/******************************************************************************

 * lfb.c

 *

 * linear frame buffer handling.

 */

#include <xen/kernel.h>

#include <xen/lib.h>

#include <xen/errno.h>

#include "lfb.h"

#include "font.h"

#define MAX_XRES 1900

#define MAX_YRES 1200

#define MAX_BPP 4

#define MAX_FONT_W 8

#define MAX_FONT_H 16

struct lfb_status {

    struct lfb_prop lfbp;

    unsigned char *lbuf, *text_buf;

    unsigned int *line_len;

    unsigned int xpos, ypos;

};

static struct lfb_status lfb;

static void lfb_show_line(

    const unsigned char *text_line,

    unsigned char *video_line,

    unsigned int nr_chars,

    unsigned int nr_cells)

{

    unsigned int i, j, b, bpp, pixel;

    bpp = (lfb.lfbp.bits_per_pixel + 7) >> 3;

    for ( i = 0; i < lfb.lfbp.font->height; i++ )

    {

        unsigned char *ptr = lfb.lbuf;

        for ( j = 0; j < nr_chars; j++ )

        {

            const unsigned char *bits = lfb.lfbp.font->data;

            bits += ((text_line[j] * lfb.lfbp.font->height + i) *

                     ((lfb.lfbp.font->width + 7) >> 3));

            for ( b = lfb.lfbp.font->width; b--; )

            {

                pixel = (*bits & (1u<<b)) ? lfb.lfbp.pixel_on : 0;

                memcpy(ptr, &pixel, bpp);

                ptr += bpp;

            }

        }

        memset(ptr, 0, (lfb.lfbp.width - nr_chars * lfb.lfbp.font->width) * bpp);

        memcpy(video_line, lfb.lbuf, nr_cells * lfb.lfbp.font->width * bpp);

        video_line += lfb.lfbp.bytes_per_line;

    }

}

/* Fast mode which redraws all modified parts of a 2D text buffer. */

void lfb_redraw_puts(const char *s)

{

    unsigned int i, min_redraw_y = lfb.ypos;

    char c;

    /* Paste characters into text buffer. */

    while ( (c = *s++) != '\0' )

    {

        if ( (c == '\n') || (lfb.xpos >= lfb.lfbp.text_columns) )

        {

            if ( ++lfb.ypos >= lfb.lfbp.text_rows )

            {

                min_redraw_y = 0;

                lfb.ypos = lfb.lfbp.text_rows - 1;

                memmove(lfb.text_buf, lfb.text_buf + lfb.lfbp.text_columns,

                        lfb.ypos * lfb.lfbp.text_columns);

                memset(lfb.text_buf + lfb.ypos * lfb.lfbp.text_columns, 0, lfb.xpos);

            }

            lfb.xpos = 0;

        }

        if ( c != '\n' )

            lfb.text_buf[lfb.xpos++ + lfb.ypos * lfb.lfbp.text_columns] = c;

    }

    /* Render modified section of text buffer to VESA linear framebuffer. */

    for ( i = min_redraw_y; i <= lfb.ypos; i++ )

    {

        const unsigned char *line = lfb.text_buf + i * lfb.lfbp.text_columns;

        unsigned int width;

        for ( width = lfb.lfbp.text_columns; width; --width )

            if ( line[width - 1] )

                 break;

        lfb_show_line(line,

                       lfb.lfbp.lfb + i * lfb.lfbp.font->height * lfb.lfbp.bytes_per_line,

                       width, max(lfb.line_len[i], width));

        lfb.line_len[i] = width;

    }

    lfb.lfbp.flush();

}

/* Slower line-based scroll mode which interacts better with dom0. */

void lfb_scroll_puts(const char *s)

{

    unsigned int i;

    char c;

    while ( (c = *s++) != '\0' )

    {

        if ( (c == '\n') || (lfb.xpos >= lfb.lfbp.text_columns) )

        {

            unsigned int bytes = (lfb.lfbp.width *

                                  ((lfb.lfbp.bits_per_pixel + 7) >> 3));

            unsigned char *src = lfb.lfbp.lfb + lfb.lfbp.font->height * lfb.lfbp.bytes_per_line;

            unsigned char *dst = lfb.lfbp.lfb;

            /* New line: scroll all previous rows up one line. */

            for ( i = lfb.lfbp.font->height; i < lfb.lfbp.height; i++ )

            {

                memcpy(dst, src, bytes);

                src += lfb.lfbp.bytes_per_line;

                dst += lfb.lfbp.bytes_per_line;

            }

            /* Render new line. */

            lfb_show_line(

                lfb.text_buf,

                lfb.lfbp.lfb + (lfb.lfbp.text_rows-1) * lfb.lfbp.font->height *

                lfb.lfbp.bytes_per_line,

                lfb.xpos, lfb.lfbp.text_columns);

            lfb.xpos = 0;

        }

        if ( c != '\n' )

            lfb.text_buf[lfb.xpos++] = c;

    }

    lfb.lfbp.flush();

}

void lfb_carriage_return(void)

{

    lfb.xpos = 0;

}

int __init lfb_init(struct lfb_prop *lfbp)

{

    if ( lfbp->width > MAX_XRES || lfbp->height > MAX_YRES )

    {

        printk(XENLOG_WARNING "Couldn't initialize a %ux%u framebuffer early.\n",

               lfbp->width, lfbp->height);

        return -EINVAL;

    }

    lfb.lfbp = *lfbp;

    lfb.lbuf = xmalloc_bytes(lfb.lfbp.bytes_per_line);

    lfb.text_buf = xzalloc_bytes(lfb.lfbp.text_columns * lfb.lfbp.text_rows);

    lfb.line_len = xzalloc_array(unsigned int, lfb.lfbp.text_columns);

    if ( !lfb.lbuf || !lfb.text_buf || !lfb.line_len )

        goto fail;

    return 0;

fail:

    printk(XENLOG_ERR "Couldn't allocate enough memory to drive the framebuffer\n");

    lfb_free();

    return -ENOMEM;

}

void lfb_free(void)

{

    xfree(lfb.lbuf);

    xfree(lfb.text_buf);

    xfree(lfb.line_len);

}