shocking@physiol.su.oz (Stephen Hocking) (11/03/88)
Hello all, Sorry for not posting to comp.unix.microport, or what ever it is now, we dont have it in Oz. I'm in the process of writing a device driver that wishes to talk to the EGA screen memory. It's a graphics driver to simply (at the moment) draw coloured lines. I've been able to do all this from user space, but one needs to do endless outbs in order to change colour, which is an agonisingly slow ioctl on /dev/mem under Uport. (V/AT 2.3). I've got to find a valid value for a char * to point to the base of video memory. Most of the driver is in place, all in C (to be converted to assembler later) with the code that worked OK in user space. The problem is finding that blasted memory location. I suspect one has to go through the gdt via mapin() on VIDEO2SEL, but this has yet to give much joy. Are you out there, John Plocher or Jim Sully? I'd love an answer on this, it's driving me nuts. I anticipate that the end result will fly. Most of the code comes from David Lewis and the July 1988 Microsystems Journal. At this stage, all the driver will end up being is a place for ioctls that ask for lines to be drawn, or blockfills to be done. If there is enough interest, I'll summarise to the net. If anybody is interested, we also have a driver for a DT2801 ADC board. Cheers, Stephen #include <std witty disclaimer> Stephen Hocking ACSnet shocking@physiol.oz UUCP ...!uunet!munnari!physiol!shocking