Miscellaneous cleanup and refactoring (#41)

* Reduce code duplication in `build.rs`, define some configuration symbols

* Reorganize and clean up the `io` module a bit

* Clean up re-exports, correctly alias target with capitalized name

* Move `Transport` type into library, extract some functions

* Change type of `tinfl_decompressor` struct's `bit_buf` field from u64 to u32

* We can now build using `opt-level = "z"`!

* Update `README.md`, rustfmt

* Tweak symbol name for RISC-V in build script

Cargo.toml

@@ -21,21 +21,21 @@ static_cell      = "2.0.0"
 [dev-dependencies]
 assert2        = "0.3.11"
 matches        = "0.1.10"
-mockall        = "0.12.0"
-mockall_double = "0.3.0"
+mockall        = "0.12.1"
+mockall_double = "0.3.1"
 
 [features]
 esp32   = ["esp32-hal"]
-esp32s2 = ["esp32s2-hal"]
-esp32s3 = ["esp32s3-hal"]
+esp32c2 = ["esp32c2-hal"]
 esp32c3 = ["esp32c3-hal"]
 esp32c6 = ["esp32c6-hal"]
 esp32h2 = ["esp32h2-hal"]
-esp32c2 = ["esp32c2-hal"]
+esp32s2 = ["esp32s2-hal"]
+esp32s3 = ["esp32s3-hal"]
 dprint  = []
 
 [profile.release]
-opt-level     = "s" # See: https://github.com/llvm/llvm-project/issues/57988
+opt-level     = "z"
 codegen-units = 1
 lto           = true
 panic         = "abort"

README.md

@@ -1,7 +1,7 @@
 # esp-flasher-stub
 
 [![GitHub Workflow Status](https://github.com/esp-rs/esp-println/actions/workflows/ci.yml/badge.svg)](https://github.com/esp-rs/esp-println/actions/workflows/ci.yml)
-![MSRV](https://img.shields.io/badge/MSRV-1.65-blue?labelColor=1C2C2E&logo=Rust&style=flat-square)
+![MSRV](https://img.shields.io/badge/MSRV-1.67-blue?labelColor=1C2C2E&logo=Rust&style=flat-square)
 [![Matrix](https://img.shields.io/matrix/esp-rs:matrix.org?label=join%20matrix&color=BEC5C9&labelColor=1C2C2E&logo=matrix&style=flat-square)](https://matrix.to/#/#esp-rs:matrix.org)
 
 Rust implementation of flasher stub located in [esptool](https://github.com/espressif/esptool/).