From cd81878e92ecdc6cc3746f2d007a4f4eebf08a2d Mon Sep 17 00:00:00 2001
From: Scott Powell <sqij@protonmail.com>
Date: Tue, 28 Jan 2025 23:26:55 +1100
Subject: * added helpers/ArduinoSerialInterface, for the 'companion radio' *
 .ini, target envs: Heltec_v3_companion_radio_usb & 
 Heltec_v3_companion_radio_ble

---
 src/helpers/ArduinoSerialInterface.cpp | 66 ++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 src/helpers/ArduinoSerialInterface.cpp

(limited to 'src/helpers/ArduinoSerialInterface.cpp')

diff --git a/src/helpers/ArduinoSerialInterface.cpp b/src/helpers/ArduinoSerialInterface.cpp
new file mode 100644
index 00000000..ac0bf848
--- /dev/null
+++ b/src/helpers/ArduinoSerialInterface.cpp
@@ -0,0 +1,66 @@
+#include "ArduinoSerialInterface.h"
+
+#define RECV_STATE_IDLE       0
+#define RECV_STATE_HDR_FOUND  1
+#define RECV_STATE_LEN_FOUND  2
+
+void ArduinoSerialInterface::enable() { 
+  _isEnabled = true;
+  _state = RECV_STATE_IDLE;
+}
+void ArduinoSerialInterface::disable() {
+  _isEnabled = false;
+}
+
+bool ArduinoSerialInterface::isConnected() const { 
+  return true;   // no way of knowing, so assume yes
+}
+
+bool ArduinoSerialInterface::isWriteBusy() const {
+  return false;
+}
+
+size_t ArduinoSerialInterface::writeFrame(const uint8_t src[], size_t len) {
+  if (len > MAX_FRAME_SIZE) {
+    // frame is too big!
+    return 0;
+  }
+
+  uint8_t hdr[2];
+  hdr[0] = '>';
+  hdr[1] = len;
+  _serial->write(hdr, 2);
+  return _serial->write(src, len);
+}
+
+size_t ArduinoSerialInterface::checkRecvFrame(uint8_t dest[]) {
+  while (_serial->available()) {
+    int c = _serial->read();
+    if (c < 0) break;
+
+    switch (_state) {
+      case RECV_STATE_IDLE:
+        if (c == '<') {
+          _state = RECV_STATE_HDR_FOUND;
+        }
+        break;
+      case RECV_STATE_HDR_FOUND:
+        _frame_len = (uint8_t)c;
+        rx_len = 0;
+        _state = _frame_len > 0 ? RECV_STATE_LEN_FOUND : RECV_STATE_IDLE;
+        break;
+      default:
+        if (rx_len < MAX_FRAME_SIZE) {
+          rx_buf[rx_len] = (uint8_t)c;   // rest of frame will be discarded if > MAX
+        }
+        rx_len++;
+        if (rx_len >= _frame_len) {  // received a complete frame?
+          if (_frame_len > MAX_FRAME_SIZE) _frame_len = MAX_FRAME_SIZE;    // truncate
+          memcpy(dest, rx_buf, _frame_len);
+          _state = RECV_STATE_IDLE;  // reset state, for next frame
+          return _frame_len;
+        }
+    }
+  }
+  return 0;
+}
-- 
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