Block Transfer

Data Structures
struct	coap_block_t
	Structure of Block options. More...

Macros
#define	COAP_MAX_BLOCK_SZX   4
	The largest value for the SZX component in a Block option. More...
#define	COAP_OPT_BLOCK_LAST(opt)   (COAP_OPT_LENGTH(opt) ? (COAP_OPT_VALUE(opt) + (COAP_OPT_LENGTH(opt)-1)) : 0)
	Returns the value of the least significant byte of a Block option opt. More...
#define	COAP_OPT_BLOCK_MORE(opt)   (COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x08) : 0)
	Returns the value of the More-bit of a Block option opt. More...
#define	COAP_OPT_BLOCK_SZX(opt)   (COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x07) : 0)
	Returns the value of the SZX-field of a Block option opt. More...

Functions
unsigned int	coap_opt_block_num (const coap_opt_t *block_opt)
	Returns the value of field num in the given block option block_opt. More...
static int	coap_more_blocks (size_t data_len, unsigned int num, unsigned short szx)
	Checks if more than num blocks are required to deliver data_len bytes of data for a block size of 1 << (szx + 4). More...
static void	coap_opt_block_set_m (coap_opt_t *block_opt, int m)
	Sets the More-bit in block_opt. More...
int	coap_get_block (coap_pdu_t *pdu, unsigned short type, coap_block_t *block)
	Initializes block from pdu. More...
int	coap_write_block_opt (coap_block_t *block, unsigned short type, coap_pdu_t *pdu, size_t data_length)
	Writes a block option of type type to message pdu. More...
int	coap_add_block (coap_pdu_t *pdu, unsigned int len, const unsigned char *data, unsigned int block_num, unsigned char block_szx)
	Adds the block_num block of size 1 << (block_szx + 4) from source data to pdu. More...

Detailed Description

Macro Definition Documentation

COAP_MAX_BLOCK_SZX

#define COAP_MAX_BLOCK_SZX   4

The largest value for the SZX component in a Block option.

Note that 1 << (COAP_MAX_BLOCK_SZX + 4) should not exceed COAP_MAX_PDU_SIZE.

Definition at line 27 of file block.h.

COAP_OPT_BLOCK_LAST

#define COAP_OPT_BLOCK_LAST

(

opt

)

(COAP_OPT_LENGTH(opt) ? (COAP_OPT_VALUE(opt) + (COAP_OPT_LENGTH(opt)-1)) : 0)

Returns the value of the least significant byte of a Block option opt.

For zero-length options (i.e. num == m == szx == 0), COAP_OPT_BLOCK_LAST returns NULL.

Definition at line 44 of file block.h.

COAP_OPT_BLOCK_MORE

#define COAP_OPT_BLOCK_MORE

(

opt

)

(COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x08) : 0)

Returns the value of the More-bit of a Block option opt.

Definition at line 48 of file block.h.

COAP_OPT_BLOCK_SZX

#define COAP_OPT_BLOCK_SZX

(

opt

)

(COAP_OPT_LENGTH(opt) ? (*COAP_OPT_BLOCK_LAST(opt) & 0x07) : 0)

Returns the value of the SZX-field of a Block option opt.

Definition at line 52 of file block.h.

Function Documentation

coap_add_block()

int coap_add_block	(	coap_pdu_t *	pdu,
		unsigned int	len,
		const unsigned char *	data,
		unsigned int	block_num,
		unsigned char	block_szx
	)

Adds the block_num block of size 1 << (block_szx + 4) from source data to pdu.

Parameters

pdu	The message to add the block.
len	The length of data.
data	The source data to fill the block with.
block_num	The actual block number.
block_szx	Encoded size of block block_number.

Returns

1 on success, 0 otherwise.

Definition at line 128 of file block.c.

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coap_get_block()

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

Initializes block from pdu.

type must be either COAP_OPTION_BLOCK1 or COAP_OPTION_BLOCK2. When option type was found in pdu, block is initialized with values from this option and the function returns the value 1. Otherwise, 0 is returned.

Parameters

pdu	The pdu to search for option type.
type	The option to search for (must be COAP_OPTION_BLOCK1 or COAP_OPTION_BLOCK2).
block	The block structure to initilize.

Returns

1 on success, 0 otherwise.

Definition at line 45 of file block.c.

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coap_more_blocks()

static int coap_more_blocks ( size_t  data_len, unsigned int  num, unsigned short  szx  )

inlinestatic

Checks if more than num blocks are required to deliver data_len bytes of data for a block size of 1 << (szx + 4).

Definition at line 65 of file block.h.

coap_opt_block_num()

unsigned int coap_opt_block_num

(

const coap_opt_t *

block_opt

)

Returns the value of field num in the given block option block_opt.

Definition at line 26 of file block.c.

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coap_opt_block_set_m()

static void coap_opt_block_set_m ( coap_opt_t *  block_opt, int  m  )

inlinestatic

Sets the More-bit in block_opt.

Definition at line 71 of file block.h.

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coap_write_block_opt()

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

Writes a block option of type type to message pdu.

If the requested block size is too large to fit in pdu, it is reduced accordingly. An exception is made for the final block when less space is required. The actual length of the resource is specified in data_length.

This function may change *block to reflect the values written to pdu. As the function takes into consideration the remaining space pdu, no more options should be added after coap_write_block_opt() has returned.

Parameters

block	The block structure to use. On return, this object is updated according to the values that have been written to pdu.
type	COAP_OPTION_BLOCK1 or COAP_OPTION_BLOCK2.
pdu	The message where the block option should be written.
data_length	The length of the actual data that will be added the pdu by calling coap_add_block().

Returns

1 on success, or a negative value on error.

Definition at line 73 of file block.c.

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