Interrupt Service Routine. More...

Collaboration diagram for ISR:

Data Structures
union	isr_eflags_t
	The EFLAGS register. More...

struct	isr_registers_t
	general purpose registers More...

struct	cpu_state_t
	The CPU's state when an interrupt occurs. More...

Macros
#define	IS_EXCEPTION(intr) ((intr) <= 0x1F)
	whether the given interrupt vector is an exception

#define	IS_IRQ(intr) ((intr) >= 0x20 && intr <= 0x2F)
	whether the given interrupt vector is an IRQ

#define	IS_SYSCALL(intr) ((intr) == 0x30)
	whether the given interrupt vector is the syscall

#define	ISR_EXCEPTION(ex) (0x00 + (ex))
	the interrupt vector for an exception

#define	ISR_IRQ(irq) (0x20 + (irq))
	the interrupt vector for an IRQ

#define	ISR_SYSCALL 0x30
	the interrupt vector for the syscall

Typedefs
typedef cpu_state_t (	isr_handler_t) (cpu_state_t *cpu)
	Handles a specific interrupt. More...

typedef uint32_t(*	isr_syscall_t) (uint32_t ebx, uint32_t ecx, uint32_t edx, uint32_t esi, uint32_t edi, cpu_state_t **cpu)
	Handles a specific syscall. More...

Functions
uint8_t	isr_enable_interrupts (uint8_t enable)
	Enables or disables interrupts. More...

uint8_t	isr_get_interrupts ()
	Returns whether interrupts are enabled or disabled. More...

void	isr_register_handler (size_t intr, isr_handler_t handler)
	Registers a handler to call whenever a given interrupt is fired. More...

void	isr_register_syscall (size_t id, void *syscall)
	Registers a syscall handler to call whenever a specified syscall is requested. More...

cpu_state_t *	isr_handle_interrupt (cpu_state_t *cpu)
	Handles all interrupts. More...

void	isr_dump_cpu (cpu_state_t *cpu)
	Dumps a CPU state. More...

static cpu_state_t *	isr_handle_syscall (cpu_state_t *cpu)
	Handles all syscalls. More...

void	isr_init ()
	Initializes syscalls and enables interrupts.

Variables
static isr_handler_t	handlers [IDT_ENTRIES] = {0}
	a table that associates interrupt vectors with handlers

static void *	syscalls [SYSCALL_NUMBER] = {0}
	a table that associates syscall IDs with handlers

Detailed Description

Interrupt Service Routine.

An ISR is responsible for handling IRQs, exceptions and syscalls. Here only one common ISR is used, isr_handle_interrupt. It dispatches interrupts to handlers (isr_handler_t) registered by isr_register_handler.

See also: isr_asm.S; http://www.lowlevel.eu/wiki/Teil_5_-_Interrupts; http://www.lowlevel.eu/wiki/ISR; http://wiki.osdev.org/Exceptions

Typedef Documentation

typedef cpu_state_t*(* isr_handler_t) (cpu_state_t *cpu)

Handles a specific interrupt.

Is registered with isr_register_handler().

Parameters

cpu	the CPU state

Returns: a (possibly altered) CPU state

See also: isr_handle_interrupt

Definition at line 90 of file isr.h.

typedef uint32_t(* isr_syscall_t) (uint32_t ebx, uint32_t ecx, uint32_t edx, uint32_t esi, uint32_t edi, cpu_state_t **cpu)

Handles a specific syscall.

Is registered with isr_register_syscall(). Unused parameters may be omitted because isr_register_syscall() works with void*. The parameters' and return value's types may differ from uint32_t, as long as they are not larger than 4 bytes (e.g. structs).

Parameters

ebx	the syscall's 1st parameter
ecx	the syscall's 2nd parameter
edx	the syscall's 3rd parameter
esi	the syscall's 4th parameter
edi	the syscall's 5th parameter
cpu	A reference to the CPU state / stack pointer. (This is a pointer to a pointer, so we can switch tasks from within a syscall!)

Returns: The syscall's return value. void is not allowed as type.

Definition at line 106 of file isr.h.

Function Documentation

void isr_dump_cpu ( cpu_state_t * cpu )

Dumps a CPU state.

The dump is logged.

Parameters

cpu	the CPU state to dump

Definition at line 123 of file isr.c.

uint8_t isr_enable_interrupts ( uint8_t enable )

Enables or disables interrupts.

Only acts if necessary.

Parameters

enable the new interrupt flag

Returns: interrupt flag before calling isr_enable_interrupts()

Definition at line 42 of file isr.c.

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uint8_t isr_get_interrupts ( )

Returns whether interrupts are enabled or disabled.

Returns: interrupt flag

Definition at line 55 of file isr.c.

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cpu_state_t* isr_handle_interrupt ( cpu_state_t * cpu )

Handles all interrupts.

This function is called whenever an interrupt is fired. It distinguishes which action to perform (call a handler, panic etc.) and, for IRQs, notifies the PIC that this interrupt has been handled.

Parameters

cpu	cpu has two functions here - as a pointer (CPU state) and as a value (ESP): cpu points to the CPU state and is the ESP pushed in isr_asm.S (the former stack pointer which points to the current task's CPU state, beginning with GS).

Returns: The pointer returned by this function is a (possibly new) ESP if we want to switch tasks (then we need to make sure that ESP points to a valid CPU state).
If we don't want to switch tasks, we just return the ESP unchanged.

See also: isr_common in isr_asm.S

Definition at line 102 of file isr.c.

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static cpu_state_t* isr_handle_syscall ( cpu_state_t * cpu )

static

Handles all syscalls.

Calls a syscall handler if registered.

Parameters

cpu	the current CPU state, see isr_handle_interrupt()

Returns: the new CPU state (if a task switch is desired)

Definition at line 139 of file isr.c.

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void isr_register_handler	(	size_t	intr,
		isr_handler_t	handler
	)

Registers a handler to call whenever a given interrupt is fired.

Parameters

intr	the interrupt vector that will be handled
handler	the function to call

Definition at line 66 of file isr.c.

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void isr_register_syscall	(	size_t	id,
		void *	syscall
	)

Registers a syscall handler to call whenever a specified syscall is requested.

Parameters

id	the ID of the syscall that will be handled
syscall	the function to call (this should be an isr_syscall_t but parameters can be omitted if desired, so we pass a void*)

Definition at line 80 of file isr.c.

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Data Structures

Macros

Typedefs

Functions

Variables

Detailed Description

Typedef Documentation

Function Documentation