spmc.c File Reference

Custom SPMC designed for high throughput handling of CAN message streams. More...

#include "spmc.h"
#include "common/rtos/rtos.h"
#include "stm32f407xx.h"

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Functions
static size_t	get_count (size_t head, size_t tail, bool is_full)
	Helper function to compute the number of items in the buffer given head and tail indices, accounting for wraparound.
void	SPMC_init (SPMC_t *spmc)
	Initializes the SPMC instance and configures CAN RX interrupts.
bool	SPMC_enqueue_from_ISR (SPMC_t *spmc, const timestamped_frame_t *incoming_frame)
	Enqueues a received CAN message into the SPMC buffer from an ISR context. ! the two producer ISRs must have the same NVIC priority to prevent preemption of each other in the middle of a write.
bool	SPMC_master_peek_chunk (SPMC_t *spmc, timestamped_frame_t **first_item)
	Peeks at the next chunk for the master (SD logging) without committing the tail.
void	SPMC_master_advance_tail (SPMC_t *spmc)
	Advances the master tail pointer by one chunk.
size_t	SPMC_follower_peek_minis (SPMC_t *spmc, timestamped_frame_t **first_item)
	Peeks at the number of contiguous mini chunks available for the follower without lapping the master's tail without committing the tail.
void	SPMC_follower_advance_tail (SPMC_t *spmc, size_t minis_consumed)
	Advances the follower tail pointer by a given number of mini chunks.

Variables
SPMC_t	g_spmc
static constexpr uint32_t	CAN_RX_IRQ_PRIO = 6

Detailed Description

Custom SPMC designed for high throughput handling of CAN message streams.

Author

Irving Wang (irvin.nosp@m.gw@p.nosp@m.urdue.nosp@m..edu)

Function Documentation

get_count()

static size_t get_count ( size_t head, size_t tail, bool is_full )

inlinestatic

Helper function to compute the number of items in the buffer given head and tail indices, accounting for wraparound.

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SPMC_enqueue_from_ISR()

bool SPMC_enqueue_from_ISR	(	SPMC_t *	spmc,
		const timestamped_frame_t *	incoming_frame )

Enqueues a received CAN message into the SPMC buffer from an ISR context. ! the two producer ISRs must have the same NVIC priority to prevent preemption of each other in the middle of a write.

Parameters

spmc	Pointer to the SPMC instance.
incoming_frame	Pointer to the timestamped_frame_t containing the received CAN message.

Returns

true if the frame was enqueued successfully, or false if the buffer is full and the frame was dropped.

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SPMC_follower_advance_tail()

void SPMC_follower_advance_tail	(	SPMC_t *	spmc,
		size_t	minis_consumed )

Advances the follower tail pointer by a given number of mini chunks.

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SPMC_follower_peek_minis()

size_t SPMC_follower_peek_minis	(	SPMC_t *	spmc,
		timestamped_frame_t **	first_item )

Peeks at the number of contiguous mini chunks available for the follower without lapping the master's tail without committing the tail.

Returns

The number of contiguous mini chunks available.

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SPMC_init()

void SPMC_init

(

SPMC_t *

spmc

)

Initializes the SPMC instance and configures CAN RX interrupts.

Parameters

spmc	Pointer to the SPMC instance to initialize.

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SPMC_master_advance_tail()

void SPMC_master_advance_tail

(

SPMC_t *

spmc

)

Advances the master tail pointer by one chunk.

Warning

this function should only be called by the master consumer context

Parameters

spmc	Pointer to the SPMC instance.

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SPMC_master_peek_chunk()

bool SPMC_master_peek_chunk	(	SPMC_t *	spmc,
		timestamped_frame_t **	first_item )

Peeks at the next chunk for the master (SD logging) without committing the tail.

Parameters

spmc	Pointer to the SPMC instance.
first_item	Output pointer that will point to the first item in the chunk if available, or NULL if no items are available.

Returns

true if a chunk is available, false if no items/not enough are available

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Variable Documentation

CAN_RX_IRQ_PRIO

uint32_t CAN_RX_IRQ_PRIO = 6

staticconstexpr

g_spmc

SPMC_t g_spmc