Revert changes except for macOS where we still delay

contrib/win32/libnfc/buses/uart.c

@@ -240,30 +240,6 @@ uart_send(serial_port sp, const uint8_t *pbtTx, const size_t szTx, int timeout)
   return NFC_SUCCESS;
 }
 
-/**
- * @brief Send \a pbtTx content to UART one byte at a time
- *
- * @return 0 on success, otherwise a driver error is returned
- */
-int
-uart_send_single(serial_port sp, const uint8_t *pbtTx, const size_t szTx, int timeout)
-{
-  (void) timeout;
-  int ret;
-  for (int i = 0; i < szTx; i++)
-  {
-    ret = uart_send(sp, pbtTx+i, 1, timeout);
-
-    // if we didn't transmit byte, bail out
-    if (ret != NFC_SUCCESS)
-      return ret;
-
-    delay_ms(1); // ceil(1_000_000us / 115200baud) = 9us but no usleep on windows
-  }
-
-  return NFC_SUCCESS;
-}
-
 BOOL is_port_available(int nPort)
 {
   TCHAR szPort[15];

libnfc/buses/uart.c

@@ -394,14 +394,22 @@ uart_send(serial_port sp, const uint8_t *pbtTx, const size_t szTx, int timeout)
 {
   (void) timeout;
   LOG_HEX(LOG_GROUP, "TX", pbtTx, szTx);
+
+#ifndef __APPLE__
   if ((int) szTx == write(UART_DATA(sp)->fd, pbtTx, szTx))
     return NFC_SUCCESS;
   else
     return NFC_EIO;
+#else
+  // macOS's termios write() to a uart is async so we need to determine how to make it sync
+  // see https://github.com/nfc-tools/libnfc/pull/633
+  // there is probably a proper way to do this, if so, please share!
+  return uart_send_single(sp, pbtTx, szTx, timeout);
+#endif
 }
 
 /**
- * @brief Send \a pbtTx content to UART one byte at a time
+ * @brief Send \a pbtTx content to UART one byte at a time with a delay (to support macOS' async write)
  *
  * @return 0 on success, otherwise a driver error is returned
  */
@@ -409,14 +417,11 @@ int
 uart_send_single(serial_port sp, const uint8_t *pbtTx, const size_t szTx, int timeout)
 {
   (void) timeout;
-  int ret;
+
   for (int i = 0; i < szTx; i++)
   {
-    ret = uart_send(sp, pbtTx+i, 1, timeout);
+    if (write(UART_DATA(sp)->fd, pbtTx+i, 1) != 1)
-
+      return NFC_EIO;
-    // if we didn't transmit byte, bail out
-    if (ret != NFC_SUCCESS)
-      return ret;
 
     usleep(9); // sleep for ceil(1_000_000us / 115200baud) = 9us
   }

libnfc/drivers/pn532_uart.c

@@ -304,7 +304,7 @@ pn532_uart_wakeup(nfc_device *pnd)
 {
   /* High Speed Unit (HSU) wake up consist to send 0x55 and wait a "long" delay for PN532 being wakeup. */
   const uint8_t pn532_wakeup_preamble[] = { 0x55, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
-  int res = uart_send_single(DRIVER_DATA(pnd)->port, pn532_wakeup_preamble, sizeof(pn532_wakeup_preamble), 0);
+  int res = uart_send(DRIVER_DATA(pnd)->port, pn532_wakeup_preamble, sizeof(pn532_wakeup_preamble), 0);
   CHIP_DATA(pnd)->power_mode = NORMAL; // PN532 should now be awake
   return res;
 }
@@ -348,7 +348,7 @@ pn532_uart_send(nfc_device *pnd, const uint8_t *pbtData, const size_t szData, in
     return pnd->last_error;
   }
 
-  res = uart_send_single(DRIVER_DATA(pnd)->port, abtFrame, szFrame, timeout);
+  res = uart_send(DRIVER_DATA(pnd)->port, abtFrame, szFrame, timeout);
   if (res != 0) {
     log_put(LOG_GROUP, LOG_CATEGORY, NFC_LOG_PRIORITY_ERROR, "%s", "Unable to transmit data. (TX)");
     pnd->last_error = res;
@@ -507,7 +507,7 @@ pn532_uart_ack(nfc_device *pnd)
       return res;
     }
   }
-  return (uart_send_single(DRIVER_DATA(pnd)->port, pn53x_ack_frame, sizeof(pn53x_ack_frame),  0));
+  return (uart_send(DRIVER_DATA(pnd)->port, pn53x_ack_frame, sizeof(pn53x_ack_frame),  0));
 }
 
 static int