Fix formating of Arg::Ixx based integer hex values

[justahero]

This PR solves #632, it formats signed integers as hex values based on their given type, instead of formating it using a i128 based value.

Before this change the following log code:

defmt::info!("x: {=i16:#x}", -1_i16);

produced the output:

0 INFO  x: 0xffffffffffffffffffffffffffffffff
└─ hello::__cortex_m_rt_main @ src/bin/hello.rs:8

After the change the decoder takes the initial integer type into account when formating integer based hex values, the output is now:

0 INFO  x: 0xffff
└─ hello::__cortex_m_rt_main @ src/bin/hello.rs:8

The reason is that the decoder parsed all integer values as either Arg::Ixx or Arg::Uxx variants with the biggest data type to store the value in (i128 & u128), while keeping the original type information in a separate Parameter as part of the Frame.

The change now passes the integer type information to function Frame::format_i128. The new helper struct Hex128 implements both the LowerHex and UpperHex traits by delegating the call to the appropriate underlying type implementation.

Note this requires an update of probe-run that uses the defmt-decoder with the fix, a release will follow soon.

• fix formating of integer based hex values
• expand snapshot program log to output a number of different hex values

[jonas-schievink]

Nice!

bors r+

[bors]

Build succeeded:

• ci