Add a demo for using LVGL, DRAM, LLVM Toolchain, ELF on an STM32F746G discovery board

[kubamracek]

See:

• https://github.com/apple/swift-embedded-examples/blob/8d60315e4b9b5cc32c9a7909d0301acf3fabc8e0/stm32-lvgl/README.md
• https://github.com/apple/swift-embedded-examples/blob/8d60315e4b9b5cc32c9a7909d0301acf3fabc8e0/stm32-lvgl/assets/video.mov

TODOs:

• Add a README.md
• Comment and explain the linker script and the way the relocation works
• Sink down the ELF section section symbol start/end extraction from the Makefile into elf2hex.py
• Add an entry with photo to the top-level README
• Add a CI preset
• Fix lint issues
• Add a SDL-based simulator

[kubamracek]

Phew, the CI finally passes

[rauhul]

we should make this part of matrix. instead of manually switching

[kubamracek]

How about like this? (I don't immediately have an idea how to avoid the ifs completely, we do need to run different commands per example.)

      - name: Set environment variables
        run: |
          echo "STM_BOARD=STM32F746G_DISCOVERY" >> $GITHUB_ENV

      - name: Build ${{ matrix.example }}
        working-directory: ${{ matrix.example }}
        run: |
          if [[ -f ./fetch-dependencies.sh ]]; then
            ./fetch-dependencies.sh
          fi

          if [[ -f ./build-elf.sh ]]; then
            ./build-elf.sh
          fi

          if [[ -f Makefile ]]; then
            make
          fi

[rauhul]

is this avoidable?

[kubamracek]

As in, the whole SwiftSDL2 dependency? I'm not sure what better alternative would there be -- the only that comes to mind seems worse: To write a custom SDL Swift wrapper + also custom multiplatform makefile build steps to build SDL from its C source...

[mkbrwr]

EDIT: fixed the problem
It's because it was dependent on compiler flag, that I've accidentally removed

Can't build the project. I get a lot of errors related to @Register macro repeated for each field

macro expansion @Register:143:30: error: property 'storage' is internal and cannot be referenced from an '@inlinable' function
`- /Users/mkbrwr/Developer/swift-embedded-examples/stm32-lvgl/Sources/Registers/FMC.swift:300:5: note: expanded code originates here
 269 |
 270 |     /// FIFO status and interrupt register
 271 |     @Register(bitWidth: 32)
     |     |- note: in expansion of macro 'Register' on struct 'SR' here
     |     `- note: in expansion of macro 'Register' on struct 'SR' here
 272 |     public struct SR {
 273 |         /// FEMPT
     :
 298 |         @ReadWrite(bits: 0..<1, as: IRSValues.self)
 299 |         public var irs: IRS
 300 |     }
     +--- macro expansion @Register ------------------------------------
     |120 | public struct Read: RegisterValueRead {
     |121 |   public typealias Value = SR
     |122 |   var storage: UInt32
     |    |       `- note: property 'storage' is not '@usableFromInline' or public
     |123 |   public init(_ value: Raw) {
     |124 |       self.storage = value.storage
     |    :
     |141 |   public var ifs: IFSValues {
     |142 |     @inlinable @inline(__always) get {
     |143 |       IFS.extract(from: self.storage)
     |    |                              `- error: property 'storage' is internal and cannot be referenced from an '@inlinable' function
     |144 |     }
     |145 |   }
     +------------------------------------------------------------------
 301 |
 302 |     /// Common memory space timing register

[kubamracek]

Can't build the project. I get a lot of errors related to @register macro repeated for each field

macro expansion @register:143:30: error: property 'storage' is internal and cannot be referenced from an '@inlinable' function
- /Users/mkbrwr/Developer/swift-embedded-examples/stm32-lvgl/Sources/Registers/FMC.swift:300:5: note: expanded code originates here 269 | 270 | /// FIFO status and interrupt register 271 | @Register(bitWidth: 32) | |- note: in expansion of macro 'Register' on struct 'SR' here | - note: in expansion of macro 'Register' on struct 'SR' here
272 | public struct SR {
273 | /// FEMPT
:
298 | @readwrite(bits: 0..<1, as: IRSValues.self)
299 | public var irs: IRS
300 | }
+--- macro expansion @register ------------------------------------
|120 | public struct Read: RegisterValueRead {
|121 | public typealias Value = SR
|122 | var storage: UInt32
| | - note: property 'storage' is not '@usableFromInline' or public |123 | public init(_ value: Raw) { |124 | self.storage = value.storage | : |141 | public var ifs: IFSValues { |142 | @inlinable @inline(__always) get { |143 | IFS.extract(from: self.storage) | | - error: property 'storage' is internal and cannot be referenced from an '@inlinable' function
|144 | }
|145 | }
+------------------------------------------------------------------
301 |
302 | /// Common memory space timing register

This has been recently fixed in swift-mmio. You might need to wipe Package.resolved to get a new "main" checkout.

[kubamracek]

Thanks everyone for reviews and feedback!