GCW Zero port started - Dos Emulator for GCW Zero

May 5th, 2013, 22:00 Posted By: wraggster

via http://rpix86.patrickaalto.com/rblog.html

During the past week I have not worked much on rpix86, as I got my new GCW Zero "engineering sample" game console. I began porting my DSTwo version to that device, and that has taken pretty much all of my free time for the past week. I plan to continue working on this during the following week as well, so my work on rpix86 is on a small break until I get something running in the GCW0 as well.
Working on GCW Zero is interesting because it uses a processor that has a MIPS32r2 architecture. This Release 2 version of the architecture brings a couple of very powerful and useful new opcodes to the MIPS ASM language, namely EXT and INS. I can use these new opcodes in quite a few places in my code to speed up the emulation, so I am very interested to see how fast zerox86 (current working name of the project) will run on the device.
I began my porting project by first porting my unit test program. I then began changing the code to use the new EXT and INS opcodes where possible. After a few changes I run the unit test program to make sure I don't break anything, and then continue making the changes. Since I use the unit test program from the special 386-enabled DSx386 version, I have also needed to fix some incompatibilities between the unit test program and my old DS2x86 sources. The current status is that opcodes 0x00..0x0E work fine, and I am working on the 386-specific 0x0F group opcodes, mainly fixing those incompatibilities.

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