wslで、最小のカーネルをコンパイル その5

概要

wslで、kernel.elfのコンパイル、やってみた。
cで、書いたカーネルで、九九、fizzbuzz、zundoko、実行してみた。

写真

サンプルコード

#include "kernel.h"

uint32 vga_index;
static uint32 next_line_index = 1;
uint8 g_fore_color = WHITE,
	g_back_color = BLUE;
int digit_ascii_codes[10] = {
	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39
};
uint16 vga_entry(unsigned char ch, uint8 fore_color, uint8 back_color) {
	uint16 ax = 0;
	uint8 ah = 0,
		al = 0;
	ah = back_color;
	ah <<= 4;
	ah |= fore_color;
	ax = ah;
	ax <<= 8;
	al = ch;
	ax |= al;
	return ax;
}
void clear_vga_buffer(uint16 ** buffer, uint8 fore_color, uint8 back_color) {
	uint32 i;
	for(i = 0; i < BUFSIZE; i++)
	{
		(* buffer) [i] = vga_entry(NULL, fore_color, back_color);
	}
	next_line_index = 1;
	vga_index = 0;
}
void init_vga(uint8 fore_color, uint8 back_color) {
	vga_buffer = (uint16 *) VGA_ADDRESS;
	clear_vga_buffer(&vga_buffer, fore_color, back_color);
	g_fore_color = fore_color;
	g_back_color = back_color;
}
void print_new_line() {
	if (next_line_index >= 55)
	{
		next_line_index = 0;
		clear_vga_buffer(&vga_buffer, g_fore_color, g_back_color);
	}
	vga_index = 80 * next_line_index;
	next_line_index++;
}
void print_char(char ch) {
	vga_buffer[vga_index] = vga_entry(ch, g_fore_color, g_back_color);
	vga_index++;
}
uint32 strlen(const char * str) {
	uint32 length = 0;
	while(str[length])
		length++;
	return length;
}
uint32 digit_count(int num) {
	uint32 count = 0;
	if (num == 0)
		return 1;
	while(num > 0)
	{
		count++;
		num = num / 10;
	}
	return count;
}
void itoa(int num, char * number) {
	int dgcount = digit_count(num);
	int index = dgcount - 1;
	char x;
	if (num == 0 && dgcount == 1)
	{
		number[0] = '0';
		number[1] = '\0';
	}
	else
	{
		while(num != 0)
		{
			x = num % 10;
			number[index] = x + '0';
			index--;
			num = num / 10;
		}
		number[dgcount] = '\0';
	}
}
void print_string(char * str) {
	uint32 index = 0;
	while(str[index])
	{
		print_char(str[index]);
		index++;
	}
}
void print_int(int num) {
	char str_num[digit_count(num) + 1];
	itoa(num, str_num);
	print_string(str_num);
}
static int randseed = 12345;
int rand(void) {
	return (randseed = randseed * 12345 + 17);
}
void kernel_entry() {
	int i,
		j,
		k;
	uint8 r = 243;
	init_vga(WHITE, BLACK);
	print_string("0 Hello World!");
	print_new_line();
	print_int(123456789);
	print_new_line();
	print_string("4 Goodbye World!");
	print_new_line();
	for (i = 1; i < 10; i++)
	{
		for (j = 1; j < 10; j++)
		{
			k = i * j;
			print_int(k);
			print_string(" ");
		}
		print_new_line();
	}
	for (i = 1; i < 101; i++)
	{
		if (i % 15 == 0)
		{
			print_string("FizzBuzz");
			print_new_line();
		}
		else if (i % 3 == 0)
		{
			print_string("Fizz ");
		}
		else if (i % 5 == 0)
		{
			print_string("Buzz ");
		}
		else
		{
			print_int(i);
			print_string(" ");
		}
	}
	i = 0;
	while (i < 4)
	{
		r = r * 5;
		r = r - 1;
		if (r < 127)
		{
			print_string("zun ");
			i++;
		}
		else
		{
			print_string("doko ");
			i = 0;
		}
	}
	print_string("doko kiyosi!!");
}

以上。