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/*
* CMOS
* Copyright (C) 2024 Raghuram Subramani <raghus2247@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <libk/string.h>
#include <driver/vga_text_buffer.h>
uint8_t vga_text_buffer_row;
uint8_t vga_text_buffer_column;
uint8_t vga_text_buffer_color;
uint16_t *vga_text_buffer_buffer;
bool vga_text_buffer_initialized = false;
static uint8_t
vga_entry_color(vga_color fg, vga_color bg)
{
/*
* bg fg
* 1110 0101
*/
return bg << 4 | fg;
}
static uint16_t
vga_entry(unsigned char character, uint8_t color)
{
/*
* color character
* 1110 0101 1001 1010
*/
return (uint16_t) color << 8 | (uint16_t) character;
}
bool
vga_text_buffer_is_initialized(void)
{
return vga_text_buffer_initialized;
}
static void
vga_text_buffer_write_entry_at(char c, uint8_t color, uint8_t x, uint8_t y)
{
size_t index = y * VGA_WIDTH + x;
vga_text_buffer_buffer[index] = vga_entry(c, color);
}
void
vga_text_buffer_initialize(void)
{
vga_text_buffer_row = 0;
vga_text_buffer_column = 0;
vga_text_buffer_color = vga_entry_color(
VGA_COLOR_LIGHT_GREY,
VGA_COLOR_BLACK
);
vga_text_buffer_buffer = (uint16_t *) 0xB8000;
for (uint8_t y = 0; y < VGA_HEIGHT; y++)
for (uint8_t x = 0; x < VGA_WIDTH; x++)
vga_text_buffer_write_entry_at(' ', vga_text_buffer_color, x, y);
vga_text_buffer_initialized = true;
}
void
vga_text_buffer_write_char(char c)
{
if (c == '\n') {
vga_text_buffer_row++;
vga_text_buffer_column = 0;
} else {
vga_text_buffer_write_entry_at(c, vga_text_buffer_color, vga_text_buffer_column, vga_text_buffer_row);
if (++vga_text_buffer_column == VGA_WIDTH) {
vga_text_buffer_column = 0;
if (++vga_text_buffer_row == VGA_HEIGHT)
vga_text_buffer_row = 0;
}
}
}
void
vga_text_buffer_write_string(char *data)
{
size_t size = strlen(data);
for (size_t i = 0; i < size; i++)
vga_text_buffer_write_char(data[i]);
}
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