[gPXE] int 10h problem

[何闯]

Dear all,
By Gene's advice & google, I found the solution, codes are here.
Ref:http://mcs.uwsuper.edu/sb/324/Intro/vga.html
 
Thanks all~~
 





At 2011-04-02，"Gene Cumm" <gene.cumm at gmail.com> wrote:

>2011/4/2 何闯 <justhechuang at 163.com>:
>> Hi all,
>> As Gene suggested, I browsed vesamenu code and found nothing useful.
>> However, I figured out how to use the 640X480 mode in mode 12h. It turns out
>> that one pixel takes one bit place. Codes are:
>> //////////////////////////////////////////////////////////////////////////////////////
>> void setvga() { __asm__ __volatile__ ( REAL_CODE ( "movw $0x12, %%ax\n\t"
>> "int $0x10\n\t")::); }
>> void putpixel(int x,int y, int c __unused ) { char v; char idx; if(vediobuf
>> == NULL) { vediobuf = (unsigned char*)phys_to_user(0xa0000); } v =
>> *(vediobuf+x/8+80*y); idx = x % 8; //One byte divided into eight bits for
>> pixels switch(idx) { case 0: *(vediobuf+x/8+80*y) = (1<<7)|v; break; case 1:
>> *(vediobuf+x/8+80*y) = (1<<6)|v; break; case 2: *(vediobuf+x/8+80*y) =
>> (1<<5)|v; break; case 3: *(vediobuf+x/8+80*y) = (1<<4)|v; break; case 4:
>> *(vediobuf+x/8+80*y) = (1<<3)|v; break; case 5: *(vediobuf+x/8+80*y) =
>> (1<<2)|v; break; case 6: *(vediobuf+x/8+80*y) = (1<<1)|v; break; case 7:
>> *(vediobuf+x/8+80*y) = (1<<0)|v; break; } }
>> ////////////////////////////////////////////////////////////////////////////////////////////
>>
>> And this works, I finally entered 640X480 mode!!! Nevertheless, one bit can
>> only hold two colors(black and white),
>> but document says that video mode 12h will enter 640X480X16 resolution,
>> which means 4bit for one pixel,
>> this conflicts with my practise. I am confused again..............
>
>Your video card might not know mode 12h and used 11h instead.
>
>Also, I'd advise against writing the video buffer directly unless
>you've asked your video card where its buffer is.  See also INT 10h
>AH=0Ch, AH=0Dh and AH=0Fh.
>
>> At 2011-04-02，"Gene Cumm" <gene.cumm at gmail.com
>>> wrote:
>>
>>>On Fri, Apr 1, 2011 at 15:15, Vaza gpxe <vaza.gpxe at gmail.com> wrote:
>>>> I'd suggest you find out how many bytes there are per pixel. I guess
>>>> you have 4 (not 1 you are using) and the resolution you think you see
>>>> is actually 640x120. You may also have limited video memory that makes
>>>> different resolutions use different pixel sizes
>>>
>>>I believe there should be only 4 bits at that video mode.
>>>
>>>Soforth, I'd suggest examining http://www.ctyme.com/intr/int-10.htm
>>>for starters.  I believe INT 10h AX 4F00h is the start of VESA related
>>>info that Syslinux uses for vesamenu.c32 (and possibly gfxboot.c32)
>>>
>>>--
>>>-Gene
>>>
>>>> In Reply to:
>>>> 2011/4/1 何闯 <justhechuang at 163.com>:
>>>>> Deal all,
>>>>> I just tested int 0x10 BIOS interrupt to draw some pictures.
>>>>> However, when I coded the follow to enter 640X480 video mode, it seems
>>>> that
>>>>> the actual video mode is 640X100,
>>>>> I draw a rectangle with range(0,0, 640, 480) to verify, and it resulted in
>>>>> range(0,0, 640,100), about a quarter square of a rectangle.
>>>>> And I noticed that 320X200 video mode is OK, and 320X200 == 640X100, is
>>>> that
>>>>> mean my machine can hand only 64000 pixels?
>>>>> Can anyone tell me why?
>>>>>
>>>> ////////////////////////////////////////////////////////////////////////////
>>>> ///////////////////////////
>>>>> void setvga()
>>>>> {
>>>>> __asm__ __volatile__ ( REAL_CODE ( "movw $0x4f02, %%ax\n\t"  //ax=0x0012
>>>>> here seem stay in the text mode
>>>>> "movw $0x0101, %%bx\n\t"
>>>>> "int $0x10\n\t" )::);
>>>>> }
>>>>> void putpixel(int x,int y,int c)
>>>>> {
>>>>>     if(vediobuf == NULL)
>>>>> {
>>>>>    vediobuf = (unsigned char*)phys_to_user(0xa0000);  //physic address of
>>>>> graphic mode
>>>>> }
>>>>>     *(vediobuf+x+640*y)=c;
>>>>> }
>>>>>
>>>> ////////////////////////////////////////////////////////////////////////////
>>>> /////////////////////////
>>>>>
>>>>>
>>>>> yours,
>>>>> soforth
>>>>
>>>> I'd suggest looking at other boot loaders and how they write to the
>>>> screen (including Syslinux's vesamenu.c32 and gfxboot.c32).  64,000
>>>> sounds like the 16-bit limit of 65,536 per segment.
>>
>>
>>
>
>
>
>-- 
>-Gene
>
>"No one ever says, 'I can't read that ASCII(plain text) e-mail you sent me.'"
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