gwj / at91sam9263 · Files

/*
 * QEMU graphical console

 *

 * Copyright (c) 2004 Fabrice Bellard

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "vl.h"

//#define DEBUG_CONSOLE

#define DEFAULT_BACKSCROLL 512
#define MAX_CONSOLES 12

#define QEMU_RGBA(r, g, b, a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))
#define QEMU_RGB(r, g, b) QEMU_RGBA(r, g, b, 0xff)

typedef struct TextAttributes {
    uint8_t fgcol:4;
    uint8_t bgcol:4;
    uint8_t bold:1;
    uint8_t uline:1;
    uint8_t blink:1;
    uint8_t invers:1;
    uint8_t unvisible:1;
} TextAttributes;

typedef struct TextCell {
    uint8_t ch;

    TextAttributes t_attrib;

} TextCell;

#define MAX_ESC_PARAMS 3

enum TTYState {
    TTY_STATE_NORM,
    TTY_STATE_ESC,
    TTY_STATE_CSI,
};

typedef struct QEMUFIFO {
    uint8_t *buf;
    int buf_size;
    int count, wptr, rptr;
} QEMUFIFO;

int qemu_fifo_write(QEMUFIFO *f, const uint8_t *buf, int len1)
{
    int l, len;

    l = f->buf_size - f->count;
    if (len1 > l)
        len1 = l;
    len = len1;
    while (len > 0) {
        l = f->buf_size - f->wptr;
        if (l > len)
            l = len;
        memcpy(f->buf + f->wptr, buf, l);
        f->wptr += l;
        if (f->wptr >= f->buf_size)
            f->wptr = 0;
        buf += l;
        len -= l;
    }
    f->count += len1;
    return len1;
}

int qemu_fifo_read(QEMUFIFO *f, uint8_t *buf, int len1)
{
    int l, len;

    if (len1 > f->count)
        len1 = f->count;
    len = len1;
    while (len > 0) {
        l = f->buf_size - f->rptr;
        if (l > len)
            l = len;
        memcpy(buf, f->buf + f->rptr, l);
        f->rptr += l;
        if (f->rptr >= f->buf_size)
            f->rptr = 0;
        buf += l;
        len -= l;
    }
    f->count -= len1;
    return len1;
}

typedef enum {
    GRAPHIC_CONSOLE,
    TEXT_CONSOLE,
    TEXT_CONSOLE_FIXED_SIZE
} console_type_t;

/* ??? This is mis-named.
   It is used for both text and graphical consoles.  */

struct TextConsole {

    console_type_t console_type;

    DisplayState *ds;

    /* Graphic console state.  */
    vga_hw_update_ptr hw_update;
    vga_hw_invalidate_ptr hw_invalidate;
    vga_hw_screen_dump_ptr hw_screen_dump;
    void *hw;

    int g_width, g_height;
    int width;
    int height;
    int total_height;
    int backscroll_height;
    int x, y;

    int x_saved, y_saved;

    int y_displayed;
    int y_base;

    TextAttributes t_attrib_default; /* default text attributes */
    TextAttributes t_attrib; /* currently active text attributes */

    TextCell *cells;

    enum TTYState state;
    int esc_params[MAX_ESC_PARAMS];
    int nb_esc_params;

    CharDriverState *chr;

    /* fifo for key pressed */
    QEMUFIFO out_fifo;
    uint8_t out_fifo_buf[16];
    QEMUTimer *kbd_timer;

};

static TextConsole *active_console;
static TextConsole *consoles[MAX_CONSOLES];
static int nb_consoles = 0;

void vga_hw_update(void)
{

    if (active_console && active_console->hw_update)

        active_console->hw_update(active_console->hw);
}

void vga_hw_invalidate(void)
{
    if (active_console->hw_invalidate)
        active_console->hw_invalidate(active_console->hw);
}

void vga_hw_screen_dump(const char *filename)
{
    /* There is currently no was of specifying which screen we want to dump,
       so always dump the dirst one.  */
    if (consoles[0]->hw_screen_dump)
        consoles[0]->hw_screen_dump(consoles[0]->hw, filename);
}

/* convert a RGBA color to a color index usable in graphic primitives */
static unsigned int vga_get_color(DisplayState *ds, unsigned int rgba)
{
    unsigned int r, g, b, color;

    switch(ds->depth) {
#if 0
    case 8:
        r = (rgba >> 16) & 0xff;
        g = (rgba >> 8) & 0xff;
        b = (rgba) & 0xff;

        color = (rgb_to_index[r] * 6 * 6) +
            (rgb_to_index[g] * 6) +

            (rgb_to_index[b]);
        break;
#endif
    case 15:
        r = (rgba >> 16) & 0xff;
        g = (rgba >> 8) & 0xff;
        b = (rgba) & 0xff;
        color = ((r >> 3) << 10) | ((g >> 3) << 5) | (b >> 3);
        break;
    case 16:
        r = (rgba >> 16) & 0xff;
        g = (rgba >> 8) & 0xff;
        b = (rgba) & 0xff;
        color = ((r >> 3) << 11) | ((g >> 2) << 5) | (b >> 3);
        break;
    case 32:
    default:
        color = rgba;
        break;
    }
    return color;
}

static void vga_fill_rect (DisplayState *ds,

                           int posx, int posy, int width, int height, uint32_t color)
{
    uint8_t *d, *d1;
    int x, y, bpp;

    bpp = (ds->depth + 7) >> 3;

    d1 = ds->data +

        ds->linesize * posy + bpp * posx;
    for (y = 0; y < height; y++) {
        d = d1;
        switch(bpp) {
        case 1:
            for (x = 0; x < width; x++) {
                *((uint8_t *)d) = color;
                d++;
            }
            break;
        case 2:
            for (x = 0; x < width; x++) {
                *((uint16_t *)d) = color;
                d += 2;
            }
            break;
        case 4:
            for (x = 0; x < width; x++) {
                *((uint32_t *)d) = color;
                d += 4;
            }
            break;
        }
        d1 += ds->linesize;
    }
}

/* copy from (xs, ys) to (xd, yd) a rectangle of size (w, h) */
static void vga_bitblt(DisplayState *ds, int xs, int ys, int xd, int yd, int w, int h)
{
    const uint8_t *s;
    uint8_t *d;
    int wb, y, bpp;

    bpp = (ds->depth + 7) >> 3;
    wb = w * bpp;
    if (yd <= ys) {

        s = ds->data +

            ds->linesize * ys + bpp * xs;

        d = ds->data +

            ds->linesize * yd + bpp * xd;
        for (y = 0; y < h; y++) {
            memmove(d, s, wb);
            d += ds->linesize;
            s += ds->linesize;
        }
    } else {

        s = ds->data +

            ds->linesize * (ys + h - 1) + bpp * xs;

        d = ds->data +

            ds->linesize * (yd + h - 1) + bpp * xd;
       for (y = 0; y < h; y++) {
            memmove(d, s, wb);
            d -= ds->linesize;
            s -= ds->linesize;
        }
    }
}

/***********************************************************/
/* basic char display */

#define FONT_HEIGHT 16
#define FONT_WIDTH 8

#include "vgafont.h"

#define cbswap_32(__x) \
((uint32_t)( \
		(((uint32_t)(__x) & (uint32_t)0x000000ffUL) << 24) | \
		(((uint32_t)(__x) & (uint32_t)0x0000ff00UL) <<  8) | \
		(((uint32_t)(__x) & (uint32_t)0x00ff0000UL) >>  8) | \
		(((uint32_t)(__x) & (uint32_t)0xff000000UL) >> 24) ))

#ifdef WORDS_BIGENDIAN
#define PAT(x) x
#else
#define PAT(x) cbswap_32(x)
#endif

static const uint32_t dmask16[16] = {
    PAT(0x00000000),
    PAT(0x000000ff),
    PAT(0x0000ff00),
    PAT(0x0000ffff),
    PAT(0x00ff0000),
    PAT(0x00ff00ff),
    PAT(0x00ffff00),
    PAT(0x00ffffff),
    PAT(0xff000000),
    PAT(0xff0000ff),
    PAT(0xff00ff00),
    PAT(0xff00ffff),
    PAT(0xffff0000),
    PAT(0xffff00ff),
    PAT(0xffffff00),
    PAT(0xffffffff),
};

static const uint32_t dmask4[4] = {
    PAT(0x00000000),
    PAT(0x0000ffff),
    PAT(0xffff0000),
    PAT(0xffffffff),
};

static uint32_t color_table[2][8];

enum color_names {
    COLOR_BLACK   = 0,
    COLOR_RED     = 1,
    COLOR_GREEN   = 2,
    COLOR_YELLOW  = 3,
    COLOR_BLUE    = 4,
    COLOR_MAGENTA = 5,
    COLOR_CYAN    = 6,
    COLOR_WHITE   = 7
};

static const uint32_t color_table_rgb[2][8] = {
    {   /* dark */

        QEMU_RGB(0x00, 0x00, 0x00),  /* black */
        QEMU_RGB(0xaa, 0x00, 0x00),  /* red */
        QEMU_RGB(0x00, 0xaa, 0x00),  /* green */
        QEMU_RGB(0xaa, 0xaa, 0x00),  /* yellow */
        QEMU_RGB(0x00, 0x00, 0xaa),  /* blue */
        QEMU_RGB(0xaa, 0x00, 0xaa),  /* magenta */
        QEMU_RGB(0x00, 0xaa, 0xaa),  /* cyan */
        QEMU_RGB(0xaa, 0xaa, 0xaa),  /* white */

    },
    {   /* bright */

        QEMU_RGB(0x00, 0x00, 0x00),  /* black */
        QEMU_RGB(0xff, 0x00, 0x00),  /* red */
        QEMU_RGB(0x00, 0xff, 0x00),  /* green */
        QEMU_RGB(0xff, 0xff, 0x00),  /* yellow */
        QEMU_RGB(0x00, 0x00, 0xff),  /* blue */
        QEMU_RGB(0xff, 0x00, 0xff),  /* magenta */
        QEMU_RGB(0x00, 0xff, 0xff),  /* cyan */
        QEMU_RGB(0xff, 0xff, 0xff),  /* white */

    }

};

static inline unsigned int col_expand(DisplayState *ds, unsigned int col)
{
    switch(ds->depth) {
    case 8:
        col |= col << 8;
        col |= col << 16;
        break;
    case 15:
    case 16:
        col |= col << 16;
        break;
    default:
        break;
    }

    return col;
}

#ifdef DEBUG_CONSOLE
static void console_print_text_attributes(TextAttributes *t_attrib, char ch)
{
    if (t_attrib->bold) {
        printf("b");
    } else {
        printf(" ");
    }
    if (t_attrib->uline) {
        printf("u");
    } else {
        printf(" ");
    }
    if (t_attrib->blink) {
        printf("l");
    } else {
        printf(" ");
    }
    if (t_attrib->invers) {
        printf("i");
    } else {
        printf(" ");
    }
    if (t_attrib->unvisible) {
        printf("n");
    } else {
        printf(" ");
    }

    printf(" fg: %d bg: %d ch:'%2X' '%c'\n", t_attrib->fgcol, t_attrib->bgcol, ch, ch);
}
#endif

static void vga_putcharxy(DisplayState *ds, int x, int y, int ch,

                          TextAttributes *t_attrib)

{
    uint8_t *d;
    const uint8_t *font_ptr;
    unsigned int font_data, linesize, xorcol, bpp;
    int i;

    unsigned int fgcol, bgcol;

#ifdef DEBUG_CONSOLE
    printf("x: %2i y: %2i", x, y);
    console_print_text_attributes(t_attrib, ch);
#endif

    if (t_attrib->invers) {
        bgcol = color_table[t_attrib->bold][t_attrib->fgcol];
        fgcol = color_table[t_attrib->bold][t_attrib->bgcol];
    } else {
        fgcol = color_table[t_attrib->bold][t_attrib->fgcol];
        bgcol = color_table[t_attrib->bold][t_attrib->bgcol];
    }

    bpp = (ds->depth + 7) >> 3;

    d = ds->data +

        ds->linesize * y * FONT_HEIGHT + bpp * x * FONT_WIDTH;
    linesize = ds->linesize;
    font_ptr = vgafont16 + FONT_HEIGHT * ch;
    xorcol = bgcol ^ fgcol;
    switch(ds->depth) {
    case 8:
        for(i = 0; i < FONT_HEIGHT; i++) {
            font_data = *font_ptr++;

            if (t_attrib->uline
                && ((i == FONT_HEIGHT - 2) || (i == FONT_HEIGHT - 3))) {
                font_data = 0xFFFF;
            }

            ((uint32_t *)d)[0] = (dmask16[(font_data >> 4)] & xorcol) ^ bgcol;
            ((uint32_t *)d)[1] = (dmask16[(font_data >> 0) & 0xf] & xorcol) ^ bgcol;
            d += linesize;
        }
        break;
    case 16:
    case 15:
        for(i = 0; i < FONT_HEIGHT; i++) {
            font_data = *font_ptr++;

            if (t_attrib->uline
                && ((i == FONT_HEIGHT - 2) || (i == FONT_HEIGHT - 3))) {
                font_data = 0xFFFF;
            }

            ((uint32_t *)d)[0] = (dmask4[(font_data >> 6)] & xorcol) ^ bgcol;
            ((uint32_t *)d)[1] = (dmask4[(font_data >> 4) & 3] & xorcol) ^ bgcol;
            ((uint32_t *)d)[2] = (dmask4[(font_data >> 2) & 3] & xorcol) ^ bgcol;
            ((uint32_t *)d)[3] = (dmask4[(font_data >> 0) & 3] & xorcol) ^ bgcol;
            d += linesize;
        }
        break;
    case 32:
        for(i = 0; i < FONT_HEIGHT; i++) {
            font_data = *font_ptr++;

            if (t_attrib->uline && ((i == FONT_HEIGHT - 2) || (i == FONT_HEIGHT - 3))) {
                font_data = 0xFFFF;
            }

            ((uint32_t *)d)[0] = (-((font_data >> 7)) & xorcol) ^ bgcol;
            ((uint32_t *)d)[1] = (-((font_data >> 6) & 1) & xorcol) ^ bgcol;
            ((uint32_t *)d)[2] = (-((font_data >> 5) & 1) & xorcol) ^ bgcol;
            ((uint32_t *)d)[3] = (-((font_data >> 4) & 1) & xorcol) ^ bgcol;
            ((uint32_t *)d)[4] = (-((font_data >> 3) & 1) & xorcol) ^ bgcol;
            ((uint32_t *)d)[5] = (-((font_data >> 2) & 1) & xorcol) ^ bgcol;
            ((uint32_t *)d)[6] = (-((font_data >> 1) & 1) & xorcol) ^ bgcol;
            ((uint32_t *)d)[7] = (-((font_data >> 0) & 1) & xorcol) ^ bgcol;
            d += linesize;
        }
        break;
    }
}

static void text_console_resize(TextConsole *s)
{
    TextCell *cells, *c, *c1;
    int w1, x, y, last_width;

    last_width = s->width;
    s->width = s->g_width / FONT_WIDTH;
    s->height = s->g_height / FONT_HEIGHT;

    w1 = last_width;
    if (s->width < w1)
        w1 = s->width;

    cells = qemu_malloc(s->width * s->total_height * sizeof(TextCell));
    for(y = 0; y < s->total_height; y++) {
        c = &cells[y * s->width];
        if (w1 > 0) {
            c1 = &s->cells[y * last_width];
            for(x = 0; x < w1; x++) {
                *c++ = *c1++;
            }
        }
        for(x = w1; x < s->width; x++) {
            c->ch = ' ';

            c->t_attrib = s->t_attrib_default;

            c++;
        }
    }

    qemu_free(s->cells);

    s->cells = cells;
}

static void update_xy(TextConsole *s, int x, int y)
{
    TextCell *c;
    int y1, y2;

    if (s == active_console) {
        y1 = (s->y_base + y) % s->total_height;
        y2 = y1 - s->y_displayed;
        if (y2 < 0)
            y2 += s->total_height;
        if (y2 < s->height) {
            c = &s->cells[y1 * s->width + x];

            vga_putcharxy(s->ds, x, y2, c->ch,

                          &(c->t_attrib));

            dpy_update(s->ds, x * FONT_WIDTH, y2 * FONT_HEIGHT,

                       FONT_WIDTH, FONT_HEIGHT);
        }
    }
}

static void console_show_cursor(TextConsole *s, int show)
{
    TextCell *c;
    int y, y1;

    if (s == active_console) {

        int x = s->x;
        if (x >= s->width) {
            x = s->width - 1;
        }

        y1 = (s->y_base + s->y) % s->total_height;
        y = y1 - s->y_displayed;
        if (y < 0)
            y += s->total_height;
        if (y < s->height) {

            c = &s->cells[y1 * s->width + x];

            if (show) {

                TextAttributes t_attrib = s->t_attrib_default;
                t_attrib.invers = !(t_attrib.invers); /* invert fg and bg */

                vga_putcharxy(s->ds, x, y, c->ch, &t_attrib);

            } else {

                vga_putcharxy(s->ds, x, y, c->ch, &(c->t_attrib));

            }

            dpy_update(s->ds, x * FONT_WIDTH, y * FONT_HEIGHT,

                       FONT_WIDTH, FONT_HEIGHT);
        }
    }
}

static void console_refresh(TextConsole *s)
{
    TextCell *c;
    int x, y, y1;

    if (s != active_console)

        return;

    vga_fill_rect(s->ds, 0, 0, s->ds->width, s->ds->height,

                  color_table[0][COLOR_BLACK]);

    y1 = s->y_displayed;
    for(y = 0; y < s->height; y++) {
        c = s->cells + y1 * s->width;
        for(x = 0; x < s->width; x++) {

            vga_putcharxy(s->ds, x, y, c->ch,

                          &(c->t_attrib));

            c++;
        }
        if (++y1 == s->total_height)
            y1 = 0;
    }
    dpy_update(s->ds, 0, 0, s->ds->width, s->ds->height);
    console_show_cursor(s, 1);
}

static void console_scroll(int ydelta)
{
    TextConsole *s;
    int i, y1;

    s = active_console;

    if (!s || (s->console_type == GRAPHIC_CONSOLE))

        return;

    if (ydelta > 0) {
        for(i = 0; i < ydelta; i++) {
            if (s->y_displayed == s->y_base)
                break;
            if (++s->y_displayed == s->total_height)
                s->y_displayed = 0;
        }
    } else {
        ydelta = -ydelta;
        i = s->backscroll_height;
        if (i > s->total_height - s->height)
            i = s->total_height - s->height;
        y1 = s->y_base - i;
        if (y1 < 0)
            y1 += s->total_height;
        for(i = 0; i < ydelta; i++) {
            if (s->y_displayed == y1)
                break;
            if (--s->y_displayed < 0)
                s->y_displayed = s->total_height - 1;
        }
    }
    console_refresh(s);
}

static void console_put_lf(TextConsole *s)
{
    TextCell *c;
    int x, y1;

    s->y++;
    if (s->y >= s->height) {
        s->y = s->height - 1;

        if (s->y_displayed == s->y_base) {
            if (++s->y_displayed == s->total_height)
                s->y_displayed = 0;
        }
        if (++s->y_base == s->total_height)
            s->y_base = 0;
        if (s->backscroll_height < s->total_height)
            s->backscroll_height++;
        y1 = (s->y_base + s->height - 1) % s->total_height;
        c = &s->cells[y1 * s->width];
        for(x = 0; x < s->width; x++) {
            c->ch = ' ';

            c->t_attrib = s->t_attrib_default;

            c++;
        }
        if (s == active_console && s->y_displayed == s->y_base) {

            vga_bitblt(s->ds, 0, FONT_HEIGHT, 0, 0,
                       s->width * FONT_WIDTH,

                       (s->height - 1) * FONT_HEIGHT);
            vga_fill_rect(s->ds, 0, (s->height - 1) * FONT_HEIGHT,

                          s->width * FONT_WIDTH, FONT_HEIGHT,

                          color_table[0][s->t_attrib_default.bgcol]);

            dpy_update(s->ds, 0, 0,

                       s->width * FONT_WIDTH, s->height * FONT_HEIGHT);
        }
    }
}

/* Set console attributes depending on the current escape codes.
 * NOTE: I know this code is not very efficient (checking every color for it
 * self) but it is more readable and better maintainable.
 */
static void console_handle_escape(TextConsole *s)
{
    int i;

    for (i=0; i<s->nb_esc_params; i++) {
        switch (s->esc_params[i]) {
            case 0: /* reset all console attributes to default */
                s->t_attrib = s->t_attrib_default;
                break;
            case 1:
                s->t_attrib.bold = 1;
                break;
            case 4:
                s->t_attrib.uline = 1;
                break;
            case 5:
                s->t_attrib.blink = 1;
                break;
            case 7:
                s->t_attrib.invers = 1;
                break;
            case 8:
                s->t_attrib.unvisible = 1;
                break;
            case 22:
                s->t_attrib.bold = 0;
                break;
            case 24:
                s->t_attrib.uline = 0;
                break;
            case 25:
                s->t_attrib.blink = 0;
                break;
            case 27:
                s->t_attrib.invers = 0;
                break;
            case 28:
                s->t_attrib.unvisible = 0;
                break;
            /* set foreground color */
            case 30:
                s->t_attrib.fgcol=COLOR_BLACK;
                break;
            case 31:
                s->t_attrib.fgcol=COLOR_RED;
                break;
            case 32:
                s->t_attrib.fgcol=COLOR_GREEN;
                break;
            case 33:
                s->t_attrib.fgcol=COLOR_YELLOW;
                break;
            case 34:
                s->t_attrib.fgcol=COLOR_BLUE;
                break;
            case 35:
                s->t_attrib.fgcol=COLOR_MAGENTA;
                break;
            case 36:
                s->t_attrib.fgcol=COLOR_CYAN;
                break;
            case 37:
                s->t_attrib.fgcol=COLOR_WHITE;
                break;
            /* set background color */
            case 40:
                s->t_attrib.bgcol=COLOR_BLACK;
                break;
            case 41:
                s->t_attrib.bgcol=COLOR_RED;
                break;
            case 42:
                s->t_attrib.bgcol=COLOR_GREEN;
                break;
            case 43:
                s->t_attrib.bgcol=COLOR_YELLOW;
                break;
            case 44:
                s->t_attrib.bgcol=COLOR_BLUE;
                break;
            case 45:
                s->t_attrib.bgcol=COLOR_MAGENTA;
                break;
            case 46:
                s->t_attrib.bgcol=COLOR_CYAN;
                break;
            case 47:
                s->t_attrib.bgcol=COLOR_WHITE;
                break;
        }
    }
}

static void console_clear_xy(TextConsole *s, int x, int y)
{
    int y1 = (s->y_base + y) % s->total_height;
    TextCell *c = &s->cells[y1 * s->width + x];
    c->ch = ' ';
    c->t_attrib = s->t_attrib_default;
    c++;
    update_xy(s, x, y);
}

static void console_putchar(TextConsole *s, int ch)
{
    TextCell *c;

    int y1, i;
    int x, y;

    switch(s->state) {
    case TTY_STATE_NORM:
        switch(ch) {

        case '\r':  /* carriage return */

            s->x = 0;
            break;

        case '\n':  /* newline */

            console_put_lf(s);
            break;

        case '\b':  /* backspace */

            if (s->x > 0)

                s->x--;

            break;
        case '\t':  /* tabspace */
            if (s->x + (8 - (s->x % 8)) > s->width) {

                s->x = 0;

                console_put_lf(s);
            } else {
                s->x = s->x + (8 - (s->x % 8));
            }
            break;
        case '\a':  /* alert aka. bell */
            /* TODO: has to be implemented */
            break;

        case 14:
            /* SI (shift in), character set 0 (ignored) */
            break;
        case 15:
            /* SO (shift out), character set 1 (ignored) */
            break;

        case 27:    /* esc (introducing an escape sequence) */

            s->state = TTY_STATE_ESC;
            break;
        default:

            if (s->x >= s->width) {
                /* line wrap */
                s->x = 0;
                console_put_lf(s);

            }

            y1 = (s->y_base + s->y) % s->total_height;
            c = &s->cells[y1 * s->width + s->x];
            c->ch = ch;

            c->t_attrib = s->t_attrib;

            update_xy(s, s->x, s->y);
            s->x++;
            break;
        }
        break;

    case TTY_STATE_ESC: /* check if it is a terminal escape sequence */

        if (ch == '[') {
            for(i=0;i<MAX_ESC_PARAMS;i++)
                s->esc_params[i] = 0;
            s->nb_esc_params = 0;
            s->state = TTY_STATE_CSI;
        } else {
            s->state = TTY_STATE_NORM;
        }
        break;

    case TTY_STATE_CSI: /* handle escape sequence parameters */

        if (ch >= '0' && ch <= '9') {
            if (s->nb_esc_params < MAX_ESC_PARAMS) {

                s->esc_params[s->nb_esc_params] =

                    s->esc_params[s->nb_esc_params] * 10 + ch - '0';
            }
        } else {
            s->nb_esc_params++;
            if (ch == ';')
                break;