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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 "zbase32.h"
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h> /* XXX only for debug printfs */
static const char*const chars="ybndrfg8ejkmcpqxot1uwisza345h769";
/* Types from zstr */
/**
* A zstr is simply an unsigned int length and a pointer to a buffer of
* unsigned chars.
*/
typedef struct {
size_t len; /* the length of the string (not counting the null-terminating character) */
unsigned char* buf; /* pointer to the first byte */
} zstr;
/**
* A zstr is simply an unsigned int length and a pointer to a buffer of
* const unsigned chars.
*/
typedef struct {
size_t len; /* the length of the string (not counting the null-terminating character) */
const unsigned char* buf; /* pointer to the first byte */
} czstr;
/* Functions from zstr */
static zstr
new_z(const size_t len)
{
zstr result;
result.buf = (unsigned char *)malloc(len+1);
if (result.buf == NULL) {
result.len = 0;
return result;
}
result.len = len;
result.buf[len] = '\0';
return result;
}
/* Functions from zutil */
static size_t
divceil(size_t n, size_t d)
{
return n/d+((n%d)!=0);
}
static 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 */
if (result.buf == NULL)
return result;
unsigned char* resp = result.buf + result.len; /* pointer into the result buffer, initially pointing to the "one-past-the-end" quintet */
const unsigned char* 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;
}
static zstr b2a_l(const czstr os, const size_t lengthinbits)
{
return b2a_l_extra_Duffy(os, lengthinbits);
}
static zstr b2a(const czstr os)
{
return b2a_l(os, os.len*8);
}
char *
zbase32_encode(const unsigned char *data, size_t length)
{
czstr input = { length, data };
zstr output = b2a(input);
return (char *)output.buf;
}
/**
* 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.
*/
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