Collaboration diagram for Task:

Data Structures
struct	task_t
	internal representation of a task More...

Macros
#define	MAX_TASKS 1024
	maximum number of tasks

#define	_4KB 0x1000
	4KB are 4096 bytes, often used for stacks

Typedefs
typedef uint8_t	task_stack_t
	stacks are measured in bytes

typedef uint32_t	task_pid_t
	unique process ID

Enumerations
enum	task_state_t { TASK_STOPPED, TASK_RUNNING }
	state of a task

Functions
static task_t *	task_get (task_pid_t pid)
	Returns the internal task structure associated with the given PID. More...

task_pid_t	task_add (task_t *task)
	Adds a new task to the task list and associates a PID. More...

static void	task_remove (task_pid_t pid)
	Removes a task from the task list. More...

static task_pid_t	task_create_detailed (void entry_point, page_directory_t page_directory, size_t kernel_stack_len, size_t user_stack_len, elf_t *elf, size_t code_segment, size_t data_segment)
	Creates a task. More...

task_pid_t	task_create_kernel (void entry_point, page_directory_t page_directory, size_t kernel_stack_len)
	Creates a kernel task. More...

task_pid_t	task_create_user (void entry_point, page_directory_t page_directory, size_t kernel_stack_len, size_t user_stack_len, void *elf)
	Creates a user task. More...

void	task_stop (task_pid_t pid)
	Stops a task. More...

void	task_destroy (task_pid_t pid)
	Destroys a task. More...

task_pid_t	task_get_next_task (task_pid_t pid)
	Returns the next task from the task list. More...

task_pid_t	task_get_next_task_with_state (task_pid_t pid, task_state_t state)
	Returns the next task from the task list with a specified state. More...

task_state_t	task_get_ticks (task_pid_t pid)
	Returns a task's number of remaining ticks. More...

uint32_t	task_set_ticks (task_pid_t pid, uint32_t ticks)
	Sets a task's number of remaining ticks. More...

cpu_state_t *	task_get_cpu (task_pid_t pid)
	Returns a task's CPU state. More...

void	task_set_cpu (task_pid_t pid, cpu_state_t *cpu)
	Sets a task's CPU state. More...

page_directory_t *	task_get_page_directory (task_pid_t pid)
	Returns a task's page directory. More...

uint8_t	task_get_vm86 (task_pid_t pid)
	Returns whether a task is a VM86 task. More...

void *	task_get_elf (task_pid_t pid)
	Returns a task's ELF file. More...

void	task_dump ()
	Dumps the task list. More...

Variables
static task_t *	tasks [MAX_TASKS]
	Array of tasks. More...

Detailed Description

Task.

This controls multitasking. Each tasks has two associated stacks, a kernel stack for interrupt handling and a user stack that serves as user call stack. Also each task has its own page directory and therefore virtual address space.

See also: http://www.lowlevel.eu/wiki/Teil_6_-_Multitasking

Function Documentation

task_pid_t task_add ( task_t * task )

Adds a new task to the task list and associates a PID.

Parameters

task	the task structure

Returns: the task's PID

Definition at line 46 of file task.c.

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static task_pid_t task_create_detailed	(	void *	entry_point,
		page_directory_t *	page_directory,
		size_t	kernel_stack_len,
		size_t	user_stack_len,
		elf_t *	elf,
		size_t	code_segment,
		size_t	data_segment
	)

static

Creates a task.

Parameters

entry_point	the virtual address where to start execution
page_directory	a page directory for the task, if 0 a new one is created
kernel_stack_len	number of bytes to allocate for the kernel stack
user_stack_len	number of bytes to allocate for the user stack
elf	an ELF file, if 0 this is not an ELF task
code_segment	a code segment in the GDT
data_segment	a data segment in the GDT

Returns: the task's PID

Prepares a CPU state to pop off when a timer interrupt occurs. The CPU state lies at the top of the task's kernel stack.

Makes an initial CPU state, setting the registers popped off in isr_asm.S.

Tells the scheduler to run this task.

Definition at line 75 of file task.c.

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task_pid_t task_create_kernel	(	void *	entry_point,
		page_directory_t *	page_directory,
		size_t	kernel_stack_len
	)

Creates a kernel task.

Parameters

entry_point	the virtual address where to start execution
page_directory	a page directory for the task, if 0 a new one is created
kernel_stack_len	number of bytes to allocate for the kernel stack

Returns: the task's PID

Definition at line 128 of file task.c.

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task_pid_t task_create_user	(	void *	entry_point,
		page_directory_t *	page_directory,
		size_t	kernel_stack_len,
		size_t	user_stack_len,
		void *	elf
	)

Creates a user task.

Parameters

entry_point	the virtual address where to start execution
page_directory	a page directory for the task, if 0 a new one is created
kernel_stack_len	number of bytes to allocate for the kernel stack
user_stack_len	number of bytes to allocate for the user stack
elf	an ELF file, if 0 this is not an ELF task

Returns: the task's PID

Definition at line 143 of file task.c.

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void task_destroy ( task_pid_t pid )

Destroys a task.

This requires the task to have been stopped before.

Parameters

pid	the task's PID

Definition at line 161 of file task.c.

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void task_dump ( )

Dumps the task list.

The dump is logged.

Definition at line 283 of file task.c.

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static task_t* task_get ( task_pid_t pid )

static

Returns the internal task structure associated with the given PID.

Parameters

pid	the task's PID

Returns: the task structure

Definition at line 33 of file task.c.

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cpu_state_t * task_get_cpu ( task_pid_t pid )

Returns a task's CPU state.

Parameters

pid	the task's PID

Returns: the task's CPU state

Definition at line 240 of file task.c.

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void * task_get_elf ( task_pid_t pid )

Returns a task's ELF file.

Parameters

pid	the task's PID

Returns: the task's ELF file or 0

Definition at line 276 of file task.c.

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task_pid_t task_get_next_task ( task_pid_t pid )

Returns the next task from the task list.

Parameters

pid	the current task's PID

Returns: the next task's PID

Definition at line 184 of file task.c.

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task_pid_t task_get_next_task_with_state	(	task_pid_t	pid,
		task_state_t	state
	)

Returns the next task from the task list with a specified state.

Parameters

pid	the current task's PID
state	the next task's desired state

Returns: the next task's PID

Definition at line 200 of file task.c.

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page_directory_t * task_get_page_directory ( task_pid_t pid )

Returns a task's page directory.

Parameters

pid	the task's PID

Returns: the task's page directory

Definition at line 258 of file task.c.

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task_state_t task_get_ticks ( task_pid_t pid )

Returns a task's number of remaining ticks.

Parameters

pid	the task's PID

Returns: the task's number of remaining ticks

Definition at line 218 of file task.c.

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uint8_t task_get_vm86 ( task_pid_t pid )

Returns whether a task is a VM86 task.

Parameters

pid	the task's PID

Returns: whether the task is a VM86 task

Definition at line 267 of file task.c.

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static void task_remove ( task_pid_t pid )

static

Removes a task from the task list.

Parameters

pid	the task's PID

Definition at line 60 of file task.c.

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void task_set_cpu	(	task_pid_t	pid,
		cpu_state_t *	cpu
	)

Sets a task's CPU state.

Parameters

pid	the task's PID
cpu	the task's CPU state

Definition at line 249 of file task.c.

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uint32_t task_set_ticks	(	task_pid_t	pid,
		uint32_t	ticks
	)

Sets a task's number of remaining ticks.

Parameters

pid	the task's PID
ticks	the number of remaining ticks

Returns: the old number of remaining ticks

Definition at line 228 of file task.c.

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void task_stop ( task_pid_t pid )

Stops a task.

This does not remove the task from the task list.

Parameters

pid	the task's PID

Definition at line 153 of file task.c.

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Variable Documentation

task_t* tasks[MAX_TASKS]

static

Array of tasks.

Fixed-size array for now, may change in the future.

Definition at line 26 of file task.c.

Data Structures

Macros

Typedefs

Enumerations

Functions

Variables

Detailed Description

Function Documentation

Variable Documentation