ab_gp_proc_ma.h File Reference

ERTMS Subset-026 §5.5 Movement Authority (MA) Management Procedure. More...

#include "ab_gp_ertms_types.h"
#include "ab_siteGP.h"
#include "ab_siteGA.h"

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Functions
bool	ab_gp_proc_ma_compute (ab_gp_ertms_train_context_t *ctx, const ab_site_ga_route_layout_t *route, uint32_t ma_seq)
	Computes and grants a new Movement Authority based on site track layout.
uint32_t	ab_gp_proc_ma_remaining_length_m (const ab_site_ga_route_layout_t *route, uint32_t nid_lrbg, uint32_t d_lrbg_m)
	Computes the Movement Authority length actually REMAINING from a train's own last-KNOWN balise to route's end signal - a direct point-to-point distance along route's own segment chain from that balise's (nid_lrbg) own physical position to the end signal's own physical position, NOT "route->length_m minus however far the balise sits from the route's own START signal" - the two are NOT interchangeable (found live: an earlier version of this function computed the latter and got a real, confirmed-wrong answer - see the .c file's own implementation doc for the concrete counter-example). Measured from the balise, NOT from nid_lrbg plus d_lrbg_m's own distance past it - on direct instruction: MA length is anchored to the train's last KNOWN, site-data-backed reference point, not a continuously self-reported odometer offset past it (d_lrbg_m is accepted for a possible future use but not used in this computation today - see the .c file's own doc). A train connecting to (or being extended into) a route it is already partway through must NOT be granted the route's own full length regardless - found live: both this function's own caller below and the flat scheme's ab_ga_il_on_route_context_changed() (safeAPIRBC2oo2GA) were granting route->length_m unconditionally, regardless of the train's own reported position - a real overrun-risk shape (the train is told it has more track ahead of it than physically remains).
bool	ab_gp_proc_ma_extend (ab_gp_ertms_train_context_t *ctx, const ab_site_ga_route_layout_t *additional_route)
	Extends an existing Movement Authority with an additional connected route.
bool	ab_gp_proc_ma_shorten (ab_gp_ertms_train_context_t *ctx, uint32_t new_ma_length_m)
	Shortens an existing Movement Authority (Subset-026 §5.5.4 / Msg 9).
bool	ab_gp_proc_ma_handle_ack (ab_gp_ertms_train_context_t *ctx, uint32_t ma_seq)
	Handles Movement Authority Acknowledgement (Msg 146).
void	ab_gp_proc_ma_revoke (ab_gp_ertms_train_context_t *ctx)
	Revokes active Movement Authority (e.g. during emergency or termination).

Detailed Description

ERTMS Subset-026 §5.5 Movement Authority (MA) Management Procedure.

Implements SIL 4 C99 Movement Authority computation, multi-packet generation (Packet 15 MA, Packet 21 Gradient, Packet 27 Speed Profile, Packet 5 Linking), MA extension, MA shortening, and acknowledgement handling.

Definition in file ab_gp_proc_ma.h.

Function Documentation

ab_gp_proc_ma_compute()

bool ab_gp_proc_ma_compute	(	ab_gp_ertms_train_context_t *	ctx,
		const ab_site_ga_route_layout_t *	route,
		uint32_t	ma_seq )

Computes and grants a new Movement Authority based on site track layout.

Parameters

[in,out]	ctx	Train ERTMS context.
[in]	route	Site route layout defining signals, segments, and balises (GA's own ab_site_ga_route_layout_t - GP no longer owns route topology, see ab_siteGA.h's own doc).
[in]	ma_seq	Monotonic MA sequence counter.

Returns

true if MA successfully computed and granted, false otherwise.

Definition at line 83 of file ab_gp_proc_ma.c.

ab_gp_proc_ma_remaining_length_m()

uint32_t ab_gp_proc_ma_remaining_length_m	(	const ab_site_ga_route_layout_t *	route,
		uint32_t	nid_lrbg,
		uint32_t	d_lrbg_m )

Computes the Movement Authority length actually REMAINING from a train's own last-KNOWN balise to route's end signal - a direct point-to-point distance along route's own segment chain from that balise's (nid_lrbg) own physical position to the end signal's own physical position, NOT "route->length_m minus however far the balise sits from the route's own START signal" - the two are NOT interchangeable (found live: an earlier version of this function computed the latter and got a real, confirmed-wrong answer - see the .c file's own implementation doc for the concrete counter-example). Measured from the balise, NOT from nid_lrbg plus d_lrbg_m's own distance past it - on direct instruction: MA length is anchored to the train's last KNOWN, site-data-backed reference point, not a continuously self-reported odometer offset past it (d_lrbg_m is accepted for a possible future use but not used in this computation today - see the .c file's own doc). A train connecting to (or being extended into) a route it is already partway through must NOT be granted the route's own full length regardless - found live: both this function's own caller below and the flat scheme's ab_ga_il_on_route_context_changed() (safeAPIRBC2oo2GA) were granting route->length_m unconditionally, regardless of the train's own reported position - a real overrun-risk shape (the train is told it has more track ahead of it than physically remains).

Falls back to the FULL route->length_m (the previously unconditional behavior) if nid_lrbg cannot be resolved to a balise on route's own segment chain at all (e.g. no position report yet, or the reported balise belongs to a different route/segment entirely) - never guesses past what site data can actually support; this is also the correct fallback for a genuine forward extension (the additional route's own balises legitimately do not include the train's current one yet).

Implemented once, here, since only GP has direct access to the physical segment/balise tables (ab_siteGP.h, ab_site_get_segment()/ab_site_get_balise()) this computation needs - GA's own ab_site_ga_route_layout_t alone (length_m, opaque segment_ids[]) cannot do it. Exposed to GA via ga_interface.h for the flat scheme's own identical use.

Parameters

route	The route being granted/extended - GA's own ab_site_ga_route_layout_t.
nid_lrbg	Train's own last-reported NID_LRBG (M136/flat scheme position report alike) - the balise this computation is anchored to.
d_lrbg_m	Train's own last-reported D_LRBG (distance past nid_lrbg, meters) - accepted but NOT used in this computation, see this function's own doc above.

Returns

Remaining MA length in meters - never more than route->length_m, never negative (clamped to 0 if the train's own reported position is already past the route's own end).

Definition at line 53 of file ab_gp_proc_ma.c.

ab_gp_proc_ma_extend()

bool ab_gp_proc_ma_extend	(	ab_gp_ertms_train_context_t *	ctx,
		const ab_site_ga_route_layout_t *	additional_route )

Extends an existing Movement Authority with an additional connected route.

Parameters

[in,out]	ctx	Train ERTMS context.
[in]	additional_route	Subsequent route layout to append.

Returns

true if MA successfully extended, false otherwise.

Definition at line 214 of file ab_gp_proc_ma.c.

ab_gp_proc_ma_shorten()

bool ab_gp_proc_ma_shorten	(	ab_gp_ertms_train_context_t *	ctx,
		uint32_t	new_ma_length_m )

Shortens an existing Movement Authority (Subset-026 §5.5.4 / Msg 9).

Parameters

[in,out]	ctx	Train ERTMS context.
[in]	new_ma_length_m	New reduced Limit of Authority in meters.

Returns

true if MA successfully shortened, false otherwise.

Definition at line 248 of file ab_gp_proc_ma.c.

ab_gp_proc_ma_handle_ack()

bool ab_gp_proc_ma_handle_ack	(	ab_gp_ertms_train_context_t *	ctx,
		uint32_t	ma_seq )

Handles Movement Authority Acknowledgement (Msg 146).

Parameters

[in,out]	ctx	Train ERTMS context.
[in]	ma_seq	Sequence counter echoed in Msg 146.

Returns

true if sequence matches active MA, false otherwise.

Definition at line 266 of file ab_gp_proc_ma.c.

ab_gp_proc_ma_revoke()

void ab_gp_proc_ma_revoke

(

ab_gp_ertms_train_context_t *

ctx

)

Revokes active Movement Authority (e.g. during emergency or termination).

Parameters

[in,out]

ctx

Train ERTMS context.

Definition at line 276 of file ab_gp_proc_ma.c.