src/main.c


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#define NB_COLS 80
#define NB_ROWS 25
#define BPC     2

#define VIDEO_BUFFER 0xB8000

/* XXX doest not always handle memory overlaps */
static void my_memmove(void *_dest, const void *_src, int n)
{
    char *dest = _dest;
    const char *src = _src;

    for (int i = 0; i < n; ++i) {
        dest[i] = src[i];
    }
}

static void my_memset(void *_dest, int c, int n)
{
    char *dest = _dest;

    for (int i = 0; i < n; ++i) {
        dest[i] = c;
    }
}

int printk(const char *str)
{
    static const long int offset = VIDEO_BUFFER;
    static char *addr = (char *) VIDEO_BUFFER;
    int count = 0;

    for (int i = 0; str[i]; ++i) {
        /* TODO add the serial port handling */

        if ((long)addr >= offset + NB_COLS * NB_ROWS * BPC) {
            /* shift up */
            addr -= NB_COLS * BPC;
            my_memmove((void *)offset, (void *)offset + NB_COLS * BPC, NB_COLS * (NB_ROWS - 1) * BPC);
            my_memset((void *)offset + NB_COLS * (NB_ROWS - 1) * BPC, ' ', NB_COLS * BPC);
        }

        *addr = str[i];
        addr += BPC;
        ++count;
    }

    return count;
}

int main(void)
{
}