Pipe IPC

Generic pipe implementation. More...

Detailed Description

Generic pipe implementation.

This pipe implementation is a tight wrapper around a ringbuffer. It sends the calling thread to sleep if the ringbuffer is full or empty, respectively. It can be used in ISRs, too.

Files
file	pipe.h

Data Structures
struct	riot_pipe
	A generic pipe. More...

Macros
#define	PIPE_BUF   (128)
	Size of a dynamically malloc'd pipe.

Typedefs
typedef struct riot_pipe	pipe_t
	A generic pipe.

Functions
void	pipe_init (pipe_t *pipe, ringbuffer_t *rb, void(*free)(void *))
	Initialize a pipe. More...
ssize_t	pipe_read (pipe_t *pipe, void *buf, size_t n)
	Read from a pipe. More...
ssize_t	pipe_write (pipe_t *pipe, const void *buf, size_t n)
	Write to a pipe. More...
pipe_t *	pipe_malloc (unsigned size)
	Dynamically allocate a pipe with room for size bytes. More...
void	pipe_free (pipe_t *rp)
	Free a pipe. More...

Function Documentation

pipe_free()

void pipe_free

(

pipe_t *

rp

)

Free a pipe.

On statically allocated pipes you do not have to call this function. Most likely you will only need this function in junction with pipe_malloc().

Parameters

rp	Pipe to free.

pipe_init()

void pipe_init	(	pipe_t *	pipe,
		ringbuffer_t *	rb,
		void(*)(void *)	free
	)

Initialize a pipe.

Parameters

[out]	pipe	Datum to initialize.
	rb	Ringbuffer to use. Needs to be initialized!
	free	Function to call by pipe_free(). Used like pipe->free(pipe). Should be NULL for statically allocated pipes.

pipe_malloc()

pipe_t* pipe_malloc

(

unsigned

size

)

Dynamically allocate a pipe with room for size bytes.

This function uses malloc() and may break real-time behaviors. Try not to use this function.

Parameters

size	Size of the underlying ringbuffer to allocate.

Returns

Newly allocated pipe. NULL if the memory is exhausted.

pipe_read()

ssize_t pipe_read	(	pipe_t *	pipe,
		void *	buf,
		size_t	n
	)

Read from a pipe.

Only one thread may access the pipe readingly at once. If the pipe is empty, then the current thread is send sleeping. It gets woken up once there is data ready in the pipe. In an ISR (irq_is_in()) 0 will returned if the pipe is empty.

Parameters

[in]	pipe	Pipe to read from.
[out]	buf	Buffer to write into
	n	Size of buffer.

Returns

> 0 if data could be read. == 0 if the pipe is empty and isISR().

pipe_write()

ssize_t pipe_write	(	pipe_t *	pipe,
		const void *	buf,
		size_t	n
	)

Write to a pipe.

Only one thread may access the pipe writingly at once. If the pipe is full, then the current thread is send sleeping. It gets woken up once there is room again in the pipe. In an ISR (irq_is_in()) 0 will returned if the pipe is full.

Parameters

[in]	pipe	Pipe to write to.
[out]	buf	Buffer to read from.
	n	Size of buffer.

Returns

> 0 if data could be written. == 0 if the pipe is full and isISR().