/*
* Copyright (C) 2009 J.A.Bezemer@opensourcepartners.nl
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* raw 76543210 76543210 76543210 76543210 76543210 76543210 76543210
* enc 65432106 54321065 43210654 32106543 21065432 10654321 06543210
* ^ ^ ^ ^ ^ ^ ^ ^
*
* 0001 1 0001 1
* 0011 3 0011 3
* 0111 7 0111 7
* 1111 f 0110 6
* 1110 e 0100 4
* 1100 c
* 1000 8
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "encoding.h"
#define BASE128_BLKSIZE_RAW 7
#define BASE128_BLKSIZE_ENC 8
/* Don't use '-' (restricted to middle of labels), prefer iso_8859-1
* accent chars since they might readily be entered in normal use,
* don't use 254-255 because of possible function overloading in DNS systems.
*/
static const unsigned char cb128[] =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
"\274\275\276\277"
"\300\301\302\303\304\305\306\307\310\311\312\313\314\315\316\317"
"\320\321\322\323\324\325\326\327\330\331\332\333\334\335\336\337"
"\340\341\342\343\344\345\346\347\350\351\352\353\354\355\356\357"
"\360\361\362\363\364\365\366\367\370\371\372\373\374\375";
static unsigned char rev128[256];
static int reverse_init = 0;
inline static void base128_reverse_init(void)
{
int i;
unsigned char c;
if (!reverse_init) {
memset (rev128, 0, 256);
for (i = 0; i < 128; i++) {
c = cb128[i];
rev128[(int) c] = i;
}
reverse_init = 1;
}
}
/*
* Fills *buf with max. *buflen characters, encoding size bytes of *data.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold the trailing '\0'.
*
* return value : #bytes filled in buf (excluding \0)
* sets *buflen to : #bytes encoded from data
*/
static int base128_encode(char *buf, size_t *buflen, const void *data,
size_t size)
{
unsigned char *ubuf = (unsigned char *) buf;
unsigned char *udata = (unsigned char *) data;
int iout = 0; /* to-be-filled output char */
int iin = 0; /* one more than last input byte that can be
successfully decoded */
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
while (1) {
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0xfe) >> 1)];
iout++;
if (iout >= *buflen || iin >= size) {
iout--; /* previous char is useless */
break;
}
ubuf[iout] = cb128[((udata[iin] & 0x01) << 6) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xfc) >> 2) : 0)];
iin++; /* 0 complete, iin=1 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x03) << 5) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xf8) >> 3) : 0)];
iin++; /* 1 complete, iin=2 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x07) << 4) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xf0) >> 4) : 0)];
iin++; /* 2 complete, iin=3 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x0f) << 3) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xe0) >> 5) : 0)];
iin++; /* 3 complete, iin=4 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x1f) << 2) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xc0) >> 6) : 0)];
iin++; /* 4 complete, iin=5 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[((udata[iin] & 0x3f) << 1) |
((iin + 1 < size) ?
((udata[iin + 1] & 0x80) >> 7) : 0)];
iin++; /* 5 complete, iin=6 */
iout++;
if (iout >= *buflen || iin >= size)
break;
ubuf[iout] = cb128[(udata[iin] & 0x7f)];
iin++; /* 6 complete, iin=7 */
iout++;
}
ubuf[iout] = '\0';
/* store number of bytes from data that was used */
*buflen = iin;
return iout;
}
#define REV128(x) rev128[(int) (x)]
/*
* Fills *buf with max. *buflen bytes, decoded from slen chars in *str.
* Decoding stops early when *str contains \0.
* Illegal encoded chars are assumed to decode to zero.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold a trailing '\0' that is added (though *buf will usually
* contain full-binary data).
*
* return value : #bytes filled in buf (excluding \0)
*/
static int base128_decode(void *buf, size_t *buflen, const char *str,
size_t slen)
{
unsigned char *ustr = (unsigned char *) str;
unsigned char *ubuf = (unsigned char *) buf;
int iout = 0; /* to-be-filled output byte */
int iin = 0; /* next input char to use in decoding */
base128_reverse_init ();
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
while (1) {
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x7f) << 1) |
((REV128(ustr[iin + 1]) & 0x40) >> 6);
iin++; /* 0 used up, iin=1 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x3f) << 2) |
((REV128(ustr[iin + 1]) & 0x60) >> 5);
iin++; /* 1 used up, iin=2 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x1f) << 3) |
((REV128(ustr[iin + 1]) & 0x70) >> 4);
iin++; /* 2 used up, iin=3 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x0f) << 4) |
((REV128(ustr[iin + 1]) & 0x78) >> 3);
iin++; /* 3 used up, iin=4 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x07) << 5) |
((REV128(ustr[iin + 1]) & 0x7c) >> 2);
iin++; /* 4 used up, iin=5 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x03) << 6) |
((REV128(ustr[iin + 1]) & 0x7e) >> 1);
iin++; /* 5 used up, iin=6 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV128(ustr[iin]) & 0x01) << 7) |
((REV128(ustr[iin + 1]) & 0x7f));
iin += 2; /* 6,7 used up, iin=8 */
iout++;
}
ubuf[iout] = '\0';
return iout;
}
const struct encoder base128_ops = {
.name = "Base128",
.encode = base128_encode,
.decode = base128_decode,
.places_dots = false,
.eats_dots = false,
.blocksize_raw = BASE128_BLKSIZE_RAW,
.blocksize_encoded = BASE128_BLKSIZE_ENC,
};