![H. Peter Anvin](/assets/img/avatar_default.png)
The current display page is an 8-bit number, even though struct screen_info gives it a 16-bit number. The number is returned in %bh, so it needs to be >> 8 before storing. Special thanks to Jeff Chua for detailed bug reporting. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
462 lines
9.5 KiB
C
462 lines
9.5 KiB
C
/* -*- linux-c -*- ------------------------------------------------------- *
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright 2007 rPath, Inc. - All Rights Reserved
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*
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* This file is part of the Linux kernel, and is made available under
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* the terms of the GNU General Public License version 2.
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*
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* ----------------------------------------------------------------------- */
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/*
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* arch/i386/boot/video.c
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*
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* Select video mode
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*/
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#include "boot.h"
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#include "video.h"
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#include "vesa.h"
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/*
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* Mode list variables
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*/
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static struct card_info cards[]; /* List of cards to probe for */
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/*
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* Common variables
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*/
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int adapter; /* 0=CGA/MDA/HGC, 1=EGA, 2=VGA+ */
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u16 video_segment;
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int force_x, force_y; /* Don't query the BIOS for cols/rows */
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int do_restore = 0; /* Screen contents changed during mode flip */
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int graphic_mode; /* Graphic mode with linear frame buffer */
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static void store_cursor_position(void)
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{
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u16 curpos;
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u16 ax, bx;
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ax = 0x0300;
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bx = 0;
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asm(INT10
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: "=d" (curpos), "+a" (ax), "+b" (bx)
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: : "ecx", "esi", "edi");
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boot_params.screen_info.orig_x = curpos;
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boot_params.screen_info.orig_y = curpos >> 8;
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}
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static void store_video_mode(void)
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{
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u16 ax, page;
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/* N.B.: the saving of the video page here is a bit silly,
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since we pretty much assume page 0 everywhere. */
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ax = 0x0f00;
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asm(INT10
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: "+a" (ax), "=b" (page)
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: : "ecx", "edx", "esi", "edi");
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/* Not all BIOSes are clean with respect to the top bit */
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boot_params.screen_info.orig_video_mode = ax & 0x7f;
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boot_params.screen_info.orig_video_page = page >> 8;
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}
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/*
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* Store the video mode parameters for later usage by the kernel.
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* This is done by asking the BIOS except for the rows/columns
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* parameters in the default 80x25 mode -- these are set directly,
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* because some very obscure BIOSes supply insane values.
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*/
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static void store_mode_params(void)
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{
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u16 font_size;
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int x, y;
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/* For graphics mode, it is up to the mode-setting driver
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(currently only video-vesa.c) to store the parameters */
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if (graphic_mode)
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return;
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store_cursor_position();
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store_video_mode();
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if (boot_params.screen_info.orig_video_mode == 0x07) {
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/* MDA, HGC, or VGA in monochrome mode */
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video_segment = 0xb000;
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} else {
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/* CGA, EGA, VGA and so forth */
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video_segment = 0xb800;
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}
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set_fs(0);
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font_size = rdfs16(0x485); /* Font size, BIOS area */
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boot_params.screen_info.orig_video_points = font_size;
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x = rdfs16(0x44a);
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y = (adapter == ADAPTER_CGA) ? 25 : rdfs8(0x484)+1;
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if (force_x)
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x = force_x;
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if (force_y)
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y = force_y;
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boot_params.screen_info.orig_video_cols = x;
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boot_params.screen_info.orig_video_lines = y;
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}
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/* Probe the video drivers and have them generate their mode lists. */
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static void probe_cards(int unsafe)
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{
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struct card_info *card;
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static u8 probed[2];
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if (probed[unsafe])
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return;
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probed[unsafe] = 1;
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for (card = video_cards; card < video_cards_end; card++) {
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if (card->unsafe == unsafe) {
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if (card->probe)
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card->nmodes = card->probe();
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else
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card->nmodes = 0;
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}
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}
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}
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/* Test if a mode is defined */
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int mode_defined(u16 mode)
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{
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struct card_info *card;
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struct mode_info *mi;
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int i;
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for (card = video_cards; card < video_cards_end; card++) {
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mi = card->modes;
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for (i = 0; i < card->nmodes; i++, mi++) {
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if (mi->mode == mode)
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return 1;
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}
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}
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return 0;
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}
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/* Set mode (without recalc) */
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static int raw_set_mode(u16 mode)
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{
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int nmode, i;
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struct card_info *card;
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struct mode_info *mi;
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/* Drop the recalc bit if set */
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mode &= ~VIDEO_RECALC;
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/* Scan for mode based on fixed ID, position, or resolution */
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nmode = 0;
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for (card = video_cards; card < video_cards_end; card++) {
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mi = card->modes;
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for (i = 0; i < card->nmodes; i++, mi++) {
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int visible = mi->x || mi->y;
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if ((mode == nmode && visible) ||
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mode == mi->mode ||
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mode == (mi->y << 8)+mi->x)
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return card->set_mode(mi);
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if (visible)
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nmode++;
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}
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}
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/* Nothing found? Is it an "exceptional" (unprobed) mode? */
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for (card = video_cards; card < video_cards_end; card++) {
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if (mode >= card->xmode_first &&
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mode < card->xmode_first+card->xmode_n) {
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struct mode_info mix;
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mix.mode = mode;
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mix.x = mix.y = 0;
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return card->set_mode(&mix);
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}
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}
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/* Otherwise, failure... */
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return -1;
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}
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/*
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* Recalculate the vertical video cutoff (hack!)
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*/
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static void vga_recalc_vertical(void)
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{
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unsigned int font_size, rows;
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u16 crtc;
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u8 pt, ov;
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set_fs(0);
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font_size = rdfs8(0x485); /* BIOS: font size (pixels) */
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rows = force_y ? force_y : rdfs8(0x484)+1; /* Text rows */
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rows *= font_size; /* Visible scan lines */
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rows--; /* ... minus one */
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crtc = vga_crtc();
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pt = in_idx(crtc, 0x11);
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pt &= ~0x80; /* Unlock CR0-7 */
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out_idx(pt, crtc, 0x11);
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out_idx((u8)rows, crtc, 0x12); /* Lower height register */
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ov = in_idx(crtc, 0x07); /* Overflow register */
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ov &= 0xbd;
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ov |= (rows >> (8-1)) & 0x02;
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ov |= (rows >> (9-6)) & 0x40;
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out_idx(ov, crtc, 0x07);
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}
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/* Set mode (with recalc if specified) */
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static int set_mode(u16 mode)
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{
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int rv;
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/* Very special mode numbers... */
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if (mode == VIDEO_CURRENT_MODE)
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return 0; /* Nothing to do... */
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else if (mode == NORMAL_VGA)
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mode = VIDEO_80x25;
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else if (mode == EXTENDED_VGA)
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mode = VIDEO_8POINT;
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rv = raw_set_mode(mode);
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if (rv)
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return rv;
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if (mode & VIDEO_RECALC)
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vga_recalc_vertical();
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return 0;
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}
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static unsigned int get_entry(void)
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{
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char entry_buf[4];
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int i, len = 0;
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int key;
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unsigned int v;
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do {
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key = getchar();
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if (key == '\b') {
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if (len > 0) {
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puts("\b \b");
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len--;
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}
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} else if ((key >= '0' && key <= '9') ||
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(key >= 'A' && key <= 'Z') ||
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(key >= 'a' && key <= 'z')) {
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if (len < sizeof entry_buf) {
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entry_buf[len++] = key;
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putchar(key);
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}
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}
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} while (key != '\r');
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putchar('\n');
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if (len == 0)
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return VIDEO_CURRENT_MODE; /* Default */
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v = 0;
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for (i = 0; i < len; i++) {
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v <<= 4;
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key = entry_buf[i] | 0x20;
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v += (key > '9') ? key-'a'+10 : key-'0';
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}
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return v;
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}
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static void display_menu(void)
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{
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struct card_info *card;
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struct mode_info *mi;
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char ch;
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int i;
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puts("Mode: COLSxROWS:\n");
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ch = '0';
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for (card = video_cards; card < video_cards_end; card++) {
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mi = card->modes;
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for (i = 0; i < card->nmodes; i++, mi++) {
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int visible = mi->x && mi->y;
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u16 mode_id = mi->mode ? mi->mode :
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(mi->y << 8)+mi->x;
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if (!visible)
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continue; /* Hidden mode */
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printf("%c %04X %3dx%-3d %s\n",
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ch, mode_id, mi->x, mi->y, card->card_name);
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if (ch == '9')
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ch = 'a';
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else if (ch == 'z' || ch == ' ')
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ch = ' '; /* Out of keys... */
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else
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ch++;
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}
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}
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}
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#define H(x) ((x)-'a'+10)
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#define SCAN ((H('s')<<12)+(H('c')<<8)+(H('a')<<4)+H('n'))
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static unsigned int mode_menu(void)
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{
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int key;
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unsigned int sel;
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puts("Press <ENTER> to see video modes available, "
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"<SPACE> to continue, or wait 30 sec\n");
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kbd_flush();
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while (1) {
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key = getchar_timeout();
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if (key == ' ' || key == 0)
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return VIDEO_CURRENT_MODE; /* Default */
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if (key == '\r')
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break;
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putchar('\a'); /* Beep! */
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}
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for (;;) {
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display_menu();
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puts("Enter a video mode or \"scan\" to scan for "
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"additional modes: ");
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sel = get_entry();
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if (sel != SCAN)
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return sel;
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probe_cards(1);
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}
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}
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#ifdef CONFIG_VIDEO_RETAIN
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/* Save screen content to the heap */
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struct saved_screen {
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int x, y;
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int curx, cury;
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u16 *data;
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} saved;
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static void save_screen(void)
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{
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/* Should be called after store_mode_params() */
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saved.x = boot_params.screen_info.orig_video_cols;
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saved.y = boot_params.screen_info.orig_video_lines;
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saved.curx = boot_params.screen_info.orig_x;
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saved.cury = boot_params.screen_info.orig_y;
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if (heap_free() < saved.x*saved.y*sizeof(u16)+512)
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return; /* Not enough heap to save the screen */
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saved.data = GET_HEAP(u16, saved.x*saved.y);
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set_fs(video_segment);
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copy_from_fs(saved.data, 0, saved.x*saved.y*sizeof(u16));
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}
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static void restore_screen(void)
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{
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/* Should be called after store_mode_params() */
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int xs = boot_params.screen_info.orig_video_cols;
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int ys = boot_params.screen_info.orig_video_lines;
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int y;
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addr_t dst = 0;
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u16 *src = saved.data;
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u16 ax, bx, dx;
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if (graphic_mode)
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return; /* Can't restore onto a graphic mode */
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if (!src)
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return; /* No saved screen contents */
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/* Restore screen contents */
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set_fs(video_segment);
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for (y = 0; y < ys; y++) {
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int npad;
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if (y < saved.y) {
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int copy = (xs < saved.x) ? xs : saved.x;
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copy_to_fs(dst, src, copy*sizeof(u16));
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dst += copy*sizeof(u16);
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src += saved.x;
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npad = (xs < saved.x) ? 0 : xs-saved.x;
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} else {
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npad = xs;
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}
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/* Writes "npad" blank characters to
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video_segment:dst and advances dst */
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asm volatile("pushw %%es ; "
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"movw %2,%%es ; "
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"shrw %%cx ; "
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"jnc 1f ; "
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"stosw \n\t"
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"1: rep;stosl ; "
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"popw %%es"
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: "+D" (dst), "+c" (npad)
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: "bdS" (video_segment),
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"a" (0x07200720));
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}
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/* Restore cursor position */
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ax = 0x0200; /* Set cursor position */
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bx = 0; /* Page number (<< 8) */
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dx = (saved.cury << 8)+saved.curx;
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asm volatile(INT10
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: "+a" (ax), "+b" (bx), "+d" (dx)
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: : "ecx", "esi", "edi");
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}
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#else
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#define save_screen() ((void)0)
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#define restore_screen() ((void)0)
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#endif
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void set_video(void)
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{
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u16 mode = boot_params.hdr.vid_mode;
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RESET_HEAP();
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store_mode_params();
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save_screen();
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probe_cards(0);
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for (;;) {
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if (mode == ASK_VGA)
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mode = mode_menu();
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if (!set_mode(mode))
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break;
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printf("Undefined video mode number: %x\n", mode);
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mode = ASK_VGA;
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}
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vesa_store_edid();
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store_mode_params();
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if (do_restore)
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restore_screen();
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}
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