Added debug_hex feature.

hnj2 commented 3 years ago

This feature will cause the uDebug implementation of for integer primitives to print hexadecimal representations of those integers.

uwriteln!(s, "{}", 0xdeadbeef_u32)    // prints: 3735928559
uwriteln!(s, "{:?}", 0xdeadbeef_u32)  // prints: deadbeef
uwriteln!(s, "{:#?}", 0xdeadbeef_u32) // prints: 0xdeadbeef

uwriteln!(s, "{}", 0xdeadbeef_u32 as i32)    // prints: -559038737
uwriteln!(s, "{:?}", 0xdeadbeef_u32 as i32)  // prints: deadbeef
uwriteln!(s, "{:#?}", 0xdeadbeef_u32 as i32) // prints: 0xdeadbeef

Advantages:

In various cases this can be useful:

For embedded systems it is often more meaningful to have a hexadecimal printout of your integers.
For systems without a 64 (or even 32) bit divide with remainder instruction the resulting code will be slightly smaller and faster.
uDebug implementation for uxx can be resued for ixx

Drawbacks:

If both uDisplay and uDebug are used for some ixx or uxx type, then less code can be reused with the debug_hex feature

Alternatives:

A uHex type together with a derive macro could be used to implement fromats with {:x?} and {:#x?}.

mutantbob commented 2 years ago

It would be better if hex encoding were triggered by the {:x} format string rather than replacing {} . https://doc.rust-lang.org/std/fmt/#formatting-traits

mutantbob commented 2 years ago

https://github.com/japaric/ufmt/pull/35 adds support for {:x}

japaric commented 2 years ago

thanks for the PR. I agree with mutantbob and prefer the alternative of having this on a separate trait rather than as a Cargo feature as that allows one to use both decimal and hexadecimal formatting in the crate based on the format string.

japaric / ufmt