matos/drivers/vga.c

#include "vga.h"
#include "io.h"
#include "klibc.h"

static uint vgaBgColor;
static uint vgaColor;
static int line, col;

int initVGA(uint bgColor, uint color)
{
	vgaBgColor = bgColor;
	vgaColor   = color;
	clearScreen(bgColor);
	line = 0;
	col  = 0;
	return 0;
}

void clearScreen(uint bgColor)
{
	volatile short *vga = (short *)VGA_ADDR;
	long int colorAttr  = bgColor << 12;
	for (int i = 0; i < VGA_WIDTH * VGA_HEIGHT; i++) {
		vga[i] = colorAttr;
	}
}

void printInt(int integer)
{
	char num[sizeof(int) *
		 3]; // int max is 2^(sizeof(int)*8) which is (2^3)^(sizeof(int)*8/3) =
		     // 8^(sizeof(int)*8/3) ~ 10^(sizeof(int)*8/3)
	int i = 0, k = 0;
	if (integer < 0) {
		printChar('-');
	}
	while (integer != 0) {
		int digit = integer % 10;
		num[i++]  = (digit > 0) ? digit : -digit;
		integer   = integer / 10;
	}
	for (k = i - 1; k >= 0; k--) {
		printChar(num[k] + '0');
	}
}

void printIntDetails(int integer, uint color, uint bgColor, int startX, int startY)
{
	char num[sizeof(int) *
		 3]; // int max is 2^(sizeof(int)*8) which is (2^3)^(sizeof(int)*8/3) =
		     // 8^(sizeof(int)*8/3) ~ 10^(sizeof(int)*8/3)
	int x = startX;
	int i = 0, k = 0;
	if (integer < 0) {
		printCharDetails('-', color, bgColor, x++, startY);
	}
	while (integer != 0) {
		int digit = integer % 10;
		num[i++]  = (digit > 0) ? digit : -digit;
		integer   = integer / 10;
	}
	for (k = i - 1; k >= 0; k--) {
		printCharDetails(num[k] + '0', color, bgColor, x++, startY);
	}
}

void printCharDetails(const char str, uint color, uint bgColor, int startX, int startY)
{
	volatile short *vga              = (short *)VGA_ADDR;
	long int colorAttr               = (bgColor << 4 | (color & 0x0f)) << 8;
	vga[VGA_WIDTH * startY + startX] = colorAttr | str;
}

void vgaScrollUp(void)
{
	long int colorAttr  = vgaBgColor << 12;
	volatile short *vga = (short *)VGA_ADDR;
	for (int i = 1; i < VGA_HEIGHT - 2;
	     i++) { // last line is status line. Do not scroll it
		memcpy((void *)&vga[VGA_WIDTH * (i - 1)], (void *)&vga[VGA_WIDTH * i],
		       VGA_WIDTH * sizeof(short));
	}
	for (int i = 0; i < VGA_WIDTH; i++) {
		vga[(VGA_HEIGHT - 2) * VGA_WIDTH + i] = colorAttr;
	}
}

void printString(const char *str)
{
	while (*str) {
		printChar(*(str++));
	}
}

void printChar(const char str)
{
	if (str == '\n') {
		line++;
		col = 0;
		if (line >= VGA_HEIGHT - 1) {
			vgaScrollUp();
			line--;
		}
	}
	else if(str == '\r')
	{
		col = 0;
	}
	else if(str == '\b')
	{
		col--;
		if (col < 0) {
			col = VGA_WIDTH - 1;
			line--;
		}
		printCharDetails(' ', vgaColor, vgaBgColor, col, line);
	}
	else
	{
		printCharDetails(str, vgaColor, vgaBgColor, col++, line);
		if (col == VGA_WIDTH) {
			col = 0;
			line++;
		}
		if (line >= VGA_HEIGHT - 1) {
			vgaScrollUp();
			line--;
		}
	}
}

void printStringDetails(const char *str, uint color, uint bgColor, int startX, int startY)
{
	volatile short *vga = (short *)VGA_ADDR;
	int i               = 0;
	long int colorAttr  = (bgColor << 4 | (color & 0x0f)) << 8;
	while (*str) {
		vga[VGA_WIDTH * startY + startX + i] = colorAttr | *str;
		str++;
		i++;
	}
}