From d4c0853e1f8c2f00274ef50dbb63053a2fb2e1aa Mon Sep 17 00:00:00 2001
From: David Given <dg@cowlark.com>
Date: Thu, 25 May 2023 22:23:28 +0200
Subject: [PATCH] Reset the Greaseweazle data stream when connecting.

---
 lib/usb/greaseweazleusb.cc | 16 ++++++++++++----
 lib/usb/serial.cc          | 19 +++++++++++++++++++
 lib/usb/serial.h           |  1 +
 3 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/lib/usb/greaseweazleusb.cc b/lib/usb/greaseweazleusb.cc
index 59a6a76f..7c091316 100644
--- a/lib/usb/greaseweazleusb.cc
+++ b/lib/usb/greaseweazleusb.cc
@@ -1,11 +1,12 @@
-#include "globals.h"
-#include "usb.h"
+#include "lib/globals.h"
 #include "protocol.h"
-#include "fluxmap.h"
-#include "bytes.h"
+#include "lib/fluxmap.h"
+#include "lib/bytes.h"
 #include "lib/usb/usb.pb.h"
 #include "greaseweazle.h"
 #include "serial.h"
+#include "usb.h"
+#include <unistd.h>
 
 static const char* gw_error(int e)
 {
@@ -96,6 +97,13 @@ public:
                 version);
         }
 
+        /* Twiddle the baud rate, which indicates to the Greaseweazle that the
+         * data stream has been reset. */
+
+        _serial->setBaudRate(10000);
+        usleep(100000);
+        _serial->setBaudRate(9600);
+
         /* Configure the hardware. */
 
         do_command({CMD_SET_BUS_TYPE, 3, (uint8_t)config.bus_type()});
diff --git a/lib/usb/serial.cc b/lib/usb/serial.cc
index 7fa0bf37..2e22b0f0 100644
--- a/lib/usb/serial.cc
+++ b/lib/usb/serial.cc
@@ -88,6 +88,17 @@ public:
         return wlen;
     }
 
+    void setBaudRate(int baudRate) override
+    {
+        DCB dcb = {.DCBlength = sizeof(DCB),
+            .BaudRate = baudRate,
+            .fBinary = true,
+            .ByteSize = 8,
+            .Parity = NOPARITY,
+            .StopBits = ONESTOPBIT};
+        SetCommState(_handle, &dcb);
+    }
+
 private:
     static std::string get_last_error_string()
     {
@@ -181,6 +192,14 @@ public:
         return wlen;
     }
 
+    void setBaudRate(int baudRate) override
+    {
+        struct termios t;
+        tcgetattr(_fd, &t);
+        cfsetspeed(&t, baudRate);
+        tcsetattr(_fd, TCSANOW, &t);
+    }
+
 private:
     int _fd;
 };
diff --git a/lib/usb/serial.h b/lib/usb/serial.h
index 15e1d8e9..c629c080 100644
--- a/lib/usb/serial.h
+++ b/lib/usb/serial.h
@@ -10,6 +10,7 @@ public:
     virtual ~SerialPort();
     virtual ssize_t readImpl(uint8_t* buffer, size_t len) = 0;
     virtual ssize_t write(const uint8_t* buffer, size_t len) = 0;
+    virtual void setBaudRate(int baudRate) = 0;
 
     void read(uint8_t* buffer, size_t len);
     void read(Bytes& bytes);