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#if !defined(__cplusplus)
#include <stdbool.h> /* C doesn't have booleans by default. */
#endif
#include <stddef.h>
#include <stdint.h>
/* Check if the compiler thinks if we 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
/* This tutorial will only work for the 32-bit ix86 targets. */
#if !defined(__i386__)
#error "This tutorial needs to be compiled with a ix86-elf compiler"
#endif
#include "multiboot.h"
extern void k_highhalf_addr;
/* Hardware text mode color constants. */
enum vga_color
{
COLOR_BLACK = 0,
COLOR_BLUE = 1,
COLOR_GREEN = 2,
COLOR_CYAN = 3,
COLOR_RED = 4,
COLOR_MAGENTA = 5,
COLOR_BROWN = 6,
COLOR_LIGHT_GREY = 7,
COLOR_DARK_GREY = 8,
COLOR_LIGHT_BLUE = 9,
COLOR_LIGHT_GREEN = 10,
COLOR_LIGHT_CYAN = 11,
COLOR_LIGHT_RED = 12,
COLOR_LIGHT_MAGENTA = 13,
COLOR_LIGHT_BROWN = 14,
COLOR_WHITE = 15,
};
uint8_t make_color(enum vga_color fg, enum vga_color bg)
{
return fg | bg << 4;
}
uint16_t make_vgaentry(char c, uint8_t color)
{
uint16_t c16 = c;
uint16_t color16 = color;
return c16 | color16 << 8;
}
size_t strlen(const char* str)
{
size_t ret = 0;
while ( str[ret] != 0 )
ret++;
return ret;
}
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;
void terminal_initialize()
{
terminal_row = 0;
terminal_column = 0;
terminal_color = make_color(COLOR_LIGHT_GREY, COLOR_BLACK);
terminal_buffer = (uint16_t*) (&k_highhalf_addr + 0xB8000);
for ( size_t y = 0; y < VGA_HEIGHT; y++ )
{
for ( size_t x = 0; x < VGA_WIDTH; x++ )
{
const size_t index = y * VGA_WIDTH + x;
terminal_buffer[index] = make_vgaentry(' ', 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] = make_vgaentry(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_writestring(const char* data)
{
size_t datalen = strlen(data);
for ( size_t i = 0; i < datalen; i++ )
terminal_putchar(data[i]);
}
#if defined(__cplusplus)
extern "C" /* Use C linkage for kernel_main. */
#endif
void kmain(struct multiboot_info_t *mbd, int32_t mb_magic)
{
terminal_initialize();
/* Since there is no support for newlines in terminal_putchar yet, \n will
produce some VGA specific character instead. This is normal. */
terminal_writestring("Hello, kernel World!\n");
}
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