From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mats Petersson Subject: Re: [PATCH v4 3/7] xen: introduce a generic framebuffer driver Date: Wed, 9 Jan 2013 14:45:21 +0000 Message-ID: <50ED8281.9070609@citrix.com> References: <1357675408-27949-3-git-send-email-stefano.stabellini@eu.citrix.com> <50ED5A4F02000078000B3FDA@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 09/01/13 14:05, Stefano Stabellini wrote: > On Wed, 9 Jan 2013, Jan Beulich wrote: >>>>> On 08.01.13 at 21:03, Stefano Stabellini wrote: >>> --- /dev/null >>> +++ b/xen/drivers/video/lfb.c >>> @@ -0,0 +1,206 @@ >>> +/****************************************************************************** >>> + * lfb.c >>> + * >>> + * linear frame buffer handling. >>> + */ >>> + >>> +#include >>> +#include >>> +#include >>> +#include >>> +#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 >>> +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)]; >> Imo it would be better to move all these __initdata definitions >> do to where the using __init functions actually live, to make >> sure unintended use of them in non-__init ones is noticed. > OK > > >>> + >>> +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<>> + 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, >> Long line? > Right > The calculation of lfb.lfbp.lfb + lfb.lfbp.font->height * lfb.lfbp.bytes_per_line; is done twice in the above section - surely that's constant over time, so could be stored in another local variable - thus making the line shorter and at the same time more obvious that "it's the same thing". -- Mats