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/*
ASN.1 routines, implementation for libdvben50221
an implementation for the High Level Common Interface
Copyright (C) 2004, 2005 Manu Abraham (manu@kromtek.com)
Copyright (C) 2006 Andrew de Quincey (adq_dvb@lidskialf.net)
This library 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 library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdio.h>
#include "asn_1.h"
int asn_1_decode(uint16_t *length, uint8_t *asn_1_array, uint32_t asn_1_array_len)
{
uint8_t length_field;
if (asn_1_array_len < 1)
return -1;
length_field = asn_1_array[0];
if (length_field < 0x80) {
// there is only one word
*length = length_field & 0x7f;
return 1;
} else if (length_field == 0x81) {
if (asn_1_array_len < 2)
return -1;
*length = asn_1_array[1];
return 2;
} else if (length_field == 0x82) {
if (asn_1_array_len < 3)
return -1;
*length = (asn_1_array[1] << 8) | asn_1_array[2];
return 3;
}
return -1;
}
int asn_1_encode(uint16_t length, uint8_t *asn_1_array, uint32_t asn_1_array_len)
{
if (length < 0x80) {
if (asn_1_array_len < 1)
return -1;
asn_1_array[0] = length & 0x7f;
return 1;
} else if (length < 0x100) {
if (asn_1_array_len < 2)
return -1;
asn_1_array[0] = 0x81;
asn_1_array[1] = length;
return 2;
} else {
if (asn_1_array_len < 3)
return -1;
asn_1_array[0] = 0x82;
asn_1_array[1] = length >> 8;
asn_1_array[2] = length;
return 3;
}
// never reached
}
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