IRQ-masked read-modify-write helper for shared registers. More...

#include <stdint.h>

Include dependency graph for ra8_register_guard.h:

This graph shows which files directly or indirectly include this file:

Data Structures
struct	ra8_register_guard_t
	Opaque save-restore handle for IRQ masking. More...

Functions
static void	ra8_register_guard_enter (ra8_register_guard_t *guard)
	Enter a critical section: save PRIMASK, mask interrupts.
static void	ra8_register_guard_exit (const ra8_register_guard_t *guard)
	Exit a critical section: restore PRIMASK.

Detailed Description

IRQ-masked read-modify-write helper for shared registers.

Most RA8D2 peripheral registers are safe to read-modify-write from a single thread, but cross-peripheral routing (ELC events, ICU IELSR entries, MSTP module stop) is updated from several drivers and needs atomicity. This module provides a tiny primitive:

ra8_register_guard_t guard;
ra8_register_guard_enter(&guard);
*reg = (*reg & ~mask) | new_value;
ra8_register_guard_exit(&guard);

_enter stores the current PRIMASK and then sets it (masking all maskable interrupts). _exit restores the saved PRIMASK. Pairs must always balance; nested calls are supported.

Copyright: Copyright (c) 2026 Brighton Sikarskie SPDX-License-Identifier: MIT

Definition in file ra8_register_guard.h.

Function Documentation

◆ ra8_register_guard_enter()

void ra8_register_guard_enter ( ra8_register_guard_t * guard )

inlinestatic

Enter a critical section: save PRIMASK, mask interrupts.

Parameters

[out] guard Pointer to a caller-allocated guard. Must not be nullptr.

Note: Nested calls are supported. Each enter must have a matching exit.

See implementation for details.

Precondition: Module has been initialized.; Caller has validated arguments.

Postcondition: Side effects bounded to documented state.; State reflects operation result.

Since: 0.1.0

Definition at line 59 of file ra8_register_guard.h.

References ra8_register_guard_t::saved_primask.

Referenced by c6_cam_audio_snapshot_wav(), priv_dfu_write_secure(), ra8_sci_abort(), ra8_sci_attach_rx_handler(), ra8_sci_attach_tx_handler(), ra8_sci_deinit(), ra8_sci_read(), ra8_sci_read_stop(), ra8_sci_receive_resume(), ra8_sci_receive_suspend(), ra8_sci_set_baud(), and ra8_sci_write().

◆ ra8_register_guard_exit()

void ra8_register_guard_exit ( const ra8_register_guard_t * guard )

inlinestatic

Exit a critical section: restore PRIMASK.

Parameters

[in] guard Pointer to a guard previously passed to ra8_register_guard_enter().