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therealprof / display-interface

Rust crates providing a generic interface for display drivers and some default implementations (GPIO, SPI and I2C)
Apache License 2.0
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WIP: use associated type for WIDTH #2

Closed almindor closed 4 years ago

almindor commented 4 years ago

First attempted WIP for associated type usage to allow easier "any Sized + Copy" for data format.

NOTE: tested with ST7789 and display-interface-spi using u8 "hardcoded", didn't try to use u16 anywhere yet.

almindor commented 4 years ago

NOTE: do not merge yet this is a WIP

almindor commented 4 years ago

Here's a "problem overview" of this approach: rust playground

See comments, basically this design forces driver writers into having most of their code in the "width specific" implementation blocks, and only basic data construction that's internal can be put outside into the "generic width" driver parts.

I still haven't figured out a better way tho...

almindor commented 4 years ago

Bumped with a DisplayFormat<'a> enum that lists each possible type and uses core::slice::Iter for internal representation.

There's a runtime cost to this approach both in the as_slice conversions (which probably can be removed if we optimize inside the DI implementations) as well as the match checks tho. It does remove the "duplication" in the driver tho, see assoc branch on ST7789 here

therealprof commented 4 years ago

Looks great to me on first glance. Let me try to convert a few drivers to it to check practicability.

almindor commented 4 years ago

For the iterator version I got blocked on https://github.com/rust-embedded/embedded-hal/issues/208