Re: How does the Sound Blaster DSP detection work?

Posted on 2016-08-11, 07:58

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by superfury

in PC Emulation

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Just added ADPCM based on Dosbox's conversion: https://bitbucket.org/superfury/unipcemu/src/3c933d8c8453ca9afbb0fd155b662b35b8f68a7e/hardware/soundblaster.c?at=master Although it still isn't detected correctly or fully working according to the SB1.5 disk(software hangs waiting for some result in the …

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Re: Properly emulating 80286+ multitasking protected mode with all exceptions etc.?

Posted on 2016-08-10, 10:19

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by superfury

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Well, logically thinking while keeping in mind that numbers are UNSIGNED: LIDT -1 will load the IDTR with base 0xFFFFFF and limit 0xFFFF on the 80286. INT 1 will then check against the limit(0xFFFF) and will be seen as valid (because 7<0xFFFF). Finally it will retrieve the IDT entry from address …

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Re: Properly emulating 80286+ multitasking protected mode with all exceptions etc.?

Posted on 2016-08-10, 00:46

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by superfury

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OK. So the code using LIDT -1 is completely wrong in that case.

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Re: Properly emulating 80286+ multitasking protected mode with all exceptions etc.?

Posted on 2016-08-09, 23:21

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by superfury

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So how does it know it's an invalid address? Does it simply check for overflow by adding the base and limit together and checking for carry? How does it know the IDTR is invalid? Btw, the manual ( https://www.google.nl/url?sa=t&source=web&rct=j&url=http://bitsavers.informatik.uni-stuttgart.de/pdf/ …

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Re: Properly emulating 80286+ multitasking protected mode with all exceptions etc.?

Posted on 2016-08-09, 21:57

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by superfury

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So the LIDT -1 would result in a valid IDT at the wrong place in memory? Thus the CPU will happily executes whatever IDT entry it finds there and only if it contains data causing an exception, it will result in an exception. Else the triple fault won't happen. Is that correct? Edit: looking at …

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Re: Properly emulating 80286+ multitasking protected mode with all exceptions etc.?

Posted on 2016-08-09, 21:48

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by superfury

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Isn't address -1 impossible to assemble? It's a 16-bit unsigned limit and a 24/32-bit unsigned offset according to what I can find. So LIDT -1 wouldn't even compile in x86? Or it would result in a LIDT FFFFFFFFFFh instruction, which is at the end of memory, wrapping around 32-bits when looking up an …

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Re: Properly emulating 80286+ multitasking protected mode with all exceptions etc.?

Posted on 2016-08-09, 20:26

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by superfury

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I'm wondering about one thing though: the technique uses LIDT -1, which essentially loads the descriptor with a base of 0xFFFFFF(16-bit) or 0xFFFFFFFF(32-bit) and a limit of 0xFFFF. Thus all interrupt fetches are fetched from address FFFFFF to FFFFFF+FFFE. But this won't result in exceptions, …

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Re: How does the Sound Blaster DSP DMA 8-bit output work?

Posted on 2016-08-09, 18:18

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by superfury

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OK. I'll leave the non-SB I/O Game Blaster ports enabled for the Game Blaster when Sound Blaster emulation is enabled. It just will ignore any reads to I/O ports that actually conflict with the Sound Blaster (the DSP Read Port is the only one as far as i can see that actually causes conflicts. …

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Re: How does the Sound Blaster DSP DMA 8-bit output work?

Posted on 2016-08-09, 16:12

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by superfury

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After looking at my IRQ code, I noticed that I've changed the high nibble of the IRQ(since there's only 16 IRQs on a x86) to mean the subchannel of the IRQ(so multiple IRQs can have their own handlers for handling interrupt acnowledge and EOI), but this wasn't handled in the PIC. Thus it was …

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Re: How does the Sound Blaster DSP DMA 8-bit output work?

Posted on 2016-08-09, 13:13

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by superfury

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Just tried the SB1.5 disks from https://www.vogonsdrivers.com/getfile.php?fileid=48&menustate=0 . When I try to install, it installs, but when I run inst-drv.exe with port 220 hex(the emulated base port of the Sound Blaster DSP), it tells me "Error in Interrupt detection". Anyone knows what this is …

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Re: How does the Sound Blaster DSP DMA 8-bit output work?

Posted on 2016-08-09, 09:38

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by superfury

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I've managed to get output pretty much working in 8-bit mode: https://bitbucket.org/superfury/unipcemu/src/2d27806f0d672711aec042fffad21bef1a541e8d/hardware/soundblaster.c?at=master Also modified the DMA to reset the DMA DACK 'signal' during Single-cycle to stop transfers when DREQ is lowered. …

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Re: How does the Sound Blaster DSP DMA 8-bit output work?

Posted on 2016-08-08, 22:46

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by superfury

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Looking at my DMA code again, I think there might be a problem with the Single-cycle mode: https://bitbucket.org/superfury/unipcemu/src/34d993552df3c4a78339619ff2b74feadb58d769/hardware/dma.c?at=master&fileviewer=file-view-default Currently both single cycle and burst/block mode start their …

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How does the Sound Blaster DSP detection work?

Posted on 2016-08-08, 20:59

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by superfury

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I'm trying to implement the Sound Blaster 1.0 DSP in UniPCemu, but so far the DMA 8-bit output doesn't work: https://bitbucket.org/superfury/unipcemu/src/34d993552df3c4a78339619ff2b74feadb58d769/hardware/soundblaster.c?at=master I'm currently testing using Mike's 8088 version of Wolfenstein 3D. It …

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Re: Properly emulating 80286+ multitasking protected mode with all exceptions etc.?

Posted on 2016-08-08, 12:08

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by superfury

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Just implemented basic double/triple fault handling: https://bitbucket.org/superfury/unipcemu/src/18a52e34ae8f6cc8513818d54255d71f657a1a6f/cpu/protection.c?at=master https://bitbucket.org/superfury/unipcemu/src/18a52e34ae8f6cc8513818d54255d71f657a1a6f/cpu/multitasking.c?at=master Still need to …

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Properly emulating 80286+ multitasking protected mode with all exceptions etc.?

Posted on 2016-08-07, 16:52

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by superfury

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I'm thinking about finishing the basics of my 80286+ protected mode. One problem I'm struggling about is the task switching and it's exception handling mechanism. Currently all exceptions are handled during the current task. As long as no task switch occurs nothing's wrong there. But how should I …

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Re: UniPCemu emulator releases

Posted on 2016-08-06, 15:13

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by superfury

in Release Announcements

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The latest UniPCemu build: UniPCemu_10160806_1624.zip Changelog: - Optimized various parts of the emulator. - Implemented Game Blaster emulation(based on Dosbox SVN information). - Fixed releasing keys in SDL2 builds, it won't end up with stuck keys anymore. - Fixed various hardware responding to …

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Game Blaster emulation based on Dosbox's gameblaster.cpp gives noisy output?

Posted on 2016-08-04, 16:40

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by superfury

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I've implemented a custom version of Dosbox SVN Gameblaster.cpp into my UniPCemu, but for some reason I get pretty noisy sound, instead of the normal sound Dosbox produces. Anyone can see what's going wrong here? https://bitbucket.org/superfury/unipcemu/src/f77fcd4a79b5779ba5bc8b2b1cc5f16fbc7e903d/ …

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Re: SDL vs SDL2 input issues?

Posted on 2016-08-03, 11:14

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by superfury

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After looking at the commits I've made to my emulator, the first commit doing anything with SDL2 is commit of 20-5-2016: https://bitbucket.org/superfury/unipcemu/src/479a5e300b0cd5c3191bedcaa843c5c56ed16adf/emu/io/input.c?at=master&fileviewer=file-view-default Before that it's SDL1.2.15 only. This …

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Re: SDL vs SDL2 input issues?

Posted on 2016-08-03, 10:11

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by superfury

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The changes in the port from SDL1 to SDL2 can be found by looking for the "#if(n)def SDL2" blocks in the code. Most of the SDL1 code is unmodified, I've just changed incompatible parts(like the big lookup table becoming a function and repeating looking at the repeat flag) to be able to run in SDL2. …

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SDL vs SDL2 input issues?

Posted on 2016-08-02, 12:44

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by superfury

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I notice that, with my UniPCemu emulator, building it for SDL2 (compared to the normal SDL build) somehow gives some strange caps lock/shift issues. I notice that when booting and starting the MS-DOS prompt, sometimes everything ends up in capital letters (without shift/caps lock being used), while …

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