What is Rust? Rust is a language that empowers everyone to build reliable and efficient software. It features: Amazing fast speed and high memory utilization High Performance: Memory errors are able to be eliminated during compilation Reliability: Great documentation, a friendly compiler with useful error messages, and top-notch tooling — an integrated package manager and build tool, smart multi-editor support with auto-completion and type inspections, an auto-formatter, and more. Productivity: Why use RUST on Embedded Development? Rust is designed to guarantee both security and high performance. The design philosophy is right into what embedded development requires. While embedded software has running problems that are mostly due to its memory. The Rust language can be regarded as a compiler-oriented language, so you can be sure that you are using memory safely while compiling. Here are some of the benefits of Rust developing on embedded devices: Powerful static analysis Flexible memory Fearless concurrency Interoperability Portability Community driven Now, let’s get it on the Open Source RT-Thread operating system to demonstrate how rust can be used for embedded development. When we’re calling the Rust code in C code, requires us to package the Rust source code as a static library file. When the C code compiles, link it in. Call Rust in C Create lib Library 1. Use to build a lib library in Clion. Add the following code to the . The following function evaluates the sum of two values of type i32 and returns the result: cargo init --lib rust_to_c lib.rs #![no_std]
use core::panic::PanicInfo;
#[no_mangle]
pub extern "C" fn sum(a: i32, b: i32) -> i32 {
    a + b
}
#[panic_handler]
fn panic(_info:&PanicInfo) -> !{
    loop{}
} 2.Add the following code to the Cargo.toml file to tell Rustc what type of library to generate. [lib]
name = "sum"
crate-type = ["staticlib"]
path = "src/lib.rs" Cross-compilation 1.Install armv7 target: rustup target add armv7a-none-eabi 2.Generate static library file: PS C:\Users\LiuKang\Desktop\RUST\rust_to_c> cargo build --target=armv7a-none-eabi --release --verbose
          Fresh rust_to_c v0.1.0 (C:\Users\LiuKang\Desktop\RUST\rust_to_c)
       Finished release [optimized] target(s) in 0.01s Generate Header File 1.Install cbindgen, cbindgen generates C/C++11 header file from the rust library: cargo install --force cbindgen 2.Create a new file under the project folder: cbindgen.toml 3.Generate header file: cbindgen --config cbindgen.toml --crate rust_to_c --output sum.h Call Rust Library File 1.Put the generated and files into the directory sum.h sum.a rt-thread\bsp\qemu-vexpress-a9\applications 2.Modify the SConscript file and add static library: from building import *
   cwd     = GetCurrentDir()
   src     = Glob('*.c') + Glob('*.cpp')
   CPPPATH = [cwd]
   LIBS = ["libsum.a"]
   LIBPATH = [GetCurrentDir()]
   group = DefineGroup('Applications', src, depend = [''], CPPPATH = CPPPATH, LIBS = LIBS, LIBPATH = LIBPATH)
   Return('group') 3.Call the sum function in the main function and get the return value and printf the value. #include <stdint.h>
   #include <stdio.h>
   #include <stdlib.h>
   #include <rtthread.h>
   #include "sum.h"
   int main(void)
   {
       int32_t tmp;
       tmp = sum(1, 2);
       printf("call rust sum(1, 2) = %d\n", tmp);
       return 0;
   } environment, use scons to compile the project and run: 4.In RT-Thread Env LiuKang@DESKTOP-538H6DE D:\repo\github\rt-thread\bsp\qemu-vexpress-a9
      $ scons -j6
      scons: Reading SConscript files ...
      scons: done reading SConscript files.
      scons: warning: you do not seem to have the pywin32 extensions installed;
      parallel (-j) builds may not work reliably with open Python files.
      File "D:\software\env_released_1.2.0\env\tools\Python27\Scripts\scons.py", line 204, in <module>
      scons: Building targets ...
      scons: building associated VariantDir targets: build
      LINK rtthread.elf
      arm-none-eabi-objcopy -O binary rtthread.elf rtthread.bin
      arm-none-eabi-size rtthread.elf
     text    data     bss     dec     hex filename
   628220    2148   86700  717068   af10c rtthread.elf
      scons: done building targets.
      LiuKang@DESKTOP-538H6DE D:\repo\github\rt-thread\bsp\qemu-vexpress-a9
      $ qemu.bat
      WARNING: Image format was not specified for 'sd.bin' and probing guessed raw.
   Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
   Specify the 'raw' format explicitly to remove the restrictions.
   \ | /
      - RT -     Thread Operating System
   / | \     4.0.4 build Jul 28 2021
   2006 - 2021 Copyright by rt-thread team
      lwIP-2.1.2 initialized!
      [I/sal.skt] Socket Abstraction Layer initialize success.
      [I/SDIO] SD card capacity 65536 KB.
      [I/SDIO] switching card to high speed failed!
      call rust sum(1, 2) = 3
      msh /> Add, subtract, multiply and divide 1.We can implement some complicated math in rust. In the file, use the rust language to implement add, subtract, multiply and divide: lib.rs #![no_std]
     use core::panic::PanicInfo;
     #[no_mangle]
     pub extern "C" fn add(a: i32, b: i32) -> i32 {
         a + b
     }
     #[no_mangle]
     pub extern "C" fn subtract(a: i32, b: i32) -> i32 {
         a - b
     }
     #[no_mangle]
     pub extern "C" fn multiply(a: i32, b: i32) -> i32 {
         a * b
     }
     #[no_mangle]
     pub extern "C" fn divide(a: i32, b: i32) -> i32 {
         a / b
     }
     #[panic_handler]
     fn panic(_info:&PanicInfo) -> !{
         loop{}
     } 2.Build library files and header files and place them in the application directory 3.Use scons to compile, if errors jumped on link up, find the solution on its official Github. LINK rtthread.elf
      d:/software/env_released_1.2.0/env/tools/gnu_gcc/arm_gcc/mingw/bin/../lib/gcc/arm-none-eabi/5.4.1/armv7-ar/thumb\libgcc.a(_arm_addsubdf3.o): In function `__aeabi_ul2d':
      (.text+0x304): multiple definition of `__aeabi_ul2d'
      applications\libsum.a(compiler_builtins-9b744f6fddf5e719.compiler_builtins.20m0qzjq-cgu.117.rcgu.o):/cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.35/src/float/conv.rs:143: first defined here
      collect2.exe: error: ld returned 1 exit status
      scons: *** [rtthread.elf] Error 1
      scons: building terminated because of errors. 4.Modify file, add the link parameter : rtconfig.py --allow-multiple-definition DEVICE = ' -march=armv7-a -marm -msoft-float'
       CFLAGS = DEVICE + ' -Wall'
       AFLAGS = ' -c' + DEVICE + ' -x assembler-with-cpp -D__ASSEMBLY__ -I.'
       LINK_SCRIPT = 'link.lds'
       LFLAGS = DEVICE + ' -nostartfiles -Wl,--gc-sections,-Map=rtthread.map,-cref,-u,system_vectors,--allow-multiple-definition'+\
                         ' -T %s' % LINK_SCRIPT
       CPATH = ''
       LPATH = '' 5.Compile and run QEMU: LiuKang@DESKTOP-538H6DE D:\repo\github\rt-thread\bsp\qemu-vexpress-a9
      $ scons -j6
      scons: Reading SConscript files ...
      scons: done reading SConscript files.
      scons: warning: you do not seem to have the pywin32 extensions installed;
      parallel (-j) builds may not work reliably with open Python files.
      File "D:\software\env_released_1.2.0\env\tools\Python27\Scripts\scons.py", line 204, in <module>
      scons: Building targets ...
      scons: building associated VariantDir targets: build
      LINK rtthread.elf
      arm-none-eabi-objcopy -O binary rtthread.elf rtthread.bin
      arm-none-eabi-size rtthread.elf
     text    data     bss     dec     hex filename
   628756    2148   86700  717604   af324 rtthread.elf
      scons: done building targets.
      LiuKang@DESKTOP-538H6DE D:\repo\github\rt-thread\bsp\qemu-vexpress-a9
      $ qemu.bat
      WARNING: Image format was not specified for 'sd.bin' and probing guessed raw.
       Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
       Specify the 'raw' format explicitly to remove the restrictions.
   \ | /
      - RT -     Thread Operating System
   / | \     4.0.4 build Jul 28 2021
   2006 - 2021 Copyright by rt-thread team
      lwIP-2.1.2 initialized!
      [I/sal.skt] Socket Abstraction Layer initialize success.
      [I/SDIO] SD card capacity 65536 KB.
      [I/SDIO] switching card to high speed failed!
      call rust sum(1, 2) = 3
      call rust subtract(2, 1) = 1
      call rust multiply(2, 2) = 4
      call rust divide(4, 2) = 2 Call C in Rust Great to know that Rust can be called in C code, let’s give a try to call the rt_kprintf function in Rust: Modify the file lib.rs // The imported rt-thread functions list
    extern "C" {
        pub fn rt_kprintf(format: *const u8, ...);
    }
    #[no_mangle]
    pub extern "C" fn add(a: i32, b: i32) -> i32 {
        unsafe {
            rt_kprintf(b"this is from rust\n" as *const u8);
        }
        a + b
    } Generate Library File cargo build --target=armv7a-none-eabi --release --verbose
       Compiling rust_to_c v0.1.0 (C:\Users\LiuKang\Desktop\RUST\rust_to_c)
         Running `rustc --crate-name sum --edition=2018 src/lib.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type staticlib --emit=dep-info,link -C opt-level=3 -C embed-bitcode=no -C metadata=a
    0723fa112c78339 -C extra-filename=-a0723fa112c78339 --out-dir C:\Users\LiuKang\Desktop\RUST\rust_to_c\target\armv7a-none-eabi\release\deps --target armv7a-none-eabi -L dependency=C:\Users\LiuKang\Desktop\RUS
    T\rust_to_c\target\armv7a-none-eabi\release\deps -L dependency=C:\Users\LiuKang\Desktop\RUST\rust_to_c\target\release\deps`
        Finished release [optimized] target(s) in 0.11s Copy the library files generated by rust into the application directory. Run LiuKang@DESKTOP-538H6DE D:\repo\github\rt-thread\bsp\qemu-vexpress-a9                                                       
    $ scons -j6                                                                                                             
    scons: Reading SConscript files ...                                                                                  
    scons: done reading SConscript files.                                                                                                     
    scons: warning: you do not seem to have the pywin32 extensions installed;                                                   
            parallel (-j) builds may not work reliably with open Python files.                                                  
    File "D:\software\env_released_1.2.0\env\tools\Python27\Scripts\scons.py", line 204, in <module>                            
    scons: Building targets ...                                                                                                 
    scons: building associated VariantDir targets: build                                                                        
    LINK rtthread.elf                                                                                                           
    arm-none-eabi-objcopy -O binary rtthread.elf rtthread.bin                                                                   
    arm-none-eabi-size rtthread.elf                                                                                             
       text    data     bss     dec     hex filename                                                                            
     628812    2148   90796  721756   b035c rtthread.elf                                                                        
    scons: done building targets.                                                                                               
    LiuKang@DESKTOP-538H6DE D:\repo\github\rt-thread\bsp\qemu-vexpress-a9                                                       
    $ qemu.bat                                                                                                                  
    WARNING: Image format was not specified for 'sd.bin' and probing guessed raw.                                               
             Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.    
             Specify the 'raw' format explicitly to remove the restrictions.                                                    
     \ | /                                                                                                                      
    - RT -     Thread Operating System                                                                                          
     / | \     4.0.4 build Jul 28 2021                                                                                          
     2006 - 2021 Copyright by rt-thread team                                                                                    
    lwIP-2.1.2 initialized!                                                                                                     
    [I/sal.skt] Socket Abstraction Layer initialize success.                                                                    
    [I/SDIO] SD card capacity 65536 KB.                                                                                         
    [I/SDIO] switching card to high speed failed!                                                                               
    this is from rust                                                                                                           
    call rust sum(1, 2) = 3                                                                                           
    call rust subtract(2, 1) = 1                                                                                                
    call rust multiply(2, 2) = 4                                                                                                
    call rust divide(4, 2) = 2                                                                                     
    msh /> As the time for approaches, we're happy to attach more details to this conference so you'll know what to expect. The virtual conference will feature 20+ trending topics, range from the latest developments in open-source RT-Thread IoT OS projects to new fields of activities. Let’s explore this New IoT World together! RT-Thread IoT OS Global Tech Conference Free Registration: https://forms.gle/8W1j2ZhCSLKFfyFQ8 View the full Agenda: https://www.rt-thread.io/announcement.html

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