I am in the process of implementing an SPI driver. Now I have the following driver code (MRE-ified): use tokio::{join, sync::mpsc}; async fn spi_transmit(write_buf: &[u32], read_buf: &mut [u32]) { assert_eq!(read_buf.len(), write_buf.len()); let (write_fifo, mut read_fifo) = mpsc::channel(2); let write_task = async { // Simulate an SPI bus that respondes with the sent data + 20,… Read More Is the pure existance of a `&[u32]` and `&mut [u32]` to the same data already considered undefined behaviour?

I have a sequence of tuples where each tuple contains another sequences. To better illustrate the problem, please have a look at the below snippet (Rust Playground): fn main() { let data = [ (vec![1, 2, 3], vec![‘a’]), (vec![4, 5, 6], vec![‘b’, ‘c’]) ]; let res: (Vec<i32>, Vec<char>) = data…? // res = (vec![1, 2,… Read More How to join a sequence of tuples, each with its own sequence?

I want this function to operate the register with the specified name, but it seems that the asm! macro does not support it? pub fn read_cpuid(reg: &str) -> u64 { let val: u64; unsafe { asm!("mrs {}, {}", out(reg) val, reg ); } val } The error message is as follows： error: expected one of… Read More How to pass in &str when using rust asm! inline assembly

I developed a fairly long build script. Now I need to add a set of unit tests to build.rs file. I tried to do the same as I do for regular files: // build.rs #[cfg(test)] mod tests { #[test] fn test1() { //… } } but seems it didn’t work. Running tests doesn’t result in… Read More Is it possible to write unit tests for rust build scripts?

If you have the following struct of booleans, Rust Analyzer says it takes up 3 bytes because there’s three fields. struct Mask { field_1: bool, field_2: bool, field_3: bool, } // size = 3, align = 1 Why doesn’t the compiler optimize this to a 1-byte bitmask? How can I make the struct a true… Read More Structs of booleans as a 1-byte bitmask

In this code snippet I declared the variable max as mut, but rust-analyer told me that it is not necessary. I removed the mut and the code still works and runs. Why is that? I am reassigning the value for max in the match statement. fn validate_in_range_u32(value:u32, min:u32, max:u32) -> bool { if value <… Read More Why doesn't this variable need to be mutable?

I am trying to deserialize a json but i am unable to get the expected result. Below is my code: use serde::{Serialize, Deserialize}; #[derive(Debug, Clone, Serialize, Deserialize)] struct StudentData{ stu1: TestResult, stu2: TestResult, stu3: TestResult, } #[derive(Debug, Clone, Serialize, Deserialize)] #[serde(untagged)] enum TestResult{ #[serde(rename = "fail")] Fail, #[serde(rename = "absent")] Absent, Pass(String) } fn main()… Read More Deserialize json into enum

I need to send an array of images to an API using form-data, so I’m using a loop to add the images, but I’m getting an error. fn main() { let json = r#"{ "imgupload": ["/home/user/Pictures/image01.jpg", "/home/user/Pictures/image02.jpg"] }"# .to_string(); let request = serde_json::from_str::<ProductRequest>(json.as_str()).unwrap(); let mut form = reqwest::blocking::multipart::Form::new(); let array = request.imgupload.unwrap(); for file_path in… Read More Rust – Add array in reqwest::blocking::multipart::Part

I am trying to create a method that takes the input from stdin. It should loop until the input is a valid integer that I can parse to an integer. The error I am getting is this: error[E0282]: type annotations needed for `Result<F, _>` –> src/lib.rs:9:13 | 9 | let parsed_int_result = line.trim().parse(); // Getting… Read More Variable needs explicit type from parse()

Could somebody explain, why if I remove the "move" from for_each, the program hangs? use std::sync::mpsc::channel; fn main() { let v = vec![0,1,2,3,4,5,6,7,8,9]; let (tx, rx) = channel(); v.iter().for_each(move |&elem| { tx.send(elem).unwrap(); }); println!("Tx’ed"); let rx_vec: Vec<_> = rx.iter().collect(); println!("Collected into vec"); } >Solution : The code hangs without move because in that variant tx… Read More Program hangs on channel rx