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#include "vga.h"
#include <string.h>
static_assert(sizeof(VGA::Entry) == 2);
VGA::VGA(vga_color fg, vga_color bg, uint32_t address) : color_fg(fg), color_bg(bg) {
buffer = reinterpret_cast<Entry*>(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].c = ' ';
buffer[index].fg = color_fg;
buffer[index].bg = color_bg;
}
}
enable_cursor(14, 15);
update_cursor();
}
void VGA::set_color(vga_color fg, vga_color bg) {
color_fg = fg;
color_bg = bg;
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].fg = color_fg;
buffer[index].bg = color_bg;
}
}
}
void VGA::enable_cursor(uint8_t start, uint8_t end) {
p_3d4.write(0x0a);
p_3d5.write((p_3d5.read() & 0xc0) | start);
p_3d4.write(0x0b);
p_3d5.write((p_3d5.read() & 0xe0) | end);
}
void VGA::disable_cursor() {
p_3d4.write(0x0a);
p_3d5.write(0x20);
}
void VGA::update_cursor() {
const uint16_t pos = row * max_columns + column;
p_3d4.write(0x0f);
p_3d5.write(static_cast<uint8_t>(pos & 0xff));
p_3d4.write(0x0e);
p_3d5.write(static_cast<uint8_t>((pos >> 8) & 0xff));
}
void VGA::write(char c) {
switch (c) {
case '\n':
column = 0;
++row;
break;
default: {
const size_t index = row * max_columns + column;
buffer[index].c = c;
++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(ViewIterator& iter) {
while (iter) {
write(iter.next());
}
}
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