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/*

 * Copyright (c) 2008 Martin Decky

 * Copyright (c) 2006 Jakub Vana

 * Copyright (c) 2006 Ondrej Palkovsky

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/**

 * @defgroup fb Graphical framebuffer

 * @brief	HelenOS graphical framebuffer.

 * @ingroup fbs

 * @{

 */

/** @file

 */

#include <stdlib.h>

#include <unistd.h>

#include <string.h>

#include <ddi.h>

#include <sysinfo.h>

#include <align.h>

#include <as.h>

#include <ipc/fb.h>

#include <ipc/ipc.h>

#include <ipc/ns.h>

#include <ipc/services.h>

#include <kernel/errno.h>

#include <kernel/genarch/fb/visuals.h>

#include <console/color.h>

#include <console/style.h>

#include <async.h>

#include <bool.h>

#include "font-8x16.h"

#include "fb.h"

#include "main.h"

#include "../console/screenbuffer.h"

#include "ppm.h"

#include "pointer.xbm"

#include "pointer_mask.xbm"

#define DEFAULT_BGCOLOR  0xf0f0f0

#define DEFAULT_FGCOLOR  0x000000

#define MAX_ANIM_LEN     8

#define MAX_ANIMATIONS   4

#define MAX_PIXMAPS      256  /**< Maximum number of saved pixmaps */

#define MAX_VIEWPORTS    128  /**< Viewport is a rectangular area on the screen */

/** Function to render a pixel from a RGB value. */

typedef void (*rgb_conv_t)(void *, uint32_t);

/** Function to draw a glyph. */

typedef void (*dg_t)(unsigned int x, unsigned int y, bool cursor,

    uint8_t *glyphs, uint8_t glyph, uint32_t fg_color, uint32_t bg_color);

struct {

	uint8_t *fb_addr;

	unsigned int xres;

	unsigned int yres;

	unsigned int scanline;

	unsigned int glyphscanline;

	unsigned int pixelbytes;

	unsigned int glyphbytes;

	rgb_conv_t rgb_conv;

} screen;

/** Backbuffer character cell. */

typedef struct {

	uint8_t glyph;

	uint32_t fg_color;

	uint32_t bg_color;

} bb_cell_t;

typedef struct {

	bool initialized;

	unsigned int x;

	unsigned int y;

	unsigned int width;

	unsigned int height;

	/* Text support in window */

	unsigned int cols;

	unsigned int rows;

	/*

	 * Style and glyphs for text printing

	 */

	/** Current attributes. */

	attr_rgb_t attr;

	/** Pre-rendered mask for rendering glyphs. Different viewports

	 * might use different drawing functions depending on whether their

	 * scanlines are aligned on a word boundary.*/

	uint8_t *glyphs;

	uint8_t *bgpixel;

	/** Glyph drawing function for this viewport. */

	dg_t dglyph;

	/* Auto-cursor position */

	bool cursor_active;

	unsigned int cur_col;

	unsigned int cur_row;

	bool cursor_shown;

	/* Back buffer */

	bb_cell_t *backbuf;

	unsigned int bbsize;

	bool bb_invalid;

} viewport_t;

typedef struct {

	bool initialized;

	bool enabled;

	unsigned int vp;

	unsigned int pos;

	unsigned int animlen;

	unsigned int pixmaps[MAX_ANIM_LEN];

} animation_t;

static animation_t animations[MAX_ANIMATIONS];

static bool anims_enabled;

typedef struct {

	unsigned int width;

	unsigned int height;

	uint8_t *data;

} pixmap_t;

static pixmap_t pixmaps[MAX_PIXMAPS];

static viewport_t viewports[128];

static bool client_connected = false;  /**< Allow only 1 connection */

static uint32_t color_table[16] = {

	[COLOR_BLACK]		= 0x000000,

	[COLOR_BLUE]		= 0x0000f0,

	[COLOR_GREEN]		= 0x00f000,

	[COLOR_CYAN]		= 0x00f0f0,

	[COLOR_RED]		= 0xf00000,

	[COLOR_MAGENTA]		= 0xf000f0,

	[COLOR_YELLOW]		= 0xf0f000,

	[COLOR_WHITE]		= 0xf0f0f0,

	[8 + COLOR_BLACK]	= 0x000000,

	[8 + COLOR_BLUE]	= 0x0000ff,

	[8 + COLOR_GREEN]	= 0x00ff00,

	[8 + COLOR_CYAN]	= 0x00ffff,

	[8 + COLOR_RED]		= 0xff0000,

	[8 + COLOR_MAGENTA]	= 0xff00ff,

	[8 + COLOR_YELLOW]	= 0xffff00,

	[8 + COLOR_WHITE]	= 0xffffff,

};

static int rgb_from_attr(attr_rgb_t *rgb, const attrs_t *a);

static int rgb_from_style(attr_rgb_t *rgb, int style);

static int rgb_from_idx(attr_rgb_t *rgb, ipcarg_t fg_color,

    ipcarg_t bg_color, ipcarg_t flags);

static int fb_set_color(viewport_t *vport, ipcarg_t fg_color,

    ipcarg_t bg_color, ipcarg_t attr);

static void draw_glyph_aligned(unsigned int x, unsigned int y, bool cursor,

    uint8_t *glyphs, uint8_t glyph, uint32_t fg_color, uint32_t bg_color);

static void draw_glyph_fallback(unsigned int x, unsigned int y, bool cursor,

    uint8_t *glyphs, uint8_t glyph, uint32_t fg_color, uint32_t bg_color);

static void draw_vp_glyph(viewport_t *vport, bool cursor, unsigned int col,

    unsigned int row);

#define RED(x, bits)                 ((x >> (8 + 8 + 8 - bits)) & ((1 << bits) - 1))

#define GREEN(x, bits)               ((x >> (8 + 8 - bits)) & ((1 << bits) - 1))

#define BLUE(x, bits)                ((x >> (8 - bits)) & ((1 << bits) - 1))

#define COL2X(col)                   ((col) * FONT_WIDTH)

#define ROW2Y(row)                   ((row) * FONT_SCANLINES)

#define X2COL(x)                     ((x) / FONT_WIDTH)

#define Y2ROW(y)                     ((y) / FONT_SCANLINES)

#define FB_POS(x, y)                 ((y) * screen.scanline + (x) * screen.pixelbytes)

#define BB_POS(vport, col, row)      ((row) * vport->cols + (col))

#define GLYPH_POS(glyph, y, cursor)  (((glyph) + (cursor) * FONT_GLYPHS) * screen.glyphbytes + (y) * screen.glyphscanline)

/** ARGB 8:8:8:8 conversion

 *

 */

static void rgb_0888(void *dst, uint32_t rgb)

{

	*((uint32_t *) dst) = rgb & 0xffffff;

}

/** ABGR 8:8:8:8 conversion

 *

 */

static void bgr_0888(void *dst, uint32_t rgb)

{

	*((uint32_t *) dst)

	    = (BLUE(rgb, 8) << 16) | (GREEN(rgb, 8) << 8) | RED(rgb, 8);

}

/** BGR 8:8:8 conversion

 *

 */

static void rgb_888(void *dst, uint32_t rgb)

{

#if defined(FB_INVERT_ENDIAN)

	((uint8_t *) dst)[0] = RED(rgb, 8);

	((uint8_t *) dst)[1] = GREEN(rgb, 8);

	((uint8_t *) dst)[2] = BLUE(rgb, 8);

#else

	((uint8_t *) dst)[0] = BLUE(rgb, 8);

	((uint8_t *) dst)[1] = GREEN(rgb, 8);

	((uint8_t *) dst)[2] = RED(rgb, 8);

#endif

}

/** RGB 5:5:5 conversion

 *

 */

static void rgb_555(void *dst, uint32_t rgb)

{

	*((uint16_t *) dst)

	    = (RED(rgb, 5) << 10) | (GREEN(rgb, 5) << 5) | BLUE(rgb, 5);

}

/** RGB 5:6:5 conversion

 *

 */

static void rgb_565(void *dst, uint32_t rgb)

{

	*((uint16_t *) dst)

	    = (RED(rgb, 5) << 11) | (GREEN(rgb, 6) << 5) | BLUE(rgb, 5);

}

/** RGB 3:2:3

 *

 */

static void rgb_323(void *dst, uint32_t rgb)

{

	*((uint8_t *) dst)

	    = ~((RED(rgb, 3) << 5) | (GREEN(rgb, 2) << 3) | BLUE(rgb, 3));

}

/** Draw a filled rectangle.

 *

 * @note Need real implementation that does not access VRAM twice.

 */

static void draw_filled_rect(unsigned int x0, unsigned int y0, unsigned int x1,

    unsigned int y1, uint32_t color)

{

	unsigned int x, y;

	unsigned int copy_bytes;

	uint8_t *sp, *dp;

	uint8_t cbuf[4];

	if (y0 >= y1 || x0 >= x1) return;

	screen.rgb_conv(cbuf, color);

	sp = &screen.fb_addr[FB_POS(x0, y0)];

	dp = sp;

	/* Draw the first line. */

	for (x = x0; x < x1; x++) {

		memcpy(dp, cbuf, screen.pixelbytes);

		dp += screen.pixelbytes;

	}

	dp = sp + screen.scanline;

	copy_bytes = (x1 - x0) * screen.pixelbytes;

	/* Draw the remaining lines by copying. */

	for (y = y0 + 1; y < y1; y++) {

		memcpy(dp, sp, copy_bytes);

		dp += screen.scanline;

	}

}

/** Redraw viewport.

 *

 * @param vport Viewport to redraw

 *

 */

static void vport_redraw(viewport_t *vport)

{

	unsigned int row, col;

	for (row = 0; row < vport->rows; row++) {

		for (col = 0; col < vport->cols; col++) {

			draw_vp_glyph(vport, false, col, row);

		}

	}

	if (COL2X(vport->cols) < vport->width) {

		draw_filled_rect(

		    vport->x + COL2X(vport->cols), vport->y,

		    vport->x + vport->width, vport->y + vport->height,

		    vport->attr.bg_color);

	}

	if (ROW2Y(vport->rows) < vport->height) {

		draw_filled_rect(

		    vport->x, vport->y + ROW2Y(vport->rows),

		    vport->x + vport->width, vport->y + vport->height,

		    vport->attr.bg_color);

	}

}

static void backbuf_clear(bb_cell_t *backbuf, size_t len, uint32_t fg_color,

    uint32_t bg_color)

{

	unsigned i;

	for (i = 0; i < len; i++) {

		backbuf[i].glyph = 0;

		backbuf[i].fg_color = fg_color;

		backbuf[i].bg_color = bg_color;

	}

}

/** Clear viewport.

 *

 * @param vport Viewport to clear

 *

 */

static void vport_clear(viewport_t *vport)

{

	backbuf_clear(vport->backbuf, vport->cols * vport->rows,

	    vport->attr.fg_color, vport->attr.bg_color);

	vport_redraw(vport);

}

/** Scroll viewport by the specified number of lines.

 *

 * @param vport Viewport to scroll

 * @param lines Number of lines to scroll

 *

 */

static void vport_scroll(viewport_t *vport, int lines)

{

	unsigned int row, col;

	unsigned int x, y;

	uint8_t glyph;

	uint32_t fg_color;

	uint32_t bg_color;

	bb_cell_t *bbp, *xbp;

	/*

	 * Redraw.

	 */

	y = vport->y;

	for (row = 0; row < vport->rows; row++) {

		x = vport->x;

		for (col = 0; col < vport->cols; col++) {

			if ((row + lines >= 0) && (row + lines < vport->rows)) {

				xbp = &vport->backbuf[BB_POS(vport, col, row + lines)];

				bbp = &vport->backbuf[BB_POS(vport, col, row)];

				glyph = xbp->glyph;

				fg_color = xbp->fg_color;

				bg_color = xbp->bg_color;

				if (bbp->glyph == glyph &&

				    bbp->fg_color == xbp->fg_color &&

				    bbp->bg_color == xbp->bg_color) {

					x += FONT_WIDTH;

					continue;

				}

			} else {

				glyph = 0;

				fg_color = vport->attr.fg_color;

				bg_color = vport->attr.bg_color;

			}

			(*vport->dglyph)(x, y, false, vport->glyphs, glyph,

			    fg_color, bg_color);

			x += FONT_WIDTH;

		}

		y += FONT_SCANLINES;

	}

	/*

	 * Scroll backbuffer.

	 */

	if (lines > 0) {

		memmove(vport->backbuf, vport->backbuf + vport->cols * lines,

		    vport->cols * (vport->rows - lines) * sizeof(bb_cell_t));

		backbuf_clear(&vport->backbuf[BB_POS(vport, 0, vport->rows - lines)],

		    vport->cols * lines, vport->attr.fg_color, vport->attr.bg_color);

	} else {

		memmove(vport->backbuf - vport->cols * lines, vport->backbuf,

		    vport->cols * (vport->rows + lines) * sizeof(bb_cell_t));

		backbuf_clear(vport->backbuf, - vport->cols * lines,

		    vport->attr.fg_color, vport->attr.bg_color);

	}

}

/** Render glyphs

 *

 * Convert glyphs from device independent font

 * description to current visual representation.

 *

 * @param vport Viewport

 *

 */

static void render_glyphs(viewport_t* vport)

{

	unsigned int glyph;

	for (glyph = 0; glyph < FONT_GLYPHS; glyph++) {

		unsigned int y;

		for (y = 0; y < FONT_SCANLINES; y++) {

			unsigned int x;

			for (x = 0; x < FONT_WIDTH; x++) {

				screen.rgb_conv(&vport->glyphs[GLYPH_POS(glyph, y, false) + x * screen.pixelbytes],

				    (fb_font[glyph * FONT_SCANLINES + y] & (1 << (7 - x)))

				    ? 0xffffff : 0x000000);

				screen.rgb_conv(&vport->glyphs[GLYPH_POS(glyph, y, true) + x * screen.pixelbytes],

				    (fb_font[glyph * FONT_SCANLINES + y] & (1 << (7 - x)))

				    ? 0x000000 : 0xffffff);

			}

		}

	}

	screen.rgb_conv(vport->bgpixel, vport->attr.bg_color);

}

/** Create new viewport

 *

 * @param x      Origin of the viewport (x).

 * @param y      Origin of the viewport (y).

 * @param width  Width of the viewport.

 * @param height Height of the viewport.

 *

 * @return New viewport number.

 *

 */

static int vport_create(unsigned int x, unsigned int y,

    unsigned int width, unsigned int height)

{

	unsigned int i;

	for (i = 0; i < MAX_VIEWPORTS; i++) {

		if (!viewports[i].initialized)

			break;

	}

	if (i == MAX_VIEWPORTS)

		return ELIMIT;

	unsigned int cols = width / FONT_WIDTH;

	unsigned int rows = height / FONT_SCANLINES;

	unsigned int bbsize = cols * rows * sizeof(bb_cell_t);

	unsigned int glyphsize = 2 * FONT_GLYPHS * screen.glyphbytes;

	unsigned int word_size = sizeof(unsigned long);

	bb_cell_t *backbuf = (bb_cell_t *) malloc(bbsize);

	if (!backbuf)

		return ENOMEM;

	uint8_t *glyphs = (uint8_t *) malloc(glyphsize);

	if (!glyphs) {

		free(backbuf);

		return ENOMEM;

	}

	uint8_t *bgpixel = (uint8_t *) malloc(screen.pixelbytes);

	if (!bgpixel) {

		free(glyphs);

		free(backbuf);

		return ENOMEM;

	}

	backbuf_clear(backbuf, cols * rows, DEFAULT_FGCOLOR, DEFAULT_BGCOLOR);

	memset(glyphs, 0, glyphsize);

	memset(bgpixel, 0, screen.pixelbytes);

	viewports[i].x = x;

	viewports[i].y = y;

	viewports[i].width = width;

	viewports[i].height = height;

	viewports[i].cols = cols;

	viewports[i].rows = rows;

	viewports[i].attr.bg_color = DEFAULT_BGCOLOR;

	viewports[i].attr.fg_color = DEFAULT_FGCOLOR;

	viewports[i].glyphs = glyphs;

	viewports[i].bgpixel = bgpixel;

	/*

	 * Conditions necessary  to select aligned version:

	 *

	 *   - word size is divisible by pixelbytes

	 *   - cell scanline size is divisible by word size

	 *   - cell scanlines are word-aligned

	 */

	if ((word_size % screen.pixelbytes) == 0 &&

	    (FONT_WIDTH * screen.pixelbytes) % word_size == 0 &&

	    (x * screen.pixelbytes) % word_size == 0 &&

	    screen.scanline % word_size == 0) {

		viewports[i].dglyph = draw_glyph_aligned;

	} else {

		viewports[i].dglyph = draw_glyph_fallback;

	}

	viewports[i].cur_col = 0;

	viewports[i].cur_row = 0;

	viewports[i].cursor_active = false;

	viewports[i].cursor_shown = false;

	viewports[i].bbsize = bbsize;

	viewports[i].backbuf = backbuf;

	viewports[i].bb_invalid = false;

	viewports[i].initialized = true;

	render_glyphs(&viewports[i]);

	return i;

}

/** Initialize framebuffer as a chardev output device

 *

 * @param addr   Address of the framebuffer

 * @param xres   Screen width in pixels

 * @param yres   Screen height in pixels

 * @param visual Bits per pixel (8, 16, 24, 32)

 * @param scan   Bytes per one scanline

 *

 */

static bool screen_init(void *addr, unsigned int xres, unsigned int yres,

    unsigned int scan, unsigned int visual)

{

	switch (visual) {

	case VISUAL_INDIRECT_8:

		screen.rgb_conv = rgb_323;

		screen.pixelbytes = 1;

		break;

	case VISUAL_RGB_5_5_5:

		screen.rgb_conv = rgb_555;

		screen.pixelbytes = 2;

		break;

	case VISUAL_RGB_5_6_5:

		screen.rgb_conv = rgb_565;

		screen.pixelbytes = 2;

		break;

	case VISUAL_RGB_8_8_8:

		screen.rgb_conv = rgb_888;

		screen.pixelbytes = 3;

		break;

	case VISUAL_RGB_8_8_8_0:

		screen.rgb_conv = rgb_888;

		screen.pixelbytes = 4;

		break;

	case VISUAL_RGB_0_8_8_8:

		screen.rgb_conv = rgb_0888;

		screen.pixelbytes = 4;

		break;

	case VISUAL_BGR_0_8_8_8:

		screen.rgb_conv = bgr_0888;

		screen.pixelbytes = 4;

		break;

	default:

		return false;

	}

	screen.fb_addr = (unsigned char *) addr;

	screen.xres = xres;

	screen.yres = yres;

	screen.scanline = scan;

	screen.glyphscanline = FONT_WIDTH * screen.pixelbytes;

	screen.glyphbytes = screen.glyphscanline * FONT_SCANLINES;

	/* Create first viewport */

	vport_create(0, 0, xres, yres);

	return true;

}

/** Draw a glyph, takes advantage of alignment.

 *

 * This version can only be used if the following conditions are met:

 *

 *   - word size is divisible by pixelbytes

 *   - cell scanline size is divisible by word size

 *   - cell scanlines are word-aligned

 *

 * It makes use of the pre-rendered mask to process (possibly) several

 * pixels at once (word size / pixelbytes pixels at a time are processed)

 * making it very fast. Most notably this version is not applicable at 24 bits

 * per pixel.

 *

 * @param x		x coordinate of top-left corner on screen.

 * @param y		y coordinate of top-left corner on screen.

 * @param cursor	Draw glyph with cursor

 * @param glyphs	Pointer to font bitmap.

 * @param glyph		Code of the glyph to draw.

 * @param fg_color	Foreground color.

 * @param bg_color	Backgroudn color.

 */

static void draw_glyph_aligned(unsigned int x, unsigned int y, bool cursor,

    uint8_t *glyphs, uint8_t glyph, uint32_t fg_color, uint32_t bg_color)

{

	unsigned int i, yd;

	unsigned long fg_buf, bg_buf;

	unsigned long *maskp, *dp;

	unsigned long mask;

	unsigned int ww, d_add;

	/*

	 * Prepare a pair of words, one filled with foreground-color

	 * pattern and the other filled with background-color pattern.

	 */

	for (i = 0; i < sizeof(unsigned long) / screen.pixelbytes; i++) {

		screen.rgb_conv(&((uint8_t *)&fg_buf)[i * screen.pixelbytes],

		    fg_color);

		screen.rgb_conv(&((uint8_t *)&bg_buf)[i * screen.pixelbytes],

		    bg_color);

	}

	/* Pointer to the current position in the mask. */

	maskp = (unsigned long *) &glyphs[GLYPH_POS(glyph, 0, cursor)];

	/* Pointer to the current position on the screen. */

	dp = (unsigned long *) &screen.fb_addr[FB_POS(x, y)];

	/* Width of the character cell in words. */

	ww = FONT_WIDTH * screen.pixelbytes / sizeof(unsigned long);

	/* Offset to add when moving to another screen scanline. */

	d_add = screen.scanline - FONT_WIDTH * screen.pixelbytes;

	for (yd = 0; yd < FONT_SCANLINES; yd++) {

		/*

		 * Now process the cell scanline, combining foreground

		 * and background color patters using the pre-rendered mask.

		 */

		for (i = 0; i < ww; i++) {

			mask = *maskp++;

			*dp++ = (fg_buf & mask) | (bg_buf & ~mask);

		}

		/* Move to the beginning of the next scanline of the cell. */

		dp = (unsigned long *) ((uint8_t *) dp + d_add);

	}

}

/** Draw a glyph, fallback version.

 *

 * This version does not make use of the pre-rendered mask, it uses

 * the font bitmap directly. It works always, but it is slower.

 *

 * @param x		x coordinate of top-left corner on screen.

 * @param y		y coordinate of top-left corner on screen.

 * @param cursor	Draw glyph with cursor

 * @param glyphs	Pointer to font bitmap.

 * @param glyph		Code of the glyph to draw.

 * @param fg_color	Foreground color.

 * @param bg_color	Backgroudn color.

 */

void draw_glyph_fallback(unsigned int x, unsigned int y, bool cursor,

    uint8_t *glyphs, uint8_t glyph, uint32_t fg_color, uint32_t bg_color)

{

	unsigned int i, j, yd;

	uint8_t fg_buf[4], bg_buf[4];

	uint8_t *dp, *sp;

	unsigned int d_add;

	uint8_t b;

	/* Pre-render 1x the foreground and background color pixels. */

	if (cursor) {

		screen.rgb_conv(fg_buf, bg_color);

		screen.rgb_conv(bg_buf, fg_color);

	} else {

		screen.rgb_conv(fg_buf, fg_color);

		screen.rgb_conv(bg_buf, bg_color);

	}

	/* Pointer to the current position on the screen. */

	dp = (uint8_t *) &screen.fb_addr[FB_POS(x, y)];

	/* Offset to add when moving to another screen scanline. */

	d_add = screen.scanline - FONT_WIDTH * screen.pixelbytes;

	for (yd = 0; yd < FONT_SCANLINES; yd++) {

		/* Byte containing bits of the glyph scanline. */

		b = fb_font[glyph * FONT_SCANLINES + yd];

		for (i = 0; i < FONT_WIDTH; i++) {

			/* Choose color based on the current bit. */

			sp = (b & 0x80) ? fg_buf : bg_buf;

			/* Copy the pixel. */

			for (j = 0; j < screen.pixelbytes; j++) {

				*dp++ = *sp++;

			}

			/* Move to the next bit. */

			b = b << 1;

		}

		/* Move to the beginning of the next scanline of the cell. */

		dp += d_add;

	}

}

/** Draw glyph at specified position in viewport. 

 *

 * @param vport  Viewport identification

 * @param cursor Draw glyph with cursor

 * @param col    Screen position relative to viewport

 * @param row    Screen position relative to viewport

 *

 */

static void draw_vp_glyph(viewport_t *vport, bool cursor, unsigned int col,

    unsigned int row)

{

	unsigned int x = vport->x + COL2X(col);

	unsigned int y = vport->y + ROW2Y(row);

	uint8_t glyph;

	uint32_t fg_color;

	uint32_t bg_color;

	glyph = vport->backbuf[BB_POS(vport, col, row)].glyph;

	fg_color = vport->backbuf[BB_POS(vport, col, row)].fg_color;

	bg_color = vport->backbuf[BB_POS(vport, col, row)].bg_color;

	(*vport->dglyph)(x, y, cursor, vport->glyphs, glyph,

	    fg_color, bg_color);

}

/** Hide cursor if it is shown

 *

 */

static void cursor_hide(viewport_t *vport)

{

	if ((vport->cursor_active) && (vport->cursor_shown)) {

		draw_vp_glyph(vport, false, vport->cur_col, vport->cur_row);

		vport->cursor_shown = false;

	}

}

/** Show cursor if cursor showing is enabled

 *

 */

static void cursor_show(viewport_t *vport)

{

	/* Do not check for cursor_shown */

	if (vport->cursor_active) {

		draw_vp_glyph(vport, true, vport->cur_col, vport->cur_row);

		vport->cursor_shown = true;

	}

}

/** Invert cursor, if it is enabled

 *

 */

static void cursor_blink(viewport_t *vport)

{

	if (vport->cursor_shown)

		cursor_hide(vport);

	else

		cursor_show(vport);

}

/** Draw character at given position relative to viewport

 *

 * @param vport  Viewport identification

 * @param c      Character to draw

 * @param col    Screen position relative to viewport

 * @param row    Screen position relative to viewport

 *

 */

static void draw_char(viewport_t *vport, uint8_t c, unsigned int col, unsigned int row)

{

	bb_cell_t *bbp;

	/* Do not hide cursor if we are going to overwrite it */

	if ((vport->cursor_active) && (vport->cursor_shown) &&

	    ((vport->cur_col != col) || (vport->cur_row != row)))

		cursor_hide(vport);

	bbp = &vport->backbuf[BB_POS(vport, col, row)];

	bbp->glyph = c;

	bbp->fg_color = vport->attr.fg_color;

	bbp->bg_color = vport->attr.bg_color;

	draw_vp_glyph(vport, false, col, row);

	vport->cur_col = col;

	vport->cur_row = row;

	vport->cur_col++;

	if (vport->cur_col >= vport->cols) {

		vport->cur_col = 0;

		vport->cur_row++;

		if (vport->cur_row >= vport->rows)

			vport->cur_row--;

	}

	cursor_show(vport);

}

/** Draw text data to viewport

 *

 * @param vport Viewport id

 * @param data  Text data fitting exactly into viewport

 *

 */

static void draw_text_data(viewport_t *vport, keyfield_t *data)

{

	unsigned int i;

	bb_cell_t *bbp;

	attrs_t *a;

	attr_rgb_t rgb;

	for (i = 0; i < vport->cols * vport->rows; i++) {

		unsigned int col = i % vport->cols;

		unsigned int row = i / vport->cols;

		bbp = &vport->backbuf[BB_POS(vport, col, row)];

		uint8_t glyph = bbp->glyph;

		a = &data[i].attrs;

		rgb_from_attr(&rgb, a);

		if (glyph != data[i].character ||

		    rgb.fg_color != bbp->fg_color ||

		    rgb.bg_color != bbp->bg_color ||

		    vport->bb_invalid) {

			bbp->glyph = data[i].character;	

			bbp->fg_color = rgb.fg_color;

			bbp->bg_color = rgb.bg_color;

			draw_vp_glyph(vport, false, col, row);

		}

	}

	cursor_show(vport);

}

static void putpixel_pixmap(void *data, unsigned int x, unsigned int y, uint32_t color)

{

	int pm = *((int *) data);

	pixmap_t *pmap = &pixmaps[pm];

	unsigned int pos = (y * pmap->width + x) * screen.pixelbytes;

	screen.rgb_conv(&pmap->data[pos], color);

}

static void putpixel(void *data, unsigned int x, unsigned int y, uint32_t color)

{

	viewport_t *vport = (viewport_t *) data;

	unsigned int dx = vport->x + x;

	unsigned int dy = vport->y + y;

	screen.rgb_conv(&screen.fb_addr[FB_POS(dx, dy)], color);

}

/** Return first free pixmap

 *

 */

static int find_free_pixmap(void)

{

	unsigned int i;

	for (i = 0; i < MAX_PIXMAPS; i++)

		if (!pixmaps[i].data)

			return i;

	return -1;

}

/** Create a new pixmap and return appropriate ID

 *

 */

static int shm2pixmap(unsigned char *shm, size_t size)

{

	int pm;

	pixmap_t *pmap;

	pm = find_free_pixmap();

	if (pm == -1)

		return ELIMIT;

	pmap = &pixmaps[pm];

	if (ppm_get_data(shm, size, &pmap->width, &pmap->height))

		return EINVAL;

	pmap->data = malloc(pmap->width * pmap->height * screen.pixelbytes);

	if (!pmap->data)

		return ENOMEM;

	ppm_draw(shm, size, 0, 0, pmap->width, pmap->height, putpixel_pixmap, (void *) &pm);

	return pm;

}

/** Handle shared memory communication calls

 *

 * Protocol for drawing pixmaps:

 * - FB_PREPARE_SHM(client shm identification)

 * - IPC_M_AS_AREA_SEND

 * - FB_DRAW_PPM(startx, starty)

 * - FB_DROP_SHM

 *

 * Protocol for text drawing

 * - IPC_M_AS_AREA_SEND

 * - FB_DRAW_TEXT_DATA

 *

 * @param callid Callid of the current call

 * @param call   Current call data

 * @param vp     Active viewport

 *

 * @return false if the call was not handled byt this function, true otherwise

 *

 * Note: this function is not threads safe, you would have

 * to redefine static variables with __thread

 *

 */

static bool shm_handle(ipc_callid_t callid, ipc_call_t *call, int vp)

{

	static keyfield_t *interbuffer = NULL;

	static size_t intersize = 0;

	static unsigned char *shm = NULL;

	static ipcarg_t shm_id = 0;

	static size_t shm_size;

	bool handled = true;

	int retval = EOK;

	viewport_t *vport = &viewports[vp];

	unsigned int x;

	unsigned int y;

	switch (IPC_GET_METHOD(*call)) {

	case IPC_M_SHARE_OUT:

		/* We accept one area for data interchange */

		if (IPC_GET_ARG1(*call) == shm_id) {

			void *dest = as_get_mappable_page(IPC_GET_ARG2(*call));

			shm_size = IPC_GET_ARG2(*call);

			if (!ipc_answer_1(callid, EOK, (sysarg_t) dest))

				shm = dest;

			else

				shm_id = 0;

			if (shm[0] != 'P')

				return false;

			return true;

		} else {

			intersize = IPC_GET_ARG2(*call);

			receive_comm_area(callid, call, (void *) &interbuffer);

		}

		return true;

	case FB_PREPARE_SHM:

		if (shm_id)

			retval = EBUSY;

		else 

			shm_id = IPC_GET_ARG1(*call);

		break;

	case FB_DROP_SHM:

		if (shm) {

			as_area_destroy(shm);

			shm = NULL;

		}

		shm_id = 0;

		break;

	case FB_SHM2PIXMAP:

		if (!shm) {

			retval = EINVAL;

			break;

		}

		retval = shm2pixmap(shm, shm_size);

		break;

	case FB_DRAW_PPM:

		if (!shm) {

			retval = EINVAL;

			break;

		}

		x = IPC_GET_ARG1(*call);

		y = IPC_GET_ARG2(*call);

		if ((x > vport->width) || (y > vport->height)) {

			retval = EINVAL;

			break;

		}

		ppm_draw(shm, shm_size, IPC_GET_ARG1(*call),

		    IPC_GET_ARG2(*call), vport->width - x, vport->height - y, putpixel, (void *) vport);

		break;

	case FB_DRAW_TEXT_DATA:

		if (!interbuffer) {

			retval = EINVAL;

			break;

		}

		if (intersize < vport->cols * vport->rows * sizeof(*interbuffer)) {

			retval = EINVAL;

			break;

		}