From a93fc844d9ff58d26c1bbd93cf3b799b57cd13ee Mon Sep 17 00:00:00 2001
From: Atomie CHEN <atomic_cwh@163.com>
Date: Fri, 11 Jun 2021 05:57:40 +0800
Subject: [PATCH] Solve issue Custom Baudrate OSX #139 of original repo;
 inspired by PySerial source code and #57 of github.com/npat-efault/picocom,
 we need to set custom baudrate after calling tcsetattr; tested on macOS
 Mojave 10.14.4 (#218)

---
 src/impl/unix.cc | 65 ++++++++++++++++++++++++++----------------------
 1 file changed, 35 insertions(+), 30 deletions(-)

diff --git a/src/impl/unix.cc b/src/impl/unix.cc
index 4309aa6..b656a56 100755
--- a/src/impl/unix.cc
+++ b/src/impl/unix.cc
@@ -304,36 +304,6 @@ Serial::SerialImpl::reconfigurePort ()
 #endif
   default:
     custom_baud = true;
-    // OS X support
-#if defined(MAC_OS_X_VERSION_10_4) && (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_4)
-    // Starting with Tiger, the IOSSIOSPEED ioctl can be used to set arbitrary baud rates
-    // other than those specified by POSIX. The driver for the underlying serial hardware
-    // ultimately determines which baud rates can be used. This ioctl sets both the input
-    // and output speed.
-    speed_t new_baud = static_cast<speed_t> (baudrate_);
-    if (-1 == ioctl (fd_, IOSSIOSPEED, &new_baud, 1)) {
-      THROW (IOException, errno);
-    }
-    // Linux Support
-#elif defined(__linux__) && defined (TIOCSSERIAL)
-    struct serial_struct ser;
-
-    if (-1 == ioctl (fd_, TIOCGSERIAL, &ser)) {
-      THROW (IOException, errno);
-    }
-
-    // set custom divisor
-    ser.custom_divisor = ser.baud_base / static_cast<int> (baudrate_);
-    // update flags
-    ser.flags &= ~ASYNC_SPD_MASK;
-    ser.flags |= ASYNC_SPD_CUST;
-
-    if (-1 == ioctl (fd_, TIOCSSERIAL, &ser)) {
-      THROW (IOException, errno);
-    }
-#else
-    throw invalid_argument ("OS does not currently support custom bauds");
-#endif
   }
   if (custom_baud == false) {
 #ifdef _BSD_SOURCE
@@ -443,6 +413,41 @@ Serial::SerialImpl::reconfigurePort ()
   // activate settings
   ::tcsetattr (fd_, TCSANOW, &options);
 
+  // apply custom baud rate, if any
+  if (custom_baud == true) {
+    // OS X support
+#if defined(MAC_OS_X_VERSION_10_4) && (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_4)
+    // Starting with Tiger, the IOSSIOSPEED ioctl can be used to set arbitrary baud rates
+    // other than those specified by POSIX. The driver for the underlying serial hardware
+    // ultimately determines which baud rates can be used. This ioctl sets both the input
+    // and output speed.
+    speed_t new_baud = static_cast<speed_t> (baudrate_);
+    // PySerial uses IOSSIOSPEED=0x80045402
+    if (-1 == ioctl (fd_, IOSSIOSPEED, &new_baud, 1)) {
+      THROW (IOException, errno);
+    }
+    // Linux Support
+#elif defined(__linux__) && defined (TIOCSSERIAL)
+    struct serial_struct ser;
+
+    if (-1 == ioctl (fd_, TIOCGSERIAL, &ser)) {
+      THROW (IOException, errno);
+    }
+
+    // set custom divisor
+    ser.custom_divisor = ser.baud_base / static_cast<int> (baudrate_);
+    // update flags
+    ser.flags &= ~ASYNC_SPD_MASK;
+    ser.flags |= ASYNC_SPD_CUST;
+
+    if (-1 == ioctl (fd_, TIOCSSERIAL, &ser)) {
+      THROW (IOException, errno);
+    }
+#else
+    throw invalid_argument ("OS does not currently support custom bauds");
+#endif
+  }
+
   // Update byte_time_ based on the new settings.
   uint32_t bit_time_ns = 1e9 / baudrate_;
   byte_time_ns_ = bit_time_ns * (1 + bytesize_ + parity_ + stopbits_);