Improve SH2 execution performance

[rtoumazet]

Currently Saturnin uses an almost classical interpreter. Various techniques exist to improve performances (dynarec, threaded interpreter, etc.) I'm putting links there in no particular order for future analysis.

• http://www.xsim.com/papers/Bario.2001.emubook.pdf
• http://www.emutalk.net/threads/55275-Threaded-interpretation-vs-Dynamic-Binary-Translation
• http://www.ittc.ku.edu/~kulkarni/teaching/EECS768/slides/chapter2.pdf
• http://www.jilp.org/vol5/v5paper12.pdf
• https://www.cs.tcd.ie/David.Gregg/papers/toplas05.pdf
• http://www.emulators.com/docs/nx25_nostradamus.htm
• http://www.gtoal.com/sbt/

[rtoumazet]

Current implementation is a basic interpreter. Next step would be to create an indirect threaded interpreter -> will be in sh2-perfs branch.

• [x] Create branch
• [x] Move existing sh2 related files to their own directory, and update the links
• [x] List the various existing types of opcodes
• [x] Create the opcode generator using templates
• [x] Create a 0x10000 lut for every template
• [x] Decouple SH2 interpreters
• [x] Add code to choose between SH2 cores

[rtoumazet]

Types of opcodes (r: n or m register, d: displacement, i: immediate, f: fixed data) :

• ffff
• ffdd
• ffii
• ffrd
• fddd
• frdd
• frii
• frff
• frrd
• frrf