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Re: [Xen-devel] [PATCH v2 3/8] xen: introduce a generic framebuffer driver



>>> On 07.12.12 at 19:02, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
wrote:
> Abstract away from vesa.c the funcions to handle a linear framebuffer
> and print characters to it.
> The corresponding functions are going to be removed from vesa.c in the
> next patch.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
>  xen/drivers/video/Makefile |    1 +
>  xen/drivers/video/fb.c     |  209 
> ++++++++++++++++++++++++++++++++++++++++++++
>  xen/drivers/video/fb.h     |   49 ++++++++++
>  3 files changed, 259 insertions(+), 0 deletions(-)
>  create mode 100644 xen/drivers/video/fb.c
>  create mode 100644 xen/drivers/video/fb.h
> 
> diff --git a/xen/drivers/video/Makefile b/xen/drivers/video/Makefile
> index 2993c39..3b3eb43 100644
> --- a/xen/drivers/video/Makefile
> +++ b/xen/drivers/video/Makefile
> @@ -2,4 +2,5 @@ obj-$(HAS_VGA) := vga.o
>  obj-$(HAS_VIDEO) += font_8x14.o
>  obj-$(HAS_VIDEO) += font_8x16.o
>  obj-$(HAS_VIDEO) += font_8x8.o
> +obj-$(HAS_VIDEO) += fb.o
>  obj-$(HAS_VGA) += vesa.o
> diff --git a/xen/drivers/video/fb.c b/xen/drivers/video/fb.c
> new file mode 100644
> index 0000000..282f97e
> --- /dev/null
> +++ b/xen/drivers/video/fb.c
> @@ -0,0 +1,209 @@
> +/**************************************************************************
> ****
> + * fb.c
> + *
> + * linear frame buffer handling.
> + */
> +
> +#include <xen/config.h>
> +#include <xen/kernel.h>
> +#include <xen/lib.h>
> +#include <xen/errno.h>
> +#include "fb.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
> +static __initdata unsigned int line_len[MAX_XRES / MAX_FONT_W];
> +static __initdata unsigned char lbuf[MAX_XRES * MAX_BPP];
> +static __initdata unsigned char text_buf[(MAX_XRES / MAX_FONT_W) * \
> +                          (MAX_YRES / MAX_FONT_H)];
> +
> +struct fb_status {
> +    struct fb_prop fbp;
> +
> +    unsigned char *lbuf, *text_buf;
> +    unsigned int *line_len;
> +    unsigned int xpos, ypos;
> +};
> +static struct fb_status fb;
> +
> +static void fb_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 = (fb.fbp.bits_per_pixel + 7) >> 3;
> +
> +    for ( i = 0; i < fb.fbp.font->height; i++ )
> +    {
> +        unsigned char *ptr = fb.lbuf;
> +
> +        for ( j = 0; j < nr_chars; j++ )
> +        {
> +            const unsigned char *bits = fb.fbp.font->data;
> +            bits += ((text_line[j] * fb.fbp.font->height + i) *
> +                     ((fb.fbp.font->width + 7) >> 3));
> +            for ( b = fb.fbp.font->width; b--; )
> +            {
> +                pixel = (*bits & (1u<<b)) ? fb.fbp.pixel_on : 0;
> +                memcpy(ptr, &pixel, bpp);
> +                ptr += bpp;
> +            }
> +        }
> +
> +        memset(ptr, 0, (fb.fbp.width - nr_chars * fb.fbp.font->width) * bpp);
> +        memcpy(video_line, fb.lbuf, nr_cells * fb.fbp.font->width * bpp);
> +        video_line += fb.fbp.bytes_per_line;
> +    }
> +}
> +
> +/* Fast mode which redraws all modified parts of a 2D text buffer. */
> +void fb_redraw_puts(const char *s)
> +{
> +    unsigned int i, min_redraw_y = fb.ypos;
> +    char c;
> +
> +    /* Paste characters into text buffer. */
> +    while ( (c = *s++) != '\0' )
> +    {
> +        if ( (c == '\n') || (fb.xpos >= fb.fbp.text_columns) )
> +        {
> +            if ( ++fb.ypos >= fb.fbp.text_rows )
> +            {
> +                min_redraw_y = 0;
> +                fb.ypos = fb.fbp.text_rows - 1;
> +                memmove(fb.text_buf, fb.text_buf + fb.fbp.text_columns,
> +                        fb.ypos * fb.fbp.text_columns);
> +                memset(fb.text_buf + fb.ypos * fb.fbp.text_columns, 0, 
> fb.xpos);
> +            }
> +            fb.xpos = 0;
> +        }
> +
> +        if ( c != '\n' )
> +            fb.text_buf[fb.xpos++ + fb.ypos * fb.fbp.text_columns] = c;
> +    }
> +
> +    /* Render modified section of text buffer to VESA linear framebuffer. 
> */
> +    for ( i = min_redraw_y; i <= fb.ypos; i++ )
> +    {
> +        const unsigned char *line = fb.text_buf + i * fb.fbp.text_columns;
> +        unsigned int width;
> +
> +        for ( width = fb.fbp.text_columns; width; --width )
> +            if ( line[width - 1] )
> +                 break;
> +        fb_show_line(line,
> +                       fb.fbp.lfb + i * fb.fbp.font->height * 
> fb.fbp.bytes_per_line,
> +                       width, max(fb.line_len[i], width));
> +        fb.line_len[i] = width;
> +    }
> +
> +    fb.fbp.flush();
> +}
> +
> +/* Slower line-based scroll mode which interacts better with dom0. */
> +void fb_scroll_puts(const char *s)
> +{
> +    unsigned int i;
> +    char c;
> +
> +    while ( (c = *s++) != '\0' )
> +    {
> +        if ( (c == '\n') || (fb.xpos >= fb.fbp.text_columns) )
> +        {
> +            unsigned int bytes = (fb.fbp.width *
> +                                  ((fb.fbp.bits_per_pixel + 7) >> 3));
> +            unsigned char *src = fb.fbp.lfb + fb.fbp.font->height * 
> fb.fbp.bytes_per_line;
> +            unsigned char *dst = fb.fbp.lfb;
> +
> +            /* New line: scroll all previous rows up one line. */
> +            for ( i = fb.fbp.font->height; i < fb.fbp.height; i++ )
> +            {
> +                memcpy(dst, src, bytes);
> +                src += fb.fbp.bytes_per_line;
> +                dst += fb.fbp.bytes_per_line;
> +            }
> +
> +            /* Render new line. */
> +            fb_show_line(
> +                fb.text_buf,
> +                fb.fbp.lfb + (fb.fbp.text_rows-1) * fb.fbp.font->height * 
> fb.fbp.bytes_per_line,
> +                fb.xpos, fb.fbp.text_columns);
> +
> +            fb.xpos = 0;
> +        }
> +
> +        if ( c != '\n' )
> +            fb.text_buf[fb.xpos++] = c;
> +    }
> +
> +    fb.fbp.flush();
> +}
> +
> +void fb_cr(void)
> +{
> +    fb.xpos = 0;
> +}
> +
> +int __init fb_init(struct fb_prop fbp)
> +{
> +    if ( fbp.width > MAX_XRES || fbp.height > MAX_YRES )
> +    {
> +        printk("Couldn't initialize a %xx%x framebuffer early.\n",
> +                        fbp.width, fbp.height);
> +        return -EINVAL;
> +    }
> +
> +    fb.fbp = fbp;
> +    fb.lbuf = lbuf;
> +    fb.text_buf = text_buf;
> +    fb.line_len = line_len;
> +    return 0;
> +}
> +
> +int __init fb_alloc(void)
> +{
> +    fb.lbuf = NULL;
> +    fb.text_buf = NULL;
> +    fb.line_len = NULL;
> +
> +    fb.lbuf = xmalloc_bytes(fb.fbp.bytes_per_line);
> +    if ( !fb.lbuf )
> +        goto fail;
> +
> +    fb.text_buf = xzalloc_bytes(fb.fbp.text_columns * fb.fbp.text_rows);
> +    if ( !fb.text_buf )
> +        goto fail;
> +
> +    fb.line_len = xzalloc_array(unsigned int, fb.fbp.text_columns);
> +    if ( !fb.line_len )
> +        goto fail;
> +
> +    memcpy(fb.lbuf, lbuf, fb.fbp.bytes_per_line);
> +    memcpy(fb.text_buf, text_buf, fb.fbp.text_columns * fb.fbp.text_rows);
> +    memcpy(fb.line_len, line_len, fb.fbp.text_columns);
> +
> +    return 0;
> +
> +fail:
> +    printk(XENLOG_ERR "Couldn't allocate enough memory to drive "
> +                    "the framebuffer\n");
> +    xfree(fb.lbuf);
> +    xfree(fb.text_buf);
> +    xfree(fb.line_len);
> +
> +    return -ENOMEM;
> +}
> +
> +void fb_free(void)
> +{
> +    xfree(fb.lbuf);
> +    xfree(fb.text_buf);
> +    xfree(fb.line_len);
> +}
> diff --git a/xen/drivers/video/fb.h b/xen/drivers/video/fb.h
> new file mode 100644
> index 0000000..558d058
> --- /dev/null
> +++ b/xen/drivers/video/fb.h
> @@ -0,0 +1,49 @@
> +/*
> + * xen/drivers/video/fb.h
> + *
> + * Cross-platform framebuffer library
> + *
> + * Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> + * Copyright (c) 2012 Citrix Systems.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _XEN_FB_H
> +#define _XEN_FB_H
> +
> +#include <xen/init.h>
> +
> +struct fb_prop {
> +    const struct font_desc *font;
> +    unsigned char *lfb;
> +    unsigned int pixel_on;
> +    uint16_t width, height;
> +    uint16_t bytes_per_line;
> +    uint16_t bits_per_pixel;
> +    void (*flush)(void);
> +
> +    unsigned int text_columns;
> +    unsigned int text_rows;
> +};
> +
> +void fb_redraw_puts(const char *s);
> +void fb_scroll_puts(const char *s);
> +void fb_cr(void);

Please make this fb_create() or alike - "cr" alone could well be
mistaken as "carriage return".

Jan

> +void fb_free(void);
> +
> +/* initialize the framebuffer, can be called early (before xmalloc is
> + * available) */
> +int __init fb_init(struct fb_prop fbp);
> +/* fb_alloc allocates internal structures using xmalloc */
> +int __init fb_alloc(void);
> +
> +#endif
> -- 
> 1.7.2.5



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