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#include "x86_64/vga/text.hpp"
#include "kapi/boot.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 BUFFER_BASE_ADDRESS = std::uintptr_t{0xb8000};
constexpr auto DEFAULT_TEXT_BUFFER_WIDTH = 80U;
constexpr auto DEFAULT_TEXT_BUFFER_HEIGHT = 25U;
constexpr auto CURSOR_ENABLED_BIT = 5U;
} // namespace
std::span<device::glyph> const device::buffer =
std::span{std::bit_cast<device::glyph *>(BUFFER_BASE_ADDRESS +
std::bit_cast<std::uintptr_t>(&teachos::boot::x86_64::TEACHOS_VMA)),
DEFAULT_TEXT_BUFFER_WIDTH * DEFAULT_TEXT_BUFFER_HEIGHT};
device::device()
: m_position{boot::bootstrap_information.vga_buffer_index}
{}
auto device::clear(attribute attribute) -> void
{
m_position = 0;
std::ranges::fill(buffer, std::pair{' ', std::bit_cast<std::byte>(attribute)});
}
auto device::cursor(bool enabled) -> void
{
auto cursor_disable_byte = std::byte{!enabled} << CURSOR_ENABLED_BIT;
crtc::address::write(crtc::registers::cursor_start);
crtc::data::write(crtc::data::read() | cursor_disable_byte);
}
auto device::newline() -> void
{
auto current_line = m_position / DEFAULT_TEXT_BUFFER_WIDTH;
auto next_line = current_line + 1;
if (std::cmp_greater_equal(next_line, DEFAULT_TEXT_BUFFER_HEIGHT))
{
auto begin = buffer.begin() + DEFAULT_TEXT_BUFFER_WIDTH;
auto end = buffer.begin() + DEFAULT_TEXT_BUFFER_WIDTH * DEFAULT_TEXT_BUFFER_HEIGHT;
std::ranges::move(begin, end, buffer.begin());
m_position = current_line * DEFAULT_TEXT_BUFFER_WIDTH;
}
else
{
m_position = next_line * DEFAULT_TEXT_BUFFER_WIDTH;
}
}
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
{
buffer[m_position++] = std::pair{code_point, std::bit_cast<std::byte>(attribute)};
};
auto device::writeln(std::string_view code_points, attribute attribute) -> void
{
std::ranges::for_each(code_points, [&](auto code_point) -> void { write(code_point, attribute); });
newline();
}
} // namespace teachos::vga::x86_64::text
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