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/*
* CMOS
* Copyright (C) 2024-2025 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 <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <libk/stdio.h>
#include <libk/string.h>
#include <drivers/vga_text_buffer.h>
static uint8_t vga_text_buffer_row;
static uint8_t vga_text_buffer_column;
static uint8_t vga_text_buffer_color;
static uint16_t *vga_text_buffer_buffer;
static uint8_t
vga_entry_color(const vga_color fg, const vga_color bg)
{
/*
* bg fg
* 1110 0101
*/
return bg << 4 | fg;
}
static uint16_t
vga_entry(const unsigned char character, const uint8_t color)
{
/*
* color character
* 1110 0101 1001 1010
*/
return (uint16_t) color << 8 | (uint16_t) character;
}
static void
vga_text_buffer_write_entry_at(const char c,
const uint8_t color,
const uint8_t x,
const 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);
}
void
vga_text_buffer_write_char(const 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(const char *string)
{
size_t size = strlen(string);
for (size_t i = 0; i < size; i++)
vga_text_buffer_write_char(string[i]);
}
void
vga_text_buffer_printf(const char *string, ...)
{
/* TODO: Dynamic Memory Allocation */
char str[256];
va_list ap;
va_start(ap, string);
vsnprintf(str, sizeof(str), string, ap);
va_end(ap);
vga_text_buffer_write_string(str);
}
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