ICARUS Semaphore Implementation. More...

#include "icarus/semaphore.h"
#include "icarus/kernel.h"
#include "icarus/scheduler.h"

Functions
bool	__semaphore_init (uint8_t semaphore_idx, uint32_t semaphore_count)
	Privileged implementation of semaphore_init.

bool	__semaphore_feed (uint8_t semaphore_idx)
	Privileged implementation of semaphore_feed.

bool	__semaphore_consume (uint8_t semaphore_idx)
	Privileged implementation of semaphore_consume.

bool	__semaphore_consume_timeout (uint8_t semaphore_idx, uint32_t max_ticks)
	Privileged implementation of semaphore_consume_timeout.

uint32_t	__semaphore_get_count (uint8_t semaphore_idx)
	Privileged implementation of semaphore_get_count.

uint32_t	__semaphore_get_max_count (uint8_t semaphore_idx)
	Privileged implementation of semaphore_get_max_count.

bool	__sem_can_feed (uint8_t semaphore_idx)
	Privileged call gate: can semaphore accept a feed?

bool	__sem_can_consume (uint8_t semaphore_idx)
	Privileged call gate: can semaphore be consumed?

void	__sem_increment (uint8_t semaphore_idx)
	Privileged write gate: increment semaphore count.

void	__sem_decrement (uint8_t semaphore_idx)
	Privileged write gate: decrement semaphore count.

Detailed Description

ICARUS Semaphore Implementation.

Version: 0.1.0

Counting semaphore implementation for task synchronization.

Author: Souham Biswas

Date: 2025

Copyright: Copyright 2025-2026 Souham Biswas https://github.com/ironhide23586/icarus-os-core Licensed under the Apache License, Version 2.0

Definition in file semaphore.c.

Function Documentation

◆ __sem_can_consume()

bool __sem_can_consume ( uint8_t semaphore_idx )

Privileged call gate: can semaphore be consumed?

Note: Returns true if engaged and count > 0 Used by __semaphore_consume spin loop.

Definition at line 186 of file semaphore.c.

References icarus_semaphore_t::count, ICARUS_MAX_SEMAPHORES, and semaphore_list.

Referenced by sem_can_consume(), and SVC_Handler_C().

◆ __sem_can_feed()

bool __sem_can_feed ( uint8_t semaphore_idx )

Privileged call gate: can semaphore accept a feed?

Note: Returns true if engaged and count < max_count Used by __semaphore_feed spin loop to avoid direct DTCM reads from unprivileged thread mode once DTCM is priv-only.

Definition at line 172 of file semaphore.c.

References icarus_semaphore_t::count, ICARUS_MAX_SEMAPHORES, icarus_semaphore_t::max_count, and semaphore_list.

Referenced by sem_can_feed(), and SVC_Handler_C().

◆ __sem_decrement()

void __sem_decrement ( uint8_t semaphore_idx )

Privileged write gate: decrement semaphore count.

Note: Called after sem_can_consume() spin loop exits Runs in privileged SVC handler — already atomic, no critical section needed

Definition at line 213 of file semaphore.c.

References icarus_semaphore_t::count, ICARUS_MAX_SEMAPHORES, os_tick_count, semaphore_list, and icarus_semaphore_t::tick_updated_at.

Referenced by sem_decrement(), and SVC_Handler_C().

◆ __sem_increment()

void __sem_increment ( uint8_t semaphore_idx )

Privileged write gate: increment semaphore count.

Note: Called after sem_can_feed() spin loop exits Runs in privileged SVC handler — already atomic, no critical section needed

Definition at line 199 of file semaphore.c.

References icarus_semaphore_t::count, ICARUS_MAX_SEMAPHORES, os_tick_count, semaphore_list, and icarus_semaphore_t::tick_updated_at.

Referenced by sem_increment(), and SVC_Handler_C().

◆ __semaphore_consume()

bool __semaphore_consume ( uint8_t semaphore_idx )

Privileged implementation of semaphore_consume.

Note: Internal function - use semaphore_consume() wrapper; Spin-wait uses sem_can_consume() SVC gate — safe with DTCM priv-only

Definition at line 81 of file semaphore.c.

References ICARUS_MAX_SEMAPHORES, sem_can_consume(), sem_decrement(), semaphore_list, and task_active_sleep().

Referenced by semaphore_consume().

◆ __semaphore_consume_timeout()

bool __semaphore_consume_timeout	(	uint8_t	semaphore_idx,
		uint32_t	max_ticks
	)

Privileged implementation of semaphore_consume_timeout.

Spins with task_active_sleep(1) checking sem_can_consume() each tick. Returns false if max_ticks elapse without the semaphore becoming available. max_ticks == 0 is a non-blocking try (check once, return immediately).

Parameters