//! A template for building applications for ARM Cortex-M microcontrollers
//!
//! # Dependencies
//!
//! - Nightly Rust toolchain from 2018-08-28 or newer: `rustup default nightly`
//! - Cargo `clone` subcommand: `cargo install cargo-clone`
//! - GDB: `sudo apt-get install gdb-arm-none-eabi` (on Ubuntu)
//! - OpenOCD: `sudo apt-get install OpenOCD` (on Ubuntu)
//! - [Optional] Cargo `add` subcommand: `cargo install cargo-edit`
//!
//! # Usage
//!
//! 0) Figure out the cross compilation *target* to use.
//!
//! - Use `thumbv6m-none-eabi` for ARM Cortex-M0 and Cortex-M0+
//! - Use `thumbv7m-none-eabi` for ARM Cortex-M3
//! - Use `thumbv7em-none-eabi` for ARM Cortex-M4 and Cortex-M7 (*no* FPU support)
//! - Use `thumbv7em-none-eabihf` for ARM Cortex-M4**F** and Cortex-M7**F** (*with* FPU support)
//!
//! 1) Install the `rust-std` component for your target, if you haven't done so already
//!
//! ``` console
//! $ rustup target add thumbv7em-none-eabihf
//! ```
//!
//! 2) Clone this crate
//!
//! ``` text
//! $ cargo clone cortex-m-quickstart --vers 0.3.4
//! ```
//!
//! 3) Change the crate name, author and version
//!
//! ``` text
//! $ edit Cargo.toml && head $_
//! [package]
//! authors = ["Jorge Aparicio <jorge@japaric.io>"]
//! name = "demo"
//! version = "0.1.0"
//! ```
//!
//! 4) Specify the memory layout of the target device
//!
//! **NOTE** board support crates sometimes provide this file for you (check the crate
//! documentation). If you are using one that does then remove *both* `memory.x` and `build.rs` from
//! the root of this crate.
//!
//! ``` text
//! $ cat >memory.x <<'EOF'
//! MEMORY
//! {
//!   /* NOTE K = KiBi = 1024 bytes */
//!   FLASH : ORIGIN = 0x08000000, LENGTH = 256K
//!   RAM : ORIGIN = 0x20000000, LENGTH = 40K
//! }
//! EOF
//! ```
//!
//! 5) Optionally, set a default build target. This way you don't have to pass `--target` to each
//! Cargo invocation.
//!
//! ``` text
//! $ cat >>.cargo/config <<'EOF'
//! [build]
//! target = "thumbv7em-none-eabihf"
//! EOF
//! ```
//!
//! 6) Optionally, depend on a device, HAL implementation or a board support crate.
//!
//! ``` text
//! $ # add a device crate, OR
//! $ cargo add stm32f30x
//!
//! $ # add a HAL implementation crate, OR
//! $ cargo add stm32f30x-hal
//!
//! $ # add a board support crate
//! $ cargo add f3
//! ```
//!
//! 7) Write the application or start from one of the examples
//!
//! ``` text
//! $ rm -r src/* && cp examples/hello.rs src/main.rs
//! ```
//!
//! 8) Build the application
//!
//! ``` text
//! $ cargo build --release
//!
//! $ # sanity check
//! $ arm-none-eabi-readelf -A target/thumbv7em-none-eabihf/release/demo
//! Attribute Section: aeabi
//! File Attributes
//!   Tag_conformance: "2.09"
//!   Tag_CPU_arch: v7E-M
//!   Tag_CPU_arch_profile: Microcontroller
//!   Tag_THUMB_ISA_use: Thumb-2
//!   Tag_FP_arch: VFPv4-D16
//!   Tag_ABI_PCS_GOT_use: direct
//!   Tag_ABI_FP_denormal: Needed
//!   Tag_ABI_FP_exceptions: Needed
//!   Tag_ABI_FP_number_model: IEEE 754
//!   Tag_ABI_align_needed: 8-byte
//!   Tag_ABI_align_preserved: 8-byte, except leaf SP
//!   Tag_ABI_HardFP_use: SP only
//!   Tag_ABI_VFP_args: VFP registers
//!   Tag_ABI_optimization_goals: Aggressive Speed
//!   Tag_CPU_unaligned_access: v6
//!   Tag_FP_HP_extension: Allowed
//!   Tag_ABI_FP_16bit_format: IEEE 754
//! ```
//!
//! 9) Flash and debug the program
//!
//! ``` text
//! $ # Launch OpenOCD on a terminal
//! $ openocd -f (..)
//! ```
//!
//! ``` text
//! $ # Start a debug session in another terminal
//! $ arm-none-eabi-gdb target/thumbv7em-none-eabihf/release/demo
//! ```
//!
//! Alternatively, you can use `cargo run` to build, flash and debug the program in a single step.
//!
//! ``` text
//! $ cargo run --example hello
//! > # drops you into a GDB session
//! ```
//!
//! # Examples
//!
//! Check the [examples module][examples]
//!
//! [examples]: ./examples/index.html
//!
//! # Troubleshooting
//!
//! This section contains fixes for common errors encountered when the
//! `cortex-m-quickstart` template is misused.
//!
//! ## Used the standard `main` interface
//!
//! Error message:
//!
//! ``` text
//! $ cargo build
//!    Compiling demo v0.1.0 (file:///home/japaric/tmp/demo)
//!
//! error: requires `start` lang_item
//! ```
//!
//! Solution: Use `#![no_main]` and `entry!` as shown in the [examples].
//!
//! ## Forgot to launch an OpenOCD instance
//!
//! Error message:
//!
//! ``` text
//! $ arm-none-eabi-gdb target/..
//! Reading symbols from hello...done.
//! .gdbinit:1: Error in sourced command file:
//! :3333: Connection timed out.
//! ```
//!
//! Solution: Launch OpenOCD on other terminal. See [Usage] section.
//!
//! [Usage]: ./index.html#usage
//!
//! ## Didn't modify the `memory.x` linker script
//!
//! Error message:
//!
//! ``` text
//! $ cargo build
//! Compiling demo v0.1.0 (file:///home/japaric/tmp/demo)
//! error: linking with `rust-lld` failed: exit code: 1
//! |
//! = note: "rust-lld" "-flavor" "gnu" "-L" (..)
//! (..)
//!  = note: rust-lld: error: section '.vector_table' will not fit in region 'FLASH': overflowed by X bytes
//!          rust-lld: error: section '.vector_table' will not fit in region 'FLASH': overflowed by Y bytes
//! (..)
//! ```
//!
//! Solution: Specify your device memory layout in the `memory.x` linker script. See [Usage]
//! section.
//!
//! ## Didn't set a default build target and forgot to pass `--target` to Cargo
//!
//! Error message:
//!
//! ``` text
//! $ cargo build
//! (..)
//! error: language item required, but not found: `eh_personality`
//!
//! error: aborting due to previous error
//! ```
//!
//! Solution: Set a default build target in the `.cargo/config` file (see [Usage] section), or call
//! Cargo with `--target` flag: `cargo build --target thumbv7em-none-eabi`.
//!
//! ## Overwrote the original `.cargo/config` file
//!
//! You won't get an error message but the output binary will be empty
//!
//! ``` text
//! $ cargo build && echo OK
//! OK
//!
//! $ size target/thumbv7m-none-eabi/debug/app
//!    text    data     bss     dec     hex filename
//!       0       0       0       0       0 target/thumbv7m-none-eabi/debug/app
//! ```
//!
//! Solution: You probably overwrote the original `.cargo/config` instead of appending the default
//! build target (e.g. `cat >` instead of `cat >>`). The less error prone way to fix this is to
//! remove the `.cargo` directory, clone a new copy of the template and then copy the `.cargo`
//! directory from that fresh template into your current project. Don't forget to *append* the
//! default build target to `.cargo/config`.
//!
//! ## Called OpenOCD with wrong arguments
//!
//! Error message:
//!
//! ``` text
//! $ openocd -f ..
//! (..)
//! Error: open failed
//! in procedure 'init'
//! in procedure 'ocd_bouncer'
//! ```
//!
//! Solution: Correct the OpenOCD arguments. Check the `/usr/share/openocd/scripts` directory (exact
//! location varies per distribution / OS) for a list of scripts that can be used.
//!
//! ## Forgot to install the `rust-std` component
//!
//! Error message:
//!
//! ``` text
//! $ cargo build
//! error[E0463]: can't find crate for `core`
//!   |
//!   = note: the `thumbv7m-none-eabi` target may not be installed
//! ```
//!
//! Solution: call `rustup target add thumbv7m-none-eabi` but with the name of your target
//!
//! ## Used an old nightly
//!
//! Error message:
//!
//! ``` text
//! $ cargo build
//! Compiling cortex-m-rt v0.2.0
//! error[E0463]: can't find crate for `core`
//! |
//! = note: the `thumbv7em-none-eabihf` target may not be installed
//!
//! error: aborting due to previous error
//! ```
//!
//! Solution: Use a more recent nightly
//!
//! ## Used the stable toolchain
//!
//! Error message:
//!
//! ``` text
//! $ cargo build
//! error[E0463]: can't find crate for `core`
//!   |
//!   = note: the `thumbv7em-none-eabihf` target may not be installed
//! ```
//!
//! Solution: We are not there yet! Switch to the nightly toolchain with `rustup default nightly`.
//!
//! ## Used `gdb` instead of `arm-none-eabi-gdb`
//!
//! Error message:
//!
//! ``` text
//! $ gdb target/..
//! Reading symbols from hello...done.
//! warning: Architecture rejected target-supplied description
//! warning: Cannot convert floating-point register value to ..
//! value has been optimized out
//! Cannot write the dashboard
//! Traceback (most recent call last):
//! File "<string>", line 353, in render
//! File "<string>", line 846, in lines
//! gdb.error: Frame is invalid.
//! 0x00000000 in ?? ()
//! semihosting is enabled
//! Loading section .text, size 0xd88 lma 0x8000000
//! Start address 0x8000000, load size 3464
//! .gdbinit:6: Error in sourced command file:
//! Remote connection closed
//! ```
//!
//! Solution: Use `arm-none-eabi-gdb target/..`
//!
//! # Used a named piped for `itm.fifo`
//!
//! Error message:
//!
//! ``` text
//! $ cargo run [--example ..]
//!
//! Reading symbols from target/thumbv7em-none-eabihf/debug/cortex-m-quickstart...done.
//! cortex_m_rt::reset_handler ()
//!     at $REGISTRY/cortex-m-rt-0.3.12/src/lib.rs:330
//! 330     unsafe extern "C" fn reset_handler() -> ! {
//! semihosting is enabled
//! Ignoring packet error, continuing...
//! Ignoring packet error, continuing...
//! ```
//!
//! Note that when you reach this point OpenOCD will become unresponsive and you'll have to kill it
//! and start a new OpenOCD process before you can invoke `cargo run` / start GDB.
//!
//! Cause: You uncommented the `monitor tpiu ..` line in `.gdbinit` and are using a named pipe to
//! receive the ITM data (i.e. you ran `mkfifo itm.fifo`). This error occurs when `itmdump -f
//! itm.fifo` (or equivalent, e.g. `cat itm.fifo`) is not running.
//!
//! Solution: Run `itmdump -f itm.fifo` (or equivalently `cat itm.fifo`) *before* invoking `cargo
//! run` / starting GDB. Note that sometimes `itmdump` will exit when the GDB session ends. In that
//! case you'll have to run `itmdump` before you start the next GDB session.
//!
//! Alternative solution: Use a plain text file instead of a named pipe. In this scenario you omit
//! the `mkfifo itm.dump` command. You can use `itmdump`'s *follow* mode (-F) to get named pipe like
//! output.

#![no_std]

pub mod examples;