On Fri, Apr 1, 2011 at 15:15, Vaza gpxe <vaza.g...@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 <justhechu...@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. _______________________________________________ gPXE mailing list gPXE@etherboot.org http://etherboot.org/mailman/listinfo/gpxe
