/* encode.h -- encoding and decoding of CoAP data types
 *
 * Copyright (C) 2010 Olaf Bergmann <bergmann@tzi.org>, Carsten Bormann
 * 
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#ifndef _COAP_ENCODE_H_
#define _COAP_ENCODE_H_

#if (BSD >= 199103)
# include <string.h>
#else
# include <strings.h>
#endif

#define N 8
#define E 4
#define HIBIT (1 << (N - 1))
#define EMASK ((1 << E) - 1)
#define MMASK ((1 << N) - 1 - EMASK)
#define MAX_VALUE ( (1 << N) - (1 << E) ) * (1 << ((1 << E) - 1))

#define COAP_PSEUDOFP_DECODE_8_4(r) (r < HIBIT ? r : (r & MMASK) << (r & EMASK))

#ifndef HAVE_FLS
/* include this only if fls() is not available */
extern int coap_fls(unsigned int i);
#else
#define coap_fls(i) fls(i)
#endif

/* ls and s must be integer variables */
#define COAP_PSEUDOFP_ENCODE_8_4_DOWN(v,ls) (v < HIBIT ? v : (ls = coap_fls(v) - N, (v >> ls) & MMASK) + ls)
#define COAP_PSEUDOFP_ENCODE_8_4_UP(v,ls,s) (v < HIBIT ? v : (ls = coap_fls(v) - N, (s = (((v + ((1<<E<<ls)-1)) >> ls) & MMASK)), s == 0 ? HIBIT + ls + 1 : s + ls))

/** 
 * Decodes multiple-length byte sequences. buf points to an input byte
 * sequence of length len. Returns the decoded value.
 */
unsigned int coap_decode_var_bytes(unsigned char *buf,unsigned int len);

/** 
 * Encodes multiple-length byte sequences. buf points to an output
 * buffer of sufficient length to store the encoded bytes. val is
 * the value to encode. Returns the number of bytes used to encode
 * val or 0 on error.
 */
unsigned int coap_encode_var_bytes(unsigned char *buf, unsigned int val);

#endif /* _COAP_ENCODE_H_ */