245 lines
5.1 KiB
C
245 lines
5.1 KiB
C
/* Based on Bare Bones tutorial on OSDev wiki */
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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/* Check if the compiler thinks you are targeting the wrong operating system. */
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#if defined(__linux__)
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#error "You are not using a cross-compiler, you will most certainly run into trouble"
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#endif
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/* This tutorial will only work for the 32-bit ix86 targets. */
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#if !defined(__i386__)
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#error "This tutorial needs to be compiled with a ix86-elf compiler"
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#endif
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/* Hardware text mode color constants. */
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enum vga_color {
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VGA_COLOR_BLACK = 0,
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VGA_COLOR_BLUE = 1,
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VGA_COLOR_GREEN = 2,
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VGA_COLOR_CYAN = 3,
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VGA_COLOR_RED = 4,
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VGA_COLOR_MAGENTA = 5,
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VGA_COLOR_BROWN = 6,
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VGA_COLOR_LIGHT_GREY = 7,
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VGA_COLOR_DARK_GREY = 8,
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VGA_COLOR_LIGHT_BLUE = 9,
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VGA_COLOR_LIGHT_GREEN = 10,
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VGA_COLOR_LIGHT_CYAN = 11,
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VGA_COLOR_LIGHT_RED = 12,
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VGA_COLOR_LIGHT_MAGENTA = 13,
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VGA_COLOR_LIGHT_BROWN = 14,
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VGA_COLOR_WHITE = 15,
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};
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static inline uint8_t vga_entry_color(enum vga_color fg, enum vga_color bg)
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{
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return fg | bg << 4;
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}
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static inline uint16_t vga_entry(unsigned char uc, uint8_t color)
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{
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return (uint16_t) uc | (uint16_t) color << 8;
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}
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size_t strlen(const char* str)
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{
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size_t len = 0;
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while (str[len])
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len++;
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return len;
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}
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static const size_t VGA_WIDTH = 80;
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static const size_t VGA_HEIGHT = 25;
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size_t terminal_row;
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size_t terminal_column;
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uint8_t terminal_color;
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uint16_t* terminal_buffer;
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void terminal_initialize(void)
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{
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terminal_row = 0;
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terminal_column = 0;
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terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
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terminal_buffer = (uint16_t*) 0xB8000;
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for (size_t y = 0; y < VGA_HEIGHT; y++) {
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for (size_t x = 0; x < VGA_WIDTH; x++) {
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const size_t index = y * VGA_WIDTH + x;
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terminal_buffer[index] = vga_entry(' ', terminal_color);
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}
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}
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}
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void terminal_setcolor(uint8_t color)
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{
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terminal_color = color;
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}
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void terminal_putentryat(char c, uint8_t color, size_t x, size_t y)
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{
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const size_t index = y * VGA_WIDTH + x;
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terminal_buffer[index] = vga_entry(c, color);
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}
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void terminal_putchar(char c)
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{
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if (c == '\n') {
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terminal_row++;
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terminal_column = 0;
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return;
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}
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terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
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if (++terminal_column == VGA_WIDTH) {
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terminal_column = 0;
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if (++terminal_row == VGA_HEIGHT)
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terminal_row = 0;
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}
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}
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void terminal_write(const char* data, size_t size)
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{
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for (size_t i = 0; i < size; i++)
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terminal_putchar(data[i]);
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}
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void terminal_writestring(const char* data)
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{
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terminal_write(data, strlen(data));
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}
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// (out|in)port from sortix, Copyright (c) 2014, 2015 Jonas 'Sortie' Termansen.
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void outport8(uint16_t port, uint8_t value)
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{
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asm volatile ("outb %1, %0" : : "dN" (port), "a" (value));
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}
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uint8_t inport8(uint16_t port)
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{
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uint8_t result;
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asm volatile("inb %1, %0" : "=a" (result) : "dN" (port));
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return result;
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}
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void command_8042(uint8_t command) {
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outport8(0x64, command);
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}
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uint8_t status_8042(void) {
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return inport8(0x64);
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}
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uint8_t read_8042(void) {
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return inport8(0x60);
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}
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void write_8042(uint8_t data) {
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outport8(0x60, data);
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}
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bool translation_initially;
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bool dual_channel;
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uint8_t read_config_8042(void) {
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command_8042(0x20);
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return read_8042();
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}
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void write_config_8042(uint8_t config) {
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command_8042(0x60);
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write_8042(config);
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}
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void init_8042(void) {
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// Disable devices
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command_8042(0xad);
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command_8042(0xa7);
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// Flush output buffer
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while (status_8042() & (1<<0))
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(void) read_8042();
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// Read configuration
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uint8_t config = read_config_8042();
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translation_initially = config & (1<<6);
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dual_channel = config & (1<<5);
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// Disable IRQ
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config &= ~(1<<0);
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config &= ~(1<<1);
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command_8042(0x60);
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write_8042(config);
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// Self test
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terminal_writestring("8042 self-test... ");
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command_8042(0xaa);
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while (!(status_8042() & (1<<0)));
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if (read_8042() != 0x55)
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terminal_writestring("failed\n");
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else
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terminal_writestring("ok\n");
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// Some controllers need this
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command_8042(0x60);
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write_8042(config);
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// Determine number of channels
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if (dual_channel) {
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command_8042(0xa8);
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dual_channel = !(read_config_8042() & (1<<5));
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if (dual_channel)
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command_8042(0xa7);
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}
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if (dual_channel)
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terminal_writestring("Dual-channel ps/2 controller\n");
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else
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terminal_writestring("Single-channel ps/2 controller\n");
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// Test channels
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terminal_writestring("Testing channel 1... ");
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command_8042(0xab);
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if (read_8042() != 0)
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terminal_writestring("failed\n");
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else
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terminal_writestring("ok\n");
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if (dual_channel) {
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terminal_writestring("Testing channel 2... ");
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command_8042(0xa9);
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if (read_8042() != 0)
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terminal_writestring("failed\n");
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else
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terminal_writestring("ok\n");
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}
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// Enable devices
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command_8042(0xae);
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if (dual_channel)
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command_8042(0xa8);
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}
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void enable_translation(void) {
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uint8_t config = read_config_8042();
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config |= 1<<6;
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write_config_8042(config);
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}
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void disable_translation(void) {
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uint8_t config = read_config_8042();
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config &= ~(1<<6);
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write_config_8042(config);
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}
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void kernel_main(void)
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{
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/* Initialize terminal interface */
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terminal_initialize();
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init_8042();
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if (single_channel)
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terminal_writestring("\nHanging\n");
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}
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