polka/src/Console.cc

/* Console.cc
 * vim: set tw=80:
 * Eryn Wells <eryn@erynwells.me>
 */
/**
 * Implementation of the Console class.
 */

#include "Console.hh"

namespace kernel {

/** Create a VGA color pair. */
static inline uint8_t
makeVGAColor(Console::Color fg,
             Console::Color bg)
{
    return uint8_t(fg) | uint8_t(bg) << 4;
}


/** Create a VGA character entry. */
static inline uint16_t
makeVGAEntry(char c,
             uint8_t color)
{
    uint16_t c16 = c;
    uint16_t color16 = color;
    return c16 | color16 << 8;
}


Console::Console()
    : mBase(reinterpret_cast<uint16_t *>(0xB8000)),
      mCursor{0, 0},
      mColor(makeVGAColor(Console::Color::LightGray, Console::Color::Black))
{ }


void
Console::clear(Console::Color color)
{
    setColor(Color::LightGray, color);
    for (size_t y = 0; y < Console::Height; y++) {
        for (size_t x = 0; x < Console::Width; x++) {
            putEntryAt(x, y, ' ', mColor);
        }
    }
}


void
Console::writeChar(char c)
{
    putEntryAt(mCursor.col, mCursor.row, c, mColor);
    if (++mCursor.col == Console::Width) {
        mCursor.col = 0;
        if (++mCursor.row == Console::Height) {
            mCursor.row = 0;
        }
    }
}

void
Console::writeString(const char *str)
{
    // XXX: THIS IS VERY UNSAFE. PUT DOWN THE POINTER ERYN. NO BAD ERYN DONT YOU DARE.
    const char *cur = str;
    while (*cur != '\0') {
        writeChar(*cur++);
    }
}

void
Console::setColor(Console::Color fg,
                  Console::Color bg)
{
    mColor = makeVGAColor(fg, bg);
}

/*
 * Private
 */

void
Console::putEntryAt(size_t x,
                    size_t y,
                    char c,
                    uint8_t color)
{
    const size_t index = y * Console::Width + x;
    mBase[index] = makeVGAEntry(c, color);
}

} /* namespace kernel */