video.s

xen 3.2.2 源码

/******************************************************************************
 * video.S
 *
 * Display adapter & video mode setup, version 2.13 (14-May-99)
 *
 * Copyright (C) 1995 -- 1998 Martin Mares <[e-mail]>
 * Based on the original setup.S code (C) Linus Torvalds and Mats Anderson
 *
 * Rewritten to use GNU 'as' by Chris Noe <[e-mail]> May 1999
 *
 * Updated and ported for Xen by Keir Fraser <[e-mail]> June 2007
 */

        .code16

#include "video.h"

/* Scratch space layout: trampoline_end to trampoline_end+0x1000. */
#define modelist       bootsym(trampoline_end)   /* 2kB (256 entries) */
#define vesa_glob_info (modelist + 0x800)        /* 1kB */
#define vesa_mode_info (vesa_glob_info + 0x400)  /* 1kB */

/* Retrieve Extended Display Identification Data. */
#define CONFIG_FIRMWARE_EDID

/* Force 400 scan lines for standard modes (hack to fix bad BIOS behaviour */
#undef CONFIG_VIDEO_400_HACK

/* Positions of various video parameters passed to the kernel */
/* (see also include/linux/tty.h) */
#define PARAM_CURSOR_POS        0x00
#define PARAM_VIDEO_MODE        0x02
#define PARAM_VIDEO_COLS        0x03
#define PARAM_VIDEO_LINES       0x04
#define PARAM_HAVE_VGA          0x05
#define PARAM_FONT_POINTS       0x06
#define PARAM_CAPABILITIES      0x08
#define PARAM_LFB_LINELENGTH    0x0c
#define PARAM_LFB_WIDTH         0x0e
#define PARAM_LFB_HEIGHT        0x10
#define PARAM_LFB_DEPTH         0x12
#define PARAM_LFB_BASE          0x14
#define PARAM_LFB_SIZE          0x18
#define PARAM_LFB_COLORS        0x1c
#define PARAM_VESAPM_SEG        0x24
#define PARAM_VESAPM_OFF        0x26
#define PARAM_VESA_ATTRIB       0x28
#define _param(param) bootsym(boot_vid_info)+(param)

video:  xorw    %ax, %ax
        movw    %ax, %gs        # GS is zero
        cld
        call    basic_detect    # Basic adapter type testing (EGA/VGA/MDA/CGA)
        cmpb    $0,_param(PARAM_HAVE_VGA)
        je      1f                # Bail if there's no VGA
        movw    bootsym(boot_vid_mode), %ax     # User selected video mode
        cmpw    $ASK_VGA, %ax                   # Bring up the menu
        jz      vid2

        call    mode_set                        # Set the mode
        jc      vid1

        leaw    bootsym(badmdt), %si            # Invalid mode ID
        call    prtstr
vid2:   call    mode_menu
vid1:   call    store_edid
        call    mode_params                     # Store mode parameters
1:      ret

# Detect if we have CGA, MDA, EGA or VGA and pass it to the kernel.
basic_detect:
        movb    $0, _param(PARAM_HAVE_VGA)
        movb    $0x12, %ah                      # Check EGA/VGA
        movb    $0x10, %bl
        int     $0x10
        cmpb    $0x10, %bl                      # No, it's a CGA/MDA/HGA card.
        je      basret
        movw    $0x1a00, %ax                    # Check EGA or VGA?
        int     $0x10
        cmpb    $0x1a, %al                      # 1a means VGA...
        jne     basret                          # anything else is EGA.
        incb    _param(PARAM_HAVE_VGA)          # We've detected a VGA
basret: ret

# Store the video mode parameters for later usage by the kernel.
# This is done by asking the BIOS except for the rows/columns
# parameters in the default 80x25 mode -- these are set directly,
# because some very obscure BIOSes supply insane values.
mode_params:
        cmpb    $0, bootsym(graphic_mode)
        jnz     mopar_gr
        movb    $0x03, %ah                      # Read cursor position
        xorb    %bh, %bh
        int     $0x10
        movw    %dx, _param(PARAM_CURSOR_POS)
        movb    $0x0f, %ah                      # Read page/mode/width
        int     $0x10
        movw    %ax, _param(PARAM_VIDEO_MODE)   # Video mode and screen width
        movw    %gs:(0x485), %ax                # Font size
        movw    %ax, _param(PARAM_FONT_POINTS)  # (valid only on EGA/VGA)
        movw    bootsym(force_size), %ax        # Forced size?
        orw     %ax, %ax
        jz      mopar1

        movb    %ah, _param(PARAM_VIDEO_COLS)
        movb    %al, _param(PARAM_VIDEO_LINES)
        ret

mopar1: movb    %gs:(0x484), %al                # On EGA/VGA, use the EGA+ BIOS
        incb    %al                             # location of max lines.
mopar2: movb    %al, _param(PARAM_VIDEO_LINES)
        ret

# Fetching of VESA frame buffer parameters
mopar_gr:
        leaw    vesa_mode_info, %di
        movb    $0x23, _param(PARAM_HAVE_VGA)
        movw    16(%di), %ax
        movw    %ax, _param(PARAM_LFB_LINELENGTH)
        movw    18(%di), %ax
        movw    %ax, _param(PARAM_LFB_WIDTH)
        movw    20(%di), %ax
        movw    %ax, _param(PARAM_LFB_HEIGHT)
        movb    25(%di), %al
        movb    $0, %ah
        movw    %ax, _param(PARAM_LFB_DEPTH)
        movl    40(%di), %eax
        movl    %eax, _param(PARAM_LFB_BASE)
        movl    31(%di), %eax
        movl    %eax, _param(PARAM_LFB_COLORS)
        movl    35(%di), %eax
        movl    %eax, _param(PARAM_LFB_COLORS+4)
        movw    0(%di), %ax
        movw    %ax, _param(PARAM_VESA_ATTRIB)

# get video mem size
        leaw    vesa_glob_info, %di
        xorl    %eax, %eax
        movw    18(%di), %ax
        movl    %eax, _param(PARAM_LFB_SIZE)

# store mode capabilities
        movl    10(%di), %eax
        movl    %eax, _param(PARAM_CAPABILITIES)

# switching the DAC to 8-bit is for <= 8 bpp only
        movw    _param(PARAM_LFB_DEPTH), %ax
        cmpw    $8, %ax
        jg      dac_done

# get DAC switching capability
        xorl    %eax, %eax
        movb    10(%di), %al
        testb   $1, %al
        jz      dac_set

# attempt to switch DAC to 8-bit
        movw    $0x4f08, %ax
        movw    $0x0800, %bx
        int     $0x10
        cmpw    $0x004f, %ax
        jne     dac_set
        movb    %bh, bootsym(dac_size)          # store actual DAC size

dac_set:
# set color size to DAC size
        movb    bootsym(dac_size), %al
        movb    %al, _param(PARAM_LFB_COLORS+0)
        movb    %al, _param(PARAM_LFB_COLORS+2)
        movb    %al, _param(PARAM_LFB_COLORS+4)
        movb    %al, _param(PARAM_LFB_COLORS+6)

# set color offsets to 0
        movb    $0, _param(PARAM_LFB_COLORS+1)
        movb    $0, _param(PARAM_LFB_COLORS+3)
        movb    $0, _param(PARAM_LFB_COLORS+5)
        movb    $0, _param(PARAM_LFB_COLORS+7)

dac_done:
# get protected mode interface informations
        movw    $0x4f0a, %ax
        xorw    %bx, %bx
        xorw    %di, %di
        int     $0x10
        cmp     $0x004f, %ax
        jnz     no_pm

        movw    %es, _param(PARAM_VESAPM_SEG)
        movw    %di, _param(PARAM_VESAPM_OFF)

no_pm:  pushw   %ds
        popw    %es
        ret

# The video mode menu
mode_menu:
        leaw    bootsym(keymsg), %si    # "Return/Space/Timeout" message
        call    prtstr
        call    flush
nokey:  call    getkt

        cmpb    $0x0d, %al              # ENTER ?
        je      listm                   # yes - manual mode selection

        cmpb    $0x20, %al              # SPACE ?
        je      defmd1                  # no - repeat

        call    beep
        jmp     nokey

defmd1: ret                             # No mode chosen? Default 80x25

listm:  call    mode_table              # List mode table
listm0: leaw    bootsym(name_bann), %si # Print adapter name
        call    prtstr
        movw    bootsym(card_name), %si
        orw     %si, %si
        jnz     an2

        leaw    bootsym(vga_name), %si
        jmp     an1

an2:    call    prtstr
        leaw    bootsym(svga_name), %si
an1:    call    prtstr
        leaw    bootsym(listhdr), %si   # Table header
        call    prtstr
        movb    $0x30, %dl              # DL holds mode number
        leaw    modelist, %si
lm1:    cmpw    $ASK_VGA, (%si)         # End?
        jz      lm2

        movb    %dl, %al                # Menu selection number
        call    prtchr
        call    prtsp2
        lodsw
        call    prthw                   # Mode ID
        call    prtsp2
        lodsw
        call    prtdec                  # Width
        movb    $0x78, %al              # the letter 'x'
        call    prtchr
        lodsw
        call    prtdec                  # Height
        testb   $0xff,(%si)
        jnz     1f
        push    %si
        leaw    bootsym(textmode), %si
        call    prtstr
        pop     %si
        lodsw
        jmp     2f
1:      movb    $0x78, %al              # the letter 'x'
        call    prtchr
        lodsw
        call    prtdec                  # Depth
2:      movb    $0x0d, %al              # New line
        call    prtchr
        movb    $0x0a, %al
        call    prtchr
        incb    %dl                     # Next character

        cmpb    $'z'+1, %dl
        jnz     skip_bail
        leaw    bootsym(menu_bail_msg), %si
        call    prtstr
        jmp     lm2

skip_bail:
        cmpb    $'i', %dl
        jnz     skip_pause
        push    %si
        push    %dx
        leaw    bootsym(menu_more_msg), %si  # '<press space>'
        call    prtstr
        call    flush
1:      call    getkey
        cmpb    $0x20, %al              # SPACE ?
        jne     1b                      # yes - manual mode selection
        leaw    bootsym(crlft), %si
        call    prtstr
        pop     %dx
        pop     %si

skip_pause:
        cmpb    $'9'+1, %dl
        jnz     lm1
        movb    $'a', %dl
        jmp     lm1

lm2:    leaw    bootsym(prompt), %si    # Mode prompt
        call    prtstr
        leaw    bootsym(edit_buf), %di  # Editor buffer
lm3:    call    getkey
        cmpb    $0x0d, %al              # Enter?
        jz      lment

        cmpb    $0x08, %al              # Backspace?
        jz      lmbs

        cmpb    $0x20, %al              # Printable?
        jc      lm3

        cmpw    $bootsym(edit_buf)+4, %di  # Enough space?
        jz      lm3

        stosb
        call    prtchr
        jmp     lm3

lmbs:   cmpw    $bootsym(edit_buf), %di # Backspace
        jz      lm3

        decw    %di
        movb    $0x08, %al
        call    prtchr
        call    prtspc
        movb    $0x08, %al
        call    prtchr
        jmp     lm3
        
lment:  movb    $0, (%di)
        leaw    bootsym(crlft), %si
        call    prtstr
        leaw    bootsym(edit_buf), %si
        cmpb    $0, (%si)               # Empty string = default mode
        jz      lmdef

        cmpb    $0, 1(%si)              # One character = menu selection
        jz      mnusel

        cmpw    $0x656d, (%si)          # 'me'
        jnz     lmhx
        cmpw    $0x756e, 2(%si)         # 'nu'
        jnz     lmhx
        jmp     listm