From b2286aecf5b88756a63923c02e91c5508e9e234a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?D=C3=A1niel=20Buga?= <bugadani@gmail.com>
Date: Wed, 29 Dec 2021 11:31:54 +0100
Subject: [PATCH 1/3] Buffer partially read responses

---
 espflash/src/connection.rs | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/espflash/src/connection.rs b/espflash/src/connection.rs
index 81d00f28..4ca02100 100644
--- a/espflash/src/connection.rs
+++ b/espflash/src/connection.rs
@@ -1,4 +1,5 @@
 use std::{
+    collections::VecDeque,
     io::{BufWriter, Write},
     thread::sleep,
     time::Duration,
@@ -28,6 +29,7 @@ pub struct CommandResponse {
 pub struct Connection {
     serial: Box<dyn SerialPort>,
     decoder: SlipDecoder,
+    buffer: VecDeque<u8>,
 }
 
 #[derive(Zeroable, Pod, Copy, Clone, Debug)]
@@ -44,6 +46,7 @@ impl Connection {
         Connection {
             serial,
             decoder: SlipDecoder::new(),
+            buffer: VecDeque::with_capacity(128),
         }
     }
 
@@ -105,11 +108,18 @@ impl Connection {
     }
 
     pub fn read_response(&mut self) -> Result<Option<CommandResponse>, Error> {
-        let response = self.read()?;
-        if response.len() < 10 {
+        const RESPONSE_LEN: usize = std::mem::size_of::<CommandResponse>();
+
+        let mut response = self.read()?;
+        self.buffer.extend(&response);
+        if self.buffer.len() < RESPONSE_LEN {
             return Ok(None);
         }
 
+        // reuse response alloc
+        response.clear();
+        response.extend(self.buffer.drain(0..RESPONSE_LEN));
+
         let mut cursor = Cursor::new(response);
         let header = cursor.read_le()?;
 

From 43aec09d467a0b447c5c9cf3e9f303222014acd5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?D=C3=A1niel=20Buga?= <bugadani@gmail.com>
Date: Wed, 29 Dec 2021 11:41:05 +0100
Subject: [PATCH 2/3] Buffer in the read method

---
 espflash/src/connection.rs | 39 +++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 17 deletions(-)

diff --git a/espflash/src/connection.rs b/espflash/src/connection.rs
index 4ca02100..6b937ce3 100644
--- a/espflash/src/connection.rs
+++ b/espflash/src/connection.rs
@@ -108,25 +108,19 @@ impl Connection {
     }
 
     pub fn read_response(&mut self) -> Result<Option<CommandResponse>, Error> {
-        const RESPONSE_LEN: usize = std::mem::size_of::<CommandResponse>();
-
-        let mut response = self.read()?;
-        self.buffer.extend(&response);
-        if self.buffer.len() < RESPONSE_LEN {
-            return Ok(None);
+        match self.read(10)? {
+            None => return Ok(None),
+            Some(response) => {
+                let mut cursor = Cursor::new(response);
+                let header = cursor.read_le()?;
+                Ok(Some(header))
+            }
         }
-
-        // reuse response alloc
-        response.clear();
-        response.extend(self.buffer.drain(0..RESPONSE_LEN));
-
-        let mut cursor = Cursor::new(response);
-        let header = cursor.read_le()?;
-
-        Ok(Some(header))
     }
 
     pub fn write_command(&mut self, command: Command) -> Result<(), Error> {
+        self.buffer.clear();
+        self.serial.clear(serialport::ClearBuffer::Input)?;
         let mut writer = BufWriter::new(&mut self.serial);
         let mut encoder = SlipEncoder::new(&mut writer)?;
         command.write(&mut encoder)?;
@@ -177,13 +171,24 @@ impl Connection {
         Ok(())
     }
 
-    fn read(&mut self) -> Result<Vec<u8>, Error> {
+    fn read(&mut self, len: usize) -> Result<Option<Vec<u8>>, Error> {
         let mut output = Vec::with_capacity(1024);
         self.decoder.decode(&mut self.serial, &mut output)?;
-        Ok(output)
+
+        self.buffer.extend(&output);
+        if self.buffer.len() < len {
+            return Ok(None);
+        }
+
+        // reuse allocation
+        output.clear();
+        output.extend(self.buffer.drain(..));
+
+        Ok(Some(output))
     }
 
     pub fn flush(&mut self) -> Result<(), Error> {
+        self.buffer.clear();
         self.serial.flush()?;
         Ok(())
     }

From b51d8a73ebbf3ca4b0a5a01975afa13cd1814a5f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?D=C3=A1niel=20Buga?= <bugadani@gmail.com>
Date: Mon, 17 Jan 2022 17:36:21 +0100
Subject: [PATCH 3/3] Pacify clippy

---
 espflash/src/connection.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/espflash/src/connection.rs b/espflash/src/connection.rs
index 6b937ce3..c6b52bc6 100644
--- a/espflash/src/connection.rs
+++ b/espflash/src/connection.rs
@@ -109,7 +109,7 @@ impl Connection {
 
     pub fn read_response(&mut self) -> Result<Option<CommandResponse>, Error> {
         match self.read(10)? {
-            None => return Ok(None),
+            None => Ok(None),
             Some(response) => {
                 let mut cursor = Cursor::new(response);
                 let header = cursor.read_le()?;