Round up when calculating register size in bytes

[Tiwalun]

This fixes the issue in #418.

[rust-highfive]

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[burrbull]

bors try

[therealprof]

Seems a bit heavy and weird to do this with floating point operations.

[Tiwalun]

You're right, it's neater this way. I applied your suggestion.

[bors]

try

Build failed

• continuous-integration/travis-ci/push

[Tiwalun]

I'm wondering if this still has an issue with larger fields, for example if I declare a 17 bit wide register,
this will use a 24 bit width to calculate the offset.

However, the register width is mapped to to the next power of two, and the register field will actually be 32 bit wide.

svd2rust/src/generate/register.rs

Line 34 in 325a304

rsize.next_power_of_two()

It might make more sense to use the actual width of the register in this calculation, instead of calculating it again.

[therealprof]

LGTM, thanks.

bors r+

[bors]

Build succeeded

• continuous-integration/travis-ci/push