block.h

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/* block.h -- block transfer
 *
 * Copyright (C) 2010--2012,2014 Olaf Bergmann <bergmann@tzi.org>
 *
 * This file is part of the CoAP library libcoap. Please see
 * README for terms of use. 
 */

#ifndef _COAP_BLOCK_H_
#define _COAP_BLOCK_H_

#include "option.h"
#include "encode.h"
#include "pdu.h"

#ifndef COAP_MAX_BLOCK_SZX

#define COAP_MAX_BLOCK_SZX      4
#endif /* COAP_MAX_BLOCK_SZX */

#if (COAP_MAX_PDU_SIZE - 6) < (1 << (COAP_MAX_BLOCK_SZX + 4))
#error "COAP_MAX_BLOCK_SZX too large"
#endif

typedef struct {
  unsigned int num:20;      
  unsigned int m:1;     
  unsigned int szx:3;       
} coap_block_t;

#define COAP_OPT_BLOCK_LAST(opt) \
  (COAP_OPT_LENGTH(opt) ? (COAP_OPT_VALUE(opt) + (COAP_OPT_LENGTH(opt)-1)) : 0)

#define COAP_OPT_BLOCK_MORE(opt) \
  (COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x08) : 0)

#define COAP_OPT_BLOCK_SZX(opt)  \
  (COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x07) : 0)

unsigned int coap_opt_block_num(const coap_opt_t *block_opt);

static inline int
coap_more_blocks(size_t data_len, unsigned int num, unsigned short szx) {
  return ((num+1) << (szx + 4)) < data_len;
}

static inline void
coap_opt_block_set_m(coap_opt_t *block_opt, int m) {
  if (m)
    *(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) |= 0x08;
  else
    *(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) &= ~0x08;
}

int coap_get_block(coap_pdu_t *pdu, unsigned short type, coap_block_t *block);

int coap_write_block_opt(coap_block_t *block, unsigned short type,
             coap_pdu_t *pdu, size_t data_length);

int coap_add_block(coap_pdu_t *pdu, unsigned int len, const unsigned char *data,
           unsigned int block_num, unsigned char block_szx);
#endif /* _COAP_BLOCK_H_ */