Add SH-2A-NoFPU processor variant for FPU-less SH-2A chips

[huehuehuehueing]

Summary

Adds a SuperH:BE:32:SH-2A-NoFPU language variant that provides all SH-2A 32-bit extended instructions (movi20, movi20s, band.b, displacement-12 MOV, etc.) without FPU instruction decoding. Targets chips like the SH7206, SH7211, and SH7214 which use the SH-2A core without a floating-point unit.

Rationale

Verified against the Renesas SDK include file hierarchy (include_sh_080130), which separates SH2A/ (SH7206, SH7211) from SH2AFPU/ (SH7203, SH7263, SH7670) directories, and against product-page descriptions where SH7214 is listed as "SH-2A CPU core" without an FPU designation.

The implementation leverages the existing @if defined(FPU) conditional blocks in superh.sinc — the new .slaspec simply defines SH_VERSION "2A" without defining FPU.

Changes

New files:

• sh-2a-nofpu.slaspec — SLEIGH spec (SH-2A without FPU define)
• superh2a-nofpu.cspec — calling convention (integer-only, no fr4-fr7)

Modified:

• superh.ldefs — register the new language variant

[GhidorahRex]

I don't think there's a significant need for a new processor variant without the FPU instructions. If I were to analayze a SH7203 binary using the original superh2a slaspec, would it produce some spurious results? The fpu instructions shouldn't be present in the binary.

[huehuehuehueing]

@GhidorahRex There is no way to load a non-FPU binary without an additional processor variant being selectable. Yes, there are spurious instructions (the compiler used by Renesas does some intra-function interleaving with data that Ghidra attempts to disassemble as instructions).

Happy to provide you with a library of firmware samples for the relevant RENESAS parts.

[emteere]

Curious how you are disassembling. Are you using normal analysis, or are you selecting an area and disasembling?

Yes if you could point us to an example firmware image (non-proprietary, and publicly available of course)

[huehuehuehueing]

@emteere I will get you that information in the coming days. As for samples, public yes, non-proprietary might be more difficult. Not many RENESAS users (and of the specific parts/MCUs) out there, besides the fact that I would need to setup a Windows XP or similar system and configure the entire IDE/compiler stack (AFAIK) if we want to be faithful.

I also believe there are legal provisions/exemptions that allow RE or disassembly for purposes of compatibility, among other reasons. This is usually the case for many car ECU related efforts.

I can confirm the samples are for public, non controversial products that are also largely end of life.