kern/arch/x86/boot/boot.c

/* See the end of this file for copyright and license terms. */

#include <string.h>

#include <arch/multiboot.h>

#include <gay/cdefs.h>
#include <gay/kprintf.h>
#include <gay/types.h>

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,
};

#define FB_ADDRESS 0xb8000
#define FB_LINES 24
#define FB_COLS 80

struct fb_cell {
	u8 c;
	enum vga_color fg:4;
	enum vga_color bg:4;
};

/* struct fb_cell gets aligned to 4 bytes for some reason, so we need to use u16 internally */
static volatile u16 *const framebuffer = (volatile u16 *)FB_ADDRESS;
/** @brief current line in the framebuffer */
static unsigned int fb_line;
/** @brief current column in the framebuffer */
static unsigned int fb_col;
/** @brief current background color */
enum vga_color fb_background;
/** @brief current foreground color */
enum vga_color fb_foreground;

static volatile struct fb_cell *cell_at(unsigned int line, unsigned int col);
#define current_cell (cell_at(fb_line, fb_col))

static ssize_t fb_write(struct kprintf_renderer *renderer, const void *buf, size_t size);
static ssize_t fb_flush(struct kprintf_renderer *renderer);
static struct kprintf_renderer fb_kprintf_renderer = {
	.write = fb_write,
	.flush = fb_flush,
};
static void fb_newline(void);
static void fb_clear(void);
static void fb_init(enum vga_color fg, enum vga_color bg);

static void print_gay_propaganda(void);

static struct mb2_tag *next_tag(struct mb2_tag *tag);
static void handle_tag(struct mb2_tag *tag);
static void handle_mmap_tag(struct mb2_tag_mmap *tag);

void _boot(u32 magic, void *address)
{
	kprintf_set_renderer(&fb_kprintf_renderer);
	fb_init(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);

	if (magic != MB2_BOOTLOADER_MAGIC) {
		kprintf("Error: invalid bootloader magic, aborting\n");
		return;
	}

	print_gay_propaganda();

	for (struct mb2_tag *tag = address + 8; tag != NULL; tag = next_tag(tag))
		handle_tag(tag);

	while (1);
}

static inline void handle_tag(struct mb2_tag *tag)
{
	switch (tag->type) {
	case MB2_TAG_TYPE_END:
		break;
	case MB2_TAG_TYPE_MMAP:
		handle_mmap_tag((struct mb2_tag_mmap *)tag);
		break;
	default:
		//kprintf("Unknown tag %u\n", tag->type);
		break;
	}
}

static inline void handle_mmap_tag(struct mb2_tag_mmap *tag)
{
	kprintf("Memory map:\n");

	struct mb2_mmap_entry *entry = tag->entries;
	while ((void *)entry < (void *)tag + tag->tag.size) {
		unsigned int type = entry->type;
		// kprintf("start = %p, ", (void *)entry->addr);
		// kprintf("len = %p, ", (void *)entry->len);
		// kprintf("type = %u\n", type);
		kprintf("start = %p, len = %p, type = %u\n",
			(void *)entry->addr, (void *)entry->len, type);

		entry = (void *)entry + tag->entry_size;
	}
}

static inline struct mb2_tag *next_tag(struct mb2_tag *tag)
{
	if (tag->type == MB2_TAG_TYPE_END)
		return NULL;
	else
		return (void *)tag + ( (tag->size + 7) & ~7 );
}

static void fb_newline(void)
{
	fb_col = 0;

	if (fb_line == FB_LINES - 1) {
		u8 *first_row = (u8 *)cell_at(0, 0);
		u8 *second_row = (u8 *)cell_at(1, 0);
		u8 *last_row_end = (u8 *)cell_at(FB_LINES, FB_COLS);
		memmove(first_row, second_row, last_row_end - second_row);
	} else {
		fb_line++;
	}
}

static ssize_t fb_write(struct kprintf_renderer *renderer, const void *buf, size_t size)
{
	ssize_t ret = 0;
	const u8 *s = buf;

	while (size > s - (const u8 *)buf) {
		u8 c = *s++;
		ret++;

		if (fb_col == FB_COLS)
			fb_newline();

		if (c == '\n') {
			fb_newline();
			continue;
		}

		current_cell->c = c;
		current_cell->fg = fb_foreground;
		current_cell->bg = fb_background;

		fb_col++;
	}

	return ret;
}

static ssize_t fb_flush(struct kprintf_renderer *renderer)
{
	return 0;
}

static void fb_clear(void)
{
	for (unsigned int l = 0; l < FB_LINES; l++) {
		for (unsigned int c = 0; c < FB_COLS; c++) {
			cell_at(l, c)->c = '\0';
			cell_at(l, c)->fg = fb_foreground;
			cell_at(l, c)->bg = fb_background;
		}
	}
}

static void fb_init(enum vga_color fg, enum vga_color bg)
{
	fb_line = 0;
	fb_col = 0;
	fb_foreground = VGA_COLOR_LIGHT_GREY;
	fb_background = VGA_COLOR_BLACK;

	fb_clear();
}

static void print_gay_propaganda(void)
{
	static const enum vga_color rainbow[] = {
		VGA_COLOR_RED,
		VGA_COLOR_LIGHT_RED,
		VGA_COLOR_LIGHT_BROWN,
		VGA_COLOR_GREEN,
		VGA_COLOR_BLUE,
		VGA_COLOR_MAGENTA,
	};

	enum vga_color bg_before = fb_background;
	enum vga_color fg_before = fb_foreground;
	for (int i = 0; i < ARRAY_SIZE(rainbow); i++) {
		fb_background = rainbow[i];
		for (int i = 0; i < FB_COLS; i++)
			fb_write(NULL, " ", 1);
	}
	fb_background = bg_before;

	kprintf("\nWelcome to ");
	const char *gaybsd = "GayBSD";
	for (const char *tmp = gaybsd; *tmp != '\0'; tmp++) {
		fb_foreground = rainbow[tmp - gaybsd];
		kprintf("%c", *tmp);
	}
	fb_foreground = fg_before;
	kprintf(", be gay do crime!\n\n");
}

static inline volatile struct fb_cell *cell_at(unsigned int line, unsigned int col)
{
	return (volatile struct fb_cell *)&framebuffer[line * FB_COLS + col];
}

/*
 * This file is part of GayBSD.
 * Copyright (c) 2021 fef <owo@fef.moe>.
 *
 * GayBSD is nonviolent software: you may only use, redistribute, and/or
 * modify it under the terms of the Cooperative Nonviolent Public License
 * (CNPL) as found in the LICENSE file in the source code root directory
 * or at <https://git.pixie.town/thufie/npl-builder>; either version 7
 * of the license, or (at your option) any later version.
 *
 * GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
 * permitted by applicable law.  See the CNPL for details.
 */