#include "framebuffer.h"
#include "kernel.h"
#include "portio.h"

uint16_t framebuffer_color = 0x0700;
uint8_t framebuffer_x;
uint8_t framebuffer_y;

void framebuffer_init() {
	union {uint8_t b[2]; uint16_t w;} pos;
	
	outb(0x3d4, 0x0f);
	inb(0x3d5, pos.b[0]);
	
	outb(0x3d4, 0x0e);
	inb(0x3d5, pos.b[1]);
	
	framebuffer_x = pos.w % 80;
	framebuffer_y = pos.w / 80;
}

void framebuffer_putchar(char c) {
	switch(c) {
		case '\f':
			framebuffer_clear();
			break;
		case '\r':
			framebuffer_x = 0;
			break;
		case '\n':
			framebuffer_x = 80;
			break;
		default:
			framebuffer[framebuffer_y][framebuffer_x++] = framebuffer_color | c;
	}
	if(framebuffer_x == 80) {
		framebuffer_x = 0;
		if(framebuffer_y < 24) {
			framebuffer_y++;
		} else {
			framebuffer_scroll();
		}
	}
}

void framebuffer_clear() {
	for(int y = 0; y < 25; y++) {
		for(int x = 0; x < 80; x++) {
			framebuffer[y][x] = framebuffer_color;
		}
	}
	framebuffer_x = framebuffer_y = 0;
}

void framebuffer_scroll() {
	for(int y = 0; y < 24; y++) {
		for(int x = 0; x < 80; x++) {
			framebuffer[y][x] = framebuffer[y + 1][x];
		}
	}
	for(int x = 0; x < 80; x++) {
		framebuffer[24][x] = framebuffer_color;
	}
}

void framebuffer_move_cursor() {
	uint16_t pos = framebuffer_y * 80 + framebuffer_x;
	
	outb(0x3d4, 0x0f);
	outb(0x3d5, pos & 0xff);
	
	outb(0x3d4, 0x0e);
	outb(0x3d5, pos >> 8);
}