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lesson 20, keyboard

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pull/6/head
Carlos 9 years ago
parent 9adde4d4bd
commit 6e5a09981a
10 changed files with 239 additions and 727 deletions
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18
20-interrupts-timer/README.md
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*Concepts you may want to Google beforehand: CPU timer, keyboard interrupts*
*Concepts you may want to Google beforehand: CPU timer, keyboard interrupts, scancode*
**Goal: Implement our first IRQ handlers: the CPU timer and the keyboard**
@ -18,3 +18,19 @@ Finally, go back to the `kernel/kernel.c` and do two things. Enable interrupts a
(very important!) and then initialize the timer interrupt.
Go `make run` and you'll see the clock ticking!
Keyboard
--------
The keyboard is even easier, with a drawback. The PIC does not send us the ASCII code
for the pressed key, but the scancode for the key-down and the key-up events, so we
will need to translate those.
Check out `drivers/keyboard.c` where there are two functions: the callback and
the initialization which configures the interrupt callback. A new `keyboard.h` was
created with the definitions.
`keyboard.c` also has a long table to translate scancodes to ASCII keys. For the time
being, we will only implement a simple subset of the US keyboard. You can read
more [about scancodes here](http://www.win.tue.nl/~aeb/linux/kbd/scancodes-1.html)

17
20-interrupts-timer/cpu/idt.c
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#include "idt.h"
#include "../kernel/util.h"
void set_idt_gate(int n, u32 handler) {
idt[n].low_offset = low_16(handler);
idt[n].sel = KERNEL_CS;
idt[n].always0 = 0;
idt[n].flags = 0x8E;
idt[n].high_offset = high_16(handler);
}
void set_idt() {
idt_reg.base = (u32) &idt;
idt_reg.limit = IDT_ENTRIES * sizeof(idt_gate_t) - 1;
/* Don't make the mistake of loading &idt -- always load &idt_reg */
__asm__ __volatile__("lidtl (%0)" : : "r" (&idt_reg));
}

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20-interrupts-timer/cpu/idt.c
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../../19-interrupts-irqs/cpu/idt.c

39
20-interrupts-timer/cpu/idt.h
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#ifndef IDT_H
#define IDT_H
#include "types.h"
/* Segment selectors */
#define KERNEL_CS 0x08
/* How every interrupt gate (handler) is defined */
typedef struct {
u16 low_offset; /* Lower 16 bits of handler function address */
u16 sel; /* Kernel segment selector */
u8 always0;
/* First byte
* Bit 7: "Interrupt is present"
* Bits 6-5: Privilege level of caller (0=kernel..3=user)
* Bit 4: Set to 0 for interrupt gates
* Bits 3-0: bits 1110 = decimal 14 = "32 bit interrupt gate" */
u8 flags;
u16 high_offset; /* Higher 16 bits of handler function address */
} __attribute__((packed)) idt_gate_t ;
/* A pointer to the array of interrupt handlers.
* Assembly instruction 'lidt' will read it */
typedef struct {
u16 limit;
u32 base;
} __attribute__((packed)) idt_register_t;
#define IDT_ENTRIES 256
idt_gate_t idt[IDT_ENTRIES];
idt_register_t idt_reg;
/* Functions implemented in idt.c */
void set_idt_gate(int n, u32 handler);
void set_idt();
#endif

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20-interrupts-timer/cpu/idt.h
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../../19-interrupts-irqs/cpu/idt.h

425
20-interrupts-timer/cpu/interrupt.asm
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; Defined in isr.c
[extern isr_handler]
[extern irq_handler]
; Common ISR code
isr_common_stub:
; 1. Save CPU state
pusha ; Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax
mov ax, ds ; Lower 16-bits of eax = ds.
push eax ; save the data segment descriptor
mov ax, 0x10 ; kernel data segment descriptor
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
; 2. Call C handler
call isr_handler
; 3. Restore state
pop eax
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
popa
add esp, 8 ; Cleans up the pushed error code and pushed ISR number
sti
iret ; pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP
; Common IRQ code. Identical to ISR code except for the 'call'
; and the 'pop ebx'
irq_common_stub:
pusha
mov ax, ds
push eax
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
call irq_handler ; Different than the ISR code
pop ebx ; Different than the ISR code
mov ds, bx
mov es, bx
mov fs, bx
mov gs, bx
popa
add esp, 8
sti
iret
; We don't get information about which interrupt was caller
; when the handler is run, so we will need to have a different handler
; for every interrupt.
; Furthermore, some interrupts push an error code onto the stack but others
; don't, so we will push a dummy error code for those which don't, so that
; we have a consistent stack for all of them.
; First make the ISRs global
global isr0
global isr1
global isr2
global isr3
global isr4
global isr5
global isr6
global isr7
global isr8
global isr9
global isr10
global isr11
global isr12
global isr13
global isr14
global isr15
global isr16
global isr17
global isr18
global isr19
global isr20
global isr21
global isr22
global isr23
global isr24
global isr25
global isr26
global isr27
global isr28
global isr29
global isr30
global isr31
; IRQs
global irq0
global irq1
global irq2
global irq3
global irq4
global irq5
global irq6
global irq7
global irq8
global irq9
global irq10
global irq11
global irq12
global irq13
global irq14
global irq15
; 0: Divide By Zero Exception
isr0:
cli
push byte 0
push byte 0
jmp isr_common_stub
; 1: Debug Exception
isr1:
cli
push byte 0
push byte 1
jmp isr_common_stub
; 2: Non Maskable Interrupt Exception
isr2:
cli
push byte 0
push byte 2
jmp isr_common_stub
; 3: Int 3 Exception
isr3:
cli
push byte 0
push byte 3
jmp isr_common_stub
; 4: INTO Exception
isr4:
cli
push byte 0
push byte 4
jmp isr_common_stub
; 5: Out of Bounds Exception
isr5:
cli
push byte 0
push byte 5
jmp isr_common_stub
; 6: Invalid Opcode Exception
isr6:
cli
push byte 0
push byte 6
jmp isr_common_stub
; 7: Coprocessor Not Available Exception
isr7:
cli
push byte 0
push byte 7
jmp isr_common_stub
; 8: Double Fault Exception (With Error Code!)
isr8:
cli
push byte 8
jmp isr_common_stub
; 9: Coprocessor Segment Overrun Exception
isr9:
cli
push byte 0
push byte 9
jmp isr_common_stub
; 10: Bad TSS Exception (With Error Code!)
isr10:
cli
push byte 10
jmp isr_common_stub
; 11: Segment Not Present Exception (With Error Code!)
isr11:
cli
push byte 11
jmp isr_common_stub
; 12: Stack Fault Exception (With Error Code!)
isr12:
cli
push byte 12
jmp isr_common_stub
; 13: General Protection Fault Exception (With Error Code!)
isr13:
cli
push byte 13
jmp isr_common_stub
; 14: Page Fault Exception (With Error Code!)
isr14:
cli
push byte 14
jmp isr_common_stub
; 15: Reserved Exception
isr15:
cli
push byte 0
push byte 15
jmp isr_common_stub
; 16: Floating Point Exception
isr16:
cli
push byte 0
push byte 16
jmp isr_common_stub
; 17: Alignment Check Exception
isr17:
cli
push byte 0
push byte 17
jmp isr_common_stub
; 18: Machine Check Exception
isr18:
cli
push byte 0
push byte 18
jmp isr_common_stub
; 19: Reserved
isr19:
cli
push byte 0
push byte 19
jmp isr_common_stub
; 20: Reserved
isr20:
cli
push byte 0
push byte 20
jmp isr_common_stub
; 21: Reserved
isr21:
cli
push byte 0
push byte 21
jmp isr_common_stub
; 22: Reserved
isr22:
cli
push byte 0
push byte 22
jmp isr_common_stub
; 23: Reserved
isr23:
cli
push byte 0
push byte 23
jmp isr_common_stub
; 24: Reserved
isr24:
cli
push byte 0
push byte 24
jmp isr_common_stub
; 25: Reserved
isr25:
cli
push byte 0
push byte 25
jmp isr_common_stub
; 26: Reserved
isr26:
cli
push byte 0
push byte 26
jmp isr_common_stub
; 27: Reserved
isr27:
cli
push byte 0
push byte 27
jmp isr_common_stub
; 28: Reserved
isr28:
cli
push byte 0
push byte 28
jmp isr_common_stub
; 29: Reserved
isr29:
cli
push byte 0
push byte 29
jmp isr_common_stub
; 30: Reserved
isr30:
cli
push byte 0
push byte 30
jmp isr_common_stub
; 31: Reserved
isr31:
cli
push byte 0
push byte 31
jmp isr_common_stub
; IRQ handlers
irq0:
cli
push byte 0
push byte 32
jmp irq_common_stub
irq1:
cli
push byte 1
push byte 33
jmp irq_common_stub
irq2:
cli
push byte 2
push byte 34
jmp irq_common_stub
irq3:
cli
push byte 3
push byte 35
jmp irq_common_stub
irq4:
cli
push byte 4
push byte 36
jmp irq_common_stub
irq5:
cli
push byte 5
push byte 37
jmp irq_common_stub
irq6:
cli
push byte 6
push byte 38
jmp irq_common_stub
irq7:
cli
push byte 7
push byte 39
jmp irq_common_stub
irq8:
cli
push byte 8
push byte 40
jmp irq_common_stub
irq9:
cli
push byte 9
push byte 41
jmp irq_common_stub
irq10:
cli
push byte 10
push byte 42
jmp irq_common_stub
irq11:
cli
push byte 11
push byte 43
jmp irq_common_stub
irq12:
cli
push byte 12
push byte 44
jmp irq_common_stub
irq13:
cli
push byte 13
push byte 45
jmp irq_common_stub
irq14:
cli
push byte 14
push byte 46
jmp irq_common_stub
irq15:
cli
push byte 15
push byte 47
jmp irq_common_stub

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20-interrupts-timer/cpu/interrupt.asm
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../../19-interrupts-irqs/cpu/interrupt.asm

140
20-interrupts-timer/cpu/isr.c
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#include "isr.h"
#include "idt.h"
#include "../drivers/screen.h"
#include "../kernel/util.h"
#include "../drivers/ports.h"
isr_t interrupt_handlers[256];
/* Can't do this with a loop because we need the address
* of the function names */
void isr_install() {
set_idt_gate(0, (u32)isr0);
set_idt_gate(1, (u32)isr1);
set_idt_gate(2, (u32)isr2);
set_idt_gate(3, (u32)isr3);
set_idt_gate(4, (u32)isr4);
set_idt_gate(5, (u32)isr5);
set_idt_gate(6, (u32)isr6);
set_idt_gate(7, (u32)isr7);
set_idt_gate(8, (u32)isr8);
set_idt_gate(9, (u32)isr9);
set_idt_gate(10, (u32)isr10);
set_idt_gate(11, (u32)isr11);
set_idt_gate(12, (u32)isr12);
set_idt_gate(13, (u32)isr13);
set_idt_gate(14, (u32)isr14);
set_idt_gate(15, (u32)isr15);
set_idt_gate(16, (u32)isr16);
set_idt_gate(17, (u32)isr17);
set_idt_gate(18, (u32)isr18);
set_idt_gate(19, (u32)isr19);
set_idt_gate(20, (u32)isr20);
set_idt_gate(21, (u32)isr21);
set_idt_gate(22, (u32)isr22);
set_idt_gate(23, (u32)isr23);
set_idt_gate(24, (u32)isr24);
set_idt_gate(25, (u32)isr25);
set_idt_gate(26, (u32)isr26);
set_idt_gate(27, (u32)isr27);
set_idt_gate(28, (u32)isr28);
set_idt_gate(29, (u32)isr29);
set_idt_gate(30, (u32)isr30);
set_idt_gate(31, (u32)isr31);
// Remap the PIC
port_byte_out(0x20, 0x11);
port_byte_out(0xA0, 0x11);
port_byte_out(0x21, 0x20);
port_byte_out(0xA1, 0x28);
port_byte_out(0x21, 0x04);
port_byte_out(0xA1, 0x02);
port_byte_out(0x21, 0x01);
port_byte_out(0xA1, 0x01);
port_byte_out(0x21, 0x0);
port_byte_out(0xA1, 0x0);
// Install the IRQs
set_idt_gate(32, (u32)irq0);
set_idt_gate(33, (u32)irq1);
set_idt_gate(34, (u32)irq2);
set_idt_gate(35, (u32)irq3);
set_idt_gate(36, (u32)irq4);
set_idt_gate(37, (u32)irq5);
set_idt_gate(38, (u32)irq6);
set_idt_gate(39, (u32)irq7);
set_idt_gate(40, (u32)irq8);
set_idt_gate(41, (u32)irq9);
set_idt_gate(42, (u32)irq10);
set_idt_gate(43, (u32)irq11);
set_idt_gate(44, (u32)irq12);
set_idt_gate(45, (u32)irq13);
set_idt_gate(46, (u32)irq14);
set_idt_gate(47, (u32)irq15);
set_idt(); // Load with ASM
}
/* To print the message which defines every exception */
char *exception_messages[] = {
"Division By Zero",
"Debug",
"Non Maskable Interrupt",
"Breakpoint",
"Into Detected Overflow",
"Out of Bounds",
"Invalid Opcode",
"No Coprocessor",
"Double Fault",
"Coprocessor Segment Overrun",
"Bad TSS",
"Segment Not Present",
"Stack Fault",
"General Protection Fault",
"Page Fault",
"Unknown Interrupt",
"Coprocessor Fault",
"Alignment Check",
"Machine Check",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved"
};
void isr_handler(registers_t r) {
kprint("received interrupt: ");
char s[3];
int_to_ascii(r.int_no, s);
kprint(s);
kprint("\n");
kprint(exception_messages[r.int_no]);
kprint("\n");
}
void register_interrupt_handler(u8 n, isr_t handler) {
interrupt_handlers[n] = handler;
}
void irq_handler(registers_t r) {
/* If the irq involves the slave (IRQ > 7), send an EOI to it */
if (r.int_no >= 40) port_byte_out(0xA0, 0x20);
port_byte_out(0x20, 0x20); /* Send EOI to master */
/* Handle the interrupt in a more modular way */
if (interrupt_handlers[r.int_no] != 0) {
isr_t handler = interrupt_handlers[r.int_no];
handler(r);
}
}

1
20-interrupts-timer/cpu/isr.c
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../../19-interrupts-irqs/cpu/isr.c

88
20-interrupts-timer/cpu/isr.h
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#ifndef ISR_H
#define ISR_H
#include "types.h"
/* ISRs reserved for CPU exceptions */
extern void isr0();
extern void isr1();
extern void isr2();
extern void isr3();
extern void isr4();
extern void isr5();
extern void isr6();
extern void isr7();
extern void isr8();
extern void isr9();
extern void isr10();
extern void isr11();
extern void isr12();
extern void isr13();
extern void isr14();
extern void isr15();
extern void isr16();
extern void isr17();
extern void isr18();
extern void isr19();
extern void isr20();
extern void isr21();
extern void isr22();
extern void isr23();
extern void isr24();
extern void isr25();
extern void isr26();
extern void isr27();
extern void isr28();
extern void isr29();
extern void isr30();
extern void isr31();
/* IRQ definitions */
extern void irq0();
extern void irq1();
extern void irq2();
extern void irq3();
extern void irq4();
extern void irq5();
extern void irq6();
extern void irq7();
extern void irq8();
extern void irq9();
extern void irq10();
extern void irq11();
extern void irq12();
extern void irq13();
extern void irq14();
extern void irq15();
#define IRQ0 32
#define IRQ1 33
#define IRQ2 34
#define IRQ3 35
#define IRQ4 36
#define IRQ5 37
#define IRQ6 38
#define IRQ7 39
#define IRQ8 40
#define IRQ9 41
#define IRQ10 42
#define IRQ11 43
#define IRQ12 44
#define IRQ13 45
#define IRQ14 46
#define IRQ15 47
/* Struct which aggregates many registers */
typedef struct {
u32 ds; /* Data segment selector */
u32 edi, esi, ebp, esp, ebx, edx, ecx, eax; /* Pushed by pusha. */
u32 int_no, err_code; /* Interrupt number and error code (if applicable) */
u32 eip, cs, eflags, useresp, ss; /* Pushed by the processor automatically */
} registers_t;
void isr_install();
void isr_handler(registers_t r);
typedef void (*isr_t)(registers_t);
void register_interrupt_handler(u8 n, isr_t handler);
#endif

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20-interrupts-timer/cpu/isr.h
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../../19-interrupts-irqs/cpu/isr.h

16
20-interrupts-timer/cpu/types.h
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#ifndef TYPES_H
#define TYPES_H
/* Instead of using 'chars' to allocate non-character bytes,
* we will use these new type with no semantic meaning */
typedef unsigned int u32;
typedef int s32;
typedef unsigned short u16;
typedef short s16;
typedef unsigned char u8;
typedef char s8;
#define low_16(address) (u16)((address) & 0xFFFF)
#define high_16(address) (u16)(((address) >> 16) & 0xFFFF)
#endif

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20-interrupts-timer/cpu/types.h
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../../19-interrupts-irqs/cpu/types.h

208
20-interrupts-timer/drivers/keyboard.c
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#include "keyboard.h"
#include "ports.h"
#include "../cpu/isr.h"
#include "screen.h"
static void keyboard_callback(registers_t regs) {
/* The PIC leaves us the scancode in port 0x60 */
u8 scancode = port_byte_in(0x60);
char *sc_ascii;
int_to_ascii(scancode, sc_ascii);
kprint("Keyboard scancode: ");
kprint(sc_ascii);
kprint(", ");
print_letter(scancode);
kprint("\n");
}
void init_keyboard() {
register_interrupt_handler(IRQ1, keyboard_callback);
}
void print_letter(u8 scancode) {
switch (scancode) {
case 0x0:
kprint("ERROR");
break;
case 0x1:
kprint("ESC");
break;
case 0x2:
kprint("1");
break;
case 0x3:
kprint("2");
break;
case 0x4:
kprint("3");
break;
case 0x5:
kprint("4");
break;
case 0x6:
kprint("5");
break;
case 0x7:
kprint("6");
break;
case 0x8:
kprint("7");
break;
case 0x9:
kprint("8");
break;
case 0x0A:
kprint("9");
break;
case 0x0B:
kprint("0");
break;
case 0x0C:
kprint("-");
break;
case 0x0D:
kprint("+");
break;
case 0x0E:
kprint("Backspace");
break;
case 0x0F:
kprint("Tab");
break;
case 0x10:
kprint("Q");
break;
case 0x11:
kprint("W");
break;
case 0x12:
kprint("E");
break;
case 0x13:
kprint("R");
break;
case 0x14:
kprint("T");
break;
case 0x15:
kprint("Y");
break;
case 0x16:
kprint("U");
break;
case 0x17:
kprint("I");
break;
case 0x18:
kprint("O");
break;
case 0x19:
kprint("P");
break;
case 0x1A:
kprint("[");
break;
case 0x1B:
kprint("]");
break;
case 0x1C:
kprint("ENTER");
break;
case 0x1D:
kprint("LCtrl");
break;
case 0x1E:
kprint("A");
break;
case 0x1F:
kprint("S");
break;
case 0x20:
kprint("D");
break;
case 0x21:
kprint("F");
break;
case 0x22:
kprint("G");
break;
case 0x23:
kprint("H");
break;
case 0x24:
kprint("J");
break;
case 0x25:
kprint("K");
break;
case 0x26:
kprint("L");
break;
case 0x27:
kprint(";");
break;
case 0x28:
kprint("'");
break;
case 0x29:
kprint("`");
break;
case 0x2A:
kprint("LShift");
break;
case 0x2B:
kprint("\\");
break;
case 0x2C:
kprint("Z");
break;
case 0x2D:
kprint("X");
break;
case 0x2E:
kprint("C");
break;
case 0x2F:
kprint("V");
break;
case 0x30:
kprint("B");
break;
case 0x31:
kprint("N");
break;
case 0x32:
kprint("M");
break;
case 0x33:
kprint(",");
break;
case 0x34:
kprint(".");
break;
case 0x35:
kprint("/");
break;
case 0x36:
kprint("Rshift");
break;
case 0x37:
kprint("Keypad *");
break;
case 0x38:
kprint("LAlt");
break;
case 0x39:
kprint("Spc");
break;
default:
/* 'keuyp' event corresponds to the 'keydown' + 0x80
* it may still be a scancode we haven't implemented yet */
if (scancode - 0x80 <= 0x39) {
kprint("key up ");
print_letter(scancode - 0x80);
} else kprint("Unknown");
break;
}
}

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20-interrupts-timer/drivers/keyboard.h
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#include "../cpu/types.h"
void init_keyboard();

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20-interrupts-timer/kernel/kernel.c
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#include "../cpu/isr.h"
#include "../cpu/timer.h"
#include "../drivers/keyboard.h"
void main() {
isr_install();
asm volatile("sti");
init_timer(50);
// init_timer(50);
/* Comment out the timer IRQ handler to read
* the keyboard IRQs easier */
init_keyboard();
}

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