |
ob[n++] = enctab[b->queue % 91]; | |
if (b->nbits > 7 || b->queue > 90) | |
ob[n++] = enctab[b->queue / 91]; | |
} | |
b->queue = 0; | |
b->nbits = 0; | |
b->val = -1; | |
return n; | |
} | |
size_t basE91_decode(struct basE91 *b, const void *i, size_t len, void *o) | |
{ | |
const unsigned char *ib = i; | |
unsigned char *ob = o; | |
size_t n = 0; | |
unsigned int d; | |
while (len--) { | |
d = dectab[*ib++]; | |
if (d == 91) | |
continue; /* ignore non-alphabet chars */ | |
if (b->val == -1) | |
b->val = d; /* start next value */ | |
else { | |
b->val += d * 91; | |
b->queue |= b->val << b->nbits; | |
b->nbits += (b->val & 8191) > 88 ? 13 : 14; | |
do { | |
ob[n++] = b->queue; | |
b->queue >>= 8; | |
b->nbits -= 8; | |
} while (b->nbits > 7); | |
b->val = -1; /* mark value complete */ | |
} | |
} | |
return n; | |
} | |
/* process remaining bits; write at most 1 byte */ | |
size_t basE91_decode_end(struct basE91 *b, void *o) | |
{ | |
unsigned char *ob = o; | |
size_t n = 0; | |
if (b->val != -1) | |
ob[n++] = b->queue | b->val << b->nbits; | |
b->queue = 0; | |
b->nbits = 0; | |
b->val = -1; | |
return n; | |
} |
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