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c++.dos.32-bits - Linear Video Memory

reply "Imran Haider" <absolute1008 hotmail.com> writes:
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Does all system support the 0C00:0000 location for linear video memory?  =
In my PC,  I could use 000A:0000 location to output VGA colors, I could =
also use 0c00:0000 to output colors. the 0c00:0000 works faster so I =
just wanted to know weather it is compatible with all PCs. If you more =
about this please tell me. Thanks. Bye.
Nov 10 2001
parent reply NancyEtRoland <nancyetroland free.fr> writes:
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Imran Haider a écrit :

 Does all system support the 0C00:0000 location for linear video
 memory?  In my PC,  I could use 000A:0000 location to output VGA
 colors, I could also use 0c00:0000 to output colors. the 0c00:0000
 works faster so I just wanted to know weather it is compatible with
 all PCs. If you more about this please tell me. Thanks. Bye.

vbe cf int 10h fc 4f01h gives you a structure like this: //---------------------------------------------------- //VesaModInfo //flag tq: // b0: 1 -> mode supporté par hard // b1: 1 -> info optionnelles / reserved (VBE>=1.2) #define _VesaModTTYOk (1<<2) //1 -> fc text bios tty ok (int 10h fc 1,2,6,7,9,a,e) #define _VesaModIsColor (1<<3) //1 -> mode couleur #define _VesaModIsGraphic (1<<4) //1 -> mode graphique // b5: 0 -> mode compatible vga // b6: 0 -> acces mode compatible vga #define _VesaModIsFlatOk (1<<7) //vbe>=2.0: 1 -> flat frame buffer mode valide //vbe <2.0: toujours a 0 #ifdef __SC__ #pragma SC align 1 #else #pragma option -a- #endif struct VesaModInfo { //cf int 10h fc 4f01h int isttyok() { return (flags & _VesaModTTYOk)!=0; } int iscolor() { return (flags & _VesaModIsColor)!=0; } int isgraphic() { return (flags & _VesaModIsGraphic)!=0; } int isflatok(); //return flat frame buffer valide //ù rem: 11/99, bug dans vbe de S3 Savage3D => return false si S3 Savage3D detecte //ù !! => vesa_init doit avoir ete execute (_vesainfo a jour) unsigned short flags; byte acces_flags1; byte acces_flags2; unsigned short acces_granul; //en ko unsigned short acces_size; //en ko unsigned short acces_seg1; unsigned short acces_seg2; dosptr acces_func; //dosptr sur fonction appellee par int 10h fc 4f05h unsigned short l_size; //size ligne en byte //optionel, en standard pour VBE 1.2 et plus: unsigned short scr_x; //szx scr en pix/char unsigned short scr_y; //szy scr en pix/char byte chr_x; byte chr_y; byte pln; //nb pln byte bpx; //bit/pix byte nbbank; //nb bank ? byte model; //model memoire byte banksize; //size bank en ko byte nbimage; //nb image byte _reserved1; //direct color: byte directcolorzone[9]; //a partir de VBE 2.0 dword physbaseptr; //addresse physique de flat frame buffer dword offscreenofs; //debut memoire off screen unsigned short offscreenmemsize; //size off screen mem en ko byte _reserved2[206]; }; #ifdef __SC__ #pragma SC align #else #pragma option -a. #endif //acces_flags tq: #define _Acces_ (1<<0) //1 -> fen dispo #define _rAcces_ (1<<1) //1 -> lecture ok #define _wAcces_ (1<<2) //1 -> ecriture ok //model tq: #define _ModelText_ 0 //-> text #define _ModelCga_ 1 //-> format graphic cga #define _ModelHerc_ 2 //-> format graphic hercules #define _ModelEga16_ 3 //-> format ega/vga 16 couleur (plan) #define _ModelNibble_ 4 //-> format compact, 2 nibble/byte #define _ModelEga256_ 5 //-> format ega/vga 256 couleur, 1 byte/pixel #define _ModelDirectColor 6 #define _ModelYUV 7 //---------------------------------------------------- if supported, flat frame buffer addresse is here: VesaModInfo::physbaseptr to access this buffer do like this (considering you work on DOSX model): byte* __accesptr; __accesptr = _x386_map_physical_address((void*)modinfo.physbaseptr,4000000ul); now you can read or write in the buffer. Ciao Roland
Nov 10 2001
parent Roland <rv ronetech.com> writes:
NancyEtRoland a écrit :

 Imran Haider a écrit :

 Does all system support the 0C00:0000 location for linear video memory?  In my
PC,  I could use 000A:0000 location to output VGA colors, I could also use
0c00:0000 to output colors. the 0c00:0000 works faster so I just wanted to know
weather it is compatible with all PCs. If you more about this please tell me.
Thanks. Bye.

vbe cf int 10h fc 4f01h gives you a structure like this...

after this reply i was expecting 2 questions: 1- how can i call a real mode interrupt not implemented by DOSX ? (easy), 2- how can i pass a buffer to a real mode interrupt ? (more complicate) Even if those questions were not asked, i reply, may be they are good candidate for the FAQ. 1- how can i call a real mode interrupt not implemented by DOSX ? call int86_real or int86x_real or define something like this if you want your code to compile on DOSX and large model as well: #if (sizeof(int)==4) #define _CALL_INT(intnum,regsin,regsout) int86_real(intnum,&(regsin),&(regsout)) #define _CALL_INTS(intnum,regsin,regsout,segregs) int86x_real(intnum,&(regsin),&(regsout),&(segregs)) #else #define _CALL_INT(intnum,regsin,regsout) int86(intnum,&regsin,&regsout) #define _CALL_INTS(intnum,regsin,regsout,segregs) int86x(intnum,&(regsin),&(regsout),&(segregs)) #endif //sizeof(int)==4 2- how can i pass a buffer to a real mode interrupt ? the real mode interrupt expects a real mode pointer (segment:offset) below 1 Mbyte limite. you have to allocate a buffer in real mode memory and pass its real mode addresse to the interrupt. do like this: unsigned short _x386_convmemalloc(unsigned size); //allocate a conventional memory block //return the conventional memory segment, 0 if error //!!! allocate 4 k byte minimum !!! //!!! there is no way to deallocate this memory !!! unsigned short _x386_convmemalloc(const unsigned size) { REGS regs; regs.x.bx = (unsigned short)((size+15)>>4); regs.h.ah = 0x48; int86(0x21,&regs,&regs); return (regs.x.flags&_cf_) ? 0 //DOS error no is in ax : regs.x.ax; } example: #if (sizeof(int)==4) unsigned convmemseg,dosptr; //real mode segment, pointer void* dosxptr; //dosx pointer #define DGROUP MKFP(getDS(),0) convmemseg = (unsigned)_x386_convmemalloc(size); dosptr = convmemseg<<16; //offset = 0 dosxptr = (void*)(-_x386_get_abs_address(DGROUP)+(convmemseg<<4)); #endif //sizeof(int)==4 (hope no syntax error) Ciao Roland
Nov 14 2001