queue.h File Reference

Deterministic, generic FIFO queue for embedded / safety-critical systems. More...

#include <stdint.h>
#include <stdbool.h>

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Data Structures
struct	queue_t
	FIFO queue control structure. More...

Enumerations
enum	queue_status_t { QUEUE_OK = 0U , QUEUE_FULL = 1U , QUEUE_EMPTY = 2U , QUEUE_ERROR = 3U }
	Queue operation status codes. More...

Functions
queue_status_t	queue_init (queue_t *q, void *buffer, uint16_t element_size, uint16_t capacity)
	Initialize a queue. More...
queue_status_t	queue_push (queue_t *q, const void *item)
	Push an element into the queue. More...
queue_status_t	queue_pop (queue_t *q, void *item)
	Pop an element from the queue. More...
bool	queue_is_empty (const queue_t *q)
	Check whether queue is empty. More...
bool	queue_is_full (const queue_t *q)
	Check whether queue is full. More...

Detailed Description

Deterministic, generic FIFO queue for embedded / safety-critical systems.

Author

niwciu (niwci.nosp@m.u@gm.nosp@m.ail.c.nosp@m.om)

Version

1.0.2

Date

2025-10-26

Queue interface designed to be MISRA-C:2012 aware and suitable for safety-critical applications (ISO 26262). Implementation uses a user-supplied raw data buffer (void *) to support multiple element types.

MISRA Deviation: DV-QUEUE-001 (Rule 11.4) Justified cast from void* to uint8_t* for byte-level memory operations.

Note

Caller is responsible for ensuring the provided buffer size is at least: (element_size * capacity) bytes, properly aligned for the element type.

Internal helper function copy_bytes(uint8_t*, const uint8_t*, uint16_t) is exercised indirectly via unit tests in group DV_QUEUE_001 to cover all branches, including NULL pointer cases and edge conditions.

Enumeration Type Documentation

queue_status_t

enum queue_status_t

Queue operation status codes.

Enumerator
QUEUE_OK	Operation completed successfully.
QUEUE_FULL	Queue is full; push operation failed.
QUEUE_EMPTY	Queue is empty; pop operation failed.
QUEUE_ERROR	General error (invalid parameters, etc.).

Function Documentation

queue_init()

queue_status_t queue_init	(	queue_t *	q,
		void *	buffer,
		uint16_t	element_size,
		uint16_t	capacity
	)

Initialize a queue.

Parameters

[in,out]	q	Pointer to queue control structure.
[in]	buffer	Pointer to storage buffer.
[in]	element_size	Element size in bytes (>0).
[in]	capacity	Number of elements (>0).

Return values

QUEUE_OK	Successful initialization.
QUEUE_ERROR	Invalid parameters.

queue_is_empty()

bool queue_is_empty

(

const queue_t *

q

)

Check whether queue is empty.

Parameters

[in]

q

Pointer to queue instance.

Returns

true if empty, false otherwise.

queue_is_full()

bool queue_is_full

(

const queue_t *

q

)

Check whether queue is full.

Parameters

[in]

q

Pointer to queue instance.

Returns

true if full, false otherwise.

queue_pop()

queue_status_t queue_pop	(	queue_t *	q,
		void *	item
	)

Pop an element from the queue.

Parameters

[in,out]	q	Pointer to queue instance.
[out]	item	Pointer to destination buffer.

Return values

QUEUE_OK	Success.
QUEUE_EMPTY	Queue empty.
QUEUE_ERROR	Invalid parameters.

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queue_push()

queue_status_t queue_push	(	queue_t *	q,
		const void *	item
	)

Push an element into the queue.

Parameters

[in,out]	q	Pointer to queue instance.
[in]	item	Pointer to data to add (element_size bytes).

Return values

QUEUE_OK	Success.
QUEUE_FULL	Queue full.
QUEUE_ERROR	Invalid parameters.

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