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113 lines
3.8 KiB
C
113 lines
3.8 KiB
C
/* block.h -- block transfer
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*
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* Copyright (C) 2010--2012 Olaf Bergmann <bergmann@tzi.org>
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*
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* This file is part of the CoAP library libcoap. Please see
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* README for terms of use.
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*/
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#ifndef _COAP_BLOCK_H_
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#define _COAP_BLOCK_H_
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#include "option.h"
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#include "encode.h"
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#include "pdu.h"
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/**
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* @defgroup block Block Transfer
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* @{
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*/
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/**
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* Structure of Block options.
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*/
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typedef struct {
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unsigned int num:20; /**< block number */
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unsigned int m:1; /**< 1 if more blocks follow, 0 otherwise */
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unsigned int szx:3; /**< block size */
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} coap_block_t;
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/** Returns the value of the least significant byte of a Block option @p opt. */
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#define COAP_OPT_BLOCK_LAST(opt) ( COAP_OPT_VALUE(opt) + (COAP_OPT_LENGTH(opt) - 1) )
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/** Returns the value of the More-bit of a Block option @p opt. */
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#define COAP_OPT_BLOCK_MORE(opt) ( *COAP_OPT_BLOCK_LAST(opt) & 0x08 )
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/** Returns the value of the SZX-field of a Block option @p opt. */
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#define COAP_OPT_BLOCK_SZX(opt) ( *COAP_OPT_BLOCK_LAST(opt) & 0x07 )
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/** Implementation of COAP_OPT_BLOCK_NUM */
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static inline unsigned int
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_coap_block_num_impl(const coap_opt_t *block_opt) {
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unsigned int num = 0;
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if (COAP_OPT_LENGTH(block_opt) > 1)
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num = coap_decode_var_bytes(COAP_OPT_VALUE(block_opt),
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COAP_OPT_LENGTH(block_opt) - 1);
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return (num << 4) | ((*COAP_OPT_BLOCK_LAST(block_opt) & 0xF0) >> 4);
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}
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/** Returns the value of field @c num in the given block option @p Block. */
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#define COAP_OPT_BLOCK_NUM(Block) _coap_block_num_impl(Block)
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/**
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* Checks if more than @p num blocks are required to deliver @p data_len
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* bytes of data for a block size of 1 << (@p szx + 4).
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*/
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static inline int
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coap_more_blocks(size_t data_len, unsigned int num, unsigned short szx) {
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return ((num+1) << (szx + 4)) < data_len;
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}
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/** Sets the More-bit in @p block_opt */
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static inline void
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coap_opt_block_set_m(coap_opt_t *block_opt, int m) {
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if (m)
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*(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) |= 0x08;
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else
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*(COAP_OPT_VALUE(block_opt) + (COAP_OPT_LENGTH(block_opt) - 1)) &= ~0x08;
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}
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/**
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* Writes a block option of type @p type to message @p pdu. If the
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* requested block size is too large to fit in @p pdu, it is reduced
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* accordingly. An exception is made for the final block when less
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* space is required. The actual length of the resource is specified
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* in @p data_length.
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*
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* This function may change **block_req and/or *block_req to reflect the
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* values written to @p pdu. As the function takes into consideration
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* the remaining space @p pdu, no more options should be added after
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* coap_write_block_opt() has returned.
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*
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* @param block_req Points to a pointer to the requested block. On
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* return, this object is updated to point to a
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* block option with the same content as in @p pdu
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* @param type COAP_OPTION_BLOCK1 or COAP_OPTION_BLOCK2
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* @param pdu The message where the block option should be
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* written.
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* @param data_length The length of the actual data that will be added
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* the @p pdu by calling coap_add_block().
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* @return @c 1 on success, or a negative value on error.
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*/
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int coap_write_block_opt(coap_opt_t **block_req, unsigned short type,
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coap_pdu_t *pdu, size_t data_length);
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/**
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* Adds the @p block_num block of size 1 << (@p block_szx + 4) from
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* source @p data to @p pdu.
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*
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* @param pdu The message to add the block
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* @param len The length of @p data.
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* @param data The source data to fill the block with
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* @param block_num The actual block number
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* @param block_szx Encoded size of block @p block_number
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* @return @c 1 on success, @c 0 otherwise.
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*/
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int coap_add_block(coap_pdu_t *pdu, unsigned int len, const unsigned char *data,
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unsigned int block_num, unsigned char block_szx);
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/**@}*/
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#endif /* _COAP_BLOCK_H_ */
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