Support for RV32EC (embedded) configuration?

[theandrew168]

Support for RV32EC (embedded) configuration?

[sahasradal]

DID a sample usart TX with bronzebeard for CH32V003 and was successful. crude code in my repository

[theandrew168]

First off, thanks for considering bronzebeard and bringing this up! I haven't looked into RV32E until today and it looks like it differs from RV32I in that it supports only 16 registers instead of the usual 32. The instruction set and other details are unchanged.

So, I'd assume that bronzebeard would already support these chips in the sense that the user would be responsible for only using valid registers (x0-x15). However, it could be useful to add a flag that enforces this constraint and throws an error if an invalid register is used.

Similarly, such a feature could probably be applied to other scenarios: (using mul on a chip without M support, etc).

[sahasradal]

I did a blinky on CH32V003 chip with bronzebeard and was successful