GCC 10 compilation issue with Arduino about brzo_i2c HOT 5 OPEN

Hi Max,

Thanks for your support... I am not the GCC expert, so, let me investigate it...

from brzo_i2c.

I think the compiler is just running out of registers. ASM blocks in read() and write() use 14 registers. Even with the old compiler, I got the RL_REGS error when I tried to add a 15th. The best fix is to rewrite assembly with fewer registers. For example, error and repeated-start flags can be in RAM without slowing the execution.

from brzo_i2c.

@beefeater94 : Well, the point is not that I do not understand what the compiler is saying, i.e. no more registers. However, the question is why this version of GCC behaves differently and which compiler flags cause thise different behaviour compared to older versions. Thus, changing flags comes before changing code ;-)

from brzo_i2c.

You should be able to just save and restore registers in the assembly code and it would not matter how many registers you use as long as the code was single threaded (ie. save registers - run code - restore registers - exit). I have no idea why a compiler would care about register usage - but I am an assembly guy, not a high level language user.

from brzo_i2c.

@JimDrewGH Well, with inline assembly you can either choose registers to be used yourself, or you can let the compiler choose them, see here. I have used the latter method.

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