OS services implementation

Description

Functions
bool	schedule_context_switch (uint32_t current_task, uint32_t next_task)
	Opt for task switch.
void	PendSV_Handler (void)
	Handle task switch.

Variables
static struct OS_thread_t *	old_task
static struct OS_thread_t *	new_task
static struct OS_process_t *	old_parent_process
static struct OS_process_t *	new_parent_process
static struct OS_process_t *	old_host_process
static struct OS_process_t *	new_host_process
static uint8_t	new_thread_id
static Process_t	new_process_id
static bool	ctxt_switch_pending
struct OS_stack_t	os_stacks
	Thread stacks.

Function Documentation

PendSV_Handler()

void PendSV_Handler

(

void

)

Handle task switch.

This function performs the heavy lifting of context switching when CPU is switched from one task to another. As of now, it stores outgoing task's application context onto stack and restores incoming task's context from its stack. It then sets PSP to point to incoming task's stack and resumes normal operation.

schedule_context_switch()

bool schedule_context_switch	(	uint32_t	current_task,
		uint32_t	next_task
	)

Opt for task switch.

Schedule context switch on next suitable moment.

Calling this function will prepare task switch. It will set up some stuff needed and then schedule PendSV.

Parameters

current_task	ID of task, which is currently running
next_task	ID of task, which should be scheduled next

Note

API of this function is dumb.

Variable Documentation

ctxt_switch_pending

bool ctxt_switch_pending

static

new_host_process

struct OS_process_t* new_host_process

static

new_parent_process

struct OS_process_t* new_parent_process

static

new_process_id

Process_t new_process_id

static

new_task

struct OS_thread_t* new_task

static

new_thread_id

uint8_t new_thread_id

static

old_host_process

struct OS_process_t* old_host_process

static

old_parent_process

struct OS_process_t* old_parent_process

static

old_task

struct OS_thread_t* old_task

static

os_stacks

struct OS_stack_t os_stacks

extern

Thread stacks.

Scheduler notion on existing stacks.