diff options
Diffstat (limited to 'firmware/libcommon/source/iso7816_fidi.c')
-rw-r--r-- | firmware/libcommon/source/iso7816_fidi.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/firmware/libcommon/source/iso7816_fidi.c b/firmware/libcommon/source/iso7816_fidi.c new file mode 100644 index 0000000..b35f068 --- /dev/null +++ b/firmware/libcommon/source/iso7816_fidi.c @@ -0,0 +1,64 @@ +/* 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; +} |