From dda946d9336424bd6ce5a73afa4bfc55415b47d2 Mon Sep 17 00:00:00 2001
From: geeksville <kevinh@geeksville.com>
Date: Mon, 27 Apr 2020 08:45:39 -0700
Subject: [PATCH] Stream API coded but not tested

---
 src/mesh/StreamAPI.cpp | 68 ++++++++++++++++++++++++++++++++++++++++++
 src/mesh/StreamAPI.h   | 13 +++++++-
 2 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/src/mesh/StreamAPI.cpp b/src/mesh/StreamAPI.cpp
index f363a001b..ece4f4f81 100644
--- a/src/mesh/StreamAPI.cpp
+++ b/src/mesh/StreamAPI.cpp
@@ -1 +1,69 @@
 #include "StreamAPI.h"
+
+#define START1 0x94
+#define START2 0xc3
+#define HEADER_LEN 4
+
+void StreamAPI::loop()
+{
+    writeStream();
+    readStream();
+}
+
+/**
+ * Read any rx chars from the link and call handleToRadio
+ */
+void StreamAPI::readStream()
+{
+    while (stream->available()) { // Currently we never want to block
+        uint8_t c = stream->read();
+
+        // Use the read pointer for a little state machine, first look for framing, then length bytes, then payload
+        size_t ptr = rxPtr++; // assume we will probably advance the rxPtr
+
+        rxBuf[ptr] = c; // store all bytes (including framing)
+
+        if (ptr == 0) { // looking for START1
+            if (c != START1)
+                rxPtr = 0;     // failed to find framing
+        } else if (ptr == 1) { // looking for START2
+            if (c != START2)
+                rxPtr = 0;                             // failed to find framing
+        } else if (ptr >= HEADER_LEN) {                // we have at least read our 4 byte framing
+            uint16_t len = (rxBuf[2] << 8) + rxBuf[3]; // big endian 16 bit length follows framing
+
+            if (ptr == HEADER_LEN) {
+                // we _just_ finished our 4 byte header, validate length now (note: a length of zero is a valid
+                // protobuf also)
+                if (len > MAX_TO_FROM_RADIO_SIZE)
+                    rxPtr = 0; // length is bogus, restart search for framing
+            }
+
+            if (rxPtr != 0 && ptr == len + HEADER_LEN) {
+                // If we didn't just fail the packet and we now have the right # of bytes, parse it
+                handleToRadio(rxBuf + HEADER_LEN, len);
+            }
+        }
+    }
+}
+
+/**
+ * call getFromRadio() and deliver encapsulated packets to the Stream
+ */
+void StreamAPI::writeStream()
+{
+    uint32_t len;
+
+    do {
+        // Send every packet we can
+        len = getFromRadio(txBuf + HEADER_LEN);
+        if (len != 0) {
+            txBuf[0] = START1;
+            txBuf[1] = START2;
+            txBuf[2] = (len >> 8) & 0xff;
+            txBuf[3] = len & 0xff;
+
+            stream->write(txBuf, len + HEADER_LEN);
+        }
+    } while (len);
+}
\ No newline at end of file
diff --git a/src/mesh/StreamAPI.h b/src/mesh/StreamAPI.h
index 0b5cfe64f..4b85ac4ef 100644
--- a/src/mesh/StreamAPI.h
+++ b/src/mesh/StreamAPI.h
@@ -37,15 +37,26 @@ class StreamAPI : public PhoneAPI
     uint8_t rxBuf[MAX_STREAM_BUF_SIZE];
     size_t rxPtr = 0;
 
+    uint8_t txBuf[MAX_STREAM_BUF_SIZE];
+
   public:
     StreamAPI(Stream *_stream) : stream(_stream) {}
 
     /**
-     * Currently we require frequent invocation from loop() to check for arrived serial packets.
+     * Currently we require frequent invocation from loop() to check for arrived serial packets and to send new packets to the
+     * phone.
      * FIXME, to support better power behavior instead move to a thread and block on serial reads.
      */
     void loop();
 
   private:
+    /**
+     * Read any rx chars from the link and call handleToRadio
+     */
     void readStream();
+
+    /**
+     * call getFromRadio() and deliver encapsulated packets to the Stream
+     */
+    void writeStream();
 };
\ No newline at end of file