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/*
* gnome-keyring
*
* Copyright (C) 2011 Collabora Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*
* Author: Stef Walter <stefw@collabora.co.uk>
*/
#include "config.h"
#include "egg-decimal.h"
#include <string.h>
gpointer
egg_decimal_decode (const gchar *data,
gssize n_data,
gsize *n_decoded)
{
gboolean saw_non_zero = FALSE;
guint8 *digits = NULL;
guint n_digits = 0;
guchar *usg;
gchar ch;
guint carry;
guint i;
guint cleared;
guchar *at_byte;
guint at_bit;
gsize length;
g_return_val_if_fail (data, NULL);
if (n_data < 0)
n_data = strlen (data);
/* Convert everything to an array of digits */
digits = g_new0 (guint8, n_data);
for (i = 0; i < n_data; i++) {
ch = data[i];
if (ch < '0' || ch > '9') {
g_free (digits);
return NULL;
} else if (ch != '0' || saw_non_zero) {
digits[n_digits] = ch - '0';
n_digits++;
saw_non_zero = TRUE;
}
}
usg = g_new0 (guchar, n_data);
cleared = 0;
at_byte = usg + n_data - 1;
at_bit = 0;
/* for every digit ... */
while (cleared < n_digits) {
/* ... store the bit depending on whether last digit is odd */
guchar bit = (digits[n_digits - 1] % 2);
*at_byte |= (bit << at_bit);
if (at_bit++ == 7) {
at_bit = 0;
at_byte--;
g_assert (at_byte >= usg);
}
/* ... divide digits by two */
carry = 0;
for (i = cleared; i < n_digits; i++) {
gboolean odd = (digits[i] % 2);
digits[i] = digits[i] / 2 + carry;
carry = odd ? 5 : 0;
if (i == cleared && digits[i] == 0)
cleared++;
}
}
if (at_bit == 0)
at_byte++;
length = n_data - (at_byte - usg);
memmove (usg, at_byte, length);
if (n_decoded)
*n_decoded = length;
return usg;
}
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