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Says he who asked almost that exact same question. Your remark is neither funny nor helpful.zaleschiemilgabriel wrote:Here we go again... :) :lol:
VESA is a BIOS specification (at least, I assume you mean VBE, the VESA BIOS extensions). So without BIOS, there's no VESA. And yes, there's plenty of documentation, and Google is your friend.iammisc wrote:Is there any way to enter a VESA graphics mode without even relying on the BIOS. Is there some documentation where I can get more information?
Code: Select all
class CVesaDriver
{
public:
void SetVideoMode(unsigned short width, unsigned short height, unsigned short depth);
void ExitVideoMode();
private:
void WriteCommand(unsigned short index, unsigned short value);
enum VBE_IOPORTS {
VBE_DISPI_IOPORT_INDEX = 0x01CE, VBE_DISPI_IOPORT_DATA = 0x01CF
};
enum VBE_COMMANDS {
VBE_DISPI_INDEX_ID, VBE_DISPI_INDEX_XRES, VBE_DISPI_INDEX_YRES,
VBE_DISPI_INDEX_BPP, VBE_DISPI_INDEX_ENABLE, VBE_DISPI_INDEX_BANK,
VBE_DISPI_INDEX_VIRT_WIDTH, VBE_DISPI_INDEX_VIRT_HEIGHT,
VBE_DISPI_INDEX_X_OFFSET, VBE_DISPI_INDEX_Y_OFFSET
};
enum VBE_FLAGS {
VBE_DISPI_DISABLED, VBE_DISPI_ENABLED, VBE_DISPI_GETCAPS,
VBE_DISPI_8BIT_DAC = 0x20, VBE_DISPI_LFB_ENABLED = 0x40, VBE_DISPI_NOCLEARMEM = 0x80
};
} VesaDriver;
void CVesaDriver::SetVideoMode(unsigned short width, unsigned short height, unsigned short depth)
{
WriteCommand(VBE_DISPI_INDEX_ENABLE, VBE_DISPI_DISABLED);
WriteCommand(VBE_DISPI_INDEX_XRES, width);
WriteCommand(VBE_DISPI_INDEX_YRES, height);
WriteCommand(VBE_DISPI_INDEX_BPP, depth);
WriteCommand(VBE_DISPI_INDEX_ENABLE, VBE_DISPI_ENABLED | VBE_DISPI_LFB_ENABLED );
}
void CVesaDriver::ExitVideoMode()
{
this->WriteCommand(VBE_DISPI_INDEX_ENABLE, VBE_DISPI_DISABLED);
}
void CVesaDriver::WriteCommand(unsigned short index, unsigned short value)
{
WriteIoWord(VBE_DISPI_IOPORT_INDEX, index);
WriteIoWord(VBE_DISPI_IOPORT_DATA, value);
}
From another thread in this forum. Googling for e.g. VBE_DISP_IOPORT_INDEX, you'll find e.g. this (the Bochs VBE sources), but also this, which is the closest thing to a description I could find.lukem_95 wrote:Jal, can i ask where you got the docs to write that code?
I think you misported something then, it should work rather straightforward.for me the code set the x dimension to 256 and set depth to 32bpp (no matter what i set as the values) and the rest of the commands it gave a warning as unknown commands. i think im using the most up to date video bios to (the VBE one, not cirrus).
)Code: Select all
void outw(u16int port, u8int value)
{
__asm__ __volatile__ ( "outw %w0, %1" : : "a" (value), "id" (port) );
}Half work is rightlukem_95 wrote:i can't see how i misported it though, unless (god knows how) my outw() code is incorrect (just to check
it seems to half work, and then just die :SCode: Select all
void outw(u16int port, u8int value) { __asm__ __volatile__ ( "outw %w0, %1" : : "a" (value), "id" (port) ); }
I don't like vm86 either. Not using vm86 mode means I can treat segment registers as constants and never save/load them (which can be expensive due to protection checks).iammisc wrote:I guess I'll just settle for the vm86 option although IMO it's kinda an ugly hack.
That would kind of explain why the resolution never got beyond 255 :))).lukem_95 wrote:how on earth did i manage to overlook that one :|
But what if some userapp is naughty and modifies one? (To a legal value -- otherwise it would GPF, of course.) You can't allow that to propogate into other userapps, can you? I thought I should force the segment registers back to default on each task switch, just as a precaution.Brendan wrote: Not using vm86 mode means I can treat segment registers as constants and never save/load them (which can be expensive due to protection checks).