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/* ISO7816-3 Fi/Di tables + computation */
/* (C) 2010-2015 by Harald Welte <hwelte@hmw-consulting.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU 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
*
*/
#include <stdint.h>
#include <errno.h>
#include "utils.h"
#include "iso7816_fidi.h"
/* Table 7 of ISO 7816-3:2006 */
static const uint16_t fi_table[] = {
372, 372, 558, 744, 1116, 1488, 1860, 0,
0, 512, 768, 1024, 1536, 2048, 0, 0
};
/* Table 8 from ISO 7816-3:2006 */
static const uint8_t di_table[] = {
0, 1, 2, 4, 8, 16, 32, 64,
12, 20, 2, 4, 8, 16, 32, 64,
};
/* compute the F/D ratio based on Fi and Di values */
int compute_fidi_ratio(uint8_t fi, uint8_t di)
{
uint16_t f, d;
int ret;
if (fi >= ARRAY_SIZE(fi_table) ||
di >= ARRAY_SIZE(di_table))
return -EINVAL;
f = fi_table[fi];
if (f == 0)
return -EINVAL;
d = di_table[di];
if (d == 0)
return -EINVAL;
/* See table 7 of ISO 7816-3: From 1000 on we divide by 1/d,
* which equals a multiplication by d */
if (di < 8)
ret = f / d;
else
ret = f * d;
return ret;
}
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