can_types.h File Reference

Type definitions and constants for the CAN transport layer. More...

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Data Structures
struct	can_msg_state_struct
struct	can_msg_struct
struct	can_main_statemachine_struct
struct	can_statemachine_info_struct
struct	alias_mapping_struct
struct	alias_mapping_info_struct
struct	listener_alias_entry_struct

Macros
#define	USER_DEFINED_CAN_MSG_BUFFER_DEPTH   10
	Number of can_msg_t buffers in the pool (can_buffer_store.h).
#define	ALIAS_MAPPING_BUFFER_DEPTH   USER_DEFINED_NODE_BUFFER_DEPTH
	Number of alias_mapping_t slots. Defaults to USER_DEFINED_NODE_BUFFER_DEPTH.
#define	LEN_CAN_FIFO_BUFFER   (USER_DEFINED_CAN_MSG_BUFFER_DEPTH + 1)
	FIFO slot count — one extra slot so head==tail always means empty.
#define	LEN_CAN_BYTE_ARRAY   8
	Number of data bytes in a CAN 2.0 frame.
#define	OFFSET_CAN_WITHOUT_DEST_ADDRESS   0
	Pass to functions when the CAN payload starts at byte 0 (no destination alias).
#define	OFFSET_CAN_WITH_DEST_ADDRESS   2
	Pass to functions when bytes 0-1 carry a destination alias; data starts at byte 2.
#define	CAN_MTI_PCER_WITH_PAYLOAD_FIRST   0x0F16
	CAN framing MTI for first frame of segmented PCER-with-payload.
#define	CAN_MTI_PCER_WITH_PAYLOAD_MIDDLE   0x0F15
	CAN framing MTI for middle frame of segmented PCER-with-payload.
#define	CAN_MTI_PCER_WITH_PAYLOAD_LAST   0x0F14
	CAN framing MTI for last frame of segmented PCER-with-payload.
#define	LISTENER_ALIAS_TABLE_DEPTH    (USER_DEFINED_MAX_LISTENERS_PER_TRAIN * USER_DEFINED_TRAIN_NODE_COUNT)
	Total listener alias table slots across all train nodes.

Typedefs
typedef uint8_t	payload_bytes_can_t[LEN_CAN_BYTE_ARRAY]
	Fixed 8-byte array holding a CAN frame payload.
typedef struct can_msg_state_struct	can_msg_state_t
	Bit-field tracking allocation status of a can_msg_t buffer.
typedef struct can_msg_struct	can_msg_t
	Complete CAN 2.0B extended frame: 29-bit identifier + up to 8 data bytes.
typedef can_msg_t	can_msg_array_t[USER_DEFINED_CAN_MSG_BUFFER_DEPTH]
	Pre-allocated array of can_msg_t buffers, sized USER_DEFINED_CAN_MSG_BUFFER_DEPTH.
typedef struct can_main_statemachine_struct	can_main_statemachine_t
	Working context for the CAN main state machine.
typedef struct can_statemachine_info_struct	can_statemachine_info_t
	Context block passed through the CAN state machine on every iteration.
typedef struct alias_mapping_struct	alias_mapping_t
	One entry in the alias mapping table: a node_id_t / 12-bit alias pair.
typedef struct alias_mapping_info_struct	alias_mapping_info_t
	Container for all alias_mapping_t entries plus a global duplicate flag.
typedef struct listener_alias_entry_struct	listener_alias_entry_t
	One entry in the listener alias table: a node_id_t / 12-bit alias pair.

Detailed Description

Type definitions and constants for the CAN transport layer.

Copyright

Copyright (c) 2024, Jim Kueneman All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Defines can_msg_t, alias_mapping_t, alias_mapping_info_t, can_statemachine_info_t, listener_alias_entry_t, and all compile-time constants shared across the CAN driver modules. No executable code — types and macros only.

Author

Jim Kueneman

Date

8 Mar 2026

Macro Definition Documentation

USER_DEFINED_CAN_MSG_BUFFER_DEPTH

#define USER_DEFINED_CAN_MSG_BUFFER_DEPTH   10

Number of can_msg_t buffers in the pool (can_buffer_store.h).

Override at compile time: -D USER_DEFINED_CAN_MSG_BUFFER_DEPTH=20

Warning

Maximum value is 254 (0xFE).

ALIAS_MAPPING_BUFFER_DEPTH

#define ALIAS_MAPPING_BUFFER_DEPTH   USER_DEFINED_NODE_BUFFER_DEPTH

Number of alias_mapping_t slots. Defaults to USER_DEFINED_NODE_BUFFER_DEPTH.

LEN_CAN_FIFO_BUFFER

#define LEN_CAN_FIFO_BUFFER   (USER_DEFINED_CAN_MSG_BUFFER_DEPTH + 1)

FIFO slot count — one extra slot so head==tail always means empty.

LEN_CAN_BYTE_ARRAY

#define LEN_CAN_BYTE_ARRAY   8

Number of data bytes in a CAN 2.0 frame.

OFFSET_CAN_WITHOUT_DEST_ADDRESS

#define OFFSET_CAN_WITHOUT_DEST_ADDRESS   0

Pass to functions when the CAN payload starts at byte 0 (no destination alias).

OFFSET_CAN_WITH_DEST_ADDRESS

#define OFFSET_CAN_WITH_DEST_ADDRESS   2

Pass to functions when bytes 0-1 carry a destination alias; data starts at byte 2.

CAN_MTI_PCER_WITH_PAYLOAD_FIRST

#define CAN_MTI_PCER_WITH_PAYLOAD_FIRST   0x0F16

CAN framing MTI for first frame of segmented PCER-with-payload.

CAN_MTI_PCER_WITH_PAYLOAD_MIDDLE

#define CAN_MTI_PCER_WITH_PAYLOAD_MIDDLE   0x0F15

CAN framing MTI for middle frame of segmented PCER-with-payload.

CAN_MTI_PCER_WITH_PAYLOAD_LAST

#define CAN_MTI_PCER_WITH_PAYLOAD_LAST   0x0F14

CAN framing MTI for last frame of segmented PCER-with-payload.

LISTENER_ALIAS_TABLE_DEPTH

#define LISTENER_ALIAS_TABLE_DEPTH    (USER_DEFINED_MAX_LISTENERS_PER_TRAIN * USER_DEFINED_TRAIN_NODE_COUNT)

Total listener alias table slots across all train nodes.

Typedef Documentation

payload_bytes_can_t

typedef uint8_t payload_bytes_can_t[LEN_CAN_BYTE_ARRAY]

Fixed 8-byte array holding a CAN frame payload.

See also

LEN_CAN_BYTE_ARRAY

can_msg_t

can_msg_state_t

typedef struct can_msg_state_struct can_msg_state_t

Bit-field tracking allocation status of a can_msg_t buffer.

See also

CanBufferStore_allocate_buffer

CanBufferStore_free_buffer

can_msg_t

typedef struct can_msg_struct can_msg_t

Complete CAN 2.0B extended frame: 29-bit identifier + up to 8 data bytes.

Warning

Maximum payload is 8 bytes.

See also

can_buffer_store.h

can_buffer_fifo.h

can_msg_array_t

typedef can_msg_t can_msg_array_t[USER_DEFINED_CAN_MSG_BUFFER_DEPTH]

Pre-allocated array of can_msg_t buffers, sized USER_DEFINED_CAN_MSG_BUFFER_DEPTH.

See also

can_buffer_store.c

can_main_statemachine_t

typedef struct can_main_statemachine_struct can_main_statemachine_t

Working context for the CAN main state machine.

can_statemachine_info_t

typedef struct can_statemachine_info_struct can_statemachine_info_t

Context block passed through the CAN state machine on every iteration.

Carries the current node pointer, a statically-allocated login frame buffer, a pointer to an outgoing frame from the pool, and control flags. The login buffer is always valid; outgoing_can_msg is NULL when no message is pending.

Warning

login_outgoing_can_msg points to a static variable in can_main_statemachine.c — do not free it.

outgoing_can_msg must be freed after successful transmission.

See also

can_main_statemachine.h

can_login_statemachine.h

alias_mapping_t

typedef struct alias_mapping_struct alias_mapping_t

One entry in the alias mapping table: a node_id_t / 12-bit alias pair.

Flags may be set from interrupt context and read from the main loop. Use lock/unlock around accesses shared between contexts.

See also

alias_mappings.h

alias_mapping_info_t

typedef struct alias_mapping_info_struct alias_mapping_info_t

Container for all alias_mapping_t entries plus a global duplicate flag.

has_duplicate_alias is a fast-check flag: when set, at least one entry has is_duplicate set and the main loop should scan the list to find and resolve it.

See also

alias_mappings.h

AliasMappings_set_has_duplicate_alias_flag

listener_alias_entry_t

typedef struct listener_alias_entry_struct listener_alias_entry_t

One entry in the listener alias table: a node_id_t / 12-bit alias pair.

Written by the CAN RX interrupt (AMD arrival) and read by the CAN TX main thread (alias resolution). Protected by the existing lock_shared_resources / unlock_shared_resources mechanism.

See also

listener_alias_table.h