mask.c File Reference

CCSDS 124.0-B-1 mask update logic. More...

#include "ccsds124.h"

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Functions
Build Vector Functions
Implements CCSDS 124.0-B-1 Section 4 (Mask Update): Build Vector Update (Equation 6) Mask Vector Update (Equation 7) Change Vector Computation (Equation 8) Authors Georges Labrèche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m — https://georges.fyi Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com See also https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard CCSDS Equation 6: Bₜ = (Iₜ XOR Iₜ₋₁) OR Bₜ₋₁ (if t > 0 and ṗₜ = 0) Bₜ = 0 (otherwise: t=0 or ṗₜ=1) The build vector accumulates bits that have changed over time. When new_mask_flag is set, the build is used to replace the mask and is then reset to zero.
void	ccsds124_update_build (bitvector_t *build, const bitvector_t *input, const bitvector_t *prev_input, int new_mask_flag, size_t t)
	Update build vector (CCSDS Equation 6).
Mask Vector Functions
CCSDS Equation 7: Mₜ = (Iₜ XOR Iₜ₋₁) OR Mₜ₋₁ (if ṗₜ = 0) Mₜ = (Iₜ XOR Iₜ₋₁) OR Bₜ₋₁ (if ṗₜ = 1) The mask tracks which bits are unpredictable. When new_mask_flag is set, the mask is replaced with the build vector.
void	ccsds124_update_mask (bitvector_t *mask, const bitvector_t *input, const bitvector_t *prev_input, const bitvector_t *build_prev, int new_mask_flag)
	Update mask vector (CCSDS Equation 7).
Change Vector Functions
CCSDS Equation 8: Dₜ = Mₜ XOR Mₜ₋₁ The change vector tracks which mask bits changed between time steps. This is used in encoding to communicate mask updates. At t=0, the caller sets Mₜ₋₁ = M₀ so that D₀ = M₀ XOR M₀ = 0 (no change at initialization).
void	ccsds124_compute_change (bitvector_t *change, const bitvector_t *mask, const bitvector_t *prev_mask, size_t t)
	Compute change vector (CCSDS Equation 8).

Detailed Description

CCSDS 124.0-B-1 mask update logic.

Definition in file mask.c.