/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2002 by Alan Korr
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/
#include "config.h"

#ifdef HAVE_LCD_BITMAP

#include "lcd.h"
#include "kernel.h"
#include "thread.h"
#include <string.h>
#include <stdlib.h>
#include "file.h"
#include "debug.h"
#include "system.h"
#include "font.h"

/*** definitions ***/

#define LCD_SET_LOWER_COLUMN_ADDRESS              ((char)0x00)
#define LCD_SET_HIGHER_COLUMN_ADDRESS             ((char)0x10)
#define LCD_SET_INTERNAL_REGULATOR_RESISTOR_RATIO ((char)0x20)
#define LCD_SET_POWER_CONTROL_REGISTER            ((char)0x28)
#define LCD_SET_DISPLAY_START_LINE                ((char)0x40)
#define LCD_SET_CONTRAST_CONTROL_REGISTER         ((char)0x81)
#define LCD_SET_SEGMENT_REMAP                     ((char)0xA0)
#define LCD_SET_LCD_BIAS                          ((char)0xA2)
#define LCD_SET_ENTIRE_DISPLAY_OFF                ((char)0xA4)
#define LCD_SET_ENTIRE_DISPLAY_ON                 ((char)0xA5)
#define LCD_SET_NORMAL_DISPLAY                    ((char)0xA6)
#define LCD_SET_REVERSE_DISPLAY                   ((char)0xA7)
#define LCD_SET_MULTIPLEX_RATIO                   ((char)0xA8)
#define LCD_SET_BIAS_TC_OSC                       ((char)0xA9)
#define LCD_SET_1OVER4_BIAS_RATIO                 ((char)0xAA)
#define LCD_SET_INDICATOR_OFF                     ((char)0xAC)
#define LCD_SET_INDICATOR_ON                      ((char)0xAD)
#define LCD_SET_DISPLAY_OFF                       ((char)0xAE)
#define LCD_SET_DISPLAY_ON                        ((char)0xAF)
#define LCD_SET_PAGE_ADDRESS                      ((char)0xB0)
#define LCD_SET_COM_OUTPUT_SCAN_DIRECTION         ((char)0xC0)
#define LCD_SET_TOTAL_FRAME_PHASES                ((char)0xD2)
#define LCD_SET_DISPLAY_OFFSET                    ((char)0xD3)
#define LCD_SET_READ_MODIFY_WRITE_MODE            ((char)0xE0)
#define LCD_SOFTWARE_RESET                        ((char)0xE2)
#define LCD_NOP                                   ((char)0xE3)
#define LCD_SET_END_OF_READ_MODIFY_WRITE_MODE     ((char)0xEE)

/* LCD command codes */
#define LCD_CNTL_RESET          0xe2    /* Software reset */
#define LCD_CNTL_POWER          0x2f    /* Power control */
#define LCD_CNTL_CONTRAST       0x81    /* Contrast */
#define LCD_CNTL_OUTSCAN        0xc8    /* Output scan direction */
#define LCD_CNTL_SEGREMAP       0xa1    /* Segment remap */
#define LCD_CNTL_DISPON         0xaf    /* Display on */

#define LCD_CNTL_PAGE           0xb0    /* Page address */
#define LCD_CNTL_HIGHCOL        0x10    /* Upper column address */
#define LCD_CNTL_LOWCOL         0x00    /* Lower column address */

#define SCROLL_SPACING 3

#define SCROLLABLE_LINES 10

struct scrollinfo {
    char line[MAX_PATH + LCD_WIDTH/2 + SCROLL_SPACING + 2];
    int len;    /* length of line in chars */
    int width;  /* length of line in pixels */
    int offset;
    int startx;
    int starty;
    bool backward; /* scroll presently forward or backward? */
    bool bidir;
    bool invert; /* invert the scrolled text */
    long start_tick;
};

static volatile int scrolling_lines=0; /* Bitpattern of which lines are scrolling */

static void scroll_thread(void);
static char scroll_stack[DEFAULT_STACK_SIZE];
static char scroll_name[] = "scroll";
static char scroll_speed = 8; /* updates per second */
static int scroll_delay = HZ/2; /* ticks delay before start */
static char scroll_step = 6;  /* pixels per scroll step */
static int bidir_limit = 50;  /* percent */
static struct scrollinfo scroll[SCROLLABLE_LINES];
static int xmargin = 0;
static int ymargin = 0;
static int curfont = FONT_SYSFIXED;

#ifndef SIMULATOR
static
#endif
unsigned char lcd_framebuffer[LCD_WIDTH][LCD_HEIGHT/8];

/* All zeros and ones bitmaps for area filling */
static unsigned char zeros[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
static unsigned char ones[8]  = { 0xff, 0xff, 0xff, 0xff,
                                  0xff, 0xff, 0xff, 0xff};

#ifdef SIMULATOR

void lcd_init(void)
{
    create_thread(scroll_thread, scroll_stack,
                  sizeof(scroll_stack), scroll_name);
}

#else

/*
 * Initialize LCD
 */
void lcd_init (void)
{
    /* Initialize PB0-3 as output pins */
    PBCR2 &= 0xff00; /* MD = 00 */
    PBIOR |= 0x000f; /* IOR = 1 */

	/* inits like the original firmware */
	lcd_write(true, LCD_SOFTWARE_RESET);
	lcd_write(true, LCD_SET_INTERNAL_REGULATOR_RESISTOR_RATIO + 4);
	lcd_write(true, LCD_SET_1OVER4_BIAS_RATIO + 0); /* force 1/4 bias: 0 */
	lcd_write(true, LCD_SET_POWER_CONTROL_REGISTER + 7); /* power control register: op-amp=1, regulator=1, booster=1 */
	lcd_write(true, LCD_SET_DISPLAY_ON);
	lcd_write(true, LCD_SET_NORMAL_DISPLAY);
	lcd_write(true, LCD_SET_SEGMENT_REMAP + 1); /* mirror horizontal: 1 */
	lcd_write(true, LCD_SET_COM_OUTPUT_SCAN_DIRECTION + 8); /* mirror vertical: 1 */
	lcd_write(true, LCD_SET_DISPLAY_START_LINE + 0);
#if 0 /* done later, depending on h/w mask bit and settings */
	lcd_write(true, LCD_SET_CONTRAST_CONTROL_REGISTER);
	lcd_write(true, 0xF1); /* contrast set to 49/64 */
#endif
	lcd_write(true, LCD_SET_PAGE_ADDRESS);
	lcd_write(true, LCD_SET_LOWER_COLUMN_ADDRESS + 0);
	lcd_write(true, LCD_SET_HIGHER_COLUMN_ADDRESS + 0);

    lcd_clear_display();
    lcd_update();
    create_thread(scroll_thread, scroll_stack,
                  sizeof(scroll_stack), scroll_name);
}

/*
 * Update the display.
 * This must be called after all other LCD functions that change the display.
 */
void lcd_update (void) __attribute__ ((section (".icode")));
void lcd_update (void)
{
    int x, y;

    /* Copy display bitmap to hardware */
    for (y = 0; y < LCD_HEIGHT/8; y++)
    {
        lcd_write (true, LCD_CNTL_PAGE | (y & 0xf));
        lcd_write (true, LCD_CNTL_HIGHCOL);
        lcd_write (true, LCD_CNTL_LOWCOL);

        for (x = 0; x < LCD_WIDTH; x++)
            lcd_write (false, lcd_framebuffer[x][y]);
    }
}

/*
 * Update a fraction of the display.
 */
void lcd_update_rect (int, int, int, int) __attribute__ ((section (".icode")));
void lcd_update_rect (int x_start, int y,
                      int width, int height)
{
    int ymax;
    int xmax;
    int x;

    /* The Y coordinates have to work on even 8 pixel rows */
    ymax = (y + height)/8;
    y /= 8;

    xmax = x_start + width;

    if(xmax > LCD_WIDTH)
        xmax = LCD_WIDTH;
    if(ymax >= LCD_HEIGHT/8)
        ymax = LCD_HEIGHT/8-1;

    /* Copy specified rectange bitmap to hardware */
    for (; y <= ymax; y++)
    {
        lcd_write (true, LCD_CNTL_PAGE | (y & 0xf));
        lcd_write (true, LCD_CNTL_HIGHCOL | ((x_start>>4) & 0xf));
        lcd_write (true, LCD_CNTL_LOWCOL | (x_start & 0xf));

        for (x = x_start; x < xmax; x++)
            lcd_write (false, lcd_framebuffer[x][y]);
    }
}

void lcd_set_contrast(int val)
{
    lcd_write(true, LCD_CNTL_CONTRAST);
    lcd_write(true, val);
}

void lcd_set_invert_display(bool yesno)
{
    if (yesno) 
        lcd_write(true, LCD_SET_REVERSE_DISPLAY);
    else 
        lcd_write(true, LCD_SET_NORMAL_DISPLAY);
}

/**
 * Rolls up the lcd display by the specified amount of lines.
 * Lines that are rolled out over the top of the screen are
 * rolled in from the bottom again. This is a hardware 
 * remapping only and all operations on the lcd are affected.
 * -> 
 * @param int lines - The number of lines that are rolled. 
 *  The value must be 0 <= pixels < LCD_HEIGHT.
 */
void lcd_roll(int lines)
{
    lcd_write(true, LCD_SET_DISPLAY_START_LINE | (lines & (LCD_HEIGHT-1)));
}

#endif /* SIMULATOR */

void lcd_clear_display (void)
{
    memset (lcd_framebuffer, 0, sizeof lcd_framebuffer);
    scrolling_lines = 0;
}

void lcd_setmargins(int x, int y)
{
    xmargin = x;
    ymargin = y;
}

int lcd_getxmargin(void)
{
    return xmargin;
}

int lcd_getymargin(void)
{
    return ymargin;
}

void lcd_setfont(int newfont)
{
    curfont = newfont;
}

int lcd_getstringsize(unsigned char *str, int *w, int *h)
{
    struct font* pf = font_get(curfont);
    int ch;
    int width = 0;

    while((ch = *str++)) {
        /* check input range*/
        if (ch < pf->firstchar || ch >= pf->firstchar+pf->size)
            ch = pf->defaultchar;
        ch -= pf->firstchar;

        /* get proportional width and glyph bits*/
        width += pf->width? pf->width[ch]: pf->maxwidth;
    }
    if ( w )
        *w = width;
    if ( h )
        *h = pf->height;
    return width;
}

/* put a string at a given char position */
void lcd_puts(int x, int y, unsigned char *str)
{
    lcd_puts_style(x, y, str, STYLE_DEFAULT);
}

void lcd_puts_style(int x, int y, unsigned char *str, int style)
{
    int xpos,ypos,w,h;

#if defined(SIMULATOR) && defined(HAVE_LCD_CHARCELLS)
    /* We make the simulator truncate the string if it reaches the right edge,
       as otherwise it'll wrap. The real target doesn't wrap. */

    char buffer[12];
    if(strlen(str)+x > 11 ) {
        strncpy(buffer, str, sizeof buffer);
        buffer[11-x]=0;
        str = buffer;
    }
    xmargin = 0;
    ymargin = 8;
#endif

    if(!str || !str[0])
        return;

    lcd_getstringsize(str, &w, &h);
    xpos = xmargin + x*w / strlen(str);
    ypos = ymargin + y*h;
    lcd_putsxy(xpos, ypos, str);
    lcd_clearrect(xpos + w, ypos, LCD_WIDTH - (xpos + w), h);
    if (style & STYLE_INVERT)
        lcd_invertrect(xpos, ypos, LCD_WIDTH - xpos, h);

#if defined(SIMULATOR) && defined(HAVE_LCD_CHARCELLS)
    lcd_update();
#endif
}

/* put a string at a given pixel position, skipping first ofs pixel columns */
static void lcd_putsxyofs(int x, int y, int ofs, unsigned char *str)
{
    int ch;
    struct font* pf = font_get(curfont);

    while ((ch = *str++) != '\0' && x < LCD_WIDTH)
    {
        int width;

        /* check input range */
        if (ch < pf->firstchar || ch >= pf->firstchar+pf->size)
            ch = pf->defaultchar;
        ch -= pf->firstchar;

        /* no partial-height drawing for now... */
        if (y + pf->height > LCD_HEIGHT)
            break;

        /* get proportional width and glyph bits */
        width = pf->width ? pf->width[ch] : pf->maxwidth;
        width = MIN (width, LCD_WIDTH - x);

        if (ofs != 0)
        {
            if (ofs > width)
            {
                ofs -= width;
                continue;
            }
            width -= ofs;
        }

        if (width > 0)
        {
            int rows = (pf->height + 7) / 8;
            bitmap_t* bits = pf->bits + 
                (pf->offset ? pf->offset[ch] : (pf->height * ch));
            lcd_bitmap (((unsigned char*) bits) + ofs*rows, x, y,
                        width, pf->height, true);
            x += width;
        }
        ofs = 0;
    }
}

/* put a string at a given pixel position */
void lcd_putsxy(int x, int y, unsigned char *str)
{
    lcd_putsxyofs(x, y, 0, str);
}

/*
 * All bitmaps have this format:
 * Bits within a byte are arranged veritcally, LSB at top.
 * Bytes are stored in column-major format, with byte 0 at top left,
 * byte 1 is 2nd from top, etc.  Bytes following left-most column
 * starts 2nd left column, etc.
 *
 * Note: The HW takes bitmap bytes in row-major order.
 *
 * Memory copy of display bitmap
 */

/*
 * Draw a bitmap at (x, y), size (nx, ny)
 * if 'clear' is true, clear destination area first
 */
void lcd_bitmap (unsigned char *src, int x, int y, int nx, int ny,
                 bool clear) __attribute__ ((section (".icode")));
void lcd_bitmap (unsigned char *src, int x, int y, int nx, int ny,
                 bool clear)
{
    unsigned char *dst;
    unsigned char *dst2;
    unsigned int data, mask, mask2, mask3, mask4;
    int shift;

    if (((unsigned)x >= LCD_WIDTH) || ((unsigned)y >= LCD_HEIGHT))
        return;
    if (((unsigned)(x + nx)) >= LCD_WIDTH)
        nx = LCD_WIDTH - x;
    if (((unsigned)(y + ny)) >= LCD_HEIGHT)
        ny = LCD_HEIGHT - y;      

    shift = y & 7;
    dst2 = &lcd_framebuffer[x][y/8];
    ny += shift;

    /* Calculate bit masks */
    mask4 = ~(0xfe << ((ny-1) & 7));
    if (clear)
    {
        mask = ~(0xff << shift);
        mask2 = 0;
        mask3 = ~mask4;
        if (ny <= 8)
            mask3 |= mask;
    }
    else
        mask = mask2 = mask3 = 0xff;

    /* Loop for each column */
    for (x = 0; x < nx; x++)
    {
        dst = dst2;
        dst2 += LCD_HEIGHT/8;
        data = 0;
        y = 0;

        if (ny > 8)
        {
            /* First partial row */
            data = *src++ << shift;
            *dst = (*dst & mask) | data;
            data >>= 8;
            dst++;

            /* Intermediate rows */
            for (y = 8; y < ny-8; y += 8)
            {
                data |= *src++ << shift;
                *dst = (*dst & mask2) | data;
                data >>= 8;
                dst++;
            }
        }

        /* Last partial row */
        if (y + shift < ny)
            data |= *src++ << shift;
        *dst = (*dst & mask3) | (data & mask4);
    }
}

/* 
 * Draw a rectangle with upper left corner at (x, y)
 * and size (nx, ny)
 */
void lcd_drawrect (int x, int y, int nx, int ny)
{
    int i;

    if (x > LCD_WIDTH)
        return;
    if (y > LCD_HEIGHT)
        return;

    if (x + nx > LCD_WIDTH)
        nx = LCD_WIDTH - x;
    if (y + ny > LCD_HEIGHT)
        ny = LCD_HEIGHT - y;

    /* vertical lines */
    for (i = 0; i < ny; i++) {
        DRAW_PIXEL(x, (y + i));
        DRAW_PIXEL((x + nx - 1), (y + i));
    }

    /* horizontal lines */
    for (i = 0; i < nx; i++) {
        DRAW_PIXEL((x + i),y);
        DRAW_PIXEL((x + i),(y + ny - 1));
    }
}

/*
 * Clear a rectangular area at (x, y), size (nx, ny)
 */
void lcd_clearrect (int x, int y, int nx, int ny)
{
    int i;
    for (i = 0; i < nx; i++)
        lcd_bitmap (zeros, x+i, y, 1, ny, true);
}

/*
 * Fill a rectangular area at (x, y), size (nx, ny)
 */
void lcd_fillrect (int x, int y, int nx, int ny)
{
    int i;
    for (i = 0; i < nx; i++)
        lcd_bitmap (ones, x+i, y, 1, ny, true);
}

/* Invert a rectangular area at (x, y), size (nx, ny) */
void lcd_invertrect (int x, int y, int nx, int ny)
{
    int i, j;

    if (x > LCD_WIDTH)
        return;
    if (y > LCD_HEIGHT)
        return;

    if (x + nx > LCD_WIDTH)
        nx = LCD_WIDTH - x;
    if (y + ny > LCD_HEIGHT)
        ny = LCD_HEIGHT - y;

    for (i = 0; i < nx; i++)
        for (j = 0; j < ny; j++)
            INVERT_PIXEL((x + i), (y + j));
}

void lcd_drawline( int x1, int y1, int x2, int y2 )
{
    int numpixels;
    int i;
    int deltax, deltay;
    int d, dinc1, dinc2;
    int x, xinc1, xinc2;
    int y, yinc1, yinc2;

    deltax = abs(x2 - x1);
    deltay = abs(y2 - y1);

    if(deltax >= deltay)
    {
        numpixels = deltax;
        d = 2 * deltay - deltax;
        dinc1 = deltay * 2;
        dinc2 = (deltay - deltax) * 2;
        xinc1 = 1;
        xinc2 = 1;
        yinc1 = 0;
        yinc2 = 1;
    }
    else
    {
        numpixels = deltay;
        d = 2 * deltax - deltay;
        dinc1 = deltax * 2;
        dinc2 = (deltax - deltay) * 2;
        xinc1 = 0;
        xinc2 = 1;
        yinc1 = 1;
        yinc2 = 1;
    }
    numpixels++; /* include endpoints */

    if(x1 > x2)
    {
        xinc1 = -xinc1;
        xinc2 = -xinc2;
    }

    if(y1 > y2)
    {
        yinc1 = -yinc1;
        yinc2 = -yinc2;
    }

    x = x1;
    y = y1;

    for(i=0; i<numpixels; i++)
    {
        DRAW_PIXEL(x,y);

        if(d < 0)
        {
            d += dinc1;
            x += xinc1;
            y += yinc1;
        }
        else
        {
            d += dinc2;
            x += xinc2;
            y += yinc2;
        }
    }
}

void lcd_clearline( int x1, int y1, int x2, int y2 )
{
    int numpixels;
    int i;
    int deltax, deltay;
    int d, dinc1, dinc2;
    int x, xinc1, xinc2;
    int y, yinc1, yinc2;

    deltax = abs(x2 - x1);
    deltay = abs(y2 - y1);

    if(deltax >= deltay)
    {
        numpixels = deltax;
        d = 2 * deltay - deltax;
        dinc1 = deltay * 2;
        dinc2 = (deltay - deltax) * 2;
        xinc1 = 1;
        xinc2 = 1;
        yinc1 = 0;
        yinc2 = 1;
    }
    else
    {
        numpixels = deltay;
        d = 2 * deltax - deltay;
        dinc1 = deltax * 2;
        dinc2 = (deltax - deltay) * 2;
        xinc1 = 0;
        xinc2 = 1;
        yinc1 = 1;
        yinc2 = 1;
    }
    numpixels++; /* include endpoints */

    if(x1 > x2)
    {
        xinc1 = -xinc1;
        xinc2 = -xinc2;
    }

    if(y1 > y2)
    {
        yinc1 = -yinc1;
        yinc2 = -yinc2;
    }

    x = x1;
    y = y1;

    for(i=0; i<numpixels; i++)
    {
        CLEAR_PIXEL(x,y);

        if(d < 0)
        {
            d += dinc1;
            x += xinc1;
            y += yinc1;
        }
        else
        {
            d += dinc2;
            x += xinc2;
            y += yinc2;
        }
    }
}

/*
 * Set a single pixel
 */
void lcd_drawpixel(int x, int y)
{
    DRAW_PIXEL(x,y);
}

/*
 * Clear a single pixel
 */
void lcd_clearpixel(int x, int y)
{
    CLEAR_PIXEL(x,y);
}

/*
 * Invert a single pixel
 */
void lcd_invertpixel(int x, int y)
{
    INVERT_PIXEL(x,y);
}

void lcd_puts_scroll(int x, int y, unsigned char *string)
{
    lcd_puts_scroll_style(x, y, string, STYLE_DEFAULT);
}

void lcd_puts_scroll_style(int x, int y, unsigned char *string, int style)
{
    struct scrollinfo* s;
    int w, h;
    int index;
    int free_index=0;

    DEBUGF("puts_scroll_style: %s\n", string);
    
    for (index = 0; index < SCROLLABLE_LINES; index++) {
        s = &scroll[index];

        if (scrolling_lines&(1<<index)) {
            if (s->starty == y) {
                /* we prefer to re-use an existing index with the
                   same y-position */
                free_index=index;
                break;
            }
        }
        else {
            /* remember the last unused one */
            free_index=index;
        }
    }
    index=free_index;
    s = &scroll[index]; /* get the proper 's' */
    s->start_tick = current_tick + scroll_delay;
    s->invert = false;
    if (style & STYLE_INVERT) {
        s->invert = true;
        lcd_puts_style(x,y,string,STYLE_INVERT);
    }
    else
        lcd_puts(x,y,string);

    lcd_getstringsize(string, &w, &h);

    if (LCD_WIDTH - x * 8 - xmargin < w) {
        /* prepare scroll line */
        char *end;

        memset(s->line, 0, sizeof s->line);
        strcpy(s->line, string);

        /* get width */
        s->width = lcd_getstringsize(s->line, &w, &h);

        /* scroll bidirectional or forward only depending on the string
           width */
        if ( bidir_limit ) {
            s->bidir = s->width < (LCD_WIDTH - xmargin) *
                (100 + bidir_limit) / 100;
        }
        else
            s->bidir = false;

        if (!s->bidir) { /* add spaces if scrolling in the round */
            strcat(s->line, "   ");
            /* get new width incl. spaces */
            s->width = lcd_getstringsize(s->line, &w, &h);
        }

        end = strchr(s->line, '\0');
        strncpy(end, string, LCD_WIDTH/2);

        s->len = strlen(string);
        s->offset = 0;
        s->startx = x;
        s->starty = y;
        s->backward = false;
        scrolling_lines |= (1<<index);
    }
    else
        /* force a bit switch-off since it doesn't scroll */
        scrolling_lines &= ~(1<<index);
}

void lcd_stop_scroll(void)
{
    scrolling_lines=0;
}

void lcd_scroll_speed(int speed)
{
    scroll_speed = speed;
}

void lcd_scroll_step(int step)
{
    scroll_step = step;
}

void lcd_scroll_delay(int ms)
{
    scroll_delay = ms / (HZ / 10);
}

void lcd_bidir_scroll(int percent)
{
    bidir_limit = percent;
}
static void scroll_thread(void)
{
    struct scrollinfo* s;
    int index;
    int w, h;
    int xpos, ypos;

    /* initialize scroll struct array */
    scrolling_lines = 0;

    while ( 1 ) {
        for ( index = 0; index < SCROLLABLE_LINES; index++ ) {
            /* really scroll? */
            if ( !(scrolling_lines&(1<<index)) )
                continue;

            s = &scroll[index];

            /* check pause */
            if (TIME_BEFORE(current_tick, s->start_tick))
                continue;

            if (s->backward)
                s->offset -= scroll_step;
            else
                s->offset += scroll_step;

            if (s->bidir) { /* scroll bidirectional */
                if (s->offset <= 0) {
                    /* at beginning of line */
                    s->offset = 0;
                    s->backward = false;
                    s->start_tick = current_tick + scroll_delay * 2;
                }
                if (s->offset >= s->width - (LCD_WIDTH - xmargin)) {
                    /* at end of line */
                    s->offset = s->width - (LCD_WIDTH - xmargin);
                    s->backward = true;
                    s->start_tick = current_tick + scroll_delay * 2;
                }
            }
            else {
                /* scroll forward the whole time */
                if (s->offset >= s->width)
                    s->offset %= s->width;
            }

            lcd_getstringsize(s->line, &w, &h);
            xpos = xmargin + s->startx * w / s->len;
            ypos = ymargin + s->starty * h;

            lcd_clearrect(xpos, ypos, LCD_WIDTH - xmargin, h);
            lcd_putsxyofs(xpos, ypos, s->offset, s->line);
            if (s->invert)
                lcd_invertrect(xpos, ypos, LCD_WIDTH - xmargin, h);
            lcd_update_rect(xpos, ypos, LCD_WIDTH - xmargin, h);
        }

        sleep(HZ/scroll_speed);
    }
}

#endif