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#include "vga.h"
#include <string.h>
constexpr uint8_t vga_entry_color(VGA::vga_color fg, VGA::vga_color bg) {
return fg | bg << 4;
}
constexpr uint16_t vga_entry(unsigned char uc, uint8_t color) {
return (uint16_t)uc | (uint16_t)color << 8;
}
VGA::VGA(uint32_t address) {
color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BROWN);
buffer = (uint16_t *)address;
// clear buffer
for (size_t y = 0; y < max_rows; y++) {
for (size_t x = 0; x < max_columns; x++) {
const size_t index = y * max_columns + x;
buffer[index] = vga_entry(' ', color);
}
}
}
void VGA::put_char(char c, size_t x, size_t y, uint8_t color) {
const size_t index = y * max_columns + x;
buffer[index] = vga_entry(c, (color == 0) ? this->color : color);
}
void VGA::write(char c) {
switch (c) {
case '\n':
column = 0;
++row;
break;
default:
put_char(c, column, row, color);
++column;
}
if (column == max_columns) {
column = 0;
++row;
}
if (row == max_rows) {
// scroll up - move rows 1~25 up by one
for (size_t y = 1; y < max_rows; y++) {
const auto prev_y = y - 1;
for (size_t x = 0; x < max_columns; ++x) {
const auto prev = prev_y * max_columns + x;
const auto idx = y * max_columns + x;
buffer[prev] = buffer[idx];
}
}
--row;
}
}
void VGA::write(const String &data) {
auto it = data.begin();
while (it) {
write(it.next());
}
}
void VGA::write(int n) {
char buffer[max_columns];
itoa<16>(n, buffer);
write(buffer);
}
void VGA::write(unsigned int n) {
// TODO
write((int)n);
}
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