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base32.c
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base32.c
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/**
* copyright 2002, 2003 Bryce "Zooko" Wilcox-O'Hearn
* mailto:zooko@zooko.com
*
* See the end of this file for the free software, open source license (BSD-style).
*/
#include "base32.h"
#include <math.h>
#include <string.h>
#include <stdio.h> /* XXX only for debug printfs */
static const char*const chars="ybndrfg8ejkmcpqxot1uwisza345h769";
/* revchars: index into this table with the ASCII value of the char. The result is the value of that quintet. */
static const zbyte revchars[]={ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 18, 255, 25, 26, 27, 30, 29, 7, 31, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 24, 1, 12, 3, 8, 5, 6, 28, 21, 9, 10, 255, 11, 2, 16, 13, 14, 4, 22, 17, 19, 255, 20, 15, 0, 23, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, };
#undef b2alen
size_t const b2alen(const size_t lengthinbits)
{
return divceil(lengthinbits, 5);
}
#undef B2ALEN
size_t const B2ALEN(const size_t lengthinbits)
{
return divceil(lengthinbits, 5);
}
zstr b2a(const czstr os)
{
return b2a_l(os, os.len*8);
}
#undef B2A
zstr B2A(const czstr os)
{
return b2a_l(os, os.len*8);
}
zstr b2a_l(const czstr os, const size_t lengthinbits)
{
return b2a_l_extra_Duffy(os, lengthinbits);
}
zstr b2a_l_extra_Duffy(const czstr os, const size_t lengthinbits)
{
zstr result = new_z(DIVCEIL(os.len*8, 5)); /* if lengthinbits is not a multiple of 8 then this is allocating space for 0, 1, or 2 extra quintets that will be truncated at the end of this function if they are not needed */
#ifndef Z_EXHAUST_EXIT
if (result.buf == NULL)
return result;
#endif /* #ifndef Z_EXHAUST_EXIT */
zbyte* resp = result.buf + result.len; /* pointer into the result buffer, initially pointing to the "one-past-the-end" quintet */
const zbyte* osp = os.buf + os.len; /* pointer into the os buffer, initially pointing to the "one-past-the-end" octet */
/* Now this is a real live Duff's device. You gotta love it. */
unsigned long x=0; /* to hold up to 32 bits worth of the input */
switch ((osp - os.buf) % 5) {
case 0:
do {
x = *--osp;
*--resp = chars[x % 32]; /* The least sig 5 bits go into the final quintet. */
x /= 32; /* ... now we have 3 bits worth in x... */
case 4:
x |= ((unsigned long)(*--osp)) << 3; /* ... now we have 11 bits worth in x... */
*--resp = chars[x % 32];
x /= 32; /* ... now we have 6 bits worth in x... */
*--resp = chars[x % 32];
x /= 32; /* ... now we have 1 bits worth in x... */
case 3:
x |= ((unsigned long)(*--osp)) << 1; /* The 8 bits from the 2-indexed octet. So now we have 9 bits worth in x... */
*--resp = chars[x % 32];
x /= 32; /* ... now we have 4 bits worth in x... */
case 2:
x |= ((unsigned long)(*--osp)) << 4; /* The 8 bits from the 1-indexed octet. So now we have 12 bits worth in x... */
*--resp = chars[x%32];
x /= 32; /* ... now we have 7 bits worth in x... */
*--resp = chars[x%32];
x /= 32; /* ... now we have 2 bits worth in x... */
case 1:
x |= ((unsigned long)(*--osp)) << 2; /* The 8 bits from the 0-indexed octet. So now we have 10 bits worth in x... */
*--resp = chars[x%32];
x /= 32; /* ... now we have 5 bits worth in x... */
*--resp = chars[x];
} while (osp > os.buf);
} /* switch ((osp - os.buf) % 5) */
/* truncate any unused trailing zero quintets */
result.len = DIVCEIL(lengthinbits, 5);
result.buf[result.len] = '\0';
return result;
}
zstr a2b(const czstr cs)
{
return a2b_l(cs, ((cs.len*5+3)/8)*8);
}
#undef A2B
zstr A2B(const czstr cs)
{
return a2b_l(cs, ((cs.len*5+3)/8)*8);
}
zstr a2b_l(const czstr cs, const size_t lengthinbits)
{
return a2b_l_very_Duffy(cs, lengthinbits);
}
zstr a2b_l_very_Duffy(const czstr cs, const size_t lengthinbits)
{
unsigned long x=0; /* to hold up to 32 bits worth of the input */
zstr result = new_z(divceil(cs.len*5, 8)); /* if lengthinbits is not a multiple of 5 then this is allocating space for 0 or 1 extra octets that will be truncated at the end of this function if they are not needed */
#ifndef Z_EXHAUST_EXIT
if (result.buf == NULL)
return result;
#endif /* #ifndef Z_EXHAUST_EXIT */
zbyte* resp = result.buf + result.len; /* pointer into the result buffer, initially pointing to the "one-past-the-end" octet */
const zbyte* csp = cs.buf + cs.len; /* pointer into the cs buffer, initially pointing to the "one-past-the-end" character */
fflush(stdout);
/* Now this is a real live Duff's device. You gotta love it. */
switch ((csp - cs.buf) % 8) {
case 0:
fflush(stdout);
do {
fflush(stdout);
x = revchars[*--csp]; /* 5 bits... */
case 7:
fflush(stdout);
x |= revchars[*--csp] << 5; /* 10 bits... */
*--resp = x % 256;
x /= 256; /* 2 bits... */
case 6:
fflush(stdout);
x |= revchars[*--csp] << 2; /* 7 bits... */
case 5:
fflush(stdout);
x |= revchars[*--csp] << 7; /* 12 bits... */
*--resp = x % 256;
x /= 256; /* 4 bits... */
case 4:
x |= revchars[*--csp] << 4; /* 9 bits... */
*--resp = x % 256;
fflush(stdout);
x /= 256; /* 1 bit... */
case 3:
x |= revchars[*--csp] << 1; /* 6 bits... */
fflush(stdout);
case 2:
x |= revchars[*--csp] << 6; /* 11 bits... */
*--resp = x % 256;
fflush(stdout);
x /= 256; /* 3 bits... */
case 1:
x |= revchars[*--csp] << 3; /* 8 bits... */
*--resp = x % 256;
fflush(stdout);
} while (csp > cs.buf);
} /* switch ((csp - cs.buf) % 8) */
/* truncate any unused trailing zero octets */
result.len = DIVCEIL(lengthinbits, 8);
result.buf[result.len] = '\0';
return result;
}
/**
* Copyright (c) 2002 Bryce "Zooko" Wilcox-O'Hearn
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software to deal in this software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of this software, and to permit
* persons to whom this software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of this software.
*
* THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THIS SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THIS SOFTWARE.
*/