config: switch to postcard encoding

Cargo.lock

@@ -174,10 +174,26 @@ dependencies = [
 ]
 
 [[package]]
-name = "half"
-version = "1.6.0"
+name = "hash32"
+version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d36fab90f82edc3c747f9d438e06cf0a491055896f2a279638bb5beed6c40177"
+checksum = "d4041af86e63ac4298ce40e5cca669066e75b6f1aa3390fe2561ffa5e1d9f4cc"
+dependencies = [
+ "byteorder",
+]
+
+[[package]]
+name = "heapless"
+version = "0.5.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "74911a68a1658cfcfb61bc0ccfbd536e3b6e906f8c2f7883ee50157e3e2184f1"
+dependencies = [
+ "as-slice",
+ "generic-array 0.13.2",
+ "hash32",
+ "serde",
+ "stable_deref_trait",
+]
 
 [[package]]
 name = "libm"
@@ -257,6 +273,23 @@ dependencies = [
  "cortex-m-semihosting",
 ]
 
+[[package]]
+name = "postcard"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b3e3f5c2e9a91383c6594ec68aa2dfdfe19a3c86f34b088ba7203f2483d2682f"
+dependencies = [
+ "heapless",
+ "postcard-cobs",
+ "serde",
+]
+
+[[package]]
+name = "postcard-cobs"
+version = "0.1.5-pre"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7c68cb38ed13fd7bc9dd5db8f165b7c8d9c1a315104083a2b10f11354c2af97f"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.20"
@@ -320,16 +353,6 @@ dependencies = [
  "serde_derive",
 ]
 
-[[package]]
-name = "serde_cbor"
-version = "0.11.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e18acfa2f90e8b735b2836ab8d538de304cbb6729a7360729ea5a895d15a622"
-dependencies = [
- "half",
- "serde",
-]
-
 [[package]]
 name = "serde_derive"
 version = "1.0.116"
@@ -440,8 +463,8 @@ dependencies = [
  "num-traits",
  "panic-abort",
  "panic-semihosting",
+ "postcard",
  "serde",
- "serde_cbor",
  "smoltcp",
  "stm32-eth",
  "stm32f4xx-hal",

Cargo.toml

@@ -34,7 +34,7 @@ nb = "0.1"
 uom = { version = "0.29", default-features = false, features = ["autoconvert", "si", "f64", "use_serde"] }
 eeprom24x = "0.3"
 serde = { version = "1.0", default-features = false, features = ["derive"] }
-serde_cbor = { version = "0.11.1", default-features = false }
+postcard = "0.5.1"
 
 [patch.crates-io]
 stm32f4xx-hal = { git = "https://github.com/stm32-rs/stm32f4xx-hal.git" }

src/config.rs

@@ -1,6 +1,5 @@
 use serde::{Serialize, Deserialize};
-use serde_cbor::Serializer;
-use serde_cbor::ser::SliceWrite;
+use postcard::to_slice;
 use crate::{
     channel_state::ChannelState,
     channels::{CHANNELS, Channels},
@@ -25,13 +24,12 @@ impl Config {
         }
     }
 
-    pub fn encode(&self, buffer: &mut [u8]) -> Result<usize, serde_cbor::Error> {
-        let writer = SliceWrite::new(buffer);
-        let mut ser = Serializer::new(writer);
-        self.serialize(&mut ser)?;
-        let writer = ser.into_inner();
-        let size = writer.bytes_written();
-        Ok(size)
+    pub fn encode<'a>(&self, buffer: &'a mut [u8]) -> Result<&'a mut [u8], postcard::Error> {
+        to_slice(self, buffer)
+    }
+
+    pub fn decode(buffer: &[u8]) -> Result<Self, postcard::Error> {
+        from_bytes(buffer)
     }
 }
 

src/main.rs

@@ -432,10 +432,10 @@ fn main() -> ! {
                                 Command::Load => {}
                                 Command::Save => {
                                     let config = Config::new(&mut channels);
-                                    let mut buf = [0; 0x200];
+                                    let mut buf = [0; 128];
                                     match config.encode(&mut buf) {
-                                        Ok(len) => {
-                                            let _ = writeln!(socket, "Encoded: {:?}", &buf[..len]);
+                                        Ok(buf) => {
+                                            let _ = writeln!(socket, "Encoded {}: {:?}", buf.len(), buf);
                                         }
                                         Err(e) => {
                                             let _ = writeln!(socket, "Error encoding configuration: {}", e);