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#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
/* Check if the compiler thinks you are targeting the wrong operating system. */
#if defined(__linux__)
#error "You are not using a cross-compiler, you will most certainly run into trouble"
#endif
#if !defined(__i386__)
#error "This kernel needs to be compiled with a ix86-elf compiler"
#endif
/* Hardware text mode color constants. */
enum vga_color {
VGA_COLOR_BLACK = 0,
VGA_COLOR_BLUE = 1,
VGA_COLOR_GREEN = 2,
VGA_COLOR_CYAN = 3,
VGA_COLOR_RED = 4,
VGA_COLOR_MAGENTA = 5,
VGA_COLOR_BROWN = 6,
VGA_COLOR_LIGHT_GREY = 7,
VGA_COLOR_DARK_GREY = 8,
VGA_COLOR_LIGHT_BLUE = 9,
VGA_COLOR_LIGHT_GREEN = 10,
VGA_COLOR_LIGHT_CYAN = 11,
VGA_COLOR_LIGHT_RED = 12,
VGA_COLOR_LIGHT_MAGENTA = 13,
VGA_COLOR_LIGHT_BROWN = 14,
VGA_COLOR_WHITE = 15
};
static const size_t VGA_WIDTH = 80;
static const size_t VGA_HEIGHT = 25;
size_t terminal_row;
size_t terminal_column;
uint8_t terminal_color;
uint16_t *terminal_buffer;
static uint8_t vga_entry_color(enum vga_color fg, enum vga_color bg)
{
return fg | bg << 4;
}
static uint16_t vga_entry(unsigned char uc, uint8_t color)
{
return (uint16_t) uc | (uint16_t) color << 8;
}
size_t strlen(const char* str)
{
size_t len = 0;
while(str[len])
len++;
return len;
}
void terminal_initialize(void)
{
size_t x, y;
terminal_row = 0;
terminal_column = 0;
terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
terminal_buffer = (uint16_t*) 0xB8000;
for(y = 0; y < VGA_HEIGHT; y++) {
for(x = 0; x < VGA_WIDTH; x++) {
const size_t index = y * VGA_WIDTH + x;
terminal_buffer[index] = vga_entry(' ', terminal_color);
}
}
}
void terminal_setcolor(uint8_t color)
{
terminal_color = color;
}
void terminal_putentryat(char c, uint8_t color, size_t x, size_t y)
{
const size_t index = y * VGA_WIDTH + x;
terminal_buffer[index] = vga_entry(c, color);
}
void terminal_putchar(char c)
{
terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
if(++terminal_column == VGA_WIDTH) {
terminal_column = 0;
if(++terminal_row == VGA_HEIGHT)
terminal_row = 0;
}
}
void terminal_write(const char* data, size_t size)
{
size_t i;
for(i = 0; i < size; i++)
terminal_putchar(data[i]);
}
void terminal_writestring(const char* data)
{
terminal_write(data, strlen(data));
}
void kernel_main(void)
{
/* Initialize terminal interface */
terminal_initialize();
terminal_writestring("Welcome to MFSOS!");
}
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