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#include "x86_64/vga/text.hpp"
#include "kapi/boot.hpp"
#include "kapi/cio.hpp"
#include "x86_64/boot/boot.hpp"
#include "x86_64/boot/ld.hpp"
#include "x86_64/vga/crtc.hpp"
#include <algorithm>
#include <bit>
#include <cstddef>
#include <cstdint>
#include <span>
#include <string_view>
#include <utility>
namespace teachos::vga::x86_64::text
{
namespace
{
constexpr auto default_buffer_address = std::uintptr_t{0xb8000};
constexpr auto default_buffer_width = 80z;
constexpr auto default_buffer_height = 25z;
constexpr auto bit_cursor_enabled = 5U;
[[maybe_unused]] constexpr auto black_on_black = attribute{.foreground_color = color::black,
.foreground_flag = foreground_flag::none,
.background_color = color::black,
.background_flag = background_flag::none};
} // namespace
device::device()
: m_width{default_buffer_width}
, m_height{default_buffer_height}
, m_buffer{std::bit_cast<device::cell *>(default_buffer_address +
std::bit_cast<std::uintptr_t>(&teachos::boot::x86_64::TEACHOS_VMA)),
m_width * m_height}
, m_position{boot::bootstrap_information.vga_buffer_index}
{
clear();
}
auto device::clear() -> void
{
m_position = 0;
std::ranges::fill(m_buffer, std::pair{' ', std::bit_cast<std::byte>(black_on_black)});
}
auto device::cursor(bool enabled) -> void
{
auto cursor_disable_byte = std::byte{!enabled} << bit_cursor_enabled;
crtc::address::write(crtc::registers::cursor_start);
crtc::data::write(crtc::data::read() | cursor_disable_byte);
}
[[nodiscard]] auto device::column() const noexcept -> std::ptrdiff_t
{
return m_position % m_width;
}
[[nodiscard]] auto device::line() const noexcept -> std::ptrdiff_t
{
return m_position / m_width;
}
auto device::handle_special_code_point(char code_point, attribute attribute) -> bool
{
switch (code_point)
{
case '\n':
newline();
return true;
case '\r':
m_position -= column();
return true;
case '\t':
put(" ", attribute);
return true;
default:
return false;
}
}
auto device::put(std::string_view code_points, attribute attribute) -> void
{
std::ranges::for_each(code_points, [&](auto code_point) -> void { put(code_point, attribute); });
}
auto device::put(char code_point, attribute attribute) -> void
{
m_buffer[m_position++] = std::pair{code_point, std::bit_cast<std::byte>(attribute)};
}
auto device::newline() -> void
{
auto free_glyphs_in_line = m_width - column();
m_position += free_glyphs_in_line;
}
auto device::scroll(std::size_t nof_lines) -> void
{
auto scroll_count = std::min(nof_lines, m_height);
auto scroll_start = m_buffer.begin() + (scroll_count * m_width);
std::ranges::move(scroll_start, m_buffer.end(), m_buffer.begin());
auto clear_start = m_buffer.begin() + (m_height - scroll_count) * m_width;
std::ranges::fill(clear_start, m_buffer.end(), cell{});
m_position = (line() - scroll_count) * m_width;
}
auto device::write(cio::output_stream stream, std::string_view text) -> void
{
auto attributes = [&] -> attribute {
switch (stream)
{
case cio::output_stream::stderr:
return red_on_black;
default:
return green_on_black;
}
}();
write(text, attributes);
}
auto device::write(std::string_view code_points, attribute attribute) -> void
{
std::ranges::for_each(code_points, [&](auto code_point) -> void { write(code_point, attribute); });
}
auto device::write(char code_point, attribute attribute) -> void
{
if (m_position + 1 > static_cast<std::ptrdiff_t>(m_height * m_width))
{
scroll();
}
if (!handle_special_code_point(code_point, attribute))
{
put(code_point, attribute);
}
};
} // namespace teachos::vga::x86_64::text
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